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Diffstat (limited to 'third_party/rust/mp4parse/src/unstable.rs')
| -rw-r--r-- | third_party/rust/mp4parse/src/unstable.rs | 541 |
1 files changed, 541 insertions, 0 deletions
diff --git a/third_party/rust/mp4parse/src/unstable.rs b/third_party/rust/mp4parse/src/unstable.rs new file mode 100644 index 0000000000..9b3e5b407b --- /dev/null +++ b/third_party/rust/mp4parse/src/unstable.rs @@ -0,0 +1,541 @@ +// 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/. +use num_traits::{CheckedAdd, CheckedSub, PrimInt, Zero}; +use std::ops::{Add, Neg, Sub}; + +use super::*; + +/// A zero-overhead wrapper around integer types for the sake of always +/// requiring checked arithmetic +#[repr(transparent)] +#[derive(Debug, Default, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)] +pub struct CheckedInteger<T>(pub T); + +impl<T> From<T> for CheckedInteger<T> { + fn from(i: T) -> Self { + Self(i) + } +} + +// Orphan rules prevent a more general implementation, but this suffices +impl From<CheckedInteger<i64>> for i64 { + fn from(checked: CheckedInteger<i64>) -> i64 { + checked.0 + } +} + +impl<T, U: Into<T>> Add<U> for CheckedInteger<T> +where + T: CheckedAdd, +{ + type Output = Option<Self>; + + fn add(self, other: U) -> Self::Output { + self.0.checked_add(&other.into()).map(Into::into) + } +} + +impl<T, U: Into<T>> Sub<U> for CheckedInteger<T> +where + T: CheckedSub, +{ + type Output = Option<Self>; + + fn sub(self, other: U) -> Self::Output { + self.0.checked_sub(&other.into()).map(Into::into) + } +} + +/// Implement subtraction of checked `u64`s returning i64 +// This is necessary for handling Mp4parseTrackInfo::media_time gracefully +impl Sub for CheckedInteger<u64> { + type Output = Option<CheckedInteger<i64>>; + + fn sub(self, other: Self) -> Self::Output { + if self >= other { + self.0 + .checked_sub(other.0) + .and_then(|u| i64::try_from(u).ok()) + .map(CheckedInteger) + } else { + other + .0 + .checked_sub(self.0) + .and_then(|u| i64::try_from(u).ok()) + .map(i64::neg) + .map(CheckedInteger) + } + } +} + +#[test] +fn u64_subtraction_returning_i64() { + // self > other + assert_eq!( + CheckedInteger(2u64) - CheckedInteger(1u64), + Some(CheckedInteger(1i64)) + ); + + // self == other + assert_eq!( + CheckedInteger(1u64) - CheckedInteger(1u64), + Some(CheckedInteger(0i64)) + ); + + // difference too large to store in i64 + assert_eq!(CheckedInteger(u64::MAX) - CheckedInteger(1u64), None); + + // self < other + assert_eq!( + CheckedInteger(1u64) - CheckedInteger(2u64), + Some(CheckedInteger(-1i64)) + ); + + // difference not representable due to overflow + assert_eq!(CheckedInteger(1u64) - CheckedInteger(u64::MAX), None); +} + +impl<T: std::cmp::PartialEq> PartialEq<T> for CheckedInteger<T> { + fn eq(&self, other: &T) -> bool { + self.0 == *other + } +} + +/// Provides the following information about a sample in the source file: +/// sample data offset (start and end), composition time in microseconds +/// (start and end) and whether it is a sync sample +#[repr(C)] +#[derive(Default, Debug, PartialEq, Eq)] +pub struct Indice { + /// The byte offset in the file where the indexed sample begins. + pub start_offset: CheckedInteger<u64>, + /// The byte offset in the file where the indexed sample ends. This is + /// equivalent to `start_offset` + the length in bytes of the indexed + /// sample. Typically this will be the `start_offset` of the next sample + /// in the file. + pub end_offset: CheckedInteger<u64>, + /// The time in ticks when the indexed sample should be displayed. + /// Analogous to the concept of presentation time stamp (pts). + pub start_composition: CheckedInteger<i64>, + /// The time in ticks when the indexed sample should stop being + /// displayed. Typically this would be the `start_composition` time of the + /// next sample if samples were ordered by composition time. + pub end_composition: CheckedInteger<i64>, + /// The time in ticks that the indexed sample should be decoded at. + /// Analogous to the concept of decode time stamp (dts). + pub start_decode: CheckedInteger<i64>, + /// Set if the indexed sample is a sync sample. The meaning of sync is + /// somewhat codec specific, but essentially amounts to if the sample is a + /// key frame. + pub sync: bool, +} + +/// Create a vector of `Indice`s with the information about track samples. +/// It uses `stsc`, `stco`, `stsz` and `stts` boxes to construct a list of +/// every sample in the file and provides offsets which can be used to read +/// raw sample data from the file. +#[allow(clippy::reversed_empty_ranges)] +pub fn create_sample_table( + track: &Track, + track_offset_time: CheckedInteger<i64>, +) -> Option<TryVec<Indice>> { + let (stsc, stco, stsz, stts) = match (&track.stsc, &track.stco, &track.stsz, &track.stts) { + (Some(a), Some(b), Some(c), Some(d)) => (a, b, c, d), + _ => return None, + }; + + // According to spec, no sync table means every sample is sync sample. + let has_sync_table = matches!(track.stss, Some(_)); + + let mut sample_size_iter = stsz.sample_sizes.iter(); + + // Get 'stsc' iterator for (chunk_id, chunk_sample_count) and calculate the sample + // offset address. + + // With large numbers of samples, the cost of many allocations dominates, + // so it's worth iterating twice to allocate sample_table just once. + let total_sample_count = sample_to_chunk_iter(&stsc.samples, &stco.offsets) + .map(|(_, sample_counts)| sample_counts.to_usize()) + .try_fold(0usize, usize::checked_add)?; + let mut sample_table = TryVec::with_capacity(total_sample_count).ok()?; + + for i in sample_to_chunk_iter(&stsc.samples, &stco.offsets) { + let chunk_id = i.0 as usize; + let sample_counts = i.1; + let mut cur_position = match stco.offsets.get(chunk_id) { + Some(&i) => i.into(), + _ => return None, + }; + for _ in 0..sample_counts { + let start_offset = cur_position; + let end_offset = match (stsz.sample_size, sample_size_iter.next()) { + (_, Some(t)) => (start_offset + *t)?, + (t, _) if t > 0 => (start_offset + t)?, + _ => 0.into(), + }; + if end_offset == 0 { + return None; + } + cur_position = end_offset; + + sample_table + .push(Indice { + start_offset, + end_offset, + sync: !has_sync_table, + ..Default::default() + }) + .ok()?; + } + } + + // Mark the sync sample in sample_table according to 'stss'. + if let Some(ref v) = track.stss { + for iter in &v.samples { + match iter + .checked_sub(&1) + .and_then(|idx| sample_table.get_mut(idx as usize)) + { + Some(elem) => elem.sync = true, + _ => return None, + } + } + } + + let ctts_iter = track.ctts.as_ref().map(|v| v.samples.as_slice().iter()); + + let mut ctts_offset_iter = TimeOffsetIterator { + cur_sample_range: (0..0), + cur_offset: 0, + ctts_iter, + track_id: track.id, + }; + + let mut stts_iter = TimeToSampleIterator { + cur_sample_count: (0..0), + cur_sample_delta: 0, + stts_iter: stts.samples.as_slice().iter(), + track_id: track.id, + }; + + // sum_delta is the sum of stts_iter delta. + // According to spec: + // decode time => DT(n) = DT(n-1) + STTS(n) + // composition time => CT(n) = DT(n) + CTTS(n) + // Note: + // composition time needs to add the track offset time from 'elst' table. + let mut sum_delta = TrackScaledTime::<i64>(0, track.id); + for sample in sample_table.as_mut_slice() { + let decode_time = sum_delta; + sum_delta = (sum_delta + stts_iter.next_delta())?; + + // ctts_offset is the current sample offset time. + let ctts_offset = ctts_offset_iter.next_offset_time(); + + let start_composition = decode_time + ctts_offset; + + let end_composition = sum_delta + ctts_offset; + + let start_decode = decode_time; + + sample.start_composition = CheckedInteger(track_offset_time.0 + start_composition?.0); + sample.end_composition = CheckedInteger(track_offset_time.0 + end_composition?.0); + sample.start_decode = CheckedInteger(start_decode.0); + } + + // Correct composition end time due to 'ctts' causes composition time re-ordering. + // + // Composition end time is not in specification. However, gecko needs it, so we need to + // calculate to correct the composition end time. + if !sample_table.is_empty() { + // Create an index table refers to sample_table and sorted by start_composisiton time. + let mut sort_table = TryVec::with_capacity(sample_table.len()).ok()?; + + for i in 0..sample_table.len() { + sort_table.push(i).ok()?; + } + + sort_table.sort_by_key(|i| match sample_table.get(*i) { + Some(v) => v.start_composition, + _ => 0.into(), + }); + + for indices in sort_table.windows(2) { + if let [current_index, peek_index] = *indices { + let next_start_composition_time = sample_table[peek_index].start_composition; + let sample = &mut sample_table[current_index]; + sample.end_composition = next_start_composition_time; + } + } + } + + Some(sample_table) +} + +// Convert a 'ctts' compact table to full table by iterator, +// (sample_with_the_same_offset_count, offset) => (offset), (offset), (offset) ... +// +// For example: +// (2, 10), (4, 9) into (10, 10, 9, 9, 9, 9) by calling next_offset_time(). +struct TimeOffsetIterator<'a> { + cur_sample_range: std::ops::Range<u32>, + cur_offset: i64, + ctts_iter: Option<std::slice::Iter<'a, TimeOffset>>, + track_id: usize, +} + +impl<'a> Iterator for TimeOffsetIterator<'a> { + type Item = i64; + + #[allow(clippy::reversed_empty_ranges)] + fn next(&mut self) -> Option<i64> { + let has_sample = self.cur_sample_range.next().or_else(|| { + // At end of current TimeOffset, find the next TimeOffset. + let iter = match self.ctts_iter { + Some(ref mut v) => v, + _ => return None, + }; + let offset_version; + self.cur_sample_range = match iter.next() { + Some(v) => { + offset_version = v.time_offset; + 0..v.sample_count + } + _ => { + offset_version = TimeOffsetVersion::Version0(0); + 0..0 + } + }; + + self.cur_offset = match offset_version { + TimeOffsetVersion::Version0(i) => i64::from(i), + TimeOffsetVersion::Version1(i) => i64::from(i), + }; + + self.cur_sample_range.next() + }); + + has_sample.and(Some(self.cur_offset)) + } +} + +impl<'a> TimeOffsetIterator<'a> { + fn next_offset_time(&mut self) -> TrackScaledTime<i64> { + match self.next() { + Some(v) => TrackScaledTime::<i64>(v, self.track_id), + _ => TrackScaledTime::<i64>(0, self.track_id), + } + } +} + +// Convert 'stts' compact table to full table by iterator, +// (sample_count_with_the_same_time, time) => (time, time, time) ... repeats +// sample_count_with_the_same_time. +// +// For example: +// (2, 3000), (1, 2999) to (3000, 3000, 2999). +struct TimeToSampleIterator<'a> { + cur_sample_count: std::ops::Range<u32>, + cur_sample_delta: u32, + stts_iter: std::slice::Iter<'a, Sample>, + track_id: usize, +} + +impl<'a> Iterator for TimeToSampleIterator<'a> { + type Item = u32; + + #[allow(clippy::reversed_empty_ranges)] + fn next(&mut self) -> Option<u32> { + let has_sample = self.cur_sample_count.next().or_else(|| { + self.cur_sample_count = match self.stts_iter.next() { + Some(v) => { + self.cur_sample_delta = v.sample_delta; + 0..v.sample_count + } + _ => 0..0, + }; + + self.cur_sample_count.next() + }); + + has_sample.and(Some(self.cur_sample_delta)) + } +} + +impl<'a> TimeToSampleIterator<'a> { + fn next_delta(&mut self) -> TrackScaledTime<i64> { + match self.next() { + Some(v) => TrackScaledTime::<i64>(i64::from(v), self.track_id), + _ => TrackScaledTime::<i64>(0, self.track_id), + } + } +} + +// Convert 'stco' compact table to full table by iterator. +// (start_chunk_num, sample_number) => (start_chunk_num, sample_number), +// (start_chunk_num + 1, sample_number), +// (start_chunk_num + 2, sample_number), +// ... +// (next start_chunk_num, next sample_number), +// ... +// +// For example: +// (1, 5), (5, 10), (9, 2) => (1, 5), (2, 5), (3, 5), (4, 5), (5, 10), (6, 10), +// (7, 10), (8, 10), (9, 2) +fn sample_to_chunk_iter<'a>( + stsc_samples: &'a TryVec<SampleToChunk>, + stco_offsets: &'a TryVec<u64>, +) -> SampleToChunkIterator<'a> { + SampleToChunkIterator { + chunks: (0..0), + sample_count: 0, + stsc_peek_iter: stsc_samples.as_slice().iter().peekable(), + remain_chunk_count: stco_offsets + .len() + .try_into() + .expect("stco.entry_count is u32"), + } +} + +struct SampleToChunkIterator<'a> { + chunks: std::ops::Range<u32>, + sample_count: u32, + stsc_peek_iter: std::iter::Peekable<std::slice::Iter<'a, SampleToChunk>>, + remain_chunk_count: u32, // total chunk number from 'stco'. +} + +impl<'a> Iterator for SampleToChunkIterator<'a> { + type Item = (u32, u32); + + fn next(&mut self) -> Option<(u32, u32)> { + let has_chunk = self.chunks.next().or_else(|| { + self.chunks = self.locate(); + self.remain_chunk_count + .checked_sub( + self.chunks + .len() + .try_into() + .expect("len() of a Range<u32> must fit in u32"), + ) + .and_then(|res| { + self.remain_chunk_count = res; + self.chunks.next() + }) + }); + + has_chunk.map(|id| (id, self.sample_count)) + } +} + +impl<'a> SampleToChunkIterator<'a> { + #[allow(clippy::reversed_empty_ranges)] + fn locate(&mut self) -> std::ops::Range<u32> { + loop { + return match (self.stsc_peek_iter.next(), self.stsc_peek_iter.peek()) { + (Some(next), Some(peek)) if next.first_chunk == peek.first_chunk => { + // Invalid entry, skip it and will continue searching at + // next loop iteration. + continue; + } + (Some(next), Some(peek)) if next.first_chunk > 0 && peek.first_chunk > 0 => { + self.sample_count = next.samples_per_chunk; + (next.first_chunk - 1)..(peek.first_chunk - 1) + } + (Some(next), None) if next.first_chunk > 0 => { + self.sample_count = next.samples_per_chunk; + // Total chunk number in 'stsc' could be different to 'stco', + // there could be more chunks at the last 'stsc' record. + match next.first_chunk.checked_add(self.remain_chunk_count) { + Some(r) => (next.first_chunk - 1)..r - 1, + _ => 0..0, + } + } + _ => 0..0, + }; + } + } +} + +/// Calculate numerator * scale / denominator, if possible. +/// +/// Applying the associativity of integer arithmetic, we divide first +/// and add the remainder after multiplying each term separately +/// to preserve precision while leaving more headroom. That is, +/// (n * s) / d is split into floor(n / d) * s + (n % d) * s / d. +/// +/// Return None on overflow or if the denominator is zero. +fn rational_scale<T, S>(numerator: T, denominator: T, scale2: S) -> Option<T> +where + T: PrimInt + Zero, + S: PrimInt, +{ + if denominator.is_zero() { + return None; + } + + let integer = numerator / denominator; + let remainder = numerator % denominator; + num_traits::cast(scale2).and_then(|s| match integer.checked_mul(&s) { + Some(integer) => remainder + .checked_mul(&s) + .and_then(|remainder| (remainder / denominator).checked_add(&integer)), + None => None, + }) +} + +#[derive(Debug, PartialEq, Eq)] +pub struct Microseconds<T>(pub T); + +/// Convert `time` in media's global (mvhd) timescale to microseconds, +/// using provided `MediaTimeScale` +pub fn media_time_to_us(time: MediaScaledTime, scale: MediaTimeScale) -> Option<Microseconds<u64>> { + let microseconds_per_second = 1_000_000; + rational_scale(time.0, scale.0, microseconds_per_second).map(Microseconds) +} + +/// Convert `time` in track's local (mdhd) timescale to microseconds, +/// using provided `TrackTimeScale<T>` +pub fn track_time_to_us<T>( + time: TrackScaledTime<T>, + scale: TrackTimeScale<T>, +) -> Option<Microseconds<T>> +where + T: PrimInt + Zero, +{ + assert_eq!(time.1, scale.1); + let microseconds_per_second = 1_000_000; + rational_scale(time.0, scale.0, microseconds_per_second).map(Microseconds) +} + +#[test] +fn rational_scale_overflow() { + assert_eq!(rational_scale::<u64, u64>(17, 3, 1000), Some(5666)); + let large = 0x4000_0000_0000_0000; + assert_eq!(rational_scale::<u64, u64>(large, 2, 2), Some(large)); + assert_eq!(rational_scale::<u64, u64>(large, 4, 4), Some(large)); + assert_eq!(rational_scale::<u64, u64>(large, 2, 8), None); + assert_eq!(rational_scale::<u64, u64>(large, 8, 4), Some(large / 2)); + assert_eq!(rational_scale::<u64, u64>(large + 1, 4, 4), Some(large + 1)); + assert_eq!(rational_scale::<u64, u64>(large, 40, 1000), None); +} + +#[test] +fn media_time_overflow() { + let scale = MediaTimeScale(90000); + let duration = MediaScaledTime(9_007_199_254_710_000); + assert_eq!( + media_time_to_us(duration, scale), + Some(Microseconds(100_079_991_719_000_000u64)) + ); +} + +#[test] +fn track_time_overflow() { + let scale = TrackTimeScale(44100u64, 0); + let duration = TrackScaledTime(4_413_527_634_807_900u64, 0); + assert_eq!( + track_time_to_us(duration, scale), + Some(Microseconds(100_079_991_719_000_000u64)) + ); +} |