path: root/third_party/rust/mp4parse/src/lib.rs

//! Module for parsing ISO Base Media Format aka video/mp4 streams.

// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at https://mozilla.org/MPL/2.0/.

// `clippy::upper_case_acronyms` is a nightly-only lint as of 2021-03-15, so we
// allow `clippy::unknown_clippy_lints` to ignore it on stable - but
// `clippy::unknown_clippy_lints` has been renamed in nightly, so we need to
// allow `renamed_and_removed_lints` to ignore a warning for that.
#![allow(renamed_and_removed_lints)]
#![allow(clippy::unknown_clippy_lints)]
#![allow(clippy::upper_case_acronyms)]

#[macro_use]
extern crate log;

extern crate bitreader;
extern crate byteorder;
extern crate fallible_collections;
extern crate num_traits;
use bitreader::{BitReader, ReadInto};
use byteorder::{ReadBytesExt, WriteBytesExt};

use fallible_collections::TryRead;
use fallible_collections::TryReserveError;

use num_traits::Num;
use std::convert::{TryFrom, TryInto as _};
use std::fmt;
use std::io::Cursor;
use std::io::{Read, Take};

#[macro_use]
mod macros;

mod boxes;
use boxes::{BoxType, FourCC};

// Unit tests.
#[cfg(test)]
mod tests;

#[cfg(feature = "unstable-api")]
pub mod unstable;

/// The HEIF image and image collection brand
/// The 'mif1' brand indicates structural requirements on files
/// See HEIF (ISO 23008-12:2017) § 10.2.1
pub const MIF1_BRAND: FourCC = FourCC { value: *b"mif1" };

/// The HEIF image sequence brand
/// The 'msf1' brand indicates structural requirements on files
/// See HEIF (ISO 23008-12:2017) § 10.3.1
pub const MSF1_BRAND: FourCC = FourCC { value: *b"msf1" };

/// The brand to identify AV1 image items
/// The 'avif' brand indicates structural requirements on files
/// See <https://aomediacodec.github.io/av1-avif/#image-and-image-collection-brand>
pub const AVIF_BRAND: FourCC = FourCC { value: *b"avif" };

/// The brand to identify AVIF image sequences
/// The 'avis' brand indicates structural requirements on files
/// See <https://aomediacodec.github.io/av1-avif/#image-and-image-collection-brand>
pub const AVIS_BRAND: FourCC = FourCC { value: *b"avis" };

/// A trait to indicate a type can be infallibly converted to `u64`.
/// This should only be implemented for infallible conversions, so only unsigned types are valid.
trait ToU64 {
    fn to_u64(self) -> u64;
}

/// Statically verify that the platform `usize` can fit within a `u64`.
/// If the size won't fit on the given platform, this will fail at compile time, but if a type
/// which can fail TryInto<usize> is used, it may panic.
impl ToU64 for usize {
    fn to_u64(self) -> u64 {
        static_assertions::const_assert!(
            std::mem::size_of::<usize>() <= std::mem::size_of::<u64>()
        );
        self.try_into().expect("usize -> u64 conversion failed")
    }
}

/// A trait to indicate a type can be infallibly converted to `usize`.
/// This should only be implemented for infallible conversions, so only unsigned types are valid.
pub trait ToUsize {
    fn to_usize(self) -> usize;
}

/// Statically verify that the given type can fit within a `usize`.
/// If the size won't fit on the given platform, this will fail at compile time, but if a type
/// which can fail TryInto<usize> is used, it may panic.
macro_rules! impl_to_usize_from {
    ( $from_type:ty ) => {
        impl ToUsize for $from_type {
            fn to_usize(self) -> usize {
                static_assertions::const_assert!(
                    std::mem::size_of::<$from_type>() <= std::mem::size_of::<usize>()
                );
                self.try_into().expect(concat!(
                    stringify!($from_type),
                    " -> usize conversion failed"
                ))
            }
        }
    };
}

impl_to_usize_from!(u8);
impl_to_usize_from!(u16);
impl_to_usize_from!(u32);

/// Indicate the current offset (i.e., bytes already read) in a reader
trait Offset {
    fn offset(&self) -> u64;
}

/// Wraps a reader to track the current offset
struct OffsetReader<'a, T: 'a> {
    reader: &'a mut T,
    offset: u64,
}

impl<'a, T> OffsetReader<'a, T> {
    fn new(reader: &'a mut T) -> Self {
        Self { reader, offset: 0 }
    }
}

impl<'a, T> Offset for OffsetReader<'a, T> {
    fn offset(&self) -> u64 {
        self.offset
    }
}

impl<'a, T: Read> Read for OffsetReader<'a, T> {
    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
        let bytes_read = self.reader.read(buf)?;
        self.offset = self
            .offset
            .checked_add(bytes_read.to_u64())
            .expect("total bytes read too large for offset type");
        Ok(bytes_read)
    }
}

pub type TryVec<T> = fallible_collections::TryVec<T>;
pub type TryString = fallible_collections::TryVec<u8>;
pub type TryHashMap<K, V> = fallible_collections::TryHashMap<K, V>;
pub type TryBox<T> = fallible_collections::TryBox<T>;

// To ensure we don't use stdlib allocating types by accident
#[allow(dead_code)]
struct Vec;
#[allow(dead_code)]
struct Box;
#[allow(dead_code)]
struct HashMap;
#[allow(dead_code)]
struct String;

/// The return value to the C API
/// Any detail that needs to be communicated to the caller must be encoded here
/// since the [`Error`] type's associated data is part of the FFI.
#[repr(C)]
#[derive(Clone, Copy, PartialEq, Debug)]
pub enum Status {
    Ok = 0,
    BadArg = 1,
    Invalid = 2,
    Unsupported = 3,
    Eof = 4,
    Io = 5,
    Oom = 6,
    MissingBrand,
    FtypNotFirst,
    NoImage,
    MultipleMoov,
    NoMoov,
    LselNoEssential,
    A1opNoEssential,
    A1lxEssential,
    TxformNoEssential,
    NoPrimaryItem,
    ImageItemType,
    ItemTypeMissing,
    ConstructionMethod,
    ItemLocNotFound,
    NoItemDataBox,
}

#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum Feature {
    A1lx,
    A1op,
    Auxc,
    Av1c,
    Avis,
    Clap,
    Colr,
    Grid,
    Imir,
    Ipro,
    Irot,
    Ispe,
    Lsel,
    Pasp,
    Pixi,
}

impl Feature {
    fn supported(self) -> bool {
        match self {
            Self::Auxc
            | Self::Av1c
            | Self::Colr
            | Self::Imir
            | Self::Irot
            | Self::Ispe
            | Self::Pasp
            | Self::Pixi => true,
            Self::A1lx
            | Self::A1op
            | Self::Clap
            | Self::Grid
            | Self::Ipro
            | Self::Lsel
            | Self::Avis => false,
        }
    }
}

impl TryFrom<&ItemProperty> for Feature {
    type Error = Error;

    fn try_from(item_property: &ItemProperty) -> Result<Self, Self::Error> {
        Ok(match item_property {
            ItemProperty::AuxiliaryType(_) => Self::Auxc,
            ItemProperty::AV1Config(_) => Self::Av1c,
            ItemProperty::Channels(_) => Self::Pixi,
            ItemProperty::CleanAperture => Self::Clap,
            ItemProperty::Colour(_) => Self::Colr,
            ItemProperty::ImageSpatialExtents(_) => Self::Ispe,
            ItemProperty::LayeredImageIndexing => Self::A1lx,
            ItemProperty::LayerSelection => Self::Lsel,
            ItemProperty::Mirroring(_) => Self::Imir,
            ItemProperty::OperatingPointSelector => Self::A1op,
            ItemProperty::PixelAspectRatio(_) => Self::Pasp,
            ItemProperty::Rotation(_) => Self::Irot,
            item_property => {
                error!("No known Feature variant for {:?}", item_property);
                return Err(Error::Unsupported("missing Feature fox ItemProperty"));
            }
        })
    }
}

/// A collection to indicate unsupported features that were encountered during
/// parsing. Since the default behavior for many such features is to ignore
/// them, this often not fatal and there may be several to report.
#[derive(Debug, Default)]
pub struct UnsupportedFeatures(u32);

impl UnsupportedFeatures {
    pub fn new() -> Self {
        Self(0x0)
    }

    pub fn into_bitfield(&self) -> u32 {
        self.0
    }

    fn feature_to_bitfield(feature: Feature) -> u32 {
        let index = feature as usize;
        assert!(
            u8::BITS.to_usize() * std::mem::size_of::<Self>() > index,
            "You're gonna need a bigger bitfield"
        );
        let bitfield = 1u32 << index;
        assert_eq!(bitfield.count_ones(), 1);
        bitfield
    }

    pub fn insert(&mut self, feature: Feature) {
        warn!("Unsupported feature: {:?}", feature);
        self.0 |= Self::feature_to_bitfield(feature);
    }

    pub fn contains(&self, feature: Feature) -> bool {
        self.0 & Self::feature_to_bitfield(feature) != 0x0
    }

    pub fn is_empty(&self) -> bool {
        self.0 == 0x0
    }
}

impl<T> From<Status> for Result<T> {
    /// A convenience method to enable shortcuts like
    /// ```
    /// # extern crate mp4parse;
    /// # use mp4parse::{Result,Status};
    /// # let _: Result<()> =
    /// Status::MissingBrand.into();
    /// ```
    /// instead of
    /// ```
    /// # extern crate mp4parse;
    /// # use mp4parse::{Error,Result,Status};
    /// # let _: Result<()> =
    /// Err(Error::from(Status::MissingBrand));
    /// ```
    /// Note that `Status::Ok` can't be supported this way and will panic.
    fn from(parse_status: Status) -> Self {
        match parse_status {
            Status::Ok => panic!("Can't determine Ok(_) inner value from Status"),
            err_status => Err(err_status.into()),
        }
    }
}

/// For convenience of creating an error for an unsupported feature which we
/// want to communicate the specific feature back to the C API caller
impl From<Status> for Error {
    fn from(parse_status: Status) -> Self {
        match parse_status {
            Status::Ok
            | Status::BadArg
            | Status::Invalid
            | Status::Unsupported
            | Status::Eof
            | Status::Io
            | Status::Oom => {
                panic!("Status -> Error is only for Status:InvalidDataDetail errors")
            }
            Status::MissingBrand
            | Status::FtypNotFirst
            | Status::NoImage
            | Status::MultipleMoov
            | Status::NoMoov
            | Status::LselNoEssential
            | Status::A1opNoEssential
            | Status::A1lxEssential
            | Status::TxformNoEssential
            | Status::NoPrimaryItem
            | Status::ImageItemType
            | Status::ItemTypeMissing
            | Status::ConstructionMethod
            | Status::ItemLocNotFound
            | Status::NoItemDataBox => Self::InvalidDataDetail(parse_status),
        }
    }
}

impl From<Status> for &str {
    fn from(status: Status) -> Self {
        match status {
            Status::Ok
            | Status::BadArg
            | Status::Invalid
            | Status::Unsupported
            | Status::Eof
            | Status::Io
            | Status::Oom => {
                panic!("Status -> Error is only for specific parsing errors")
            }
            Status::MissingBrand => {
                "The file shall list 'avif' or 'avis' in the compatible_brands field
                 of the FileTypeBox \
                 per https://aomediacodec.github.io/av1-avif/#file-constraints"
            }
            Status::FtypNotFirst => {
                "The FileTypeBox shall be placed as early as possible in the file \
                 per ISOBMFF (ISO 14496-12:2020) § 4.3.1"
            }
            Status::NoImage => "No primary image or image sequence found",
            Status::NoMoov => {
                "No moov box found; \
                 files with avis or msf1 brands shall contain exactly one moov box \
                 per ISOBMFF (ISO 14496-12:2020) § 8.2.1.1"
            }
            Status::MultipleMoov => {
                "Multiple moov boxes found; \
                 files with avis or msf1 brands shall contain exactly one moov box \
                 per ISOBMFF (ISO 14496-12:2020) § 8.2.1.1"
            }
            Status::LselNoEssential => {
                "LayerSelectorProperty (lsel) shall be marked as essential \
                 per HEIF (ISO/IEC 23008-12:2017) § 6.5.11.1"
            }
            Status::A1opNoEssential => {
                "OperatingPointSelectorProperty (a1op) shall be marked as essential \
                 per https://aomediacodec.github.io/av1-avif/#operating-point-selector-property-description"
            }
            Status::A1lxEssential => {
                "AV1LayeredImageIndexingProperty (a1lx) shall not be marked as essential \
                 per https://aomediacodec.github.io/av1-avif/#layered-image-indexing-property-description"
            }
            Status::TxformNoEssential => {
                "All transformative properties associated with coded and \
                 derived images required or conditionally required by this \
                 document shall be marked as essential \
                 per MIAF (ISO 23000-22:2019) § 7.3.9"
            }
            Status::NoPrimaryItem => {
                "Missing required PrimaryItemBox (pitm), required \
                 per HEIF (ISO/IEC 23008-12:2017) § 10.2.1"
            }
            Status::ImageItemType => {
                "Image item type is neither 'av01' nor 'grid'"
            }
            Status::ItemTypeMissing => {
                "No ItemInfoEntry for item_ID"
            }
            Status::ConstructionMethod => {
                "construction_method shall be 0 (file) or 1 (idat) per MIAF (ISO 23000-22:2019) § 7.2.1.7"
            }
            Status::ItemLocNotFound => {
                "ItemLocationBox (iloc) contains an extent not present in any mdat or idat box"
            }
            Status::NoItemDataBox => {
                "ItemLocationBox (iloc) construction_method indicates 1 (idat), \
                 but no idat box is present."
            }
        }
    }
}

impl From<Error> for Status {
    fn from(error: Error) -> Self {
        match error {
            Error::InvalidData(_) => Self::Invalid,
            Error::Unsupported(_) => Self::Unsupported,
            Error::InvalidDataDetail(parse_status) => parse_status,
            Error::UnexpectedEOF => Self::Eof,
            Error::Io(_) => {
                // Getting std::io::ErrorKind::UnexpectedEof is normal
                // but our From trait implementation should have converted
                // those to our Error::UnexpectedEOF variant.
                Self::Io
            }
            Error::NoMoov => Self::NoMoov,
            Error::OutOfMemory => Self::Oom,
        }
    }
}

impl From<Result<(), Status>> for Status {
    fn from(result: Result<(), Status>) -> Self {
        match result {
            Ok(()) => Status::Ok,
            Err(Status::Ok) => unreachable!(),
            Err(e) => e,
        }
    }
}

impl<T> From<Result<T>> for Status {
    fn from(result: Result<T>) -> Self {
        match result {
            Ok(_) => Status::Ok,
            Err(e) => Status::from(e),
        }
    }
}

impl From<fallible_collections::TryReserveError> for Status {
    fn from(_: fallible_collections::TryReserveError) -> Self {
        Status::Oom
    }
}

impl From<std::io::Error> for Status {
    fn from(_: std::io::Error) -> Self {
        Status::Io
    }
}

/// Describes parser failures.
///
/// This enum wraps the standard `io::Error` type, unified with
/// our own parser error states and those of crates we use.
#[derive(Debug)]
pub enum Error {
    /// Parse error caused by corrupt or malformed data.
    InvalidData(&'static str),
    /// Similar to [`Self::InvalidData`], but for errors that have a specific
    /// [`Status`] variant for communicating the detail across FFI.
    /// See the helper [`From<Status> for Error`](enum.Error.html#impl-From<Status>)
    InvalidDataDetail(Status),
    /// Parse error caused by limited parser support rather than invalid data.
    Unsupported(&'static str),
    /// Reflect `std::io::ErrorKind::UnexpectedEof` for short data.
    UnexpectedEOF,
    /// Propagate underlying errors from `std::io`.
    Io(std::io::Error),
    /// read_mp4 terminated without detecting a moov box.
    NoMoov,
    /// Out of memory
    OutOfMemory,
}

impl std::fmt::Display for Error {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{:?}", self)
    }
}

impl std::error::Error for Error {}

impl From<bitreader::BitReaderError> for Error {
    fn from(_: bitreader::BitReaderError) -> Error {
        Error::InvalidData("invalid data")
    }
}

impl From<std::io::Error> for Error {
    fn from(err: std::io::Error) -> Error {
        match err.kind() {
            std::io::ErrorKind::UnexpectedEof => Error::UnexpectedEOF,
            _ => Error::Io(err),
        }
    }
}

impl From<std::string::FromUtf8Error> for Error {
    fn from(_: std::string::FromUtf8Error) -> Error {
        Error::InvalidData("invalid utf8")
    }
}

impl From<std::str::Utf8Error> for Error {
    fn from(_: std::str::Utf8Error) -> Error {
        Error::InvalidData("invalid utf8")
    }
}

impl From<std::num::TryFromIntError> for Error {
    fn from(_: std::num::TryFromIntError) -> Error {
        Error::Unsupported("integer conversion failed")
    }
}

impl From<Error> for std::io::Error {
    fn from(err: Error) -> Self {
        let kind = match err {
            Error::InvalidData(_) => std::io::ErrorKind::InvalidData,
            Error::UnexpectedEOF => std::io::ErrorKind::UnexpectedEof,
            Error::Io(io_err) => return io_err,
            _ => std::io::ErrorKind::Other,
        };
        Self::new(kind, err)
    }
}

impl From<TryReserveError> for Error {
    fn from(_: TryReserveError) -> Error {
        Error::OutOfMemory
    }
}

/// Result shorthand using our Error enum.
pub type Result<T, E = Error> = std::result::Result<T, E>;

/// Basic ISO box structure.
///
/// mp4 files are a sequence of possibly-nested 'box' structures.  Each box
/// begins with a header describing the length of the box's data and a
/// four-byte box type which identifies the type of the box. Together these
/// are enough to interpret the contents of that section of the file.
///
/// See ISOBMFF (ISO 14496-12:2020) § 4.2
#[derive(Debug, Clone, Copy)]
struct BoxHeader {
    /// Box type.
    name: BoxType,
    /// Size of the box in bytes.
    size: u64,
    /// Offset to the start of the contained data (or header size).
    offset: u64,
    /// Uuid for extended type.
    #[allow(dead_code)] // See https://github.com/mozilla/mp4parse-rust/issues/340
    uuid: Option<[u8; 16]>,
}

impl BoxHeader {
    const MIN_SIZE: u64 = 8; // 4-byte size + 4-byte type
    const MIN_LARGE_SIZE: u64 = 16; // 4-byte size + 4-byte type + 16-byte size
}

/// File type box 'ftyp'.
#[derive(Debug)]
struct FileTypeBox {
    #[allow(dead_code)] // See https://github.com/mozilla/mp4parse-rust/issues/340
    major_brand: FourCC,
    #[allow(dead_code)] // See https://github.com/mozilla/mp4parse-rust/issues/340
    minor_version: u32,
    compatible_brands: TryVec<FourCC>,
}

impl FileTypeBox {
    fn contains(&self, brand: &FourCC) -> bool {
        self.compatible_brands.contains(brand) || self.major_brand == *brand
    }
}

/// Movie header box 'mvhd'.
#[derive(Debug)]
struct MovieHeaderBox {
    pub timescale: u32,
    #[allow(dead_code)] // See https://github.com/mozilla/mp4parse-rust/issues/340
    duration: u64,
}

#[derive(Debug, Clone, Copy)]
pub struct Matrix {
    pub a: i32, // 16.16 fix point
    pub b: i32, // 16.16 fix point
    pub u: i32, // 2.30 fix point
    pub c: i32, // 16.16 fix point
    pub d: i32, // 16.16 fix point
    pub v: i32, // 2.30 fix point
    pub x: i32, // 16.16 fix point
    pub y: i32, // 16.16 fix point
    pub w: i32, // 2.30 fix point
}

/// Track header box 'tkhd'
#[derive(Debug, Clone)]
pub struct TrackHeaderBox {
    track_id: u32,
    pub disabled: bool,
    pub duration: u64,
    pub width: u32,
    pub height: u32,
    pub matrix: Matrix,
}

/// Edit list box 'elst'
#[derive(Debug)]
struct EditListBox {
    edits: TryVec<Edit>,
}

#[derive(Debug)]
struct Edit {
    segment_duration: u64,
    media_time: i64,
    #[allow(dead_code)] // See https://github.com/mozilla/mp4parse-rust/issues/340
    media_rate_integer: i16,
    #[allow(dead_code)] // See https://github.com/mozilla/mp4parse-rust/issues/340
    media_rate_fraction: i16,
}

/// Media header box 'mdhd'
#[derive(Debug)]
struct MediaHeaderBox {
    timescale: u32,
    duration: u64,
}

// Chunk offset box 'stco' or 'co64'
#[derive(Debug)]
pub struct ChunkOffsetBox {
    pub offsets: TryVec<u64>,
}

// Sync sample box 'stss'
#[derive(Debug)]
pub struct SyncSampleBox {
    pub samples: TryVec<u32>,
}

// Sample to chunk box 'stsc'
#[derive(Debug)]
pub struct SampleToChunkBox {
    pub samples: TryVec<SampleToChunk>,
}

#[derive(Debug)]
pub struct SampleToChunk {
    pub first_chunk: u32,
    pub samples_per_chunk: u32,
    pub sample_description_index: u32,
}

// Sample size box 'stsz'
#[derive(Debug)]
pub struct SampleSizeBox {
    pub sample_size: u32,
    pub sample_sizes: TryVec<u32>,
}

// Time to sample box 'stts'
#[derive(Debug)]
pub struct TimeToSampleBox {
    pub samples: TryVec<Sample>,
}

#[repr(C)]
#[derive(Debug)]
pub struct Sample {
    pub sample_count: u32,
    pub sample_delta: u32,
}

#[derive(Debug, Clone, Copy)]
pub enum TimeOffsetVersion {
    Version0(u32),
    Version1(i32),
}

#[derive(Debug, Clone)]
pub struct TimeOffset {
    pub sample_count: u32,
    pub time_offset: TimeOffsetVersion,
}

#[derive(Debug)]
pub struct CompositionOffsetBox {
    pub samples: TryVec<TimeOffset>,
}

// Handler reference box 'hdlr'
#[derive(Debug)]
struct HandlerBox {
    handler_type: FourCC,
}

// Sample description box 'stsd'
#[derive(Debug)]
pub struct SampleDescriptionBox {
    pub descriptions: TryVec<SampleEntry>,
}

#[derive(Debug)]
pub enum SampleEntry {
    Audio(AudioSampleEntry),
    Video(VideoSampleEntry),
    Unknown,
}

/// An Elementary Stream Descriptor
/// See MPEG-4 Systems (ISO 14496-1:2010) § 7.2.6.5
#[allow(non_camel_case_types)]
#[derive(Debug, Default)]
pub struct ES_Descriptor {
    pub audio_codec: CodecType,
    pub audio_object_type: Option<u16>,
    pub extended_audio_object_type: Option<u16>,
    pub audio_sample_rate: Option<u32>,
    pub audio_channel_count: Option<u16>,
    #[cfg(feature = "mp4v")]
    pub video_codec: CodecType,
    pub codec_esds: TryVec<u8>,
    pub decoder_specific_data: TryVec<u8>, // Data in DECODER_SPECIFIC_TAG
}

#[allow(non_camel_case_types)]
#[derive(Debug)]
pub enum AudioCodecSpecific {
    ES_Descriptor(ES_Descriptor),
    FLACSpecificBox(FLACSpecificBox),
    OpusSpecificBox(OpusSpecificBox),
    ALACSpecificBox(ALACSpecificBox),
    MP3,
    LPCM,
    #[cfg(feature = "3gpp")]
    AMRSpecificBox(TryVec<u8>),
}

#[derive(Debug)]
pub struct AudioSampleEntry {
    pub codec_type: CodecType,
    #[allow(dead_code)] // See https://github.com/mozilla/mp4parse-rust/issues/340
    data_reference_index: u16,
    pub channelcount: u32,
    pub samplesize: u16,
    pub samplerate: f64,
    pub codec_specific: AudioCodecSpecific,
    pub protection_info: TryVec<ProtectionSchemeInfoBox>,
}

#[derive(Debug)]
pub enum VideoCodecSpecific {
    AVCConfig(TryVec<u8>),
    VPxConfig(VPxConfigBox),
    AV1Config(AV1ConfigBox),
    ESDSConfig(TryVec<u8>),
    H263Config(TryVec<u8>),
}

#[derive(Debug)]
pub struct VideoSampleEntry {
    pub codec_type: CodecType,
    #[allow(dead_code)] // See https://github.com/mozilla/mp4parse-rust/issues/340
    data_reference_index: u16,
    pub width: u16,
    pub height: u16,
    pub codec_specific: VideoCodecSpecific,
    pub protection_info: TryVec<ProtectionSchemeInfoBox>,
}

/// Represent a Video Partition Codec Configuration 'vpcC' box (aka vp9). The meaning of each
/// field is covered in detail in "VP Codec ISO Media File Format Binding".
#[derive(Debug)]
pub struct VPxConfigBox {
    /// An integer that specifies the VP codec profile.
    #[allow(dead_code)] // See https://github.com/mozilla/mp4parse-rust/issues/340
    profile: u8,
    /// An integer that specifies a VP codec level all samples conform to the following table.
    /// For a description of the various levels, please refer to the VP9 Bitstream Specification.
    #[allow(dead_code)] // See https://github.com/mozilla/mp4parse-rust/issues/340
    level: u8,
    /// An integer that specifies the bit depth of the luma and color components. Valid values
    /// are 8, 10, and 12.
    pub bit_depth: u8,
    /// Really an enum defined by the "Colour primaries" section of ISO 23091-2:2019 § 8.1.
    pub colour_primaries: u8,
    /// Really an enum defined by "VP Codec ISO Media File Format Binding".
    pub chroma_subsampling: u8,
    /// Really an enum defined by the "Transfer characteristics" section of ISO 23091-2:2019 § 8.2.
    #[allow(dead_code)] // See https://github.com/mozilla/mp4parse-rust/issues/340
    transfer_characteristics: u8,
    /// Really an enum defined by the "Matrix coefficients" section of ISO 23091-2:2019 § 8.3.
    /// Available in 'VP Codec ISO Media File Format' version 1 only.
    #[allow(dead_code)] // See https://github.com/mozilla/mp4parse-rust/issues/340
    matrix_coefficients: Option<u8>,
    /// Indicates the black level and range of the luma and chroma signals. 0 = legal range
    /// (e.g. 16-235 for 8 bit sample depth); 1 = full range (e.g. 0-255 for 8-bit sample depth).
    #[allow(dead_code)] // See https://github.com/mozilla/mp4parse-rust/issues/340
    video_full_range_flag: bool,
    /// This is not used for VP8 and VP9 . Intended for binary codec initialization data.
    pub codec_init: TryVec<u8>,
}

/// See [AV1-ISOBMFF § 2.3.3](https://aomediacodec.github.io/av1-isobmff/#av1codecconfigurationbox-syntax)
#[derive(Debug)]
pub struct AV1ConfigBox {
    pub profile: u8,
    pub level: u8,
    pub tier: u8,
    pub bit_depth: u8,
    pub monochrome: bool,
    pub chroma_subsampling_x: u8,
    pub chroma_subsampling_y: u8,
    pub chroma_sample_position: u8,
    pub initial_presentation_delay_present: bool,
    pub initial_presentation_delay_minus_one: u8,
    // The raw config contained in the av1c box. Because some decoders accept this data as a binary
    // blob, rather than as structured data, we store the blob here for convenience.
    pub raw_config: TryVec<u8>,
}

impl AV1ConfigBox {
    const CONFIG_OBUS_OFFSET: usize = 4;

    pub fn config_obus(&self) -> &[u8] {
        &self.raw_config[Self::CONFIG_OBUS_OFFSET..]
    }
}

#[derive(Debug)]
pub struct FLACMetadataBlock {
    pub block_type: u8,
    pub data: TryVec<u8>,
}

/// Represents a FLACSpecificBox 'dfLa'
#[derive(Debug)]
pub struct FLACSpecificBox {
    #[allow(dead_code)] // See https://github.com/mozilla/mp4parse-rust/issues/340
    version: u8,
    pub blocks: TryVec<FLACMetadataBlock>,
}

#[derive(Debug)]
struct ChannelMappingTable {
    stream_count: u8,
    coupled_count: u8,
    channel_mapping: TryVec<u8>,
}

/// Represent an OpusSpecificBox 'dOps'
#[derive(Debug)]
pub struct OpusSpecificBox {
    pub version: u8,
    output_channel_count: u8,
    pre_skip: u16,
    input_sample_rate: u32,
    output_gain: i16,
    channel_mapping_family: u8,
    channel_mapping_table: Option<ChannelMappingTable>,
}

/// Represent an ALACSpecificBox 'alac'
#[derive(Debug)]
pub struct ALACSpecificBox {
    #[allow(dead_code)] // See https://github.com/mozilla/mp4parse-rust/issues/340
    version: u8,
    pub data: TryVec<u8>,
}

#[derive(Debug)]
pub struct MovieExtendsBox {
    pub fragment_duration: Option<MediaScaledTime>,
}

pub type ByteData = TryVec<u8>;

#[derive(Debug, Default)]
pub struct ProtectionSystemSpecificHeaderBox {
    pub system_id: ByteData,
    pub kid: TryVec<ByteData>,
    pub data: ByteData,

    // The entire pssh box (include header) required by Gecko.
    pub box_content: ByteData,
}

#[derive(Debug, Default, Clone)]
pub struct SchemeTypeBox {
    pub scheme_type: FourCC,
    pub scheme_version: u32,
}

#[derive(Debug, Default)]
pub struct TrackEncryptionBox {
    pub is_encrypted: u8,
    pub iv_size: u8,
    pub kid: TryVec<u8>,
    // Members for pattern encryption schemes
    pub crypt_byte_block_count: Option<u8>,
    pub skip_byte_block_count: Option<u8>,
    pub constant_iv: Option<TryVec<u8>>,
    // End pattern encryption scheme members
}

#[derive(Debug, Default)]
pub struct ProtectionSchemeInfoBox {
    pub original_format: FourCC,
    pub scheme_type: Option<SchemeTypeBox>,
    pub tenc: Option<TrackEncryptionBox>,
}

/// Represents a userdata box 'udta'.
/// Currently, only the metadata atom 'meta'
/// is parsed.
#[derive(Debug, Default)]
pub struct UserdataBox {
    pub meta: Option<MetadataBox>,
}

/// Represents possible contents of the
/// ©gen or gnre atoms within a metadata box.
/// 'udta.meta.ilst' may only have either a
/// standard genre box 'gnre' or a custom
/// genre box '©gen', but never both at once.
#[derive(Debug, PartialEq)]
pub enum Genre {
    /// A standard ID3v1 numbered genre.
    StandardGenre(u8),
    /// Any custom genre string.
    CustomGenre(TryString),
}

/// Represents the contents of a 'stik'
/// atom that indicates content types within
/// iTunes.
#[derive(Debug, Clone, Eq, PartialEq)]
pub enum MediaType {
    /// Movie is stored as 0 in a 'stik' atom.
    Movie, // 0
    /// Normal is stored as 1 in a 'stik' atom.
    Normal, // 1
    /// AudioBook is stored as 2 in a 'stik' atom.
    AudioBook, // 2
    /// WhackedBookmark is stored as 5 in a 'stik' atom.
    WhackedBookmark, // 5
    /// MusicVideo is stored as 6 in a 'stik' atom.
    MusicVideo, // 6
    /// ShortFilm is stored as 9 in a 'stik' atom.
    ShortFilm, // 9
    /// TVShow is stored as 10 in a 'stik' atom.
    TVShow, // 10
    /// Booklet is stored as 11 in a 'stik' atom.
    Booklet, // 11
    /// An unknown 'stik' value.
    Unknown(u8),
}

/// Represents the parental advisory rating on the track,
/// stored within the 'rtng' atom.
#[derive(Debug, Clone, Eq, PartialEq)]
pub enum AdvisoryRating {
    /// Clean is always stored as 2 in an 'rtng' atom.
    Clean, // 2
    /// A value of 0 in an 'rtng' atom indicates 'Inoffensive'
    Inoffensive, // 0
    /// Any non 2 or 0 value in 'rtng' indicates the track is explicit.
    Explicit(u8),
}

/// Represents the contents of 'ilst' atoms within
/// a metadata box 'meta', parsed as iTunes metadata using
/// the conventional tags.
#[derive(Debug, Default)]
pub struct MetadataBox {
    /// The album name, '©alb'
    pub album: Option<TryString>,
    /// The artist name '©art' or '©ART'
    pub artist: Option<TryString>,
    /// The album artist 'aART'
    pub album_artist: Option<TryString>,
    /// Track comments '©cmt'
    pub comment: Option<TryString>,
    /// The date or year field '©day'
    ///
    /// This is stored as an arbitrary string,
    /// and may not necessarily be in a valid date
    /// format.
    pub year: Option<TryString>,
    /// The track title '©nam'
    pub title: Option<TryString>,
    /// The track genre '©gen' or 'gnre'.
    pub genre: Option<Genre>,
    /// The track number 'trkn'.
    pub track_number: Option<u8>,
    /// The disc number 'disk'
    pub disc_number: Option<u8>,
    /// The total number of tracks on the disc,
    /// stored in 'trkn'
    pub total_tracks: Option<u8>,
    /// The total number of discs in the album,
    /// stored in 'disk'
    pub total_discs: Option<u8>,
    /// The composer of the track '©wrt'
    pub composer: Option<TryString>,
    /// The encoder used to create this track '©too'
    pub encoder: Option<TryString>,
    /// The encoded-by settingo this track '©enc'
    pub encoded_by: Option<TryString>,
    /// The tempo or BPM of the track 'tmpo'
    pub beats_per_minute: Option<u8>,
    /// Copyright information of the track 'cprt'
    pub copyright: Option<TryString>,
    /// Whether or not this track is part of a compilation 'cpil'
    pub compilation: Option<bool>,
    /// The advisory rating of this track 'rtng'
    pub advisory: Option<AdvisoryRating>,
    /// The personal rating of this track, 'rate'.
    ///
    /// This is stored in the box as string data, but
    /// the format is an integer percentage from 0 - 100,
    /// where 100 is displayed as 5 stars out of 5.
    pub rating: Option<TryString>,
    /// The grouping this track belongs to '©grp'
    pub grouping: Option<TryString>,
    /// The media type of this track 'stik'
    pub media_type: Option<MediaType>, // stik
    /// Whether or not this track is a podcast 'pcst'
    pub podcast: Option<bool>,
    /// The category of ths track 'catg'
    pub category: Option<TryString>,
    /// The podcast keyword 'keyw'
    pub keyword: Option<TryString>,
    /// The podcast url 'purl'
    pub podcast_url: Option<TryString>,
    /// The podcast episode GUID 'egid'
    pub podcast_guid: Option<TryString>,
    /// The description of the track 'desc'
    pub description: Option<TryString>,
    /// The long description of the track 'ldes'.
    ///
    /// Unlike other string fields, the long description field
    /// can be longer than 256 characters.
    pub long_description: Option<TryString>,
    /// The lyrics of the track '©lyr'.
    ///
    /// Unlike other string fields, the lyrics field
    /// can be longer than 256 characters.
    pub lyrics: Option<TryString>,
    /// The name of the TV network this track aired on 'tvnn'.
    pub tv_network_name: Option<TryString>,
    /// The name of the TV Show for this track 'tvsh'.
    pub tv_show_name: Option<TryString>,
    /// The name of the TV Episode for this track 'tven'.
    pub tv_episode_name: Option<TryString>,
    /// The number of the TV Episode for this track 'tves'.
    pub tv_episode_number: Option<u8>,
    /// The season of the TV Episode of this track 'tvsn'.
    pub tv_season: Option<u8>,
    /// The date this track was purchased 'purd'.
    pub purchase_date: Option<TryString>,
    /// Whether or not this track supports gapless playback 'pgap'
    pub gapless_playback: Option<bool>,
    /// Any cover artwork attached to this track 'covr'
    ///
    /// 'covr' is unique in that it may contain multiple 'data' sub-entries,
    /// each an image file. Here, each subentry's raw binary data is exposed,
    /// which may contain image data in JPEG or PNG format.
    pub cover_art: Option<TryVec<TryVec<u8>>>,
    /// The owner of the track 'ownr'
    pub owner: Option<TryString>,
    /// Whether or not this track is HD Video 'hdvd'
    pub hd_video: Option<bool>,
    /// The name of the track to sort by 'sonm'
    pub sort_name: Option<TryString>,
    /// The name of the album to sort by 'soal'
    pub sort_album: Option<TryString>,
    /// The name of the artist to sort by 'soar'
    pub sort_artist: Option<TryString>,
    /// The name of the album artist to sort by 'soaa'
    pub sort_album_artist: Option<TryString>,
    /// The name of the composer to sort by 'soco'
    pub sort_composer: Option<TryString>,
    /// Metadata
    #[cfg(feature = "meta-xml")]
    pub xml: Option<XmlBox>,
}

/// See ISOBMFF (ISO 14496-12:2020) § 8.11.2.1
#[cfg(feature = "meta-xml")]
#[derive(Debug)]
pub enum XmlBox {
    /// XML metadata
    StringXmlBox(TryString),
    /// Binary XML metadata
    BinaryXmlBox(TryVec<u8>),
}

/// Internal data structures.
#[derive(Debug, Default)]
pub struct MediaContext {
    pub timescale: Option<MediaTimeScale>,
    /// Tracks found in the file.
    pub tracks: TryVec<Track>,
    pub mvex: Option<MovieExtendsBox>,
    pub psshs: TryVec<ProtectionSystemSpecificHeaderBox>,
    pub userdata: Option<Result<UserdataBox>>,
    #[cfg(feature = "meta-xml")]
    pub metadata: Option<Result<MetadataBox>>,
}

/// An ISOBMFF item as described by an iloc box. For the sake of avoiding copies,
/// this can either be represented by the `Location` variant, which indicates
/// where the data exists within a `MediaDataBox` stored separately, or the
/// `Data` variant which owns the data. Unfortunately, it's not simple to
/// represent this as a [`std::borrow::Cow`], or other reference-based type, because
/// multiple instances may references different parts of the same [`MediaDataBox`]
/// and we want to avoid the copy that splitting the storage would entail.
enum IsobmffItem {
    MdatLocation(Extent),
    IdatLocation(Extent),
    Data(TryVec<u8>),
}

impl fmt::Debug for IsobmffItem {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match &self {
            IsobmffItem::MdatLocation(extent) | IsobmffItem::IdatLocation(extent) => f
                .debug_struct("IsobmffItem::Location")
                .field("0", &format_args!("{:?}", extent))
                .finish(),
            IsobmffItem::Data(data) => f
                .debug_struct("IsobmffItem::Data")
                .field("0", &format_args!("{} bytes", data.len()))
                .finish(),
        }
    }
}

#[derive(Debug)]
struct AvifItem {
    /// The `item_ID` from ISOBMFF (ISO 14496-12:2020) § 8.11.3
    ///
    /// See [`read_iloc`]
    id: ItemId,

    /// AV1 Image Item per <https://aomediacodec.github.io/av1-avif/#image-item>
    image_data: IsobmffItem,
}

impl AvifItem {
    fn with_inline_data(id: ItemId) -> Self {
        Self {
            id,
            image_data: IsobmffItem::Data(TryVec::new()),
        }
    }
}

#[derive(Debug)]
pub struct AvifContext {
    /// Level of deviation from the specification before failing the parse
    strictness: ParseStrictness,
    /// Referred to by the `IsobmffItem::*Location` variants of the `AvifItem`s in this struct
    media_storage: TryVec<MediaDataBox>,
    /// The item indicated by the `pitm` box, See ISOBMFF (ISO 14496-12:2020) § 8.11.4
    /// May be `None` in the pure image sequence case.
    primary_item: Option<AvifItem>,
    /// Associated alpha channel for the primary item, if any
    alpha_item: Option<AvifItem>,
    /// If true, divide RGB values by the alpha value.
    /// See `prem` in MIAF (ISO 23000-22:2019) § 7.3.5.2
    pub premultiplied_alpha: bool,
    /// All properties associated with `primary_item` or `alpha_item`
    item_properties: ItemPropertiesBox,
    /// Should probably only ever be [`AVIF_BRAND`] or [`AVIS_BRAND`], but other values
    /// are legal as long as one of the two is the `compatible_brand` list.
    pub major_brand: FourCC,
    /// True if a `moov` box is present
    pub has_sequence: bool,
    /// A collection of unsupported features encountered during the parse
    pub unsupported_features: UnsupportedFeatures,
}

impl AvifContext {
    pub fn primary_item_coded_data(&self) -> Option<&[u8]> {
        self.primary_item
            .as_ref()
            .map(|item| self.item_as_slice(item))
    }

    pub fn primary_item_bits_per_channel(&self) -> Option<Result<&[u8]>> {
        self.primary_item
            .as_ref()
            .map(|item| self.image_bits_per_channel(item.id))
    }

    pub fn alpha_item_coded_data(&self) -> Option<&[u8]> {
        self.alpha_item
            .as_ref()
            .map(|item| self.item_as_slice(item))
    }

    pub fn alpha_item_bits_per_channel(&self) -> Option<Result<&[u8]>> {
        self.alpha_item
            .as_ref()
            .map(|item| self.image_bits_per_channel(item.id))
    }

    fn image_bits_per_channel(&self, item_id: ItemId) -> Result<&[u8]> {
        match self
            .item_properties
            .get(item_id, BoxType::PixelInformationBox)?
        {
            Some(ItemProperty::Channels(pixi)) => Ok(pixi.bits_per_channel.as_slice()),
            Some(other_property) => panic!("property key mismatch: {:?}", other_property),
            None => Ok(&[]),
        }
    }

    pub fn spatial_extents_ptr(&self) -> Result<*const ImageSpatialExtentsProperty> {
        if let Some(primary_item) = &self.primary_item {
            match self
                .item_properties
                .get(primary_item.id, BoxType::ImageSpatialExtentsProperty)?
            {
                Some(ItemProperty::ImageSpatialExtents(ispe)) => Ok(ispe),
                Some(other_property) => panic!("property key mismatch: {:?}", other_property),
                None => {
                    fail_if(
                        self.strictness != ParseStrictness::Permissive,
                        "ispe is a mandatory property",
                    )?;
                    Ok(std::ptr::null())
                }
            }
        } else {
            Ok(std::ptr::null())
        }
    }

    /// Returns None if there is no primary item or it has no associated NCLX colour boxes.
    pub fn nclx_colour_information_ptr(&self) -> Option<Result<*const NclxColourInformation>> {
        if let Some(primary_item) = &self.primary_item {
            match self.item_properties.get_multiple(primary_item.id, |prop| {
                matches!(prop, ItemProperty::Colour(ColourInformation::Nclx(_)))
            }) {
                Ok(nclx_colr_boxes) => match *nclx_colr_boxes.as_slice() {
                    [] => None,
                    [ItemProperty::Colour(ColourInformation::Nclx(nclx)), ..] => {
                        if nclx_colr_boxes.len() > 1 {
                            warn!("Multiple nclx colr boxes, using first");
                        }
                        Some(Ok(nclx))
                    }
                    _ => unreachable!("Expect only ColourInformation::Nclx(_) matches"),
                },
                Err(e) => Some(Err(e)),
            }
        } else {
            None
        }
    }

    /// Returns None if there is no primary item or it has no associated ICC colour boxes.
    pub fn icc_colour_information(&self) -> Option<Result<&[u8]>> {
        if let Some(primary_item) = &self.primary_item {
            match self.item_properties.get_multiple(primary_item.id, |prop| {
                matches!(prop, ItemProperty::Colour(ColourInformation::Icc(_, _)))
            }) {
                Ok(icc_colr_boxes) => match *icc_colr_boxes.as_slice() {
                    [] => None,
                    [ItemProperty::Colour(ColourInformation::Icc(icc, _)), ..] => {
                        if icc_colr_boxes.len() > 1 {
                            warn!("Multiple ICC profiles in colr boxes, using first");
                        }
                        Some(Ok(icc.bytes.as_slice()))
                    }
                    _ => unreachable!("Expect only ColourInformation::Icc(_) matches"),
                },
                Err(e) => Some(Err(e)),
            }
        } else {
            None
        }
    }

    pub fn image_rotation(&self) -> Result<ImageRotation> {
        if let Some(primary_item) = &self.primary_item {
            match self
                .item_properties
                .get(primary_item.id, BoxType::ImageRotation)?
            {
                Some(ItemProperty::Rotation(irot)) => Ok(*irot),
                Some(other_property) => panic!("property key mismatch: {:?}", other_property),
                None => Ok(ImageRotation::D0),
            }
        } else {
            Ok(ImageRotation::D0)
        }
    }

    pub fn image_mirror_ptr(&self) -> Result<*const ImageMirror> {
        if let Some(primary_item) = &self.primary_item {
            match self
                .item_properties
                .get(primary_item.id, BoxType::ImageMirror)?
            {
                Some(ItemProperty::Mirroring(imir)) => Ok(imir),
                Some(other_property) => panic!("property key mismatch: {:?}", other_property),
                None => Ok(std::ptr::null()),
            }
        } else {
            Ok(std::ptr::null())
        }
    }

    pub fn pixel_aspect_ratio_ptr(&self) -> Result<*const PixelAspectRatio> {
        if let Some(primary_item) = &self.primary_item {
            match self
                .item_properties
                .get(primary_item.id, BoxType::PixelAspectRatioBox)?
            {
                Some(ItemProperty::PixelAspectRatio(pasp)) => Ok(pasp),
                Some(other_property) => panic!("property key mismatch: {:?}", other_property),
                None => Ok(std::ptr::null()),
            }
        } else {
            Ok(std::ptr::null())
        }
    }

    /// A helper for the various `AvifItem`s to expose a reference to the
    /// underlying data while avoiding copies.
    fn item_as_slice<'a>(&'a self, item: &'a AvifItem) -> &'a [u8] {
        match &item.image_data {
            IsobmffItem::MdatLocation(extent) => {
                for mdat in &self.media_storage {
                    if let Some(slice) = mdat.get(extent) {
                        return slice;
                    }
                }
                unreachable!(
                    "IsobmffItem::Location requires the location exists in AvifContext::media_storage"
                );
            }
            IsobmffItem::IdatLocation(_) => unimplemented!(),
            IsobmffItem::Data(data) => data.as_slice(),
        }
    }
}

struct AvifMeta {
    item_references: TryVec<SingleItemTypeReferenceBox>,
    item_properties: ItemPropertiesBox,
    /// Required for AvifImageType::Primary, but optional otherwise
    /// See HEIF (ISO/IEC 23008-12:2017) § 7.1, 10.2.1
    primary_item_id: Option<ItemId>,
    item_infos: TryVec<ItemInfoEntry>,
    iloc_items: TryHashMap<ItemId, ItemLocationBoxItem>,
    item_data_box: Option<ItemDataBox>,
}

/// An Item Data Box
/// See ISOBMFF (ISO 14496-12:2020) § 8.11.11
struct ItemDataBox {
    data: TryVec<u8>,
}

/// A Media Data Box
/// See ISOBMFF (ISO 14496-12:2020) § 8.1.1
struct MediaDataBox {
    /// Offset of `data` from the beginning of the "file". See ConstructionMethod::File.
    /// Note: the file may not be an actual file, read_avif supports any `&mut impl Read`
    /// source for input. However we try to match the terminology used in the spec.
    file_offset: u64,
    data: TryVec<u8>,
}

impl fmt::Debug for MediaDataBox {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.debug_struct("MediaDataBox")
            .field("file_offset", &self.file_offset)
            .field("data", &format_args!("{} bytes", self.data.len()))
            .finish()
    }
}

fn u64_to_usize_logged(x: u64) -> Option<usize> {
    match x.try_into() {
        Ok(x) => Some(x),
        Err(e) => {
            error!("{:?} converting {:?}", e, x);
            None
        }
    }
}

/// Generalizes the different data boxes a [`ItemLocationBoxItem`] can refer to
trait DataBox {
    fn data(&self) -> &[u8];

    /// Convert an absolute offset to an offset relative to the beginning of the
    /// slice [`DataBox::data`] returns. Returns None if the offset would be
    /// negative or if the offset would overflow a `usize`.
    fn start(&self, offset: u64) -> Option<usize>;

    /// Returns an appropriate variant of [`IsobmffItem`] to describe the extent
    /// referencing data within this type of box.
    fn location(&self, extent: &Extent) -> IsobmffItem;

    /// Return a slice from the DataBox specified by the provided `extent`.
    /// Returns `None` if the extent isn't fully contained by the DataBox or if
    /// either the offset or length (if the extent is bounded) of the slice
    /// would overflow a `usize`.
    fn get<'a>(&'a self, extent: &'a Extent) -> Option<&'a [u8]> {
        match extent {
            Extent::WithLength { offset, len } => {
                let start = self.start(*offset)?;
                let end = start.checked_add(*len);
                if end.is_none() {
                    error!("Overflow adding {} + {}", start, len);
                }
                self.data().get(start..end?)
            }
            Extent::ToEnd { offset } => {
                let start = self.start(*offset)?;
                self.data().get(start..)
            }
        }
    }
}

impl DataBox for ItemDataBox {
    fn data(&self) -> &[u8] {
        &self.data
    }

    fn start(&self, offset: u64) -> Option<usize> {
        u64_to_usize_logged(offset)
    }

    fn location(&self, extent: &Extent) -> IsobmffItem {
        IsobmffItem::IdatLocation(extent.clone())
    }
}

impl DataBox for MediaDataBox {
    fn data(&self) -> &[u8] {
        &self.data
    }

    fn start(&self, offset: u64) -> Option<usize> {
        let start = offset.checked_sub(self.file_offset);
        if start.is_none() {
            error!("Overflow subtracting {} + {}", offset, self.file_offset);
        }
        u64_to_usize_logged(start?)
    }

    fn location(&self, extent: &Extent) -> IsobmffItem {
        IsobmffItem::MdatLocation(extent.clone())
    }
}

#[cfg(test)]
mod media_data_box_tests {
    use super::*;

    impl MediaDataBox {
        fn at_offset(file_offset: u64, data: std::vec::Vec<u8>) -> Self {
            MediaDataBox {
                file_offset,
                data: data.into(),
            }
        }
    }

    #[test]
    fn extent_with_length_before_mdat_returns_none() {
        let mdat = MediaDataBox::at_offset(100, vec![1; 5]);
        let extent = Extent::WithLength { offset: 0, len: 2 };

        assert!(mdat.get(&extent).is_none());
    }

    #[test]
    fn extent_to_end_before_mdat_returns_none() {
        let mdat = MediaDataBox::at_offset(100, vec![1; 5]);
        let extent = Extent::ToEnd { offset: 0 };

        assert!(mdat.get(&extent).is_none());
    }

    #[test]
    fn extent_with_length_crossing_front_mdat_boundary_returns_none() {
        let mdat = MediaDataBox::at_offset(100, vec![1; 5]);
        let extent = Extent::WithLength { offset: 99, len: 3 };

        assert!(mdat.get(&extent).is_none());
    }

    #[test]
    fn extent_with_length_which_is_subset_of_mdat() {
        let mdat = MediaDataBox::at_offset(100, vec![1; 5]);
        let extent = Extent::WithLength {
            offset: 101,
            len: 2,
        };

        assert_eq!(mdat.get(&extent), Some(&[1, 1][..]));
    }

    #[test]
    fn extent_to_end_which_is_subset_of_mdat() {
        let mdat = MediaDataBox::at_offset(100, vec![1; 5]);
        let extent = Extent::ToEnd { offset: 101 };

        assert_eq!(mdat.get(&extent), Some(&[1, 1, 1, 1][..]));
    }

    #[test]
    fn extent_with_length_which_is_all_of_mdat() {
        let mdat = MediaDataBox::at_offset(100, vec![1; 5]);
        let extent = Extent::WithLength {
            offset: 100,
            len: 5,
        };

        assert_eq!(mdat.get(&extent), Some(mdat.data.as_slice()));
    }

    #[test]
    fn extent_to_end_which_is_all_of_mdat() {
        let mdat = MediaDataBox::at_offset(100, vec![1; 5]);
        let extent = Extent::ToEnd { offset: 100 };

        assert_eq!(mdat.get(&extent), Some(mdat.data.as_slice()));
    }

    #[test]
    fn extent_with_length_crossing_back_mdat_boundary_returns_none() {
        let mdat = MediaDataBox::at_offset(100, vec![1; 5]);
        let extent = Extent::WithLength {
            offset: 103,
            len: 3,
        };

        assert!(mdat.get(&extent).is_none());
    }

    #[test]
    fn extent_with_length_after_mdat_returns_none() {
        let mdat = MediaDataBox::at_offset(100, vec![1; 5]);
        let extent = Extent::WithLength {
            offset: 200,
            len: 2,
        };

        assert!(mdat.get(&extent).is_none());
    }

    #[test]
    fn extent_to_end_after_mdat_returns_none() {
        let mdat = MediaDataBox::at_offset(100, vec![1; 5]);
        let extent = Extent::ToEnd { offset: 200 };

        assert!(mdat.get(&extent).is_none());
    }

    #[test]
    fn extent_with_length_which_overflows_usize() {
        let mdat = MediaDataBox::at_offset(std::u64::MAX - 1, vec![1; 5]);
        let extent = Extent::WithLength {
            offset: std::u64::MAX,
            len: std::usize::MAX,
        };

        assert!(mdat.get(&extent).is_none());
    }

    // The end of the range would overflow `usize` if it were calculated, but
    // because the range end is unbounded, we don't calculate it.
    #[test]
    fn extent_to_end_which_overflows_usize() {
        let mdat = MediaDataBox::at_offset(std::u64::MAX - 1, vec![1; 5]);
        let extent = Extent::ToEnd {
            offset: std::u64::MAX,
        };

        assert_eq!(mdat.get(&extent), Some(&[1, 1, 1, 1][..]));
    }
}

#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
struct PropertyIndex(u16);
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, PartialOrd)]
struct ItemId(u32);

impl ItemId {
    fn read(src: &mut impl ReadBytesExt, version: u8) -> Result<ItemId> {
        Ok(ItemId(if version == 0 {
            be_u16(src)?.into()
        } else {
            be_u32(src)?
        }))
    }
}

/// Used for 'infe' boxes within 'iinf' boxes
/// See ISOBMFF (ISO 14496-12:2020) § 8.11.6
/// Only versions {2, 3} are supported
#[derive(Debug)]
struct ItemInfoEntry {
    item_id: ItemId,
    item_type: u32,
}

/// See ISOBMFF (ISO 14496-12:2020) § 8.11.12
#[derive(Debug)]
struct SingleItemTypeReferenceBox {
    item_type: FourCC,
    from_item_id: ItemId,
    to_item_id: ItemId,
}

/// Potential sizes (in bytes) of variable-sized fields of the 'iloc' box
/// See ISOBMFF (ISO 14496-12:2020) § 8.11.3
#[derive(Debug, Clone, Copy, PartialEq)]
enum IlocFieldSize {
    Zero,
    Four,
    Eight,
}

impl IlocFieldSize {
    fn as_bits(&self) -> u8 {
        match self {
            IlocFieldSize::Zero => 0,
            IlocFieldSize::Four => 32,
            IlocFieldSize::Eight => 64,
        }
    }
}

impl TryFrom<u8> for IlocFieldSize {
    type Error = Error;

    fn try_from(value: u8) -> Result<Self> {
        match value {
            0 => Ok(Self::Zero),
            4 => Ok(Self::Four),
            8 => Ok(Self::Eight),
            _ => Err(Error::InvalidData("value must be in the set {0, 4, 8}")),
        }
    }
}

#[derive(Debug, PartialEq)]
enum IlocVersion {
    Zero,
    One,
    Two,
}

impl TryFrom<u8> for IlocVersion {
    type Error = Error;

    fn try_from(value: u8) -> Result<Self> {
        match value {
            0 => Ok(Self::Zero),
            1 => Ok(Self::One),
            2 => Ok(Self::Two),
            _ => Err(Error::Unsupported("unsupported version in 'iloc' box")),
        }
    }
}

/// Used for 'iloc' boxes
/// See ISOBMFF (ISO 14496-12:2020) § 8.11.3
/// `base_offset` is omitted since it is integrated into the ranges in `extents`
/// `data_reference_index` is omitted, since only 0 (i.e., this file) is supported
#[derive(Debug)]
struct ItemLocationBoxItem {
    construction_method: ConstructionMethod,
    /// Unused for ConstructionMethod::Idat
    extents: TryVec<Extent>,
}

/// See ISOBMFF (ISO 14496-12:2020) § 8.11.3
///
/// Note: per MIAF (ISO 23000-22:2019) § 7.2.1.7:<br />
/// > MIAF image items are constrained as follows:<br />
/// > — `construction_method` shall be equal to 0 for MIAF image items that are coded image items.<br />
/// > — `construction_method` shall be equal to 0 or 1 for MIAF image items that are derived image items.
#[derive(Clone, Copy, Debug, PartialEq)]
enum ConstructionMethod {
    File = 0,
    Idat = 1,
    Item = 2,
}

/// Describes a region where a item specified by an `ItemLocationBoxItem` is stored.
/// The offset is `u64` since that's the maximum possible size and since the relative
/// nature of `MediaDataBox` means this can still possibly succeed even in the case
/// that the raw value exceeds std::usize::MAX on platforms where that type is smaller
/// than u64. However, `len` is stored as a `usize` since no value larger than
/// `std::usize::MAX` can be used in a successful indexing operation in rust.
/// `extent_index` is omitted since it's only used for ConstructionMethod::Item which
/// is currently not implemented.
#[derive(Clone, Debug)]
enum Extent {
    WithLength { offset: u64, len: usize },
    ToEnd { offset: u64 },
}

#[derive(Debug, PartialEq)]
pub enum TrackType {
    Audio,
    Video,
    Metadata,
    Unknown,
}

impl Default for TrackType {
    fn default() -> Self {
        TrackType::Unknown
    }
}

// This type is used by mp4parse_capi since it needs to be passed from FFI consumers
// The C-visible struct is renamed via mp4parse_capi/cbindgen.toml to match naming conventions
#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum ParseStrictness {
    Permissive, // Error only on ambiguous inputs
    Normal,     // Error on "shall" directives, log warnings for "should"
    Strict,     // Error on "should" directives
}

/// Prefer [`fail_with_error_if`] so all the explanatory strings can be collected
/// in `From<Status> for &str`.
fn fail_if(violation: bool, message: &'static str) -> Result<()> {
    if violation {
        Err(Error::InvalidData(message))
    } else {
        warn!("{}", message);
        Ok(())
    }
}

fn fail_with_error_if(violation: bool, error: Error) -> Result<()> {
    if violation {
        Err(error)
    } else {
        warn!("{:?}", error);
        Ok(())
    }
}

#[derive(Debug, Clone, Copy, PartialEq)]
pub enum CodecType {
    Unknown,
    MP3,
    AAC,
    FLAC,
    Opus,
    H264, // 14496-10
    MP4V, // 14496-2
    AV1,
    VP9,
    VP8,
    EncryptedVideo,
    EncryptedAudio,
    LPCM, // QT
    ALAC,
    H263,
    #[cfg(feature = "3gpp")]
    AMRNB,
    #[cfg(feature = "3gpp")]
    AMRWB,
}

impl Default for CodecType {
    fn default() -> Self {
        CodecType::Unknown
    }
}

/// The media's global (mvhd) timescale in units per second.
#[derive(Debug, Copy, Clone, PartialEq)]
pub struct MediaTimeScale(pub u64);

/// A time to be scaled by the media's global (mvhd) timescale.
#[derive(Debug, Copy, Clone, PartialEq)]
pub struct MediaScaledTime(pub u64);

/// The track's local (mdhd) timescale.
/// Members are timescale units per second and the track id.
#[derive(Debug, Copy, Clone, PartialEq)]
pub struct TrackTimeScale<T: Num>(pub T, pub usize);

/// A time to be scaled by the track's local (mdhd) timescale.
/// Members are time in scale units and the track id.
#[derive(Debug, Copy, Clone, PartialEq)]
pub struct TrackScaledTime<T>(pub T, pub usize);

impl<T> std::ops::Add for TrackScaledTime<T>
where
    T: num_traits::CheckedAdd,
{
    type Output = Option<Self>;

    fn add(self, other: TrackScaledTime<T>) -> Self::Output {
        self.0.checked_add(&other.0).map(|sum| Self(sum, self.1))
    }
}

#[derive(Debug, Default)]
pub struct Track {
    pub id: usize,
    pub track_type: TrackType,
    pub empty_duration: Option<MediaScaledTime>,
    pub media_time: Option<TrackScaledTime<u64>>,
    pub timescale: Option<TrackTimeScale<u64>>,
    pub duration: Option<TrackScaledTime<u64>>,
    pub track_id: Option<u32>,
    pub tkhd: Option<TrackHeaderBox>, // TODO(kinetik): find a nicer way to export this.
    pub stsd: Option<SampleDescriptionBox>,
    pub stts: Option<TimeToSampleBox>,
    pub stsc: Option<SampleToChunkBox>,
    pub stsz: Option<SampleSizeBox>,
    pub stco: Option<ChunkOffsetBox>, // It is for stco or co64.
    pub stss: Option<SyncSampleBox>,
    pub ctts: Option<CompositionOffsetBox>,
}

impl Track {
    fn new(id: usize) -> Track {
        Track {
            id,
            ..Default::default()
        }
    }
}

/// See ISOBMFF (ISO 14496-12:2020) § 4.2
struct BMFFBox<'a, T: 'a> {
    head: BoxHeader,
    content: Take<&'a mut T>,
}

struct BoxIter<'a, T: 'a> {
    src: &'a mut T,
}

impl<'a, T: Read> BoxIter<'a, T> {
    fn new(src: &mut T) -> BoxIter<T> {
        BoxIter { src }
    }

    fn next_box(&mut self) -> Result<Option<BMFFBox<T>>> {
        let r = read_box_header(self.src);
        match r {
            Ok(h) => Ok(Some(BMFFBox {
                head: h,
                content: self.src.take(h.size - h.offset),
            })),
            Err(Error::UnexpectedEOF) => Ok(None),
            Err(e) => Err(e),
        }
    }
}

impl<'a, T: Read> Read for BMFFBox<'a, T> {
    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
        self.content.read(buf)
    }
}

impl<'a, T: Read> TryRead for BMFFBox<'a, T> {
    fn try_read_to_end(&mut self, buf: &mut TryVec<u8>) -> std::io::Result<usize> {
        fallible_collections::try_read_up_to(self, self.bytes_left(), buf)
    }
}

impl<'a, T: Offset> Offset for BMFFBox<'a, T> {
    fn offset(&self) -> u64 {
        self.content.get_ref().offset()
    }
}

impl<'a, T: Read> BMFFBox<'a, T> {
    fn bytes_left(&self) -> u64 {
        self.content.limit()
    }

    fn get_header(&self) -> &BoxHeader {
        &self.head
    }

    fn box_iter<'b>(&'b mut self) -> BoxIter<BMFFBox<'a, T>> {
        BoxIter::new(self)
    }
}

impl<'a, T> Drop for BMFFBox<'a, T> {
    fn drop(&mut self) {
        if self.content.limit() > 0 {
            let name: FourCC = From::from(self.head.name);
            debug!("Dropping {} bytes in '{}'", self.content.limit(), name);
        }
    }
}

/// Read and parse a box header.
///
/// Call this first to determine the type of a particular mp4 box
/// and its length. Used internally for dispatching to specific
/// parsers for the internal content, or to get the length to
/// skip unknown or uninteresting boxes.
///
/// See ISOBMFF (ISO 14496-12:2020) § 4.2
fn read_box_header<T: ReadBytesExt>(src: &mut T) -> Result<BoxHeader> {
    let size32 = be_u32(src)?;
    let name = BoxType::from(be_u32(src)?);
    let size = match size32 {
        // valid only for top-level box and indicates it's the last box in the file.  usually mdat.
        0 => return Err(Error::Unsupported("unknown sized box")),
        1 => {
            let size64 = be_u64(src)?;
            if size64 < BoxHeader::MIN_LARGE_SIZE {
                return Err(Error::InvalidData("malformed wide size"));
            }
            size64
        }
        _ => {
            if u64::from(size32) < BoxHeader::MIN_SIZE {
                return Err(Error::InvalidData("malformed size"));
            }
            u64::from(size32)
        }
    };
    let mut offset = match size32 {
        1 => BoxHeader::MIN_LARGE_SIZE,
        _ => BoxHeader::MIN_SIZE,
    };
    let uuid = if name == BoxType::UuidBox {
        if size >= offset + 16 {
            let mut buffer = [0u8; 16];
            let count = src.read(&mut buffer)?;
            offset += count.to_u64();
            if count == 16 {
                Some(buffer)
            } else {
                debug!("malformed uuid (short read), skipping");
                None
            }
        } else {
            debug!("malformed uuid, skipping");
            None
        }
    } else {
        None
    };
    assert!(offset <= size);
    Ok(BoxHeader {
        name,
        size,
        offset,
        uuid,
    })
}

/// Parse the extra header fields for a full box.
fn read_fullbox_extra<T: ReadBytesExt>(src: &mut T) -> Result<(u8, u32)> {
    let version = src.read_u8()?;
    let flags_a = src.read_u8()?;
    let flags_b = src.read_u8()?;
    let flags_c = src.read_u8()?;
    Ok((
        version,
        u32::from(flags_a) << 16 | u32::from(flags_b) << 8 | u32::from(flags_c),
    ))
}

// Parse the extra fields for a full box whose flag fields must be zero.
fn read_fullbox_version_no_flags<T: ReadBytesExt>(src: &mut T) -> Result<u8> {
    let (version, flags) = read_fullbox_extra(src)?;

    if flags != 0 {
        return Err(Error::Unsupported("expected flags to be 0"));
    }

    Ok(version)
}

/// Skip over the entire contents of a box.
fn skip_box_content<T: Read>(src: &mut BMFFBox<T>) -> Result<()> {
    // Skip the contents of unknown chunks.
    let to_skip = {
        let header = src.get_header();
        debug!("{:?} (skipped)", header);
        header
            .size
            .checked_sub(header.offset)
            .expect("header offset > size")
    };
    assert_eq!(to_skip, src.bytes_left());
    skip(src, to_skip)
}

/// Skip over the remain data of a box.
fn skip_box_remain<T: Read>(src: &mut BMFFBox<T>) -> Result<()> {
    let remain = {
        let header = src.get_header();
        let len = src.bytes_left();
        debug!("remain {} (skipped) in {:?}", len, header);
        len
    };
    skip(src, remain)
}

#[derive(Debug)]
enum AvifImageType {
    Primary,
    Sequence,
    Both,
}

impl AvifImageType {
    fn has_primary(&self) -> bool {
        match self {
            Self::Primary | Self::Both => true,
            Self::Sequence => false,
        }
    }

    fn has_sequence(&self) -> bool {
        match self {
            Self::Primary => false,
            Self::Sequence | Self::Both => true,
        }
    }
}

/// Read the contents of an AVIF file
pub fn read_avif<T: Read>(f: &mut T, strictness: ParseStrictness) -> Result<AvifContext> {
    let _ = env_logger::try_init();

    debug!("read_avif(strictness: {:?})", strictness);

    let mut f = OffsetReader::new(f);
    let mut iter = BoxIter::new(&mut f);
    let expected_image_type;
    let mut unsupported_features = UnsupportedFeatures::new();

    // 'ftyp' box must occur first; see ISOBMFF (ISO 14496-12:2020) § 4.3.1
    let major_brand = if let Some(mut b) = iter.next_box()? {
        if b.head.name == BoxType::FileTypeBox {
            let ftyp = read_ftyp(&mut b)?;

            let has_avif_brand = ftyp.contains(&AVIF_BRAND);
            let has_avis_brand = ftyp.contains(&AVIS_BRAND);
            let has_mif1_brand = ftyp.contains(&MIF1_BRAND);
            let has_msf1_brand = ftyp.contains(&MSF1_BRAND);

            let primary_image_expected = has_mif1_brand || has_avif_brand;
            let image_sequence_expected = has_msf1_brand || has_avis_brand;

            expected_image_type = if primary_image_expected && image_sequence_expected {
                AvifImageType::Both
            } else if primary_image_expected {
                AvifImageType::Primary
            } else if image_sequence_expected {
                AvifImageType::Sequence
            } else {
                return Status::NoImage.into();
            };
            debug!("expected_image_type: {:?}", expected_image_type);

            if primary_image_expected && !has_mif1_brand {
                // This mandatory inclusion of this brand is in the process of being changed
                // to optional. In anticipation of that, only give an error in strict mode
                // See https://github.com/MPEGGroup/MIAF/issues/5
                // and https://github.com/MPEGGroup/FileFormat/issues/23
                fail_if(
                    strictness == ParseStrictness::Strict,
                    "The FileTypeBox should contain 'mif1' in the compatible_brands list \
                     per MIAF (ISO 23000-22:2019) § 7.2.1.2",
                )?;
            }

            if !has_avif_brand && !has_avis_brand {
                fail_with_error_if(
                    strictness != ParseStrictness::Permissive,
                    Status::MissingBrand.into(),
                )?;
            }

            ftyp.major_brand
        } else {
            return Status::FtypNotFirst.into();
        }
    } else {
        return Status::FtypNotFirst.into();
    };

    if major_brand == AVIS_BRAND {
        unsupported_features.insert(Feature::Avis);
    }

    let mut meta = None;
    let mut image_sequence = None;
    let mut media_storage = TryVec::new();

    while let Some(mut b) = iter.next_box()? {
        trace!("read_avif parsing {:?} box", b.head.name);
        match b.head.name {
            BoxType::MetadataBox => {
                if meta.is_some() {
                    return Err(Error::InvalidData(
                        "There should be zero or one meta boxes per ISOBMFF (ISO 14496-12:2020) § 8.11.1.1",
                    ));
                }
                meta = Some(read_avif_meta(
                    &mut b,
                    strictness,
                    &mut unsupported_features,
                )?);
            }
            BoxType::MovieBox if expected_image_type.has_sequence() => {
                if image_sequence.is_some() {
                    return Status::MultipleMoov.into();
                }
                image_sequence = Some(read_moov(&mut b, None)?);
            }
            BoxType::MediaDataBox => {
                if b.bytes_left() > 0 {
                    let file_offset = b.offset();
                    let data = b.read_into_try_vec()?;
                    media_storage.push(MediaDataBox { file_offset, data })?;
                }
            }
            _ => skip_box_content(&mut b)?,
        }

        check_parser_state!(b.content);
    }

    let AvifMeta {
        item_references,
        item_properties,
        primary_item_id,
        item_infos,
        iloc_items,
        item_data_box,
    } = meta.ok_or(Error::InvalidData("missing meta"))?;

    let (alpha_item_id, premultiplied_alpha) = if let Some(primary_item_id) = primary_item_id {
        let mut alpha_item_ids = item_references
            .iter()
            // Auxiliary image for the primary image
            .filter(|iref| {
                iref.to_item_id == primary_item_id
                    && iref.from_item_id != primary_item_id
                    && iref.item_type == b"auxl"
            })
            .map(|iref| iref.from_item_id)
            // which has the alpha property
            .filter(|&item_id| item_properties.is_alpha(item_id));
        let alpha_item_id = alpha_item_ids.next();
        if alpha_item_ids.next().is_some() {
            return Err(Error::InvalidData("multiple alpha planes"));
        }

        let premultiplied_alpha = alpha_item_id.map_or(false, |alpha_item_id| {
            item_references.iter().any(|iref| {
                iref.from_item_id == primary_item_id
                    && iref.to_item_id == alpha_item_id
                    && iref.item_type == b"prem"
            })
        });

        (alpha_item_id, premultiplied_alpha)
    } else {
        (None, false)
    };

    debug!("primary_item_id: {:?}", primary_item_id);
    debug!("alpha_item_id: {:?}", alpha_item_id);
    let mut primary_item = None;
    let mut alpha_item = None;

    // store data or record location of relevant items
    for (item_id, loc) in iloc_items {
        let item = if Some(item_id) == primary_item_id {
            &mut primary_item
        } else if Some(item_id) == alpha_item_id {
            &mut alpha_item
        } else {
            continue;
        };

        assert!(item.is_none());

        // If our item is spread over multiple extents, we'll need to copy it
        // into a contiguous buffer. Otherwise, we can just store the extent
        // and return a pointer into the mdat/idat later to avoid the copy.
        if loc.extents.len() > 1 {
            *item = Some(AvifItem::with_inline_data(item_id))
        }

        trace!(
            "{:?} construction_method: {:?}",
            item_id,
            loc.construction_method
        );

        // Generalize the process of connecting items to their data; returns
        // true if the extent is successfully added to the AvifItem
        let mut find_and_add_to_item = |extent: &Extent, dat: &dyn DataBox| -> Result<bool> {
            if let Some(extent_slice) = dat.get(extent) {
                match item {
                    None => {
                        trace!("Using IsobmffItem::Location");
                        *item = Some(AvifItem {
                            id: item_id,
                            image_data: dat.location(extent),
                        });
                    }
                    Some(AvifItem {
                        image_data: IsobmffItem::Data(bytes),
                        ..
                    }) => {
                        trace!("Using IsobmffItem::Data");
                        // We could potentially optimize memory usage by trying to avoid reading
                        // or storing dat boxes which aren't used by our API, but for now it seems
                        // like unnecessary complexity
                        bytes.extend_from_slice(extent_slice)?;
                    }
                    _ => unreachable!(),
                }
                return Ok(true);
            }
            Ok(false)
        };

        match loc.construction_method {
            ConstructionMethod::File => {
                for extent in loc.extents {
                    let mut found = false;
                    // try to find an mdat which contains the extent
                    for mdat in media_storage.iter() {
                        if find_and_add_to_item(&extent, mdat)? {
                            found = true;
                            break;
                        }
                    }

                    if !found {
                        return Status::ItemLocNotFound.into();
                    }
                }
            }
            ConstructionMethod::Idat => {
                if let Some(idat) = &item_data_box {
                    for extent in loc.extents {
                        let found = find_and_add_to_item(&extent, idat)?;
                        if !found {
                            return Status::ItemLocNotFound.into();
                        }
                    }
                } else {
                    return Status::NoItemDataBox.into();
                }
            }
            ConstructionMethod::Item => {
                fail_with_error_if(
                    strictness != ParseStrictness::Permissive,
                    Status::ConstructionMethod.into(),
                )?;
            }
        }

        assert!(item.is_some());
    }

    assert!(primary_item.is_none() || primary_item_id.is_some());
    assert!(alpha_item.is_none() || alpha_item_id.is_some());

    if expected_image_type.has_primary() && primary_item_id.is_none() {
        fail_with_error_if(
            strictness != ParseStrictness::Permissive,
            Status::NoPrimaryItem.into(),
        )?;
    }

    // Lacking a brand that requires them, it's fine for moov boxes to exist in
    // BMFF files; they're simply ignored
    if expected_image_type.has_sequence() && image_sequence.is_none() {
        fail_with_error_if(
            strictness != ParseStrictness::Permissive,
            Status::NoMoov.into(),
        )?;
    }

    // Returns true iff `id` is `Some` and there is no corresponding property for it
    let missing_property_for = |id: Option<ItemId>, property: BoxType| -> bool {
        id.map_or(false, |id| {
            item_properties
                .get(id, property)
                .map_or(true, |opt| opt.is_none())
        })
    };

    // TODO: add ispe check for alpha https://github.com/mozilla/mp4parse-rust/issues/353
    if missing_property_for(primary_item_id, BoxType::ImageSpatialExtentsProperty) {
        fail_if(
            strictness != ParseStrictness::Permissive,
            "Missing 'ispe' property for primary item, required \
             per HEIF (ISO/IEC 23008-12:2017) § 6.5.3.1",
        )?;
    }

    // Generalize the property checks so we can apply them to primary and alpha items
    let mut check_image_item = |item: &mut Option<AvifItem>| -> Result<()> {
        let item_id = item.as_ref().map(|item| item.id);
        let item_type = item_id.and_then(|item_id| {
            item_infos
                .iter()
                .find(|item_info| item_id == item_info.item_id)
                .map(|item_info| item_info.item_type)
        });

        match item_type.map(u32::to_be_bytes).as_ref() {
            Some(b"av01") => {
                if missing_property_for(item_id, BoxType::AV1CodecConfigurationBox) {
                    fail_if(
                        strictness != ParseStrictness::Permissive,
                        "One AV1 Item Configuration Property (av1C) is mandatory for an \
                         image item of type 'av01' \
                         per AVIF specification § 2.2.1",
                    )?;
                }

                if missing_property_for(item_id, BoxType::PixelInformationBox) {
                    // The requirement to include pixi is in the process of being changed
                    // to allowing its omission to imply a default value. In anticipation
                    // of that, only give an error in strict mode
                    // See https://github.com/MPEGGroup/MIAF/issues/9
                    fail_if(
                        if cfg!(feature = "missing-pixi-permitted") {
                            strictness == ParseStrictness::Strict
                        } else {
                            strictness != ParseStrictness::Permissive
                        },
                        "The pixel information property shall be associated with every image \
                         that is displayable (not hidden) \
                         per MIAF (ISO/IEC 23000-22:2019) specification § 7.3.6.6",
                    )?;
                }
            }
            Some(b"grid") => {
                // TODO: https://github.com/mozilla/mp4parse-rust/issues/198
                unsupported_features.insert(Feature::Grid);
                *item = None;
            }
            Some(_other_type) => return Status::ImageItemType.into(),
            None => {
                if item.is_some() {
                    return Status::ItemTypeMissing.into();
                }
            }
        }

        if let Some(AvifItem { id, .. }) = item {
            if item_properties.forbidden_items.contains(id) {
                error!("Not processing item id {:?} since it is associated with essential, but unsupported properties", id);
                *item = None;
            }
        }

        Ok(())
    };

    check_image_item(&mut primary_item)?;
    check_image_item(&mut alpha_item)?;

    Ok(AvifContext {
        strictness,
        media_storage,
        primary_item,
        alpha_item,
        premultiplied_alpha,
        item_properties,
        major_brand,
        has_sequence: image_sequence.is_some(),
        unsupported_features,
    })
}

/// Parse a metadata box in the context of an AVIF
/// Currently requires the primary item to be an av01 item type and generates
/// an error otherwise.
/// See ISOBMFF (ISO 14496-12:2020) § 8.11.1
fn read_avif_meta<T: Read + Offset>(
    src: &mut BMFFBox<T>,
    strictness: ParseStrictness,
    unsupported_features: &mut UnsupportedFeatures,
) -> Result<AvifMeta> {
    let version = read_fullbox_version_no_flags(src)?;

    if version != 0 {
        return Err(Error::Unsupported("unsupported meta version"));
    }

    let mut read_handler_box = false;
    let mut primary_item_id = None;
    let mut item_infos = None;
    let mut iloc_items = None;
    let mut item_references = None;
    let mut item_properties = None;
    let mut item_data_box = None;

    let mut iter = src.box_iter();
    while let Some(mut b) = iter.next_box()? {
        trace!("read_avif_meta parsing {:?} box", b.head.name);

        if !read_handler_box && b.head.name != BoxType::HandlerBox {
            fail_if(
                strictness != ParseStrictness::Permissive,
                "The HandlerBox shall be the first contained box within the MetaBox \
                 per MIAF (ISO 23000-22:2019) § 7.2.1.5",
            )?;
        }

        match b.head.name {
            BoxType::HandlerBox => {
                if read_handler_box {
                    return Err(Error::InvalidData(
                        "There shall be exactly one hdlr box per ISOBMFF (ISO 14496-12:2020) § 8.4.3.1",
                    ));
                }
                let HandlerBox { handler_type } = read_hdlr(&mut b, strictness)?;
                if handler_type != b"pict" {
                    fail_if(
                        strictness != ParseStrictness::Permissive,
                        "The HandlerBox handler_type must be 'pict' \
                         per MIAF (ISO 23000-22:2019) § 7.2.1.5",
                    )?;
                }
                read_handler_box = true;
            }
            BoxType::ItemInfoBox => {
                if item_infos.is_some() {
                    return Err(Error::InvalidData(
                        "There shall be zero or one iinf boxes per ISOBMFF (ISO 14496-12:2020) § 8.11.6.1",
                    ));
                }
                item_infos = Some(read_iinf(&mut b, strictness, unsupported_features)?);
            }
            BoxType::ItemLocationBox => {
                if iloc_items.is_some() {
                    return Err(Error::InvalidData(
                        "There shall be zero or one iloc boxes per ISOBMFF (ISO 14496-12:2020) § 8.11.3.1",
                    ));
                }
                iloc_items = Some(read_iloc(&mut b)?);
            }
            BoxType::PrimaryItemBox => {
                if primary_item_id.is_some() {
                    return Err(Error::InvalidData(
                        "There shall be zero or one pitm boxes per ISOBMFF (ISO 14496-12:2020) § 8.11.4.1",
                    ));
                }
                primary_item_id = Some(read_pitm(&mut b)?);
            }
            BoxType::ItemReferenceBox => {
                if item_references.is_some() {
                    return Err(Error::InvalidData("There shall be zero or one iref boxes per ISOBMFF (ISO 14496-12:2020) § 8.11.12.1"));
                }
                item_references = Some(read_iref(&mut b)?);
            }
            BoxType::ItemPropertiesBox => {
                if item_properties.is_some() {
                    return Err(Error::InvalidData("There shall be zero or one iprp boxes per ISOBMFF (ISO 14496-12:2020) § 8.11.14.1"));
                }
                item_properties = Some(read_iprp(
                    &mut b,
                    MIF1_BRAND,
                    strictness,
                    unsupported_features,
                )?);
            }
            BoxType::ItemDataBox => {
                if item_data_box.is_some() {
                    return Err(Error::InvalidData(
                        "There shall be zero or one idat boxes per ISOBMFF (ISO 14496-12:2020) § 8.11.11",
                    ));
                }
                item_data_box = Some(ItemDataBox {
                    data: b.read_into_try_vec()?,
                });
            }
            _ => skip_box_content(&mut b)?,
        }

        check_parser_state!(b.content);
    }

    Ok(AvifMeta {
        item_properties: item_properties.unwrap_or_default(),
        item_references: item_references.unwrap_or_default(),
        primary_item_id,
        item_infos: item_infos.unwrap_or_default(),
        iloc_items: iloc_items.ok_or(Error::InvalidData("iloc missing"))?,
        item_data_box,
    })
}

/// Parse a Primary Item Box
/// See ISOBMFF (ISO 14496-12:2020) § 8.11.4
fn read_pitm<T: Read>(src: &mut BMFFBox<T>) -> Result<ItemId> {
    let version = read_fullbox_version_no_flags(src)?;

    let item_id = ItemId(match version {
        0 => be_u16(src)?.into(),
        1 => be_u32(src)?,
        _ => return Err(Error::Unsupported("unsupported pitm version")),
    });

    Ok(item_id)
}

/// Parse an Item Information Box
/// See ISOBMFF (ISO 14496-12:2020) § 8.11.6
fn read_iinf<T: Read>(
    src: &mut BMFFBox<T>,
    strictness: ParseStrictness,
    unsupported_features: &mut UnsupportedFeatures,
) -> Result<TryVec<ItemInfoEntry>> {
    let version = read_fullbox_version_no_flags(src)?;

    match version {
        0 | 1 => (),
        _ => return Err(Error::Unsupported("unsupported iinf version")),
    }

    let entry_count = if version == 0 {
        be_u16(src)?.to_usize()
    } else {
        be_u32(src)?.to_usize()
    };
    let mut item_infos = TryVec::with_capacity(entry_count)?;

    let mut iter = src.box_iter();
    while let Some(mut b) = iter.next_box()? {
        if b.head.name != BoxType::ItemInfoEntry {
            return Err(Error::InvalidData(
                "iinf box shall contain only infe boxes per ISOBMFF (ISO 14496-12:2020) § 8.11.6.2",
            ));
        }

        if let Some(infe) = read_infe(&mut b, strictness, unsupported_features)? {
            item_infos.push(infe)?;
        }

        check_parser_state!(b.content);
    }

    Ok(item_infos)
}

/// A simple wrapper to interpret a u32 as a 4-byte string in big-endian
/// order without requiring any allocation.
struct U32BE(u32);

impl std::fmt::Display for U32BE {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match std::str::from_utf8(&self.0.to_be_bytes()) {
            Ok(s) => f.write_str(s),
            Err(_) => write!(f, "{:x?}", self.0),
        }
    }
}

/// Parse an Item Info Entry
/// See ISOBMFF (ISO 14496-12:2020) § 8.11.6.2
fn read_infe<T: Read>(
    src: &mut BMFFBox<T>,
    strictness: ParseStrictness,
    unsupported_features: &mut UnsupportedFeatures,
) -> Result<Option<ItemInfoEntry>> {
    let (version, flags) = read_fullbox_extra(src)?;

    // According to the standard, it seems the flags field shall be 0, but at
    // least one sample AVIF image has a nonzero value.
    // See https://github.com/AOMediaCodec/av1-avif/issues/146
    if flags != 0 {
        fail_if(
            strictness == ParseStrictness::Strict,
            "'infe' flags field shall be 0 \
             per ISOBMFF (ISO 14496-12:2020) § 8.11.6.2",
        )?;
    }

    // mif1 brand (see HEIF (ISO 23008-12:2017) § 10.2.1) only requires v2 and 3
    let item_id = ItemId(match version {
        2 => be_u16(src)?.into(),
        3 => be_u32(src)?,
        _ => return Err(Error::Unsupported("unsupported version in 'infe' box")),
    });

    let item_protection_index = be_u16(src)?;

    let item_type = be_u32(src)?;
    debug!("infe {:?} item_type: {}", item_id, U32BE(item_type));

    // There are some additional fields here, but they're not of interest to us
    skip_box_remain(src)?;

    if item_protection_index != 0 {
        unsupported_features.insert(Feature::Ipro);
        Ok(None)
    } else {
        Ok(Some(ItemInfoEntry { item_id, item_type }))
    }
}

/// Parse an Item Reference Box
/// See ISOBMFF (ISO 14496-12:2020) § 8.11.12
fn read_iref<T: Read>(src: &mut BMFFBox<T>) -> Result<TryVec<SingleItemTypeReferenceBox>> {
    let mut item_references = TryVec::new();
    let version = read_fullbox_version_no_flags(src)?;
    if version > 1 {
        return Err(Error::Unsupported("iref version"));
    }

    let mut iter = src.box_iter();
    while let Some(mut b) = iter.next_box()? {
        trace!("read_iref parsing {:?} referenceType", b.head.name);
        let from_item_id = ItemId::read(&mut b, version)?;
        let reference_count = be_u16(&mut b)?;
        item_references.reserve(reference_count.to_usize())?;
        for _ in 0..reference_count {
            let to_item_id = ItemId::read(&mut b, version)?;
            if from_item_id == to_item_id {
                return Err(Error::InvalidData(
                    "from_item_id and to_item_id must be different",
                ));
            }
            item_references.push(SingleItemTypeReferenceBox {
                item_type: b.head.name.into(),
                from_item_id,
                to_item_id,
            })?;
        }
        check_parser_state!(b.content);
    }

    trace!("read_iref -> {:#?}", item_references);

    Ok(item_references)
}

/// Parse an Item Properties Box
///
/// See ISOBMFF (ISO 14496-12:2020 § 8.11.14)
///
/// Note: HEIF (ISO 23008-12:2017) § 9.3.1 also defines the `iprp` box and
/// related types, but lacks additional requirements specified in 14496-12:2020.
///
/// Note: Currently HEIF (ISO 23008-12:2017) § 6.5.5.1 specifies "At most one"
/// `colr` box per item, but this is being amended in [DIS 23008-12](https://www.iso.org/standard/83650.html).
/// The new text is likely to be "At most one for a given value of `colour_type`",
/// so this implementation adheres to that language for forward compatibility.
fn read_iprp<T: Read>(
    src: &mut BMFFBox<T>,
    brand: FourCC,
    strictness: ParseStrictness,
    unsupported_features: &mut UnsupportedFeatures,
) -> Result<ItemPropertiesBox> {
    let mut iter = src.box_iter();

    let properties = match iter.next_box()? {
        Some(mut b) if b.head.name == BoxType::ItemPropertyContainerBox => {
            read_ipco(&mut b, strictness)
        }
        Some(_) => Err(Error::InvalidData("unexpected iprp child")),
        None => Err(Error::UnexpectedEOF),
    }?;

    let mut ipma_version_and_flag_values_seen = TryVec::with_capacity(1)?;
    let mut association_entries = TryVec::<ItemPropertyAssociationEntry>::new();
    let mut forbidden_items = TryVec::new();

    while let Some(mut b) = iter.next_box()? {
        if b.head.name != BoxType::ItemPropertyAssociationBox {
            return Err(Error::InvalidData("unexpected iprp child"));
        }

        let (version, flags) = read_fullbox_extra(&mut b)?;
        if ipma_version_and_flag_values_seen.contains(&(version, flags)) {
            fail_if(
                strictness != ParseStrictness::Permissive,
                "There shall be at most one ItemPropertyAssociationbox with a given pair of \
                 values of version and flags \
                 per ISOBMFF (ISO 14496-12:2020 § 8.11.14.1",
            )?;
        }
        if flags != 0 && properties.len() <= 127 {
            fail_if(
                strictness == ParseStrictness::Strict,
                "Unless there are more than 127 properties in the ItemPropertyContainerBox, \
                 flags should be equal to 0 \
                 per ISOBMFF (ISO 14496-12:2020 § 8.11.14.1",
            )?;
        }
        ipma_version_and_flag_values_seen.push((version, flags))?;
        for association_entry in read_ipma(&mut b, strictness, version, flags)? {
            if forbidden_items.contains(&association_entry.item_id) {
                warn!(
                    "Skipping {:?} since the item referenced shall not be processed",
                    association_entry
                );
            }

            if let Some(previous_entry) = association_entries
                .iter()
                .find(|e| association_entry.item_id == e.item_id)
            {
                error!(
                    "Duplicate ipma entries for item_id\n1: {:?}\n2: {:?}",
                    previous_entry, association_entry
                );
                // It's technically possible to make sense of this situation by merging ipma
                // boxes, but this is a "shall" requirement, so we'd only do it in
                // ParseStrictness::Permissive mode, and this hasn't shown up in the wild
                return Err(Error::InvalidData(
                    "There shall be at most one occurrence of a given item_ID, \
                     in the set of ItemPropertyAssociationBox boxes \
                     per ISOBMFF (ISO 14496-12:2020) § 8.11.14.1",
                ));
            }

            const TRANSFORM_ORDER_ERROR: &str =
                "These properties, if used, shall be indicated to be applied \
                 in the following order: clean aperture first, then rotation, \
                 then mirror. \
                 per MIAF (ISO/IEC 23000-22:2019) § 7.3.6.7";
            const TRANSFORM_ORDER: &[BoxType] = &[
                BoxType::CleanApertureBox,
                BoxType::ImageRotation,
                BoxType::ImageMirror,
            ];
            let mut prev_transform_index = None;
            // Realistically, there should only ever be 1 nclx and 1 icc
            let mut colour_type_indexes: TryHashMap<FourCC, PropertyIndex> =
                TryHashMap::with_capacity(2)?;

            for a in &association_entry.associations {
                if a.property_index == PropertyIndex(0) {
                    if a.essential {
                        fail_if(
                            strictness != ParseStrictness::Permissive,
                            "the essential indicator shall be 0 for property index 0 \
                             per ISOBMFF (ISO 14496-12:2020 § 8.11.14.3",
                        )?;
                    }
                    continue;
                }

                if let Some(property) = properties.get(&a.property_index) {
                    assert!(brand == MIF1_BRAND);

                    let feature = Feature::try_from(property);
                    let property_supported = match feature {
                        Ok(feature) => {
                            if feature.supported() {
                                true
                            } else {
                                unsupported_features.insert(feature);
                                false
                            }
                        }
                        Err(_) => false,
                    };

                    if !property_supported {
                        if a.essential && strictness != ParseStrictness::Permissive {
                            error!("Unsupported essential property {:?}", property);
                            forbidden_items.push(association_entry.item_id)?;
                        } else {
                            debug!(
                                "Ignoring unknown {} property {:?}",
                                if a.essential {
                                    "essential"
                                } else {
                                    "non-essential"
                                },
                                property
                            );
                        }
                    }

                    // Check additional requirements on specific properties
                    match property {
                        ItemProperty::AV1Config(_)
                        | ItemProperty::CleanAperture
                        | ItemProperty::Mirroring(_)
                        | ItemProperty::Rotation(_) => {
                            if !a.essential {
                                warn!("{:?} is missing required 'essential' bit", property);
                                // This is a "shall", but it is likely to change, so only
                                // fail if using strict parsing.
                                // See https://github.com/mozilla/mp4parse-rust/issues/284
                                fail_with_error_if(
                                    strictness == ParseStrictness::Strict,
                                    Status::TxformNoEssential.into(),
                                )?;
                            }
                        }

                        // NOTE: this is contrary to the published specification; see doc comment
                        // at the beginning of this function for more details
                        ItemProperty::Colour(colr) => {
                            let colour_type = colr.colour_type();
                            if let Some(prev_colr_index) = colour_type_indexes.get(&colour_type) {
                                warn!(
                                    "Multiple '{}' type colr associations with {:?}: {:?} and {:?}",
                                    colour_type,
                                    association_entry.item_id,
                                    a.property_index,
                                    prev_colr_index
                                );
                                fail_if(
                                    strictness != ParseStrictness::Permissive,
                                    "Each item shall have at most one property association with a
                                     ColourInformationBox (colr) for a given value of colour_type \
                                     per HEIF (ISO/IEC DIS 23008-12) § 6.5.5.1",
                                )?;
                            } else {
                                colour_type_indexes.insert(colour_type, a.property_index)?;
                            }
                        }

                        // The following properties are unsupported, but we still enforce that
                        // they've been correctly marked as essential or not.
                        ItemProperty::LayeredImageIndexing => {
                            assert!(feature.is_ok() && unsupported_features.contains(feature?));
                            if a.essential {
                                fail_with_error_if(
                                    strictness != ParseStrictness::Permissive,
                                    Status::A1lxEssential.into(),
                                )?;
                            }
                        }

                        ItemProperty::LayerSelection => {
                            assert!(feature.is_ok() && unsupported_features.contains(feature?));
                            if a.essential {
                                assert!(
                                    forbidden_items.contains(&association_entry.item_id)
                                        || strictness == ParseStrictness::Permissive
                                );
                            } else {
                                fail_with_error_if(
                                    strictness != ParseStrictness::Permissive,
                                    Status::LselNoEssential.into(),
                                )?;
                            }
                        }

                        ItemProperty::OperatingPointSelector => {
                            assert!(feature.is_ok() && unsupported_features.contains(feature?));
                            if a.essential {
                                assert!(
                                    forbidden_items.contains(&association_entry.item_id)
                                        || strictness == ParseStrictness::Permissive
                                );
                            } else {
                                fail_with_error_if(
                                    strictness != ParseStrictness::Permissive,
                                    Status::A1opNoEssential.into(),
                                )?;
                            }
                        }

                        other_property => {
                            trace!("No additional checks for {:?}", other_property);
                        }
                    }

                    if let Some(transform_index) = TRANSFORM_ORDER
                        .iter()
                        .position(|t| *t == BoxType::from(property))
                    {
                        if let Some(prev) = prev_transform_index {
                            if prev >= transform_index {
                                error!(
                                    "{:?} after {:?}",
                                    TRANSFORM_ORDER[transform_index], TRANSFORM_ORDER[prev]
                                );
                                return Err(Error::InvalidData(TRANSFORM_ORDER_ERROR));
                            }
                        }
                        prev_transform_index = Some(transform_index);
                    }
                } else {
                    error!(
                        "Missing property at {:?} for {:?}",
                        a.property_index, association_entry.item_id
                    );
                    fail_if(
                        strictness != ParseStrictness::Permissive,
                        "Invalid property index in ipma",
                    )?;
                }
            }
            association_entries.push(association_entry)?
        }

        check_parser_state!(b.content);
    }

    let iprp = ItemPropertiesBox {
        properties,
        association_entries,
        forbidden_items,
    };
    trace!("read_iprp -> {:#?}", iprp);
    Ok(iprp)
}

/// See ISOBMFF (ISO 14496-12:2020 § 8.11.14.1
/// Variants with no associated data are recognized but not necessarily supported.
/// See [`Feature`] to determine support.
#[derive(Debug)]
pub enum ItemProperty {
    AuxiliaryType(AuxiliaryTypeProperty),
    AV1Config(AV1ConfigBox),
    Channels(PixelInformation),
    CleanAperture,
    Colour(ColourInformation),
    ImageSpatialExtents(ImageSpatialExtentsProperty),
    LayeredImageIndexing,
    LayerSelection,
    Mirroring(ImageMirror),
    OperatingPointSelector,
    PixelAspectRatio(PixelAspectRatio),
    Rotation(ImageRotation),
    /// Necessary to validate property indices in read_iprp
    Unsupported(BoxType),
}

impl From<&ItemProperty> for BoxType {
    fn from(item_property: &ItemProperty) -> Self {
        match item_property {
            ItemProperty::AuxiliaryType(_) => BoxType::AuxiliaryTypeProperty,
            ItemProperty::AV1Config(_) => BoxType::AV1CodecConfigurationBox,
            ItemProperty::CleanAperture => BoxType::CleanApertureBox,
            ItemProperty::Colour(_) => BoxType::ColourInformationBox,
            ItemProperty::LayeredImageIndexing => BoxType::AV1LayeredImageIndexingProperty,
            ItemProperty::LayerSelection => BoxType::LayerSelectorProperty,
            ItemProperty::Mirroring(_) => BoxType::ImageMirror,
            ItemProperty::OperatingPointSelector => BoxType::OperatingPointSelectorProperty,
            ItemProperty::PixelAspectRatio(_) => BoxType::PixelAspectRatioBox,
            ItemProperty::Rotation(_) => BoxType::ImageRotation,
            ItemProperty::ImageSpatialExtents(_) => BoxType::ImageSpatialExtentsProperty,
            ItemProperty::Channels(_) => BoxType::PixelInformationBox,
            ItemProperty::Unsupported(box_type) => *box_type,
        }
    }
}

#[derive(Debug)]
struct ItemPropertyAssociationEntry {
    item_id: ItemId,
    associations: TryVec<Association>,
}

/// For storing ItemPropertyAssociation data
/// See ISOBMFF (ISO 14496-12:2020 § 8.11.14.1
#[derive(Debug)]
struct Association {
    essential: bool,
    property_index: PropertyIndex,
}

/// See ISOBMFF (ISO 14496-12:2020 § 8.11.14.1
///
/// The properties themselves are stored in `properties`, but the items they're
/// associated with are stored in `association_entries`. It's necessary to
/// maintain this indirection because multiple items can reference the same
/// property. For example, both the primary item and alpha item can share the
/// same [`ImageSpatialExtentsProperty`].
#[derive(Debug, Default)]
pub struct ItemPropertiesBox {
    /// `ItemPropertyContainerBox property_container` in the spec
    properties: TryHashMap<PropertyIndex, ItemProperty>,
    /// `ItemPropertyAssociationBox association[]` in the spec
    association_entries: TryVec<ItemPropertyAssociationEntry>,
    /// Items that shall not be processed due to unsupported properties that
    /// have been marked essential.
    /// See HEIF (ISO/IEC 23008-12:2017) § 9.3.1
    forbidden_items: TryVec<ItemId>,
}

impl ItemPropertiesBox {
    /// For displayable images `av1C`, `pixi` and `ispe` are mandatory, `colr`
    /// is typically included too, so we might as well use an even power of 2.
    const MIN_PROPERTIES: usize = 4;

    fn is_alpha(&self, item_id: ItemId) -> bool {
        match self.get(item_id, BoxType::AuxiliaryTypeProperty) {
            Ok(Some(ItemProperty::AuxiliaryType(urn))) => {
                urn.aux_type.as_slice() == "urn:mpeg:mpegB:cicp:systems:auxiliary:alpha".as_bytes()
            }
            Ok(Some(other_property)) => panic!("property key mismatch: {:?}", other_property),
            Ok(None) => false,
            Err(e) => {
                error!(
                    "is_alpha: Error checking AuxiliaryTypeProperty ({}), returning false",
                    e
                );
                false
            }
        }
    }

    fn get(&self, item_id: ItemId, property_type: BoxType) -> Result<Option<&ItemProperty>> {
        match self
            .get_multiple(item_id, |prop| BoxType::from(prop) == property_type)?
            .as_slice()
        {
            &[] => Ok(None),
            &[single_value] => Ok(Some(single_value)),
            multiple_values => {
                error!(
                    "Multiple values for {:?}: {:?}",
                    property_type, multiple_values
                );
                // TODO: add test
                Err(Error::InvalidData("conflicting item property values"))
            }
        }
    }

    fn get_multiple(
        &self,
        item_id: ItemId,
        filter: impl Fn(&ItemProperty) -> bool,
    ) -> Result<TryVec<&ItemProperty>> {
        let mut values = TryVec::new();
        for entry in &self.association_entries {
            for a in &entry.associations {
                if entry.item_id == item_id {
                    match self.properties.get(&a.property_index) {
                        Some(ItemProperty::Unsupported(_)) => {}
                        Some(property) if filter(property) => values.push(property)?,
                        _ => {}
                    }
                }
            }
        }

        Ok(values)
    }
}

/// An upper bound which can be used to check overflow at compile time
trait UpperBounded {
    const MAX: u64;
}

/// Implement type $name as a newtype wrapper around an unsigned int which
/// implements the UpperBounded trait.
macro_rules! impl_bounded {
    ( $name:ident, $inner:ty ) => {
        #[derive(Clone, Copy)]
        pub struct $name($inner);

        impl $name {
            pub const fn new(n: $inner) -> Self {
                Self(n)
            }

            #[allow(dead_code)]
            pub fn get(self) -> $inner {
                self.0
            }
        }

        impl UpperBounded for $name {
            const MAX: u64 = <$inner>::MAX as u64;
        }
    };
}

/// Implement type $name as a type representing the product of two unsigned ints
/// which implements the UpperBounded trait.
macro_rules! impl_bounded_product {
    ( $name:ident, $multiplier:ty, $multiplicand:ty, $inner:ty) => {
        #[derive(Clone, Copy)]
        pub struct $name($inner);

        impl $name {
            pub fn new(value: $inner) -> Self {
                assert!(value <= Self::MAX);
                Self(value)
            }

            pub fn get(self) -> $inner {
                self.0
            }
        }

        impl UpperBounded for $name {
            const MAX: u64 = <$multiplier>::MAX * <$multiplicand>::MAX;
        }
    };
}

mod bounded_uints {
    use UpperBounded;

    impl_bounded!(U8, u8);
    impl_bounded!(U16, u16);
    impl_bounded!(U32, u32);
    impl_bounded!(U64, u64);

    impl_bounded_product!(U32MulU8, U32, U8, u64);
    impl_bounded_product!(U32MulU16, U32, U16, u64);

    impl UpperBounded for std::num::NonZeroU8 {
        const MAX: u64 = u8::MAX as u64;
    }
}

use bounded_uints::*;

/// Implement the multiplication operator for $lhs * $rhs giving $output, which
/// is internally represented as $inner. The operation is statically checked
/// to ensure the product won't overflow $inner, nor exceed <$output>::MAX.
macro_rules! impl_mul {
    ( ($lhs:ty , $rhs:ty) => ($output:ty, $inner:ty) ) => {
        impl std::ops::Mul<$rhs> for $lhs {
            type Output = $output;

            fn mul(self, rhs: $rhs) -> Self::Output {
                static_assertions::const_assert!(<$output>::MAX <= <$inner>::MAX as u64);
                static_assertions::const_assert!(<$lhs>::MAX * <$rhs>::MAX <= <$output>::MAX);

                let lhs: $inner = self.get().into();
                let rhs: $inner = rhs.get().into();
                Self::Output::new(lhs.checked_mul(rhs).expect("infallible"))
            }
        }
    };
}

impl_mul!((U8, std::num::NonZeroU8) => (U16, u16));
impl_mul!((U32, std::num::NonZeroU8) => (U32MulU8, u64));
impl_mul!((U32, U16) => (U32MulU16, u64));

impl std::ops::Add<U32MulU16> for U32MulU8 {
    type Output = U64;

    fn add(self, rhs: U32MulU16) -> Self::Output {
        static_assertions::const_assert!(U32MulU8::MAX + U32MulU16::MAX < U64::MAX);
        let lhs: u64 = self.get();
        let rhs: u64 = rhs.get();
        Self::Output::new(lhs.checked_add(rhs).expect("infallible"))
    }
}

const MAX_IPMA_ASSOCIATION_COUNT: U8 = U8::new(u8::MAX);

/// After reading only the `entry_count` field of an ipma box, we can check its
/// basic validity and calculate (assuming validity) the number of associations
/// which will be contained (allowing preallocation of the storage).
/// All the arithmetic is compile-time verified to not overflow via supporting
/// types implementing the UpperBounded trait. Types are declared explicitly to
/// show there isn't any accidental inference to primitive types.
///
/// See ISOBMFF (ISO 14496-12:2020 § 8.11.14.1
fn calculate_ipma_total_associations(
    version: u8,
    bytes_left: u64,
    entry_count: U32,
    num_association_bytes: std::num::NonZeroU8,
) -> Result<usize> {
    let min_entry_bytes =
        std::num::NonZeroU8::new(1 /* association_count */ + if version == 0 { 2 } else { 4 })
            .unwrap();

    let total_non_association_bytes: U32MulU8 = entry_count * min_entry_bytes;
    let total_association_bytes: u64 =
        if let Some(difference) = bytes_left.checked_sub(total_non_association_bytes.get()) {
            // All the storage for the `essential` and `property_index` parts (assuming a valid ipma box size)
            difference
        } else {
            return Err(Error::InvalidData(
                "ipma box below minimum size for entry_count",
            ));
        };

    let max_association_bytes_per_entry: U16 = MAX_IPMA_ASSOCIATION_COUNT * num_association_bytes;
    let max_total_association_bytes: U32MulU16 = entry_count * max_association_bytes_per_entry;
    let max_bytes_left: U64 = total_non_association_bytes + max_total_association_bytes;

    if bytes_left > max_bytes_left.get() {
        return Err(Error::InvalidData(
            "ipma box exceeds maximum size for entry_count",
        ));
    }

    let total_associations: u64 = total_association_bytes / u64::from(num_association_bytes.get());

    Ok(total_associations.try_into()?)
}

/// Parse an ItemPropertyAssociation box
///
/// See ISOBMFF (ISO 14496-12:2020 § 8.11.14.1
fn read_ipma<T: Read>(
    src: &mut BMFFBox<T>,
    strictness: ParseStrictness,
    version: u8,
    flags: u32,
) -> Result<TryVec<ItemPropertyAssociationEntry>> {
    let entry_count = be_u32(src)?;
    let num_association_bytes =
        std::num::NonZeroU8::new(if flags & 1 == 1 { 2 } else { 1 }).unwrap();

    let total_associations = calculate_ipma_total_associations(
        version,
        src.bytes_left(),
        U32::new(entry_count),
        num_association_bytes,
    )?;
    // Assuming most items will have at least `MIN_PROPERTIES` and knowing the
    // total number of item -> property associations (`total_associations`),
    // we can provide a good estimate for how many elements we'll need in this
    // vector, even though we don't know precisely how many items there will be
    // properties for.
    let mut entries = TryVec::<ItemPropertyAssociationEntry>::with_capacity(
        total_associations / ItemPropertiesBox::MIN_PROPERTIES,
    )?;

    for _ in 0..entry_count {
        let item_id = ItemId::read(src, version)?;

        if let Some(previous_association) = entries.last() {
            #[allow(clippy::comparison_chain)]
            if previous_association.item_id > item_id {
                return Err(Error::InvalidData(
                    "Each ItemPropertyAssociation box shall be ordered by increasing item_ID",
                ));
            } else if previous_association.item_id == item_id {
                return Err(Error::InvalidData("There shall be at most one association box for each item_ID, in any ItemPropertyAssociation box"));
            }
        }

        let association_count = src.read_u8()?;
        let mut associations = TryVec::with_capacity(association_count.to_usize())?;
        for _ in 0..association_count {
            let association = src
                .take(num_association_bytes.get().into())
                .read_into_try_vec()?;
            let mut association = BitReader::new(association.as_slice());
            let essential = association.read_bool()?;
            let property_index =
                PropertyIndex(association.read_u16(association.remaining().try_into()?)?);
            associations.push(Association {
                essential,
                property_index,
            })?;
        }

        entries.push(ItemPropertyAssociationEntry {
            item_id,
            associations,
        })?;
    }

    check_parser_state!(src.content);

    if version != 0 {
        if let Some(ItemPropertyAssociationEntry {
            item_id: max_item_id,
            ..
        }) = entries.last()
        {
            if *max_item_id <= ItemId(u16::MAX.into()) {
                fail_if(
                    strictness == ParseStrictness::Strict,
                    "The ipma version 0 should be used unless 32-bit item_ID values are needed \
                     per ISOBMFF (ISO 14496-12:2020 § 8.11.14.1",
                )?;
            }
        }
    }

    trace!("read_ipma -> {:#?}", entries);

    Ok(entries)
}

/// Parse an ItemPropertyContainerBox
///
/// See ISOBMFF (ISO 14496-12:2020 § 8.11.14.1
fn read_ipco<T: Read>(
    src: &mut BMFFBox<T>,
    strictness: ParseStrictness,
) -> Result<TryHashMap<PropertyIndex, ItemProperty>> {
    let mut properties = TryHashMap::with_capacity(ItemPropertiesBox::MIN_PROPERTIES)?;

    let mut index = PropertyIndex(1); // ipma uses 1-based indexing
    let mut iter = src.box_iter();
    while let Some(mut b) = iter.next_box()? {
        let property = match b.head.name {
            BoxType::AuxiliaryTypeProperty => ItemProperty::AuxiliaryType(read_auxc(&mut b)?),
            BoxType::AV1CodecConfigurationBox => ItemProperty::AV1Config(read_av1c(&mut b)?),
            BoxType::ColourInformationBox => ItemProperty::Colour(read_colr(&mut b, strictness)?),
            BoxType::ImageMirror => ItemProperty::Mirroring(read_imir(&mut b)?),
            BoxType::ImageRotation => ItemProperty::Rotation(read_irot(&mut b)?),
            BoxType::ImageSpatialExtentsProperty => {
                ItemProperty::ImageSpatialExtents(read_ispe(&mut b)?)
            }
            BoxType::PixelAspectRatioBox => ItemProperty::PixelAspectRatio(read_pasp(&mut b)?),
            BoxType::PixelInformationBox => ItemProperty::Channels(read_pixi(&mut b)?),

            other_box_type => {
                // Even if we didn't do anything with other property types, we still store
                // a record at the index to identify invalid indices in ipma boxes
                skip_box_remain(&mut b)?;
                let item_property = match other_box_type {
                    BoxType::AV1LayeredImageIndexingProperty => ItemProperty::LayeredImageIndexing,
                    BoxType::CleanApertureBox => ItemProperty::CleanAperture,
                    BoxType::LayerSelectorProperty => ItemProperty::LayerSelection,
                    BoxType::OperatingPointSelectorProperty => ItemProperty::OperatingPointSelector,
                    _ => {
                        warn!("No ItemProperty variant for {:?}", other_box_type);
                        ItemProperty::Unsupported(other_box_type)
                    }
                };
                debug!("Storing empty record {:?}", item_property);
                item_property
            }
        };
        properties.insert(index, property)?;

        index = PropertyIndex(
            index
                .0
                .checked_add(1) // must include ignored properties to have correct indexes
                .ok_or(Error::InvalidData("ipco index overflow"))?,
        );

        check_parser_state!(b.content);
    }

    Ok(properties)
}

#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct ImageSpatialExtentsProperty {
    image_width: u32,
    image_height: u32,
}

/// Parse image spatial extents property
///
/// See HEIF (ISO 23008-12:2017) § 6.5.3.1
fn read_ispe<T: Read>(src: &mut BMFFBox<T>) -> Result<ImageSpatialExtentsProperty> {
    if read_fullbox_version_no_flags(src)? != 0 {
        return Err(Error::Unsupported("ispe version"));
    }

    let image_width = be_u32(src)?;
    let image_height = be_u32(src)?;

    Ok(ImageSpatialExtentsProperty {
        image_width,
        image_height,
    })
}

#[repr(C)]
#[derive(Debug)]
pub struct PixelAspectRatio {
    h_spacing: u32,
    v_spacing: u32,
}

/// Parse pixel aspect ratio property
///
/// See HEIF (ISO 23008-12:2017) § 6.5.4.1
/// See ISOBMFF (ISO 14496-12:2020) § 12.1.4.2
fn read_pasp<T: Read>(src: &mut BMFFBox<T>) -> Result<PixelAspectRatio> {
    let h_spacing = be_u32(src)?;
    let v_spacing = be_u32(src)?;

    Ok(PixelAspectRatio {
        h_spacing,
        v_spacing,
    })
}

#[derive(Debug)]
pub struct PixelInformation {
    bits_per_channel: TryVec<u8>,
}

/// Parse pixel information
/// See HEIF (ISO 23008-12:2017) § 6.5.6
fn read_pixi<T: Read>(src: &mut BMFFBox<T>) -> Result<PixelInformation> {
    let version = read_fullbox_version_no_flags(src)?;
    if version != 0 {
        return Err(Error::Unsupported("pixi version"));
    }

    let num_channels = src.read_u8()?;
    let mut bits_per_channel = TryVec::with_capacity(num_channels.to_usize())?;
    let num_channels_read = src.try_read_to_end(&mut bits_per_channel)?;

    if u8::try_from(num_channels_read)? != num_channels {
        return Err(Error::InvalidData("invalid num_channels"));
    }

    check_parser_state!(src.content);
    Ok(PixelInformation { bits_per_channel })
}

/// Despite [Rec. ITU-T H.273] (12/2016) defining the CICP fields as having a
/// range of 0-255, and only a small fraction of those values being used,
/// ISOBMFF (ISO 14496-12:2020) § 12.1.5 defines them as 16-bit values in the
/// `colr` box. Since we have no use for the additional range, and it would
/// complicate matters later, we fallibly convert before storing the input.
///
/// [Rec. ITU-T H.273]: https://www.itu.int/rec/T-REC-H.273-201612-I/en
#[repr(C)]
#[derive(Debug)]
pub struct NclxColourInformation {
    colour_primaries: u8,
    transfer_characteristics: u8,
    matrix_coefficients: u8,
    full_range_flag: bool,
}

/// The raw bytes of the ICC profile
#[repr(C)]
pub struct IccColourInformation {
    bytes: TryVec<u8>,
}

impl fmt::Debug for IccColourInformation {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        f.debug_struct("IccColourInformation")
            .field("data", &format_args!("{} bytes", self.bytes.len()))
            .finish()
    }
}

#[repr(C)]
#[derive(Debug)]
pub enum ColourInformation {
    Nclx(NclxColourInformation),
    Icc(IccColourInformation, FourCC),
}

impl ColourInformation {
    fn colour_type(&self) -> FourCC {
        match self {
            Self::Nclx(_) => FourCC::from(*b"nclx"),
            Self::Icc(_, colour_type) => colour_type.clone(),
        }
    }
}

/// Parse colour information
/// See ISOBMFF (ISO 14496-12:2020) § 12.1.5
fn read_colr<T: Read>(
    src: &mut BMFFBox<T>,
    strictness: ParseStrictness,
) -> Result<ColourInformation> {
    let colour_type = be_u32(src)?.to_be_bytes();

    match &colour_type {
        b"nclx" => {
            const NUM_RESERVED_BITS: u8 = 7;
            let colour_primaries = be_u16(src)?.try_into()?;
            let transfer_characteristics = be_u16(src)?.try_into()?;
            let matrix_coefficients = be_u16(src)?.try_into()?;
            let bytes = src.read_into_try_vec()?;
            let mut bit_reader = BitReader::new(&bytes);
            let full_range_flag = bit_reader.read_bool()?;
            if bit_reader.remaining() != NUM_RESERVED_BITS.into() {
                error!(
                    "read_colr expected {} reserved bits, found {}",
                    NUM_RESERVED_BITS,
                    bit_reader.remaining()
                );
                return Err(Error::InvalidData("Unexpected size for colr box"));
            }
            if bit_reader.read_u8(NUM_RESERVED_BITS)? != 0 {
                fail_if(
                    strictness != ParseStrictness::Permissive,
                    "The 7 reserved bits at the end of the ColourInformationBox \
                     for colour_type == 'nclx' must be 0 \
                     per ISOBMFF (ISO 14496-12:2020) § 12.1.5.2",
                )?;
            }

            Ok(ColourInformation::Nclx(NclxColourInformation {
                colour_primaries,
                transfer_characteristics,
                matrix_coefficients,
                full_range_flag,
            }))
        }
        b"rICC" | b"prof" => Ok(ColourInformation::Icc(
            IccColourInformation {
                bytes: src.read_into_try_vec()?,
            },
            FourCC::from(colour_type),
        )),
        _ => {
            error!("read_colr colour_type: {:?}", colour_type);
            Err(Error::InvalidData(
                "Unsupported colour_type for ColourInformationBox",
            ))
        }
    }
}

#[repr(C)]
#[derive(Clone, Copy, Debug)]
/// Rotation in the positive (that is, anticlockwise) direction
/// Visualized in terms of starting with (⥠) UPWARDS HARPOON WITH BARB LEFT FROM BAR
/// similar to a DIGIT ONE (1)
pub enum ImageRotation {
    /// ⥠ UPWARDS HARPOON WITH BARB LEFT FROM BAR
    D0,
    /// ⥞ LEFTWARDS HARPOON WITH BARB DOWN FROM BAR
    D90,
    /// ⥝ DOWNWARDS HARPOON WITH BARB RIGHT FROM BAR
    D180,
    /// ⥛  RIGHTWARDS HARPOON WITH BARB UP FROM BAR
    D270,
}

/// Parse image rotation box
/// See HEIF (ISO 23008-12:2017) § 6.5.10
fn read_irot<T: Read>(src: &mut BMFFBox<T>) -> Result<ImageRotation> {
    let irot = src.read_into_try_vec()?;
    let mut irot = BitReader::new(&irot);
    let _reserved = irot.read_u8(6)?;
    let image_rotation = match irot.read_u8(2)? {
        0 => ImageRotation::D0,
        1 => ImageRotation::D90,
        2 => ImageRotation::D180,
        3 => ImageRotation::D270,
        _ => unreachable!(),
    };

    check_parser_state!(src.content);

    Ok(image_rotation)
}

/// The axis about which the image is mirrored (opposite of flip)
/// Visualized in terms of starting with (⥠) UPWARDS HARPOON WITH BARB LEFT FROM BAR
/// similar to a DIGIT ONE (1)
#[repr(C)]
#[derive(Debug)]
pub enum ImageMirror {
    /// top and bottom parts exchanged
    /// ⥡ DOWNWARDS HARPOON WITH BARB LEFT FROM BAR
    TopBottom,
    /// left and right parts exchanged
    /// ⥜ UPWARDS HARPOON WITH BARB RIGHT FROM BAR
    LeftRight,
}

/// Parse image mirroring box
/// See HEIF (ISO 23008-12:2017) § 6.5.12<br />
/// Note: [ISO/IEC 23008-12:2017/DAmd 2](https://www.iso.org/standard/81688.html)
/// reverses the interpretation of the 'imir' box in § 6.5.12.3:
/// > `axis` specifies a vertical (`axis` = 0) or horizontal (`axis` = 1) axis
/// > for the mirroring operation.
///
/// is replaced with:
/// > `mode` specifies how the mirroring is performed: 0 indicates that the top
/// > and bottom parts of the image are exchanged; 1 specifies that the left and
/// > right parts are exchanged.
/// >
/// > NOTE: In Exif, orientation tag can be used to signal mirroring operations.
/// > Exif orientation tag 4 corresponds to `mode` = 0 of `ImageMirror`, and
/// > Exif orientation tag 2 corresponds to `mode` = 1 accordingly.
///
/// This implementation conforms to the text in Draft Amendment 2, which is the
/// opposite of the published standard as of 4 June 2021.
fn read_imir<T: Read>(src: &mut BMFFBox<T>) -> Result<ImageMirror> {
    let imir = src.read_into_try_vec()?;
    let mut imir = BitReader::new(&imir);
    let _reserved = imir.read_u8(7)?;
    let image_mirror = match imir.read_u8(1)? {
        0 => ImageMirror::TopBottom,
        1 => ImageMirror::LeftRight,
        _ => unreachable!(),
    };

    check_parser_state!(src.content);

    Ok(image_mirror)
}

/// See HEIF (ISO 23008-12:2017) § 6.5.8
#[derive(Debug, PartialEq)]
pub struct AuxiliaryTypeProperty {
    aux_type: TryString,
    aux_subtype: TryString,
}

/// Parse image properties for auxiliary images
/// See HEIF (ISO 23008-12:2017) § 6.5.8
fn read_auxc<T: Read>(src: &mut BMFFBox<T>) -> Result<AuxiliaryTypeProperty> {
    let version = read_fullbox_version_no_flags(src)?;
    if version != 0 {
        return Err(Error::Unsupported("auxC version"));
    }

    let mut aux = TryString::new();
    src.try_read_to_end(&mut aux)?;

    let (aux_type, aux_subtype): (TryString, TryVec<u8>);
    if let Some(nul_byte_pos) = aux.iter().position(|&b| b == b'\0') {
        let (a, b) = aux.as_slice().split_at(nul_byte_pos);
        aux_type = a.try_into()?;
        aux_subtype = (&b[1..]).try_into()?;
    } else {
        aux_type = aux;
        aux_subtype = TryVec::new();
    }

    Ok(AuxiliaryTypeProperty {
        aux_type,
        aux_subtype,
    })
}

/// Parse an item location box inside a meta box
/// See ISOBMFF (ISO 14496-12:2020) § 8.11.3
fn read_iloc<T: Read>(src: &mut BMFFBox<T>) -> Result<TryHashMap<ItemId, ItemLocationBoxItem>> {
    let version: IlocVersion = read_fullbox_version_no_flags(src)?.try_into()?;

    let iloc = src.read_into_try_vec()?;
    let mut iloc = BitReader::new(&iloc);

    let offset_size: IlocFieldSize = iloc.read_u8(4)?.try_into()?;
    let length_size: IlocFieldSize = iloc.read_u8(4)?.try_into()?;
    let base_offset_size: IlocFieldSize = iloc.read_u8(4)?.try_into()?;

    let index_size: Option<IlocFieldSize> = match version {
        IlocVersion::One | IlocVersion::Two => Some(iloc.read_u8(4)?.try_into()?),
        IlocVersion::Zero => {
            let _reserved = iloc.read_u8(4)?;
            None
        }
    };

    let item_count = match version {
        IlocVersion::Zero | IlocVersion::One => iloc.read_u32(16)?,
        IlocVersion::Two => iloc.read_u32(32)?,
    };

    let mut items = TryHashMap::with_capacity(item_count.to_usize())?;

    for _ in 0..item_count {
        let item_id = ItemId(match version {
            IlocVersion::Zero | IlocVersion::One => iloc.read_u32(16)?,
            IlocVersion::Two => iloc.read_u32(32)?,
        });

        // The spec isn't entirely clear how an `iloc` should be interpreted for version 0,
        // which has no `construction_method` field. It does say:
        // "For maximum compatibility, version 0 of this box should be used in preference to
        //  version 1 with `construction_method==0`, or version 2 when possible."
        // We take this to imply version 0 can be interpreted as using file offsets.
        let construction_method = match version {
            IlocVersion::Zero => ConstructionMethod::File,
            IlocVersion::One | IlocVersion::Two => {
                let _reserved = iloc.read_u16(12)?;
                match iloc.read_u16(4)? {
                    0 => ConstructionMethod::File,
                    1 => ConstructionMethod::Idat,
                    2 => ConstructionMethod::Item,
                    _ => return Err(Error::InvalidData("construction_method is taken from the set 0, 1 or 2 per ISOBMFF (ISO 14496-12:2020) § 8.11.3.3"))
                }
            }
        };

        let data_reference_index = iloc.read_u16(16)?;
        if data_reference_index != 0 {
            return Err(Error::Unsupported(
                "external file references (iloc.data_reference_index != 0) are not supported",
            ));
        }
        let base_offset = iloc.read_u64(base_offset_size.as_bits())?;
        let extent_count = iloc.read_u16(16)?;

        if extent_count < 1 {
            return Err(Error::InvalidData(
                "extent_count must have a value 1 or greater per ISOBMFF (ISO 14496-12:2020) § 8.11.3.3",
            ));
        }

        // "If only one extent is used (extent_count = 1) then either or both of the
        //  offset and length may be implied"
        if extent_count != 1
            && (offset_size == IlocFieldSize::Zero || length_size == IlocFieldSize::Zero)
        {
            return Err(Error::InvalidData(
                "extent_count != 1 requires explicit offset and length per ISOBMFF (ISO 14496-12:2020) § 8.11.3.3",
            ));
        }

        let mut extents = TryVec::with_capacity(extent_count.to_usize())?;

        for _ in 0..extent_count {
            // Parsed but currently ignored, see `Extent`
            let _extent_index = match &index_size {
                None | Some(IlocFieldSize::Zero) => None,
                Some(index_size) => {
                    debug_assert!(version == IlocVersion::One || version == IlocVersion::Two);
                    Some(iloc.read_u64(index_size.as_bits())?)
                }
            };

            // Per ISOBMFF (ISO 14496-12:2020) § 8.11.3.1:
            // "If the offset is not identified (the field has a length of zero), then the
            //  beginning of the source (offset 0) is implied"
            // This behavior will follow from BitReader::read_u64(0) -> 0.
            let extent_offset = iloc.read_u64(offset_size.as_bits())?;
            let extent_length = iloc.read_u64(length_size.as_bits())?.try_into()?;

            // "If the length is not specified, or specified as zero, then the entire length of
            //  the source is implied" (ibid)
            let offset = base_offset
                .checked_add(extent_offset)
                .ok_or(Error::InvalidData("offset calculation overflow"))?;
            let extent = if extent_length == 0 {
                Extent::ToEnd { offset }
            } else {
                Extent::WithLength {
                    offset,
                    len: extent_length,
                }
            };

            extents.push(extent)?;
        }

        let loc = ItemLocationBoxItem {
            construction_method,
            extents,
        };

        if items.insert(item_id, loc)?.is_some() {
            return Err(Error::InvalidData("duplicate item_ID in iloc"));
        }
    }

    if iloc.remaining() == 0 {
        Ok(items)
    } else {
        Err(Error::InvalidData("invalid iloc size"))
    }
}

/// Read the contents of a box, including sub boxes.
pub fn read_mp4<T: Read>(f: &mut T) -> Result<MediaContext> {
    let mut context = None;
    let mut found_ftyp = false;
    // TODO(kinetik): Top-level parsing should handle zero-sized boxes
    // rather than throwing an error.
    let mut iter = BoxIter::new(f);
    while let Some(mut b) = iter.next_box()? {
        // box ordering: ftyp before any variable length box (inc. moov),
        // but may not be first box in file if file signatures etc. present
        // fragmented mp4 order: ftyp, moov, pairs of moof/mdat (1-multiple), mfra

        // "special": uuid, wide (= 8 bytes)
        // isom: moov, mdat, free, skip, udta, ftyp, moof, mfra
        // iso2: pdin, meta
        // iso3: meco
        // iso5: styp, sidx, ssix, prft
        // unknown, maybe: id32

        // qt: pnot

        // possibly allow anything where all printable and/or all lowercase printable
        // "four printable characters from the ISO 8859-1 character set"
        match b.head.name {
            BoxType::FileTypeBox => {
                let ftyp = read_ftyp(&mut b)?;
                found_ftyp = true;
                debug!("{:?}", ftyp);
            }
            BoxType::MovieBox => {
                context = Some(read_moov(&mut b, context)?);
            }
            #[cfg(feature = "meta-xml")]
            BoxType::MetadataBox => {
                if let Some(ctx) = &mut context {
                    ctx.metadata = Some(read_meta(&mut b));
                }
            }
            _ => skip_box_content(&mut b)?,
        };
        check_parser_state!(b.content);
        if context.is_some() {
            debug!(
                "found moov {}, could stop pure 'moov' parser now",
                if found_ftyp {
                    "and ftyp"
                } else {
                    "but no ftyp"
                }
            );
        }
    }

    // XXX(kinetik): This isn't perfect, as a "moov" with no contents is
    // treated as okay but we haven't found anything useful.  Needs more
    // thought for clearer behaviour here.
    context.ok_or(Error::NoMoov)
}

/// Parse a Movie Header Box
/// See ISOBMFF (ISO 14496-12:2020) § 8.2.2
fn parse_mvhd<T: Read>(f: &mut BMFFBox<T>) -> Result<Option<MediaTimeScale>> {
    let mvhd = read_mvhd(f)?;
    debug!("{:?}", mvhd);
    if mvhd.timescale == 0 {
        return Err(Error::InvalidData("zero timescale in mdhd"));
    }
    let timescale = Some(MediaTimeScale(u64::from(mvhd.timescale)));
    Ok(timescale)
}

/// Parse a Movie Box
/// See ISOBMFF (ISO 14496-12:2020) § 8.2.1
/// Note that despite the spec indicating "exactly one" moov box should exist at
/// the file container level, we support reading and merging multiple moov boxes
/// such as with tests/test_case_1185230.mp4.
fn read_moov<T: Read>(f: &mut BMFFBox<T>, context: Option<MediaContext>) -> Result<MediaContext> {
    let MediaContext {
        mut timescale,
        mut tracks,
        mut mvex,
        mut psshs,
        mut userdata,
        #[cfg(feature = "meta-xml")]
        metadata,
    } = context.unwrap_or_default();

    let mut iter = f.box_iter();
    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::MovieHeaderBox => {
                timescale = parse_mvhd(&mut b)?;
            }
            BoxType::TrackBox => {
                let mut track = Track::new(tracks.len());
                read_trak(&mut b, &mut track)?;
                tracks.push(track)?;
            }
            BoxType::MovieExtendsBox => {
                mvex = Some(read_mvex(&mut b)?);
                debug!("{:?}", mvex);
            }
            BoxType::ProtectionSystemSpecificHeaderBox => {
                let pssh = read_pssh(&mut b)?;
                debug!("{:?}", pssh);
                psshs.push(pssh)?;
            }
            BoxType::UserdataBox => {
                userdata = Some(read_udta(&mut b));
                debug!("{:?}", userdata);
                if let Some(Err(_)) = userdata {
                    // There was an error parsing userdata. Such failures are not fatal to overall
                    // parsing, just skip the rest of the box.
                    skip_box_remain(&mut b)?;
                }
            }
            _ => skip_box_content(&mut b)?,
        };
        check_parser_state!(b.content);
    }

    Ok(MediaContext {
        timescale,
        tracks,
        mvex,
        psshs,
        userdata,
        #[cfg(feature = "meta-xml")]
        metadata,
    })
}

fn read_pssh<T: Read>(src: &mut BMFFBox<T>) -> Result<ProtectionSystemSpecificHeaderBox> {
    let len = src.bytes_left();
    let mut box_content = read_buf(src, len)?;
    let (system_id, kid, data) = {
        let pssh = &mut Cursor::new(&box_content);

        let (version, _) = read_fullbox_extra(pssh)?;

        let system_id = read_buf(pssh, 16)?;

        let mut kid = TryVec::<ByteData>::new();
        if version > 0 {
            let count = be_u32(pssh)?;
            for _ in 0..count {
                let item = read_buf(pssh, 16)?;
                kid.push(item)?;
            }
        }

        let data_size = be_u32(pssh)?;
        let data = read_buf(pssh, data_size.into())?;

        (system_id, kid, data)
    };

    let mut pssh_box = TryVec::new();
    write_be_u32(&mut pssh_box, src.head.size.try_into()?)?;
    pssh_box.extend_from_slice(b"pssh")?;
    pssh_box.append(&mut box_content)?;

    Ok(ProtectionSystemSpecificHeaderBox {
        system_id,
        kid,
        data,
        box_content: pssh_box,
    })
}

/// Parse a Movie Extends Box
/// See ISOBMFF (ISO 14496-12:2020) § 8.8.1
fn read_mvex<T: Read>(src: &mut BMFFBox<T>) -> Result<MovieExtendsBox> {
    let mut iter = src.box_iter();
    let mut fragment_duration = None;
    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::MovieExtendsHeaderBox => {
                let duration = read_mehd(&mut b)?;
                fragment_duration = Some(duration);
            }
            _ => skip_box_content(&mut b)?,
        }
    }
    Ok(MovieExtendsBox { fragment_duration })
}

fn read_mehd<T: Read>(src: &mut BMFFBox<T>) -> Result<MediaScaledTime> {
    let (version, _) = read_fullbox_extra(src)?;
    let fragment_duration = match version {
        1 => be_u64(src)?,
        0 => u64::from(be_u32(src)?),
        _ => return Err(Error::InvalidData("unhandled mehd version")),
    };
    Ok(MediaScaledTime(fragment_duration))
}

/// Parse a Track Box
/// See ISOBMFF (ISO 14496-12:2020) § 8.3.1.
fn read_trak<T: Read>(f: &mut BMFFBox<T>, track: &mut Track) -> Result<()> {
    let mut iter = f.box_iter();
    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::TrackHeaderBox => {
                let tkhd = read_tkhd(&mut b)?;
                track.track_id = Some(tkhd.track_id);
                track.tkhd = Some(tkhd.clone());
                debug!("{:?}", tkhd);
            }
            BoxType::EditBox => read_edts(&mut b, track)?,
            BoxType::MediaBox => read_mdia(&mut b, track)?,
            _ => skip_box_content(&mut b)?,
        };
        check_parser_state!(b.content);
    }
    Ok(())
}

fn read_edts<T: Read>(f: &mut BMFFBox<T>, track: &mut Track) -> Result<()> {
    let mut iter = f.box_iter();
    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::EditListBox => {
                let elst = read_elst(&mut b)?;
                if elst.edits.is_empty() {
                    debug!("empty edit list");
                    continue;
                }
                let mut empty_duration = 0;
                let mut idx = 0;
                if elst.edits[idx].media_time == -1 {
                    if elst.edits.len() < 2 {
                        debug!("expected additional edit, ignoring edit list");
                        continue;
                    }
                    empty_duration = elst.edits[idx].segment_duration;
                    idx += 1;
                }
                track.empty_duration = Some(MediaScaledTime(empty_duration));
                let media_time = elst.edits[idx].media_time;
                if media_time < 0 {
                    debug!("unexpected negative media time in edit");
                }
                track.media_time = Some(TrackScaledTime::<u64>(
                    std::cmp::max(0, media_time) as u64,
                    track.id,
                ));
                if elst.edits.len() > 2 {
                    debug!("ignoring edit list with {} entries", elst.edits.len());
                }
                debug!("{:?}", elst);
            }
            _ => skip_box_content(&mut b)?,
        };
        check_parser_state!(b.content);
    }
    Ok(())
}

#[allow(clippy::type_complexity)] // Allow the complex return, maybe rework in future
fn parse_mdhd<T: Read>(
    f: &mut BMFFBox<T>,
    track: &mut Track,
) -> Result<(
    MediaHeaderBox,
    Option<TrackScaledTime<u64>>,
    Option<TrackTimeScale<u64>>,
)> {
    let mdhd = read_mdhd(f)?;
    let duration = match mdhd.duration {
        std::u64::MAX => None,
        duration => Some(TrackScaledTime::<u64>(duration, track.id)),
    };
    if mdhd.timescale == 0 {
        return Err(Error::InvalidData("zero timescale in mdhd"));
    }
    let timescale = Some(TrackTimeScale::<u64>(u64::from(mdhd.timescale), track.id));
    Ok((mdhd, duration, timescale))
}

fn read_mdia<T: Read>(f: &mut BMFFBox<T>, track: &mut Track) -> Result<()> {
    let mut iter = f.box_iter();
    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::MediaHeaderBox => {
                let (mdhd, duration, timescale) = parse_mdhd(&mut b, track)?;
                track.duration = duration;
                track.timescale = timescale;
                debug!("{:?}", mdhd);
            }
            BoxType::HandlerBox => {
                let hdlr = read_hdlr(&mut b, ParseStrictness::Permissive)?;

                match hdlr.handler_type.value.as_ref() {
                    b"vide" => track.track_type = TrackType::Video,
                    b"soun" => track.track_type = TrackType::Audio,
                    b"meta" => track.track_type = TrackType::Metadata,
                    _ => (),
                }
                debug!("{:?}", hdlr);
            }
            BoxType::MediaInformationBox => read_minf(&mut b, track)?,
            _ => skip_box_content(&mut b)?,
        };
        check_parser_state!(b.content);
    }
    Ok(())
}

fn read_minf<T: Read>(f: &mut BMFFBox<T>, track: &mut Track) -> Result<()> {
    let mut iter = f.box_iter();
    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::SampleTableBox => read_stbl(&mut b, track)?,
            _ => skip_box_content(&mut b)?,
        };
        check_parser_state!(b.content);
    }
    Ok(())
}

fn read_stbl<T: Read>(f: &mut BMFFBox<T>, track: &mut Track) -> Result<()> {
    let mut iter = f.box_iter();
    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::SampleDescriptionBox => {
                let stsd = read_stsd(&mut b, track)?;
                debug!("{:?}", stsd);
                track.stsd = Some(stsd);
            }
            BoxType::TimeToSampleBox => {
                let stts = read_stts(&mut b)?;
                debug!("{:?}", stts);
                track.stts = Some(stts);
            }
            BoxType::SampleToChunkBox => {
                let stsc = read_stsc(&mut b)?;
                debug!("{:?}", stsc);
                track.stsc = Some(stsc);
            }
            BoxType::SampleSizeBox => {
                let stsz = read_stsz(&mut b)?;
                debug!("{:?}", stsz);
                track.stsz = Some(stsz);
            }
            BoxType::ChunkOffsetBox => {
                let stco = read_stco(&mut b)?;
                debug!("{:?}", stco);
                track.stco = Some(stco);
            }
            BoxType::ChunkLargeOffsetBox => {
                let co64 = read_co64(&mut b)?;
                debug!("{:?}", co64);
                track.stco = Some(co64);
            }
            BoxType::SyncSampleBox => {
                let stss = read_stss(&mut b)?;
                debug!("{:?}", stss);
                track.stss = Some(stss);
            }
            BoxType::CompositionOffsetBox => {
                let ctts = read_ctts(&mut b)?;
                debug!("{:?}", ctts);
                track.ctts = Some(ctts);
            }
            _ => skip_box_content(&mut b)?,
        };
        check_parser_state!(b.content);
    }
    Ok(())
}

/// Parse an ftyp box.
/// See ISOBMFF (ISO 14496-12:2020) § 4.3
fn read_ftyp<T: Read>(src: &mut BMFFBox<T>) -> Result<FileTypeBox> {
    let major = be_u32(src)?;
    let minor = be_u32(src)?;
    let bytes_left = src.bytes_left();
    if bytes_left % 4 != 0 {
        return Err(Error::InvalidData("invalid ftyp size"));
    }
    // Is a brand_count of zero valid?
    let brand_count = bytes_left / 4;
    let mut brands = TryVec::with_capacity(brand_count.try_into()?)?;
    for _ in 0..brand_count {
        brands.push(be_u32(src)?.into())?;
    }
    Ok(FileTypeBox {
        major_brand: From::from(major),
        minor_version: minor,
        compatible_brands: brands,
    })
}

/// Parse an mvhd box.
fn read_mvhd<T: Read>(src: &mut BMFFBox<T>) -> Result<MovieHeaderBox> {
    let (version, _) = read_fullbox_extra(src)?;
    match version {
        // 64 bit creation and modification times.
        1 => {
            skip(src, 16)?;
        }
        // 32 bit creation and modification times.
        0 => {
            skip(src, 8)?;
        }
        _ => return Err(Error::InvalidData("unhandled mvhd version")),
    }
    let timescale = be_u32(src)?;
    let duration = match version {
        1 => be_u64(src)?,
        0 => {
            let d = be_u32(src)?;
            if d == std::u32::MAX {
                std::u64::MAX
            } else {
                u64::from(d)
            }
        }
        _ => return Err(Error::InvalidData("unhandled mvhd version")),
    };
    // Skip remaining fields.
    skip(src, 80)?;
    Ok(MovieHeaderBox {
        timescale,
        duration,
    })
}

/// Parse a tkhd box.
fn read_tkhd<T: Read>(src: &mut BMFFBox<T>) -> Result<TrackHeaderBox> {
    let (version, flags) = read_fullbox_extra(src)?;
    let disabled = flags & 0x1u32 == 0 || flags & 0x2u32 == 0;
    match version {
        // 64 bit creation and modification times.
        1 => {
            skip(src, 16)?;
        }
        // 32 bit creation and modification times.
        0 => {
            skip(src, 8)?;
        }
        _ => return Err(Error::InvalidData("unhandled tkhd version")),
    }
    let track_id = be_u32(src)?;
    skip(src, 4)?;
    let duration = match version {
        1 => be_u64(src)?,
        0 => u64::from(be_u32(src)?),
        _ => return Err(Error::InvalidData("unhandled tkhd version")),
    };
    // Skip uninteresting fields.
    skip(src, 16)?;

    let matrix = Matrix {
        a: be_i32(src)?,
        b: be_i32(src)?,
        u: be_i32(src)?,
        c: be_i32(src)?,
        d: be_i32(src)?,
        v: be_i32(src)?,
        x: be_i32(src)?,
        y: be_i32(src)?,
        w: be_i32(src)?,
    };

    let width = be_u32(src)?;
    let height = be_u32(src)?;
    Ok(TrackHeaderBox {
        track_id,
        disabled,
        duration,
        width,
        height,
        matrix,
    })
}

/// Parse a elst box.
/// See ISOBMFF (ISO 14496-12:2020) § 8.6.6
fn read_elst<T: Read>(src: &mut BMFFBox<T>) -> Result<EditListBox> {
    let (version, _) = read_fullbox_extra(src)?;
    let edit_count = be_u32(src)?;
    let mut edits = TryVec::with_capacity(edit_count.to_usize())?;
    for _ in 0..edit_count {
        let (segment_duration, media_time) = match version {
            1 => {
                // 64 bit segment duration and media times.
                (be_u64(src)?, be_i64(src)?)
            }
            0 => {
                // 32 bit segment duration and media times.
                (u64::from(be_u32(src)?), i64::from(be_i32(src)?))
            }
            _ => return Err(Error::InvalidData("unhandled elst version")),
        };
        let media_rate_integer = be_i16(src)?;
        let media_rate_fraction = be_i16(src)?;
        edits.push(Edit {
            segment_duration,
            media_time,
            media_rate_integer,
            media_rate_fraction,
        })?;
    }

    // Padding could be added in some contents.
    skip_box_remain(src)?;

    Ok(EditListBox { edits })
}

/// Parse a mdhd box.
fn read_mdhd<T: Read>(src: &mut BMFFBox<T>) -> Result<MediaHeaderBox> {
    let (version, _) = read_fullbox_extra(src)?;
    let (timescale, duration) = match version {
        1 => {
            // Skip 64-bit creation and modification times.
            skip(src, 16)?;

            // 64 bit duration.
            (be_u32(src)?, be_u64(src)?)
        }
        0 => {
            // Skip 32-bit creation and modification times.
            skip(src, 8)?;

            // 32 bit duration.
            let timescale = be_u32(src)?;
            let duration = {
                // Since we convert the 32-bit duration to 64-bit by
                // upcasting, we need to preserve the special all-1s
                // ("unknown") case by hand.
                let d = be_u32(src)?;
                if d == std::u32::MAX {
                    std::u64::MAX
                } else {
                    u64::from(d)
                }
            };
            (timescale, duration)
        }
        _ => return Err(Error::InvalidData("unhandled mdhd version")),
    };

    // Skip uninteresting fields.
    skip(src, 4)?;

    Ok(MediaHeaderBox {
        timescale,
        duration,
    })
}

/// Parse a stco box.
/// See ISOBMFF (ISO 14496-12:2020) § 8.7.5
fn read_stco<T: Read>(src: &mut BMFFBox<T>) -> Result<ChunkOffsetBox> {
    let (_, _) = read_fullbox_extra(src)?;
    let offset_count = be_u32(src)?;
    let mut offsets = TryVec::with_capacity(offset_count.to_usize())?;
    for _ in 0..offset_count {
        offsets.push(be_u32(src)?.into())?;
    }

    // Padding could be added in some contents.
    skip_box_remain(src)?;

    Ok(ChunkOffsetBox { offsets })
}

/// Parse a co64 box.
/// See ISOBMFF (ISO 14496-12:2020) § 8.7.5
fn read_co64<T: Read>(src: &mut BMFFBox<T>) -> Result<ChunkOffsetBox> {
    let (_, _) = read_fullbox_extra(src)?;
    let offset_count = be_u32(src)?;
    let mut offsets = TryVec::with_capacity(offset_count.to_usize())?;
    for _ in 0..offset_count {
        offsets.push(be_u64(src)?)?;
    }

    // Padding could be added in some contents.
    skip_box_remain(src)?;

    Ok(ChunkOffsetBox { offsets })
}

/// Parse a stss box.
/// See ISOBMFF (ISO 14496-12:2020) § 8.6.2
fn read_stss<T: Read>(src: &mut BMFFBox<T>) -> Result<SyncSampleBox> {
    let (_, _) = read_fullbox_extra(src)?;
    let sample_count = be_u32(src)?;
    let mut samples = TryVec::with_capacity(sample_count.to_usize())?;
    for _ in 0..sample_count {
        samples.push(be_u32(src)?)?;
    }

    // Padding could be added in some contents.
    skip_box_remain(src)?;

    Ok(SyncSampleBox { samples })
}

/// Parse a stsc box.
/// See ISOBMFF (ISO 14496-12:2020) § 8.7.4
fn read_stsc<T: Read>(src: &mut BMFFBox<T>) -> Result<SampleToChunkBox> {
    let (_, _) = read_fullbox_extra(src)?;
    let sample_count = be_u32(src)?;
    let mut samples = TryVec::with_capacity(sample_count.to_usize())?;
    for _ in 0..sample_count {
        let first_chunk = be_u32(src)?;
        let samples_per_chunk = be_u32(src)?;
        let sample_description_index = be_u32(src)?;
        samples.push(SampleToChunk {
            first_chunk,
            samples_per_chunk,
            sample_description_index,
        })?;
    }

    // Padding could be added in some contents.
    skip_box_remain(src)?;

    Ok(SampleToChunkBox { samples })
}

/// Parse a Composition Time to Sample Box
/// See ISOBMFF (ISO 14496-12:2020) § 8.6.1.3
fn read_ctts<T: Read>(src: &mut BMFFBox<T>) -> Result<CompositionOffsetBox> {
    let (version, _) = read_fullbox_extra(src)?;

    let counts = be_u32(src)?;

    if counts
        .checked_mul(8)
        .map_or(true, |bytes| u64::from(bytes) > src.bytes_left())
    {
        return Err(Error::InvalidData("insufficient data in 'ctts' box"));
    }

    let mut offsets = TryVec::with_capacity(counts.to_usize())?;
    for _ in 0..counts {
        let (sample_count, time_offset) = match version {
            // According to spec, Version0 shoule be used when version == 0;
            // however, some buggy contents have negative value when version == 0.
            // So we always use Version1 here.
            0..=1 => {
                let count = be_u32(src)?;
                let offset = TimeOffsetVersion::Version1(be_i32(src)?);
                (count, offset)
            }
            _ => {
                return Err(Error::InvalidData("unsupported version in 'ctts' box"));
            }
        };
        offsets.push(TimeOffset {
            sample_count,
            time_offset,
        })?;
    }

    check_parser_state!(src.content);

    Ok(CompositionOffsetBox { samples: offsets })
}

/// Parse a stsz box.
/// See ISOBMFF (ISO 14496-12:2020) § 8.7.3.2
fn read_stsz<T: Read>(src: &mut BMFFBox<T>) -> Result<SampleSizeBox> {
    let (_, _) = read_fullbox_extra(src)?;
    let sample_size = be_u32(src)?;
    let sample_count = be_u32(src)?;
    let mut sample_sizes = TryVec::new();
    if sample_size == 0 {
        sample_sizes.reserve(sample_count.to_usize())?;
        for _ in 0..sample_count {
            sample_sizes.push(be_u32(src)?)?;
        }
    }

    // Padding could be added in some contents.
    skip_box_remain(src)?;

    Ok(SampleSizeBox {
        sample_size,
        sample_sizes,
    })
}

/// Parse a stts box.
/// See ISOBMFF (ISO 14496-12:2020) § 8.6.1.2
fn read_stts<T: Read>(src: &mut BMFFBox<T>) -> Result<TimeToSampleBox> {
    let (_, _) = read_fullbox_extra(src)?;
    let sample_count = be_u32(src)?;
    let mut samples = TryVec::with_capacity(sample_count.to_usize())?;
    for _ in 0..sample_count {
        let sample_count = be_u32(src)?;
        let sample_delta = be_u32(src)?;
        samples.push(Sample {
            sample_count,
            sample_delta,
        })?;
    }

    // Padding could be added in some contents.
    skip_box_remain(src)?;

    Ok(TimeToSampleBox { samples })
}

/// Parse a VPx Config Box.
fn read_vpcc<T: Read>(src: &mut BMFFBox<T>) -> Result<VPxConfigBox> {
    let (version, _) = read_fullbox_extra(src)?;
    let supported_versions = [0, 1];
    if !supported_versions.contains(&version) {
        return Err(Error::Unsupported("unknown vpcC version"));
    }

    let profile = src.read_u8()?;
    let level = src.read_u8()?;
    let (
        bit_depth,
        colour_primaries,
        chroma_subsampling,
        transfer_characteristics,
        matrix_coefficients,
        video_full_range_flag,
    ) = if version == 0 {
        let (bit_depth, colour_primaries) = {
            let byte = src.read_u8()?;
            ((byte >> 4) & 0x0f, byte & 0x0f)
        };
        // Note, transfer_characteristics was known as transfer_function in v0
        let (chroma_subsampling, transfer_characteristics, video_full_range_flag) = {
            let byte = src.read_u8()?;
            ((byte >> 4) & 0x0f, (byte >> 1) & 0x07, (byte & 1) == 1)
        };
        (
            bit_depth,
            colour_primaries,
            chroma_subsampling,
            transfer_characteristics,
            None,
            video_full_range_flag,
        )
    } else {
        let (bit_depth, chroma_subsampling, video_full_range_flag) = {
            let byte = src.read_u8()?;
            ((byte >> 4) & 0x0f, (byte >> 1) & 0x07, (byte & 1) == 1)
        };
        let colour_primaries = src.read_u8()?;
        let transfer_characteristics = src.read_u8()?;
        let matrix_coefficients = src.read_u8()?;

        (
            bit_depth,
            colour_primaries,
            chroma_subsampling,
            transfer_characteristics,
            Some(matrix_coefficients),
            video_full_range_flag,
        )
    };

    let codec_init_size = be_u16(src)?;
    let codec_init = read_buf(src, codec_init_size.into())?;

    // TODO(rillian): validate field value ranges.
    Ok(VPxConfigBox {
        profile,
        level,
        bit_depth,
        colour_primaries,
        chroma_subsampling,
        transfer_characteristics,
        matrix_coefficients,
        video_full_range_flag,
        codec_init,
    })
}

/// See [AV1-ISOBMFF § 2.3.3](https://aomediacodec.github.io/av1-isobmff/#av1codecconfigurationbox-syntax)
fn read_av1c<T: Read>(src: &mut BMFFBox<T>) -> Result<AV1ConfigBox> {
    // We want to store the raw config as well as a structured (parsed) config, so create a copy of
    // the raw config so we have it later, and then parse the structured data from that.
    let raw_config = src.read_into_try_vec()?;
    let mut raw_config_slice = raw_config.as_slice();
    let marker_byte = raw_config_slice.read_u8()?;
    if marker_byte & 0x80 != 0x80 {
        return Err(Error::Unsupported("missing av1C marker bit"));
    }
    if marker_byte & 0x7f != 0x01 {
        return Err(Error::Unsupported("missing av1C marker bit"));
    }
    let profile_byte = raw_config_slice.read_u8()?;
    let profile = (profile_byte & 0xe0) >> 5;
    let level = profile_byte & 0x1f;
    let flags_byte = raw_config_slice.read_u8()?;
    let tier = (flags_byte & 0x80) >> 7;
    let bit_depth = match flags_byte & 0x60 {
        0x60 => 12,
        0x40 => 10,
        _ => 8,
    };
    let monochrome = flags_byte & 0x10 == 0x10;
    let chroma_subsampling_x = (flags_byte & 0x08) >> 3;
    let chroma_subsampling_y = (flags_byte & 0x04) >> 2;
    let chroma_sample_position = flags_byte & 0x03;
    let delay_byte = raw_config_slice.read_u8()?;
    let initial_presentation_delay_present = (delay_byte & 0x10) == 0x10;
    let initial_presentation_delay_minus_one = if initial_presentation_delay_present {
        delay_byte & 0x0f
    } else {
        0
    };

    Ok(AV1ConfigBox {
        profile,
        level,
        tier,
        bit_depth,
        monochrome,
        chroma_subsampling_x,
        chroma_subsampling_y,
        chroma_sample_position,
        initial_presentation_delay_present,
        initial_presentation_delay_minus_one,
        raw_config,
    })
}

fn read_flac_metadata<T: Read>(src: &mut BMFFBox<T>) -> Result<FLACMetadataBlock> {
    let temp = src.read_u8()?;
    let block_type = temp & 0x7f;
    let length = be_u24(src)?.into();
    if length > src.bytes_left() {
        return Err(Error::InvalidData(
            "FLACMetadataBlock larger than parent box",
        ));
    }
    let data = read_buf(src, length)?;
    Ok(FLACMetadataBlock { block_type, data })
}

/// See MPEG-4 Systems (ISO 14496-1:2010) § 7.2.6.5
fn find_descriptor(data: &[u8], esds: &mut ES_Descriptor) -> Result<()> {
    // Tags for elementary stream description
    const ESDESCR_TAG: u8 = 0x03;
    const DECODER_CONFIG_TAG: u8 = 0x04;
    const DECODER_SPECIFIC_TAG: u8 = 0x05;

    let mut remains = data;

    // Descriptor length should be more than 2 bytes.
    while remains.len() > 2 {
        let des = &mut Cursor::new(remains);
        let tag = des.read_u8()?;

        // See MPEG-4 Systems (ISO 14496-1:2010) § 8.3.3 for interpreting size of expandable classes

        let mut end: u32 = 0; // It's u8 without declaration type that is incorrect.
                              // MSB of extend_or_len indicates more bytes, up to 4 bytes.
        for _ in 0..4 {
            if des.position() == remains.len().to_u64() {
                // There's nothing more to read, the 0x80 was actually part of
                // the content, and not an extension size.
                end = des.position() as u32;
                break;
            }
            let extend_or_len = des.read_u8()?;
            end = (end << 7) + u32::from(extend_or_len & 0x7F);
            if (extend_or_len & 0b1000_0000) == 0 {
                end += des.position() as u32;
                break;
            }
        }

        if end.to_usize() > remains.len() || u64::from(end) < des.position() {
            return Err(Error::InvalidData("Invalid descriptor."));
        }

        let descriptor = &remains[des.position().try_into()?..end.to_usize()];

        match tag {
            ESDESCR_TAG => {
                read_es_descriptor(descriptor, esds)?;
            }
            DECODER_CONFIG_TAG => {
                read_dc_descriptor(descriptor, esds)?;
            }
            DECODER_SPECIFIC_TAG => {
                read_ds_descriptor(descriptor, esds)?;
            }
            _ => {
                debug!("Unsupported descriptor, tag {}", tag);
            }
        }

        remains = &remains[end.to_usize()..remains.len()];
        debug!("remains.len(): {}", remains.len());
    }

    Ok(())
}

fn get_audio_object_type(bit_reader: &mut BitReader) -> Result<u16> {
    let mut audio_object_type: u16 = ReadInto::read(bit_reader, 5)?;

    // Extend audio object type, for example, HE-AAC.
    if audio_object_type == 31 {
        let audio_object_type_ext: u16 = ReadInto::read(bit_reader, 6)?;
        audio_object_type = 32 + audio_object_type_ext;
    }
    Ok(audio_object_type)
}

/// See MPEG-4 Systems (ISO 14496-1:2010) § 7.2.6.7 and probably 14496-3 somewhere?
fn read_ds_descriptor(data: &[u8], esds: &mut ES_Descriptor) -> Result<()> {
    #[cfg(feature = "mp4v")]
    // Check if we are in a Visual esda Box.
    if esds.video_codec != CodecType::Unknown {
        esds.decoder_specific_data.extend_from_slice(data)?;
        return Ok(());
    }

    // We are in an Audio esda Box.
    let frequency_table = vec![
        (0x0, 96000),
        (0x1, 88200),
        (0x2, 64000),
        (0x3, 48000),
        (0x4, 44100),
        (0x5, 32000),
        (0x6, 24000),
        (0x7, 22050),
        (0x8, 16000),
        (0x9, 12000),
        (0xa, 11025),
        (0xb, 8000),
        (0xc, 7350),
    ];

    let bit_reader = &mut BitReader::new(data);

    let mut audio_object_type = get_audio_object_type(bit_reader)?;

    let sample_index: u32 = ReadInto::read(bit_reader, 4)?;

    // Sample frequency could be from table, or retrieved from stream directly
    // if index is 0x0f.
    let sample_frequency = match sample_index {
        0x0F => Some(ReadInto::read(bit_reader, 24)?),
        _ => frequency_table
            .iter()
            .find(|item| item.0 == sample_index)
            .map(|x| x.1),
    };

    let channel_configuration: u16 = ReadInto::read(bit_reader, 4)?;

    let extended_audio_object_type = match audio_object_type {
        5 | 29 => Some(5),
        _ => None,
    };

    if audio_object_type == 5 || audio_object_type == 29 {
        // We have an explicit signaling for BSAC extension, should the decoder
        // decode the BSAC extension (all Gecko's AAC decoders do), then this is
        // what the stream will actually look like once decoded.
        let _extended_sample_index = ReadInto::read(bit_reader, 4)?;
        let _extended_sample_frequency: Option<u32> = match _extended_sample_index {
            0x0F => Some(ReadInto::read(bit_reader, 24)?),
            _ => frequency_table
                .iter()
                .find(|item| item.0 == sample_index)
                .map(|x| x.1),
        };
        audio_object_type = get_audio_object_type(bit_reader)?;
        let _extended_channel_configuration = match audio_object_type {
            22 => ReadInto::read(bit_reader, 4)?,
            _ => channel_configuration,
        };
    };

    match audio_object_type {
        1..=4 | 6 | 7 | 17 | 19..=23 => {
            if sample_frequency.is_none() {
                return Err(Error::Unsupported("unknown frequency"));
            }

            // parsing GASpecificConfig

            // If the sampling rate is not one of the rates listed in the right
            // column in Table 4.82, the sampling frequency dependent tables
            // (code tables, scale factor band tables etc.) must be deduced in
            // order for the bitstream payload to be parsed. Since a given
            // sampling frequency is associated with only one sampling frequency
            // table, and since maximum flexibility is desired in the range of
            // possible sampling frequencies, the following table shall be used
            // to associate an implied sampling frequency with the desired
            // sampling frequency dependent tables.
            let sample_frequency_value = match sample_frequency.unwrap() {
                0..=9390 => 8000,
                9391..=11501 => 11025,
                11502..=13855 => 12000,
                13856..=18782 => 16000,
                18783..=23003 => 22050,
                23004..=27712 => 24000,
                27713..=37565 => 32000,
                37566..=46008 => 44100,
                46009..=55425 => 48000,
                55426..=75131 => 64000,
                75132..=92016 => 88200,
                _ => 96000,
            };

            bit_reader.skip(1)?; // frameLengthFlag
            let depend_on_core_order: u8 = ReadInto::read(bit_reader, 1)?;
            if depend_on_core_order > 0 {
                bit_reader.skip(14)?; // codeCoderDelay
            }
            bit_reader.skip(1)?; // extensionFlag

            let channel_counts = match channel_configuration {
                0 => {
                    debug!("Parsing program_config_element for channel counts");

                    bit_reader.skip(4)?; // element_instance_tag
                    bit_reader.skip(2)?; // object_type
                    bit_reader.skip(4)?; // sampling_frequency_index
                    let num_front_channel: u8 = ReadInto::read(bit_reader, 4)?;
                    let num_side_channel: u8 = ReadInto::read(bit_reader, 4)?;
                    let num_back_channel: u8 = ReadInto::read(bit_reader, 4)?;
                    let num_lfe_channel: u8 = ReadInto::read(bit_reader, 2)?;
                    bit_reader.skip(3)?; // num_assoc_data
                    bit_reader.skip(4)?; // num_valid_cc

                    let mono_mixdown_present: bool = ReadInto::read(bit_reader, 1)?;
                    if mono_mixdown_present {
                        bit_reader.skip(4)?; // mono_mixdown_element_number
                    }

                    let stereo_mixdown_present: bool = ReadInto::read(bit_reader, 1)?;
                    if stereo_mixdown_present {
                        bit_reader.skip(4)?; // stereo_mixdown_element_number
                    }

                    let matrix_mixdown_idx_present: bool = ReadInto::read(bit_reader, 1)?;
                    if matrix_mixdown_idx_present {
                        bit_reader.skip(2)?; // matrix_mixdown_idx
                        bit_reader.skip(1)?; // pseudo_surround_enable
                    }
                    let mut _channel_counts = 0;
                    _channel_counts += read_surround_channel_count(bit_reader, num_front_channel)?;
                    _channel_counts += read_surround_channel_count(bit_reader, num_side_channel)?;
                    _channel_counts += read_surround_channel_count(bit_reader, num_back_channel)?;
                    _channel_counts += read_surround_channel_count(bit_reader, num_lfe_channel)?;
                    _channel_counts
                }
                1..=7 => channel_configuration,
                // Amendment 4 of the AAC standard in 2013 below
                11 => 7,      // 6.1 Amendment 4 of the AAC standard in 2013
                12 | 14 => 8, // 7.1 (a/d) of ITU BS.2159
                _ => {
                    return Err(Error::Unsupported("invalid channel configuration"));
                }
            };

            esds.audio_object_type = Some(audio_object_type);
            esds.extended_audio_object_type = extended_audio_object_type;
            esds.audio_sample_rate = Some(sample_frequency_value);
            esds.audio_channel_count = Some(channel_counts);
            if !esds.decoder_specific_data.is_empty() {
                return Err(Error::InvalidData(
                    "There can be only one DecSpecificInfoTag descriptor",
                ));
            }
            esds.decoder_specific_data.extend_from_slice(data)?;

            Ok(())
        }
        _ => Err(Error::Unsupported("unknown aac audio object type")),
    }
}

fn read_surround_channel_count(bit_reader: &mut BitReader, channels: u8) -> Result<u16> {
    let mut count = 0;
    for _ in 0..channels {
        let is_cpe: bool = ReadInto::read(bit_reader, 1)?;
        count += if is_cpe { 2 } else { 1 };
        bit_reader.skip(4)?;
    }
    Ok(count)
}

/// See MPEG-4 Systems (ISO 14496-1:2010) § 7.2.6.6
fn read_dc_descriptor(data: &[u8], esds: &mut ES_Descriptor) -> Result<()> {
    let des = &mut Cursor::new(data);
    let object_profile = des.read_u8()?;

    #[cfg(feature = "mp4v")]
    {
        esds.video_codec = match object_profile {
            0x20..=0x24 => CodecType::MP4V,
            _ => CodecType::Unknown,
        };
    }

    // Skip uninteresting fields.
    skip(des, 12)?;

    if data.len().to_u64() > des.position() {
        find_descriptor(&data[des.position().try_into()?..data.len()], esds)?;
    }

    esds.audio_codec = match object_profile {
        0x40 | 0x66 | 0x67 => CodecType::AAC,
        0x69 | 0x6B => CodecType::MP3,
        _ => CodecType::Unknown,
    };

    debug!(
        "read_dc_descriptor: esds.audio_codec = {:?}",
        esds.audio_codec
    );

    Ok(())
}

/// See MPEG-4 Systems (ISO 14496-1:2010) § 7.2.6.5
fn read_es_descriptor(data: &[u8], esds: &mut ES_Descriptor) -> Result<()> {
    let des = &mut Cursor::new(data);

    skip(des, 2)?;

    let esds_flags = des.read_u8()?;

    // Stream dependency flag, first bit from left most.
    if esds_flags & 0x80 > 0 {
        // Skip uninteresting fields.
        skip(des, 2)?;
    }

    // Url flag, second bit from left most.
    if esds_flags & 0x40 > 0 {
        // Skip uninteresting fields.
        let skip_es_len = u64::from(des.read_u8()?) + 2;
        skip(des, skip_es_len)?;
    }

    if data.len().to_u64() > des.position() {
        find_descriptor(&data[des.position().try_into()?..data.len()], esds)?;
    }

    Ok(())
}

/// See MP4 (ISO 14496-14:2020) § 6.7.2
fn read_esds<T: Read>(src: &mut BMFFBox<T>) -> Result<ES_Descriptor> {
    let (_, _) = read_fullbox_extra(src)?;

    let esds_array = read_buf(src, src.bytes_left())?;

    let mut es_data = ES_Descriptor::default();
    find_descriptor(&esds_array, &mut es_data)?;

    es_data.codec_esds = esds_array;

    Ok(es_data)
}

/// Parse `FLACSpecificBox`.
/// See [Encapsulation of FLAC in ISO Base Media File Format](https://github.com/xiph/flac/blob/master/doc/isoflac.txt) §  3.3.2
fn read_dfla<T: Read>(src: &mut BMFFBox<T>) -> Result<FLACSpecificBox> {
    let (version, flags) = read_fullbox_extra(src)?;
    if version != 0 {
        return Err(Error::Unsupported("unknown dfLa (FLAC) version"));
    }
    if flags != 0 {
        return Err(Error::InvalidData("no-zero dfLa (FLAC) flags"));
    }
    let mut blocks = TryVec::new();
    while src.bytes_left() > 0 {
        let block = read_flac_metadata(src)?;
        blocks.push(block)?;
    }
    // The box must have at least one meta block, and the first block
    // must be the METADATA_BLOCK_STREAMINFO
    if blocks.is_empty() {
        return Err(Error::InvalidData("FLACSpecificBox missing metadata"));
    } else if blocks[0].block_type != 0 {
        return Err(Error::InvalidData(
            "FLACSpecificBox must have STREAMINFO metadata first",
        ));
    } else if blocks[0].data.len() != 34 {
        return Err(Error::InvalidData(
            "FLACSpecificBox STREAMINFO block is the wrong size",
        ));
    }
    Ok(FLACSpecificBox { version, blocks })
}

/// Parse `OpusSpecificBox`.
fn read_dops<T: Read>(src: &mut BMFFBox<T>) -> Result<OpusSpecificBox> {
    let version = src.read_u8()?;
    if version != 0 {
        return Err(Error::Unsupported("unknown dOps (Opus) version"));
    }

    let output_channel_count = src.read_u8()?;
    let pre_skip = be_u16(src)?;
    let input_sample_rate = be_u32(src)?;
    let output_gain = be_i16(src)?;
    let channel_mapping_family = src.read_u8()?;

    let channel_mapping_table = if channel_mapping_family == 0 {
        None
    } else {
        let stream_count = src.read_u8()?;
        let coupled_count = src.read_u8()?;
        let channel_mapping = read_buf(src, output_channel_count.into())?;

        Some(ChannelMappingTable {
            stream_count,
            coupled_count,
            channel_mapping,
        })
    };

    // TODO(kinetik): validate field value ranges.
    Ok(OpusSpecificBox {
        version,
        output_channel_count,
        pre_skip,
        input_sample_rate,
        output_gain,
        channel_mapping_family,
        channel_mapping_table,
    })
}

/// Re-serialize the Opus codec-specific config data as an `OpusHead` packet.
///
/// Some decoders expect the initialization data in the format used by the
/// Ogg and WebM encapsulations. To support this we prepend the `OpusHead`
/// tag and byte-swap the data from big- to little-endian relative to the
/// dOps box.
pub fn serialize_opus_header<W: byteorder::WriteBytesExt + std::io::Write>(
    opus: &OpusSpecificBox,
    dst: &mut W,
) -> Result<()> {
    match dst.write(b"OpusHead") {
        Err(e) => return Err(Error::from(e)),
        Ok(bytes) => {
            if bytes != 8 {
                return Err(Error::InvalidData("Couldn't write OpusHead tag."));
            }
        }
    }
    // In mp4 encapsulation, the version field is 0, but in ogg
    // it is 1. While decoders generally accept zero as well, write
    // out the version of the header we're supporting rather than
    // whatever we parsed out of mp4.
    dst.write_u8(1)?;
    dst.write_u8(opus.output_channel_count)?;
    dst.write_u16::<byteorder::LittleEndian>(opus.pre_skip)?;
    dst.write_u32::<byteorder::LittleEndian>(opus.input_sample_rate)?;
    dst.write_i16::<byteorder::LittleEndian>(opus.output_gain)?;
    dst.write_u8(opus.channel_mapping_family)?;
    match opus.channel_mapping_table {
        None => {}
        Some(ref table) => {
            dst.write_u8(table.stream_count)?;
            dst.write_u8(table.coupled_count)?;
            match dst.write(&table.channel_mapping) {
                Err(e) => return Err(Error::from(e)),
                Ok(bytes) => {
                    if bytes != table.channel_mapping.len() {
                        return Err(Error::InvalidData(
                            "Couldn't write channel mapping table data.",
                        ));
                    }
                }
            }
        }
    };
    Ok(())
}

/// Parse `ALACSpecificBox`.
fn read_alac<T: Read>(src: &mut BMFFBox<T>) -> Result<ALACSpecificBox> {
    let (version, flags) = read_fullbox_extra(src)?;
    if version != 0 {
        return Err(Error::Unsupported("unknown alac (ALAC) version"));
    }
    if flags != 0 {
        return Err(Error::InvalidData("no-zero alac (ALAC) flags"));
    }

    let length = match src.bytes_left() {
        x @ 24 | x @ 48 => x,
        _ => {
            return Err(Error::InvalidData(
                "ALACSpecificBox magic cookie is the wrong size",
            ))
        }
    };
    let data = read_buf(src, length)?;

    Ok(ALACSpecificBox { version, data })
}

/// Parse a Handler Reference Box.<br />
/// See ISOBMFF (ISO 14496-12:2020) § 8.4.3<br />
/// See [\[ISOBMFF\]: reserved (field = 0;) handling is ambiguous](https://github.com/MPEGGroup/FileFormat/issues/36)
fn read_hdlr<T: Read>(src: &mut BMFFBox<T>, strictness: ParseStrictness) -> Result<HandlerBox> {
    if read_fullbox_version_no_flags(src)? != 0 {
        return Err(Error::Unsupported("hdlr version"));
    }

    let pre_defined = be_u32(src)?;
    if pre_defined != 0 {
        fail_if(
            strictness == ParseStrictness::Strict,
            "The HandlerBox 'pre_defined' field shall be 0 \
             per ISOBMFF (ISO 14496-12:2020) § 8.4.3.2",
        )?;
    }

    let handler_type = FourCC::from(be_u32(src)?);

    for _ in 1..=3 {
        let reserved = be_u32(src)?;
        if reserved != 0 {
            fail_if(
                strictness == ParseStrictness::Strict,
                "The HandlerBox 'reserved' fields shall be 0 \
                 per ISOBMFF (ISO 14496-12:2020) § 8.4.3.2",
            )?;
        }
    }

    match std::str::from_utf8(src.read_into_try_vec()?.as_slice()) {
        Ok(name) => {
            match name.bytes().filter(|&b| b == b'\0').count() {
                0 => fail_if(
                    strictness != ParseStrictness::Permissive,
                    "The HandlerBox 'name' field shall be null-terminated \
                     per ISOBMFF (ISO 14496-12:2020) § 8.4.3.2",
                )?,
                1 => (),
                n =>
                // See https://github.com/MPEGGroup/FileFormat/issues/35
                {
                    error!("Found {} nul bytes in {:x?}", n, name);
                    fail_if(
                        strictness == ParseStrictness::Strict,
                        "The HandlerBox 'name' field shall have a NUL byte \
                         only in the final position \
                         per ISOBMFF (ISO 14496-12:2020) § 8.4.3.2",
                    )?
                }
            }
        }
        Err(_) => fail_if(
            strictness != ParseStrictness::Permissive,
            "The HandlerBox 'name' field shall be valid utf8 \
             per ISOBMFF (ISO 14496-12:2020) § 8.4.3.2",
        )?,
    }

    Ok(HandlerBox { handler_type })
}

/// Parse an video description inside an stsd box.
fn read_video_sample_entry<T: Read>(src: &mut BMFFBox<T>) -> Result<SampleEntry> {
    let name = src.get_header().name;
    let codec_type = match name {
        BoxType::AVCSampleEntry | BoxType::AVC3SampleEntry => CodecType::H264,
        BoxType::MP4VideoSampleEntry => CodecType::MP4V,
        BoxType::VP8SampleEntry => CodecType::VP8,
        BoxType::VP9SampleEntry => CodecType::VP9,
        BoxType::AV1SampleEntry => CodecType::AV1,
        BoxType::ProtectedVisualSampleEntry => CodecType::EncryptedVideo,
        BoxType::H263SampleEntry => CodecType::H263,
        _ => {
            debug!("Unsupported video codec, box {:?} found", name);
            CodecType::Unknown
        }
    };

    // Skip uninteresting fields.
    skip(src, 6)?;

    let data_reference_index = be_u16(src)?;

    // Skip uninteresting fields.
    skip(src, 16)?;

    let width = be_u16(src)?;
    let height = be_u16(src)?;

    // Skip uninteresting fields.
    skip(src, 50)?;

    // Skip clap/pasp/etc. for now.
    let mut codec_specific = None;
    let mut protection_info = TryVec::new();
    let mut iter = src.box_iter();
    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::AVCConfigurationBox => {
                if (name != BoxType::AVCSampleEntry
                    && name != BoxType::AVC3SampleEntry
                    && name != BoxType::ProtectedVisualSampleEntry)
                    || codec_specific.is_some()
                {
                    return Err(Error::InvalidData("malformed video sample entry"));
                }
                let avcc_size = b
                    .head
                    .size
                    .checked_sub(b.head.offset)
                    .expect("offset invalid");
                let avcc = read_buf(&mut b.content, avcc_size)?;
                debug!("{:?} (avcc)", avcc);
                // TODO(kinetik): Parse avcC box?  For now we just stash the data.
                codec_specific = Some(VideoCodecSpecific::AVCConfig(avcc));
            }
            BoxType::H263SpecificBox => {
                if (name != BoxType::H263SampleEntry) || codec_specific.is_some() {
                    return Err(Error::InvalidData("malformed video sample entry"));
                }
                let h263_dec_spec_struc_size = b
                    .head
                    .size
                    .checked_sub(b.head.offset)
                    .expect("offset invalid");
                let h263_dec_spec_struc = read_buf(&mut b.content, h263_dec_spec_struc_size)?;
                debug!("{:?} (h263DecSpecStruc)", h263_dec_spec_struc);

                codec_specific = Some(VideoCodecSpecific::H263Config(h263_dec_spec_struc));
            }
            BoxType::VPCodecConfigurationBox => {
                // vpcC
                if (name != BoxType::VP8SampleEntry
                    && name != BoxType::VP9SampleEntry
                    && name != BoxType::ProtectedVisualSampleEntry)
                    || codec_specific.is_some()
                {
                    return Err(Error::InvalidData("malformed video sample entry"));
                }
                let vpcc = read_vpcc(&mut b)?;
                codec_specific = Some(VideoCodecSpecific::VPxConfig(vpcc));
            }
            BoxType::AV1CodecConfigurationBox => {
                if name != BoxType::AV1SampleEntry && name != BoxType::ProtectedVisualSampleEntry {
                    return Err(Error::InvalidData("malformed video sample entry"));
                }
                let av1c = read_av1c(&mut b)?;
                codec_specific = Some(VideoCodecSpecific::AV1Config(av1c));
            }
            BoxType::ESDBox => {
                if name != BoxType::MP4VideoSampleEntry || codec_specific.is_some() {
                    return Err(Error::InvalidData("malformed video sample entry"));
                }
                #[cfg(not(feature = "mp4v"))]
                {
                    let (_, _) = read_fullbox_extra(&mut b.content)?;
                    // Subtract 4 extra to offset the members of fullbox not
                    // accounted for in head.offset
                    let esds_size = b
                        .head
                        .size
                        .checked_sub(b.head.offset + 4)
                        .expect("offset invalid");
                    let esds = read_buf(&mut b.content, esds_size)?;
                    codec_specific = Some(VideoCodecSpecific::ESDSConfig(esds));
                }
                #[cfg(feature = "mp4v")]
                {
                    // Read ES_Descriptor inside an esds box.
                    // See ISOBMFF (ISO 14496-1:2010 §7.2.6.5)
                    let esds = read_esds(&mut b)?;
                    codec_specific =
                        Some(VideoCodecSpecific::ESDSConfig(esds.decoder_specific_data));
                }
            }
            BoxType::ProtectionSchemeInfoBox => {
                if name != BoxType::ProtectedVisualSampleEntry {
                    return Err(Error::InvalidData("malformed video sample entry"));
                }
                let sinf = read_sinf(&mut b)?;
                debug!("{:?} (sinf)", sinf);
                protection_info.push(sinf)?;
            }
            _ => {
                debug!("Unsupported video codec, box {:?} found", b.head.name);
                skip_box_content(&mut b)?;
            }
        }
        check_parser_state!(b.content);
    }

    Ok(
        codec_specific.map_or(SampleEntry::Unknown, |codec_specific| {
            SampleEntry::Video(VideoSampleEntry {
                codec_type,
                data_reference_index,
                width,
                height,
                codec_specific,
                protection_info,
            })
        }),
    )
}

fn read_qt_wave_atom<T: Read>(src: &mut BMFFBox<T>) -> Result<ES_Descriptor> {
    let mut codec_specific = None;
    let mut iter = src.box_iter();
    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::ESDBox => {
                let esds = read_esds(&mut b)?;
                codec_specific = Some(esds);
            }
            _ => skip_box_content(&mut b)?,
        }
    }

    codec_specific.ok_or(Error::InvalidData("malformed audio sample entry"))
}

/// Parse an audio description inside an stsd box.
/// See ISOBMFF (ISO 14496-12:2020) § 12.2.3
fn read_audio_sample_entry<T: Read>(src: &mut BMFFBox<T>) -> Result<SampleEntry> {
    let name = src.get_header().name;

    // Skip uninteresting fields.
    skip(src, 6)?;

    let data_reference_index = be_u16(src)?;

    // XXX(kinetik): This is "reserved" in BMFF, but some old QT MOV variant
    // uses it, need to work out if we have to support it.  Without checking
    // here and reading extra fields after samplerate (or bailing with an
    // error), the parser loses sync completely.
    let version = be_u16(src)?;

    // Skip uninteresting fields.
    skip(src, 6)?;

    let mut channelcount = u32::from(be_u16(src)?);
    let samplesize = be_u16(src)?;

    // Skip uninteresting fields.
    skip(src, 4)?;

    let mut samplerate = f64::from(be_u32(src)? >> 16); // 16.16 fixed point;

    match version {
        0 => (),
        1 => {
            // Quicktime sound sample description version 1.
            // Skip uninteresting fields.
            skip(src, 16)?;
        }
        2 => {
            // Quicktime sound sample description version 2.
            skip(src, 4)?;
            samplerate = f64::from_bits(be_u64(src)?);
            channelcount = be_u32(src)?;
            skip(src, 20)?;
        }
        _ => {
            return Err(Error::Unsupported(
                "unsupported non-isom audio sample entry",
            ))
        }
    }

    let (mut codec_type, mut codec_specific) = match name {
        BoxType::MP3AudioSampleEntry => (CodecType::MP3, Some(AudioCodecSpecific::MP3)),
        BoxType::LPCMAudioSampleEntry => (CodecType::LPCM, Some(AudioCodecSpecific::LPCM)),
        // Some mp4 file with AMR doesn't have AMRSpecificBox "damr" in followed while loop,
        // we use empty box by default.
        #[cfg(feature = "3gpp")]
        BoxType::AMRNBSampleEntry => (
            CodecType::AMRNB,
            Some(AudioCodecSpecific::AMRSpecificBox(Default::default())),
        ),
        #[cfg(feature = "3gpp")]
        BoxType::AMRWBSampleEntry => (
            CodecType::AMRWB,
            Some(AudioCodecSpecific::AMRSpecificBox(Default::default())),
        ),
        _ => (CodecType::Unknown, None),
    };
    let mut protection_info = TryVec::new();
    let mut iter = src.box_iter();
    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::ESDBox => {
                if (name != BoxType::MP4AudioSampleEntry
                    && name != BoxType::ProtectedAudioSampleEntry)
                    || codec_specific.is_some()
                {
                    return Err(Error::InvalidData("malformed audio sample entry"));
                }
                let esds = read_esds(&mut b)?;
                codec_type = esds.audio_codec;
                codec_specific = Some(AudioCodecSpecific::ES_Descriptor(esds));
            }
            BoxType::FLACSpecificBox => {
                if (name != BoxType::FLACSampleEntry && name != BoxType::ProtectedAudioSampleEntry)
                    || codec_specific.is_some()
                {
                    return Err(Error::InvalidData("malformed audio sample entry"));
                }
                let dfla = read_dfla(&mut b)?;
                codec_type = CodecType::FLAC;
                codec_specific = Some(AudioCodecSpecific::FLACSpecificBox(dfla));
            }
            BoxType::OpusSpecificBox => {
                if (name != BoxType::OpusSampleEntry && name != BoxType::ProtectedAudioSampleEntry)
                    || codec_specific.is_some()
                {
                    return Err(Error::InvalidData("malformed audio sample entry"));
                }
                let dops = read_dops(&mut b)?;
                codec_type = CodecType::Opus;
                codec_specific = Some(AudioCodecSpecific::OpusSpecificBox(dops));
            }
            BoxType::ALACSpecificBox => {
                if name != BoxType::ALACSpecificBox || codec_specific.is_some() {
                    return Err(Error::InvalidData("malformed audio sample entry"));
                }
                let alac = read_alac(&mut b)?;
                codec_type = CodecType::ALAC;
                codec_specific = Some(AudioCodecSpecific::ALACSpecificBox(alac));
            }
            BoxType::QTWaveAtom => {
                let qt_esds = read_qt_wave_atom(&mut b)?;
                codec_type = qt_esds.audio_codec;
                codec_specific = Some(AudioCodecSpecific::ES_Descriptor(qt_esds));
            }
            BoxType::ProtectionSchemeInfoBox => {
                if name != BoxType::ProtectedAudioSampleEntry {
                    return Err(Error::InvalidData("malformed audio sample entry"));
                }
                let sinf = read_sinf(&mut b)?;
                debug!("{:?} (sinf)", sinf);
                codec_type = CodecType::EncryptedAudio;
                protection_info.push(sinf)?;
            }
            #[cfg(feature = "3gpp")]
            BoxType::AMRSpecificBox => {
                if codec_type != CodecType::AMRNB && codec_type != CodecType::AMRWB {
                    return Err(Error::InvalidData("malformed audio sample entry"));
                }
                let amr_dec_spec_struc_size = b
                    .head
                    .size
                    .checked_sub(b.head.offset)
                    .expect("offset invalid");
                let amr_dec_spec_struc = read_buf(&mut b.content, amr_dec_spec_struc_size)?;
                debug!("{:?} (AMRDecSpecStruc)", amr_dec_spec_struc);
                codec_specific = Some(AudioCodecSpecific::AMRSpecificBox(amr_dec_spec_struc));
            }
            _ => {
                debug!("Unsupported audio codec, box {:?} found", b.head.name);
                skip_box_content(&mut b)?;
            }
        }
        check_parser_state!(b.content);
    }

    Ok(
        codec_specific.map_or(SampleEntry::Unknown, |codec_specific| {
            SampleEntry::Audio(AudioSampleEntry {
                codec_type,
                data_reference_index,
                channelcount,
                samplesize,
                samplerate,
                codec_specific,
                protection_info,
            })
        }),
    )
}

/// Parse a stsd box.
/// See ISOBMFF (ISO 14496-12:2020) § 8.5.2
/// See MP4 (ISO 14496-14:2020) § 6.7.2
fn read_stsd<T: Read>(src: &mut BMFFBox<T>, track: &mut Track) -> Result<SampleDescriptionBox> {
    let (_, _) = read_fullbox_extra(src)?;

    let description_count = be_u32(src)?;
    let mut descriptions = TryVec::new();

    {
        let mut iter = src.box_iter();
        while let Some(mut b) = iter.next_box()? {
            let description = match track.track_type {
                TrackType::Video => read_video_sample_entry(&mut b),
                TrackType::Audio => read_audio_sample_entry(&mut b),
                TrackType::Metadata => Err(Error::Unsupported("metadata track")),
                TrackType::Unknown => Err(Error::Unsupported("unknown track type")),
            };
            let description = match description {
                Ok(desc) => desc,
                Err(Error::Unsupported(_)) => {
                    // read_{audio,video}_desc may have returned Unsupported
                    // after partially reading the box content, so we can't
                    // simply use skip_box_content here.
                    let to_skip = b.bytes_left();
                    skip(&mut b, to_skip)?;
                    SampleEntry::Unknown
                }
                Err(e) => return Err(e),
            };
            descriptions.push(description)?;
            check_parser_state!(b.content);
            if descriptions.len() == description_count.to_usize() {
                break;
            }
        }
    }

    // Padding could be added in some contents.
    skip_box_remain(src)?;

    Ok(SampleDescriptionBox { descriptions })
}

fn read_sinf<T: Read>(src: &mut BMFFBox<T>) -> Result<ProtectionSchemeInfoBox> {
    let mut sinf = ProtectionSchemeInfoBox::default();

    let mut iter = src.box_iter();
    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::OriginalFormatBox => {
                sinf.original_format = FourCC::from(be_u32(&mut b)?);
            }
            BoxType::SchemeTypeBox => {
                sinf.scheme_type = Some(read_schm(&mut b)?);
            }
            BoxType::SchemeInformationBox => {
                // We only need tenc box in schi box so far.
                sinf.tenc = read_schi(&mut b)?;
            }
            _ => skip_box_content(&mut b)?,
        }
        check_parser_state!(b.content);
    }

    Ok(sinf)
}

fn read_schi<T: Read>(src: &mut BMFFBox<T>) -> Result<Option<TrackEncryptionBox>> {
    let mut tenc = None;
    let mut iter = src.box_iter();
    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::TrackEncryptionBox => {
                if tenc.is_some() {
                    return Err(Error::InvalidData(
                        "tenc box should be only one at most in sinf box",
                    ));
                }
                tenc = Some(read_tenc(&mut b)?);
            }
            _ => skip_box_content(&mut b)?,
        }
    }

    Ok(tenc)
}

fn read_tenc<T: Read>(src: &mut BMFFBox<T>) -> Result<TrackEncryptionBox> {
    let (version, _) = read_fullbox_extra(src)?;

    // reserved byte
    skip(src, 1)?;
    // the next byte is used to signal the default pattern in version >= 1
    let (default_crypt_byte_block, default_skip_byte_block) = match version {
        0 => {
            skip(src, 1)?;
            (None, None)
        }
        _ => {
            let pattern_byte = src.read_u8()?;
            let crypt_bytes = pattern_byte >> 4;
            let skip_bytes = pattern_byte & 0x0f;
            (Some(crypt_bytes), Some(skip_bytes))
        }
    };
    let default_is_encrypted = src.read_u8()?;
    let default_iv_size = src.read_u8()?;
    let default_kid = read_buf(src, 16)?;
    // If default_is_encrypted == 1 && default_iv_size == 0 we expect a default_constant_iv
    let default_constant_iv = match (default_is_encrypted, default_iv_size) {
        (1, 0) => {
            let default_constant_iv_size = src.read_u8()?;
            Some(read_buf(src, default_constant_iv_size.into())?)
        }
        _ => None,
    };

    Ok(TrackEncryptionBox {
        is_encrypted: default_is_encrypted,
        iv_size: default_iv_size,
        kid: default_kid,
        crypt_byte_block_count: default_crypt_byte_block,
        skip_byte_block_count: default_skip_byte_block,
        constant_iv: default_constant_iv,
    })
}

fn read_schm<T: Read>(src: &mut BMFFBox<T>) -> Result<SchemeTypeBox> {
    // Flags can be used to signal presence of URI in the box, but we don't
    // use the URI so don't bother storing the flags.
    let (_, _) = read_fullbox_extra(src)?;
    let scheme_type = FourCC::from(be_u32(src)?);
    let scheme_version = be_u32(src)?;
    // Null terminated scheme URI may follow, but we don't use it right now.
    skip_box_remain(src)?;
    Ok(SchemeTypeBox {
        scheme_type,
        scheme_version,
    })
}

/// Parse a metadata box inside a moov, trak, or mdia box.
/// See ISOBMFF (ISO 14496-12:2020) § 8.10.1.
fn read_udta<T: Read>(src: &mut BMFFBox<T>) -> Result<UserdataBox> {
    let mut iter = src.box_iter();
    let mut udta = UserdataBox { meta: None };

    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::MetadataBox => {
                let meta = read_meta(&mut b)?;
                udta.meta = Some(meta);
            }
            _ => skip_box_content(&mut b)?,
        };
        check_parser_state!(b.content);
    }
    Ok(udta)
}

/// Parse the meta box
/// See ISOBMFF (ISO 14496-12:2020) § 8.11.1
fn read_meta<T: Read>(src: &mut BMFFBox<T>) -> Result<MetadataBox> {
    let (_, _) = read_fullbox_extra(src)?;
    let mut iter = src.box_iter();
    let mut meta = MetadataBox::default();
    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::MetadataItemListEntry => read_ilst(&mut b, &mut meta)?,
            #[cfg(feature = "meta-xml")]
            BoxType::MetadataXMLBox => read_xml_(&mut b, &mut meta)?,
            #[cfg(feature = "meta-xml")]
            BoxType::MetadataBXMLBox => read_bxml(&mut b, &mut meta)?,
            _ => skip_box_content(&mut b)?,
        };
        check_parser_state!(b.content);
    }
    Ok(meta)
}

/// Parse a XML box inside a meta box
/// See ISOBMFF (ISO 14496-12:2020) § 8.11.2
#[cfg(feature = "meta-xml")]
fn read_xml_<T: Read>(src: &mut BMFFBox<T>, meta: &mut MetadataBox) -> Result<()> {
    if read_fullbox_version_no_flags(src)? != 0 {
        return Err(Error::Unsupported("unsupported XmlBox version"));
    }
    meta.xml = Some(XmlBox::StringXmlBox(src.read_into_try_vec()?));
    Ok(())
}

/// Parse a Binary XML box inside a meta box
/// See ISOBMFF (ISO 14496-12:2020) § 8.11.2
#[cfg(feature = "meta-xml")]
fn read_bxml<T: Read>(src: &mut BMFFBox<T>, meta: &mut MetadataBox) -> Result<()> {
    if read_fullbox_version_no_flags(src)? != 0 {
        return Err(Error::Unsupported("unsupported XmlBox version"));
    }
    meta.xml = Some(XmlBox::BinaryXmlBox(src.read_into_try_vec()?));
    Ok(())
}

/// Parse a metadata box inside a udta box
fn read_ilst<T: Read>(src: &mut BMFFBox<T>, meta: &mut MetadataBox) -> Result<()> {
    let mut iter = src.box_iter();
    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::AlbumEntry => meta.album = read_ilst_string_data(&mut b)?,
            BoxType::ArtistEntry | BoxType::ArtistLowercaseEntry => {
                meta.artist = read_ilst_string_data(&mut b)?
            }
            BoxType::AlbumArtistEntry => meta.album_artist = read_ilst_string_data(&mut b)?,
            BoxType::CommentEntry => meta.comment = read_ilst_string_data(&mut b)?,
            BoxType::DateEntry => meta.year = read_ilst_string_data(&mut b)?,
            BoxType::TitleEntry => meta.title = read_ilst_string_data(&mut b)?,
            BoxType::CustomGenreEntry => {
                meta.genre = read_ilst_string_data(&mut b)?.map(Genre::CustomGenre)
            }
            BoxType::StandardGenreEntry => {
                meta.genre = read_ilst_u8_data(&mut b)?
                    .and_then(|gnre| Some(Genre::StandardGenre(gnre.get(1).copied()?)))
            }
            BoxType::ComposerEntry => meta.composer = read_ilst_string_data(&mut b)?,
            BoxType::EncoderEntry => meta.encoder = read_ilst_string_data(&mut b)?,
            BoxType::EncodedByEntry => meta.encoded_by = read_ilst_string_data(&mut b)?,
            BoxType::CopyrightEntry => meta.copyright = read_ilst_string_data(&mut b)?,
            BoxType::GroupingEntry => meta.grouping = read_ilst_string_data(&mut b)?,
            BoxType::CategoryEntry => meta.category = read_ilst_string_data(&mut b)?,
            BoxType::KeywordEntry => meta.keyword = read_ilst_string_data(&mut b)?,
            BoxType::PodcastUrlEntry => meta.podcast_url = read_ilst_string_data(&mut b)?,
            BoxType::PodcastGuidEntry => meta.podcast_guid = read_ilst_string_data(&mut b)?,
            BoxType::DescriptionEntry => meta.description = read_ilst_string_data(&mut b)?,
            BoxType::LongDescriptionEntry => meta.long_description = read_ilst_string_data(&mut b)?,
            BoxType::LyricsEntry => meta.lyrics = read_ilst_string_data(&mut b)?,
            BoxType::TVNetworkNameEntry => meta.tv_network_name = read_ilst_string_data(&mut b)?,
            BoxType::TVEpisodeNameEntry => meta.tv_episode_name = read_ilst_string_data(&mut b)?,
            BoxType::TVShowNameEntry => meta.tv_show_name = read_ilst_string_data(&mut b)?,
            BoxType::PurchaseDateEntry => meta.purchase_date = read_ilst_string_data(&mut b)?,
            BoxType::RatingEntry => meta.rating = read_ilst_string_data(&mut b)?,
            BoxType::OwnerEntry => meta.owner = read_ilst_string_data(&mut b)?,
            BoxType::HDVideoEntry => meta.hd_video = read_ilst_bool_data(&mut b)?,
            BoxType::SortNameEntry => meta.sort_name = read_ilst_string_data(&mut b)?,
            BoxType::SortArtistEntry => meta.sort_artist = read_ilst_string_data(&mut b)?,
            BoxType::SortAlbumEntry => meta.sort_album = read_ilst_string_data(&mut b)?,
            BoxType::SortAlbumArtistEntry => {
                meta.sort_album_artist = read_ilst_string_data(&mut b)?
            }
            BoxType::SortComposerEntry => meta.sort_composer = read_ilst_string_data(&mut b)?,
            BoxType::TrackNumberEntry => {
                if let Some(trkn) = read_ilst_u8_data(&mut b)? {
                    meta.track_number = trkn.get(3).copied();
                    meta.total_tracks = trkn.get(5).copied();
                };
            }
            BoxType::DiskNumberEntry => {
                if let Some(disk) = read_ilst_u8_data(&mut b)? {
                    meta.disc_number = disk.get(3).copied();
                    meta.total_discs = disk.get(5).copied();
                };
            }
            BoxType::TempoEntry => {
                meta.beats_per_minute =
                    read_ilst_u8_data(&mut b)?.and_then(|tmpo| tmpo.get(1).copied())
            }
            BoxType::CompilationEntry => meta.compilation = read_ilst_bool_data(&mut b)?,
            BoxType::AdvisoryEntry => {
                meta.advisory = read_ilst_u8_data(&mut b)?.and_then(|rtng| {
                    Some(match rtng.get(0)? {
                        2 => AdvisoryRating::Clean,
                        0 => AdvisoryRating::Inoffensive,
                        r => AdvisoryRating::Explicit(*r),
                    })
                })
            }
            BoxType::MediaTypeEntry => {
                meta.media_type = read_ilst_u8_data(&mut b)?.and_then(|stik| {
                    Some(match stik.get(0)? {
                        0 => MediaType::Movie,
                        1 => MediaType::Normal,
                        2 => MediaType::AudioBook,
                        5 => MediaType::WhackedBookmark,
                        6 => MediaType::MusicVideo,
                        9 => MediaType::ShortFilm,
                        10 => MediaType::TVShow,
                        11 => MediaType::Booklet,
                        s => MediaType::Unknown(*s),
                    })
                })
            }
            BoxType::PodcastEntry => meta.podcast = read_ilst_bool_data(&mut b)?,
            BoxType::TVSeasonNumberEntry => {
                meta.tv_season = read_ilst_u8_data(&mut b)?.and_then(|tvsn| tvsn.get(3).copied())
            }
            BoxType::TVEpisodeNumberEntry => {
                meta.tv_episode_number =
                    read_ilst_u8_data(&mut b)?.and_then(|tves| tves.get(3).copied())
            }
            BoxType::GaplessPlaybackEntry => meta.gapless_playback = read_ilst_bool_data(&mut b)?,
            BoxType::CoverArtEntry => meta.cover_art = read_ilst_multiple_u8_data(&mut b).ok(),
            _ => skip_box_content(&mut b)?,
        };
        check_parser_state!(b.content);
    }
    Ok(())
}

fn read_ilst_bool_data<T: Read>(src: &mut BMFFBox<T>) -> Result<Option<bool>> {
    Ok(read_ilst_u8_data(src)?.and_then(|d| Some(d.get(0)? == &1)))
}

fn read_ilst_string_data<T: Read>(src: &mut BMFFBox<T>) -> Result<Option<TryString>> {
    read_ilst_u8_data(src)
}

fn read_ilst_u8_data<T: Read>(src: &mut BMFFBox<T>) -> Result<Option<TryVec<u8>>> {
    // For all non-covr atoms, there must only be one data atom.
    Ok(read_ilst_multiple_u8_data(src)?.pop())
}

fn read_ilst_multiple_u8_data<T: Read>(src: &mut BMFFBox<T>) -> Result<TryVec<TryVec<u8>>> {
    let mut iter = src.box_iter();
    let mut data = TryVec::new();
    while let Some(mut b) = iter.next_box()? {
        match b.head.name {
            BoxType::MetadataItemDataEntry => {
                data.push(read_ilst_data(&mut b)?)?;
            }
            _ => skip_box_content(&mut b)?,
        };
        check_parser_state!(b.content);
    }
    Ok(data)
}

fn read_ilst_data<T: Read>(src: &mut BMFFBox<T>) -> Result<TryVec<u8>> {
    // Skip past the padding bytes
    skip(&mut src.content, src.head.offset)?;
    let size = src.content.limit();
    read_buf(&mut src.content, size)
}

/// Skip a number of bytes that we don't care to parse.
fn skip<T: Read>(src: &mut T, bytes: u64) -> Result<()> {
    std::io::copy(&mut src.take(bytes), &mut std::io::sink())?;
    Ok(())
}

/// Read size bytes into a Vector or return error.
fn read_buf<T: Read>(src: &mut T, size: u64) -> Result<TryVec<u8>> {
    let buf = src.take(size).read_into_try_vec()?;
    if buf.len().to_u64() != size {
        return Err(Error::InvalidData("failed buffer read"));
    }

    Ok(buf)
}

fn be_i16<T: ReadBytesExt>(src: &mut T) -> Result<i16> {
    src.read_i16::<byteorder::BigEndian>().map_err(From::from)
}

fn be_i32<T: ReadBytesExt>(src: &mut T) -> Result<i32> {
    src.read_i32::<byteorder::BigEndian>().map_err(From::from)
}

fn be_i64<T: ReadBytesExt>(src: &mut T) -> Result<i64> {
    src.read_i64::<byteorder::BigEndian>().map_err(From::from)
}

fn be_u16<T: ReadBytesExt>(src: &mut T) -> Result<u16> {
    src.read_u16::<byteorder::BigEndian>().map_err(From::from)
}

fn be_u24<T: ReadBytesExt>(src: &mut T) -> Result<u32> {
    src.read_u24::<byteorder::BigEndian>().map_err(From::from)
}

fn be_u32<T: ReadBytesExt>(src: &mut T) -> Result<u32> {
    src.read_u32::<byteorder::BigEndian>().map_err(From::from)
}

fn be_u64<T: ReadBytesExt>(src: &mut T) -> Result<u64> {
    src.read_u64::<byteorder::BigEndian>().map_err(From::from)
}

fn write_be_u32<T: WriteBytesExt>(des: &mut T, num: u32) -> Result<()> {
    des.write_u32::<byteorder::BigEndian>(num)
        .map_err(From::from)
}