path: root/dom/media/platforms/ffmpeg/ffmpeg60/include/libavcodec/avcodec.h

/*
 * copyright (c) 2001 Fabrice Bellard
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#ifndef AVCODEC_AVCODEC_H
#define AVCODEC_AVCODEC_H

/**
 * @file
 * @ingroup libavc
 * Libavcodec external API header
 */

#include "libavutil/samplefmt.h"
#include "libavutil/attributes.h"
#include "libavutil/avutil.h"
#include "libavutil/buffer.h"
#include "libavutil/dict.h"
#include "libavutil/frame.h"
#include "libavutil/log.h"
#include "libavutil/pixfmt.h"
#include "libavutil/rational.h"

#include "codec.h"
#include "codec_desc.h"
#include "codec_par.h"
#include "codec_id.h"
#include "defs.h"
#include "packet.h"
#include "version_major.h"
#ifndef HAVE_AV_CONFIG_H
/* When included as part of the ffmpeg build, only include the major version
 * to avoid unnecessary rebuilds. When included externally, keep including
 * the full version information. */
#  include "version.h"
#endif

/**
 * @defgroup libavc libavcodec
 * Encoding/Decoding Library
 *
 * @{
 *
 * @defgroup lavc_decoding Decoding
 * @{
 * @}
 *
 * @defgroup lavc_encoding Encoding
 * @{
 * @}
 *
 * @defgroup lavc_codec Codecs
 * @{
 * @defgroup lavc_codec_native Native Codecs
 * @{
 * @}
 * @defgroup lavc_codec_wrappers External library wrappers
 * @{
 * @}
 * @defgroup lavc_codec_hwaccel Hardware Accelerators bridge
 * @{
 * @}
 * @}
 * @defgroup lavc_internal Internal
 * @{
 * @}
 * @}
 */

/**
 * @ingroup libavc
 * @defgroup lavc_encdec send/receive encoding and decoding API overview
 * @{
 *
 * The avcodec_send_packet()/avcodec_receive_frame()/avcodec_send_frame()/
 * avcodec_receive_packet() functions provide an encode/decode API, which
 * decouples input and output.
 *
 * The API is very similar for encoding/decoding and audio/video, and works as
 * follows:
 * - Set up and open the AVCodecContext as usual.
 * - Send valid input:
 *   - For decoding, call avcodec_send_packet() to give the decoder raw
 *     compressed data in an AVPacket.
 *   - For encoding, call avcodec_send_frame() to give the encoder an AVFrame
 *     containing uncompressed audio or video.
 *
 *   In both cases, it is recommended that AVPackets and AVFrames are
 *   refcounted, or libavcodec might have to copy the input data. (libavformat
 *   always returns refcounted AVPackets, and av_frame_get_buffer() allocates
 *   refcounted AVFrames.)
 * - Receive output in a loop. Periodically call one of the avcodec_receive_*()
 *   functions and process their output:
 *   - For decoding, call avcodec_receive_frame(). On success, it will return
 *     an AVFrame containing uncompressed audio or video data.
 *   - For encoding, call avcodec_receive_packet(). On success, it will return
 *     an AVPacket with a compressed frame.
 *
 *   Repeat this call until it returns AVERROR(EAGAIN) or an error. The
 *   AVERROR(EAGAIN) return value means that new input data is required to
 *   return new output. In this case, continue with sending input. For each
 *   input frame/packet, the codec will typically return 1 output frame/packet,
 *   but it can also be 0 or more than 1.
 *
 * At the beginning of decoding or encoding, the codec might accept multiple
 * input frames/packets without returning a frame, until its internal buffers
 * are filled. This situation is handled transparently if you follow the steps
 * outlined above.
 *
 * In theory, sending input can result in EAGAIN - this should happen only if
 * not all output was received. You can use this to structure alternative decode
 * or encode loops other than the one suggested above. For example, you could
 * try sending new input on each iteration, and try to receive output if that
 * returns EAGAIN.
 *
 * End of stream situations. These require "flushing" (aka draining) the codec,
 * as the codec might buffer multiple frames or packets internally for
 * performance or out of necessity (consider B-frames).
 * This is handled as follows:
 * - Instead of valid input, send NULL to the avcodec_send_packet() (decoding)
 *   or avcodec_send_frame() (encoding) functions. This will enter draining
 *   mode.
 * - Call avcodec_receive_frame() (decoding) or avcodec_receive_packet()
 *   (encoding) in a loop until AVERROR_EOF is returned. The functions will
 *   not return AVERROR(EAGAIN), unless you forgot to enter draining mode.
 * - Before decoding can be resumed again, the codec has to be reset with
 *   avcodec_flush_buffers().
 *
 * Using the API as outlined above is highly recommended. But it is also
 * possible to call functions outside of this rigid schema. For example, you can
 * call avcodec_send_packet() repeatedly without calling
 * avcodec_receive_frame(). In this case, avcodec_send_packet() will succeed
 * until the codec's internal buffer has been filled up (which is typically of
 * size 1 per output frame, after initial input), and then reject input with
 * AVERROR(EAGAIN). Once it starts rejecting input, you have no choice but to
 * read at least some output.
 *
 * Not all codecs will follow a rigid and predictable dataflow; the only
 * guarantee is that an AVERROR(EAGAIN) return value on a send/receive call on
 * one end implies that a receive/send call on the other end will succeed, or
 * at least will not fail with AVERROR(EAGAIN). In general, no codec will
 * permit unlimited buffering of input or output.
 *
 * A codec is not allowed to return AVERROR(EAGAIN) for both sending and
 * receiving. This would be an invalid state, which could put the codec user
 * into an endless loop. The API has no concept of time either: it cannot happen
 * that trying to do avcodec_send_packet() results in AVERROR(EAGAIN), but a
 * repeated call 1 second later accepts the packet (with no other receive/flush
 * API calls involved). The API is a strict state machine, and the passage of
 * time is not supposed to influence it. Some timing-dependent behavior might
 * still be deemed acceptable in certain cases. But it must never result in both
 * send/receive returning EAGAIN at the same time at any point. It must also
 * absolutely be avoided that the current state is "unstable" and can
 * "flip-flop" between the send/receive APIs allowing progress. For example,
 * it's not allowed that the codec randomly decides that it actually wants to
 * consume a packet now instead of returning a frame, after it just returned
 * AVERROR(EAGAIN) on an avcodec_send_packet() call.
 * @}
 */

/**
 * @defgroup lavc_core Core functions/structures.
 * @ingroup libavc
 *
 * Basic definitions, functions for querying libavcodec capabilities,
 * allocating core structures, etc.
 * @{
 */

/**
 * @ingroup lavc_encoding
 * minimum encoding buffer size
 * Used to avoid some checks during header writing.
 */
#define AV_INPUT_BUFFER_MIN_SIZE 16384

/**
 * @ingroup lavc_encoding
 */
typedef struct RcOverride {
  int start_frame;
  int end_frame;
  int qscale;  // If this is 0 then quality_factor will be used instead.
  float quality_factor;
} RcOverride;

/* encoding support
   These flags can be passed in AVCodecContext.flags before initialization.
   Note: Not everything is supported yet.
*/

/**
 * Allow decoders to produce frames with data planes that are not aligned
 * to CPU requirements (e.g. due to cropping).
 */
#define AV_CODEC_FLAG_UNALIGNED (1 << 0)
/**
 * Use fixed qscale.
 */
#define AV_CODEC_FLAG_QSCALE (1 << 1)
/**
 * 4 MV per MB allowed / advanced prediction for H.263.
 */
#define AV_CODEC_FLAG_4MV (1 << 2)
/**
 * Output even those frames that might be corrupted.
 */
#define AV_CODEC_FLAG_OUTPUT_CORRUPT (1 << 3)
/**
 * Use qpel MC.
 */
#define AV_CODEC_FLAG_QPEL (1 << 4)
/**
 * Don't output frames whose parameters differ from first
 * decoded frame in stream.
 */
#define AV_CODEC_FLAG_DROPCHANGED (1 << 5)
/**
 * Request the encoder to output reconstructed frames, i.e.\ frames that would
 * be produced by decoding the encoded bistream. These frames may be retrieved
 * by calling avcodec_receive_frame() immediately after a successful call to
 * avcodec_receive_packet().
 *
 * Should only be used with encoders flagged with the
 * @ref AV_CODEC_CAP_ENCODER_RECON_FRAME capability.
 */
#define AV_CODEC_FLAG_RECON_FRAME (1 << 6)
/**
 * @par decoding
 * Request the decoder to propagate each packets AVPacket.opaque and
 * AVPacket.opaque_ref to its corresponding output AVFrame.
 *
 * @par encoding:
 * Request the encoder to propagate each frame's AVFrame.opaque and
 * AVFrame.opaque_ref values to its corresponding output AVPacket.
 *
 * @par
 * May only be set on encoders that have the
 * @ref AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE capability flag.
 *
 * @note
 * While in typical cases one input frame produces exactly one output packet
 * (perhaps after a delay), in general the mapping of frames to packets is
 * M-to-N, so
 * - Any number of input frames may be associated with any given output packet.
 *   This includes zero - e.g. some encoders may output packets that carry only
 *   metadata about the whole stream.
 * - A given input frame may be associated with any number of output packets.
 *   Again this includes zero - e.g. some encoders may drop frames under certain
 *   conditions.
 * .
 * This implies that when using this flag, the caller must NOT assume that
 * - a given input frame's opaques will necessarily appear on some output
 * packet;
 * - every output packet will have some non-NULL opaque value.
 * .
 * When an output packet contains multiple frames, the opaque values will be
 * taken from the first of those.
 *
 * @note
 * The converse holds for decoders, with frames and packets switched.
 */
#define AV_CODEC_FLAG_COPY_OPAQUE (1 << 7)
/**
 * Signal to the encoder that the values of AVFrame.duration are valid and
 * should be used (typically for transferring them to output packets).
 *
 * If this flag is not set, frame durations are ignored.
 */
#define AV_CODEC_FLAG_FRAME_DURATION (1 << 8)
/**
 * Use internal 2pass ratecontrol in first pass mode.
 */
#define AV_CODEC_FLAG_PASS1 (1 << 9)
/**
 * Use internal 2pass ratecontrol in second pass mode.
 */
#define AV_CODEC_FLAG_PASS2 (1 << 10)
/**
 * loop filter.
 */
#define AV_CODEC_FLAG_LOOP_FILTER (1 << 11)
/**
 * Only decode/encode grayscale.
 */
#define AV_CODEC_FLAG_GRAY (1 << 13)
/**
 * error[?] variables will be set during encoding.
 */
#define AV_CODEC_FLAG_PSNR (1 << 15)
/**
 * Use interlaced DCT.
 */
#define AV_CODEC_FLAG_INTERLACED_DCT (1 << 18)
/**
 * Force low delay.
 */
#define AV_CODEC_FLAG_LOW_DELAY (1 << 19)
/**
 * Place global headers in extradata instead of every keyframe.
 */
#define AV_CODEC_FLAG_GLOBAL_HEADER (1 << 22)
/**
 * Use only bitexact stuff (except (I)DCT).
 */
#define AV_CODEC_FLAG_BITEXACT (1 << 23)
/* Fx : Flag for H.263+ extra options */
/**
 * H.263 advanced intra coding / MPEG-4 AC prediction
 */
#define AV_CODEC_FLAG_AC_PRED (1 << 24)
/**
 * interlaced motion estimation
 */
#define AV_CODEC_FLAG_INTERLACED_ME (1 << 29)
#define AV_CODEC_FLAG_CLOSED_GOP (1U << 31)

/**
 * Allow non spec compliant speedup tricks.
 */
#define AV_CODEC_FLAG2_FAST (1 << 0)
/**
 * Skip bitstream encoding.
 */
#define AV_CODEC_FLAG2_NO_OUTPUT (1 << 2)
/**
 * Place global headers at every keyframe instead of in extradata.
 */
#define AV_CODEC_FLAG2_LOCAL_HEADER (1 << 3)

/**
 * Input bitstream might be truncated at a packet boundaries
 * instead of only at frame boundaries.
 */
#define AV_CODEC_FLAG2_CHUNKS (1 << 15)
/**
 * Discard cropping information from SPS.
 */
#define AV_CODEC_FLAG2_IGNORE_CROP (1 << 16)

/**
 * Show all frames before the first keyframe
 */
#define AV_CODEC_FLAG2_SHOW_ALL (1 << 22)
/**
 * Export motion vectors through frame side data
 */
#define AV_CODEC_FLAG2_EXPORT_MVS (1 << 28)
/**
 * Do not skip samples and export skip information as frame side data
 */
#define AV_CODEC_FLAG2_SKIP_MANUAL (1 << 29)
/**
 * Do not reset ASS ReadOrder field on flush (subtitles decoding)
 */
#define AV_CODEC_FLAG2_RO_FLUSH_NOOP (1 << 30)
/**
 * Generate/parse ICC profiles on encode/decode, as appropriate for the type of
 * file. No effect on codecs which cannot contain embedded ICC profiles, or
 * when compiled without support for lcms2.
 */
#define AV_CODEC_FLAG2_ICC_PROFILES (1U << 31)

/* Exported side data.
   These flags can be passed in AVCodecContext.export_side_data before
   initialization.
*/
/**
 * Export motion vectors through frame side data
 */
#define AV_CODEC_EXPORT_DATA_MVS (1 << 0)
/**
 * Export encoder Producer Reference Time through packet side data
 */
#define AV_CODEC_EXPORT_DATA_PRFT (1 << 1)
/**
 * Decoding only.
 * Export the AVVideoEncParams structure through frame side data.
 */
#define AV_CODEC_EXPORT_DATA_VIDEO_ENC_PARAMS (1 << 2)
/**
 * Decoding only.
 * Do not apply film grain, export it instead.
 */
#define AV_CODEC_EXPORT_DATA_FILM_GRAIN (1 << 3)

/**
 * The decoder will keep a reference to the frame and may reuse it later.
 */
#define AV_GET_BUFFER_FLAG_REF (1 << 0)

/**
 * The encoder will keep a reference to the packet and may reuse it later.
 */
#define AV_GET_ENCODE_BUFFER_FLAG_REF (1 << 0)

struct AVCodecInternal;

/**
 * main external API structure.
 * New fields can be added to the end with minor version bumps.
 * Removal, reordering and changes to existing fields require a major
 * version bump.
 * You can use AVOptions (av_opt* / av_set/get*()) to access these fields from
 * user applications. The name string for AVOptions options matches the
 * associated command line parameter name and can be found in
 * libavcodec/options_table.h The AVOption/command line parameter names differ
 * in some cases from the C structure field names for historic reasons or
 * brevity. sizeof(AVCodecContext) must not be used outside libav*.
 */
typedef struct AVCodecContext {
  /**
   * information on struct for av_log
   * - set by avcodec_alloc_context3
   */
  const AVClass* av_class;
  int log_level_offset;

  enum AVMediaType codec_type; /* see AVMEDIA_TYPE_xxx */
  const struct AVCodec* codec;
  enum AVCodecID codec_id; /* see AV_CODEC_ID_xxx */

  /**
   * fourcc (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
   * This is used to work around some encoder bugs.
   * A demuxer should set this to what is stored in the field used to identify
   * the codec. If there are multiple such fields in a container then the
   * demuxer should choose the one which maximizes the information about the
   * used codec. If the codec tag field in a container is larger than 32 bits
   * then the demuxer should remap the longer ID to 32 bits with a table or
   * other structure. Alternatively a new extra_codec_tag + size could be added
   * but for this a clear advantage must be demonstrated first.
   * - encoding: Set by user, if not then the default based on codec_id will be
   * used.
   * - decoding: Set by user, will be converted to uppercase by libavcodec
   * during init.
   */
  unsigned int codec_tag;

  void* priv_data;

  /**
   * Private context used for internal data.
   *
   * Unlike priv_data, this is not codec-specific. It is used in general
   * libavcodec functions.
   */
  struct AVCodecInternal* internal;

  /**
   * Private data of the user, can be used to carry app specific stuff.
   * - encoding: Set by user.
   * - decoding: Set by user.
   */
  void* opaque;

  /**
   * the average bitrate
   * - encoding: Set by user; unused for constant quantizer encoding.
   * - decoding: Set by user, may be overwritten by libavcodec
   *             if this info is available in the stream
   */
  int64_t bit_rate;

  /**
   * number of bits the bitstream is allowed to diverge from the reference.
   *           the reference can be CBR (for CBR pass1) or VBR (for pass2)
   * - encoding: Set by user; unused for constant quantizer encoding.
   * - decoding: unused
   */
  int bit_rate_tolerance;

  /**
   * Global quality for codecs which cannot change it per frame.
   * This should be proportional to MPEG-1/2/4 qscale.
   * - encoding: Set by user.
   * - decoding: unused
   */
  int global_quality;

  /**
   * - encoding: Set by user.
   * - decoding: unused
   */
  int compression_level;
#define FF_COMPRESSION_DEFAULT -1

  /**
   * AV_CODEC_FLAG_*.
   * - encoding: Set by user.
   * - decoding: Set by user.
   */
  int flags;

  /**
   * AV_CODEC_FLAG2_*
   * - encoding: Set by user.
   * - decoding: Set by user.
   */
  int flags2;

  /**
   * some codecs need / can use extradata like Huffman tables.
   * MJPEG: Huffman tables
   * rv10: additional flags
   * MPEG-4: global headers (they can be in the bitstream or here)
   * The allocated memory should be AV_INPUT_BUFFER_PADDING_SIZE bytes larger
   * than extradata_size to avoid problems if it is read with the bitstream
   * reader. The bytewise contents of extradata must not depend on the
   * architecture or CPU endianness. Must be allocated with the av_malloc()
   * family of functions.
   * - encoding: Set/allocated/freed by libavcodec.
   * - decoding: Set/allocated/freed by user.
   */
  uint8_t* extradata;
  int extradata_size;

  /**
   * This is the fundamental unit of time (in seconds) in terms
   * of which frame timestamps are represented. For fixed-fps content,
   * timebase should be 1/framerate and timestamp increments should be
   * identically 1.
   * This often, but not always is the inverse of the frame rate or field rate
   * for video. 1/time_base is not the average frame rate if the frame rate is
   * not constant.
   *
   * Like containers, elementary streams also can store timestamps, 1/time_base
   * is the unit in which these timestamps are specified.
   * As example of such codec time base see ISO/IEC 14496-2:2001(E)
   * vop_time_increment_resolution and fixed_vop_rate
   * (fixed_vop_rate == 0 implies that it is different from the framerate)
   *
   * - encoding: MUST be set by user.
   * - decoding: unused.
   */
  AVRational time_base;

  /**
   * For some codecs, the time base is closer to the field rate than the frame
   * rate. Most notably, H.264 and MPEG-2 specify time_base as half of frame
   * duration if no telecine is used ...
   *
   * Set to time_base ticks per frame. Default 1, e.g., H.264/MPEG-2 set it
   * to 2.
   */
  int ticks_per_frame;

  /**
   * Codec delay.
   *
   * Encoding: Number of frames delay there will be from the encoder input to
   *           the decoder output. (we assume the decoder matches the spec)
   * Decoding: Number of frames delay in addition to what a standard decoder
   *           as specified in the spec would produce.
   *
   * Video:
   *   Number of frames the decoded output will be delayed relative to the
   *   encoded input.
   *
   * Audio:
   *   For encoding, this field is unused (see initial_padding).
   *
   *   For decoding, this is the number of samples the decoder needs to
   *   output before the decoder's output is valid. When seeking, you should
   *   start decoding this many samples prior to your desired seek point.
   *
   * - encoding: Set by libavcodec.
   * - decoding: Set by libavcodec.
   */
  int delay;

  /* video only */
  /**
   * picture width / height.
   *
   * @note Those fields may not match the values of the last
   * AVFrame output by avcodec_receive_frame() due frame
   * reordering.
   *
   * - encoding: MUST be set by user.
   * - decoding: May be set by the user before opening the decoder if known e.g.
   *             from the container. Some decoders will require the dimensions
   *             to be set by the caller. During decoding, the decoder may
   *             overwrite those values as required while parsing the data.
   */
  int width, height;

  /**
   * Bitstream width / height, may be different from width/height e.g. when
   * the decoded frame is cropped before being output or lowres is enabled.
   *
   * @note Those field may not match the value of the last
   * AVFrame output by avcodec_receive_frame() due frame
   * reordering.
   *
   * - encoding: unused
   * - decoding: May be set by the user before opening the decoder if known
   *             e.g. from the container. During decoding, the decoder may
   *             overwrite those values as required while parsing the data.
   */
  int coded_width, coded_height;

  /**
   * the number of pictures in a group of pictures, or 0 for intra_only
   * - encoding: Set by user.
   * - decoding: unused
   */
  int gop_size;

  /**
   * Pixel format, see AV_PIX_FMT_xxx.
   * May be set by the demuxer if known from headers.
   * May be overridden by the decoder if it knows better.
   *
   * @note This field may not match the value of the last
   * AVFrame output by avcodec_receive_frame() due frame
   * reordering.
   *
   * - encoding: Set by user.
   * - decoding: Set by user if known, overridden by libavcodec while
   *             parsing the data.
   */
  enum AVPixelFormat pix_fmt;

  /**
   * If non NULL, 'draw_horiz_band' is called by the libavcodec
   * decoder to draw a horizontal band. It improves cache usage. Not
   * all codecs can do that. You must check the codec capabilities
   * beforehand.
   * When multithreading is used, it may be called from multiple threads
   * at the same time; threads might draw different parts of the same AVFrame,
   * or multiple AVFrames, and there is no guarantee that slices will be drawn
   * in order.
   * The function is also used by hardware acceleration APIs.
   * It is called at least once during frame decoding to pass
   * the data needed for hardware render.
   * In that mode instead of pixel data, AVFrame points to
   * a structure specific to the acceleration API. The application
   * reads the structure and can change some fields to indicate progress
   * or mark state.
   * - encoding: unused
   * - decoding: Set by user.
   * @param height the height of the slice
   * @param y the y position of the slice
   * @param type 1->top field, 2->bottom field, 3->frame
   * @param offset offset into the AVFrame.data from which the slice should be
   * read
   */
  void (*draw_horiz_band)(struct AVCodecContext* s, const AVFrame* src,
                          int offset[AV_NUM_DATA_POINTERS], int y, int type,
                          int height);

  /**
   * Callback to negotiate the pixel format. Decoding only, may be set by the
   * caller before avcodec_open2().
   *
   * Called by some decoders to select the pixel format that will be used for
   * the output frames. This is mainly used to set up hardware acceleration,
   * then the provided format list contains the corresponding hwaccel pixel
   * formats alongside the "software" one. The software pixel format may also
   * be retrieved from \ref sw_pix_fmt.
   *
   * This callback will be called when the coded frame properties (such as
   * resolution, pixel format, etc.) change and more than one output format is
   * supported for those new properties. If a hardware pixel format is chosen
   * and initialization for it fails, the callback may be called again
   * immediately.
   *
   * This callback may be called from different threads if the decoder is
   * multi-threaded, but not from more than one thread simultaneously.
   *
   * @param fmt list of formats which may be used in the current
   *            configuration, terminated by AV_PIX_FMT_NONE.
   * @warning Behavior is undefined if the callback returns a value other
   *          than one of the formats in fmt or AV_PIX_FMT_NONE.
   * @return the chosen format or AV_PIX_FMT_NONE
   */
  enum AVPixelFormat (*get_format)(struct AVCodecContext* s,
                                   const enum AVPixelFormat* fmt);

  /**
   * maximum number of B-frames between non-B-frames
   * Note: The output will be delayed by max_b_frames+1 relative to the input.
   * - encoding: Set by user.
   * - decoding: unused
   */
  int max_b_frames;

  /**
   * qscale factor between IP and B-frames
   * If > 0 then the last P-frame quantizer will be used (q=
   * lastp_q*factor+offset). If < 0 then normal ratecontrol will be done (q=
   * -normal_q*factor+offset).
   * - encoding: Set by user.
   * - decoding: unused
   */
  float b_quant_factor;

  /**
   * qscale offset between IP and B-frames
   * - encoding: Set by user.
   * - decoding: unused
   */
  float b_quant_offset;

  /**
   * Size of the frame reordering buffer in the decoder.
   * For MPEG-2 it is 1 IPB or 0 low delay IP.
   * - encoding: Set by libavcodec.
   * - decoding: Set by libavcodec.
   */
  int has_b_frames;

  /**
   * qscale factor between P- and I-frames
   * If > 0 then the last P-frame quantizer will be used (q = lastp_q * factor +
   * offset). If < 0 then normal ratecontrol will be done (q=
   * -normal_q*factor+offset).
   * - encoding: Set by user.
   * - decoding: unused
   */
  float i_quant_factor;

  /**
   * qscale offset between P and I-frames
   * - encoding: Set by user.
   * - decoding: unused
   */
  float i_quant_offset;

  /**
   * luminance masking (0-> disabled)
   * - encoding: Set by user.
   * - decoding: unused
   */
  float lumi_masking;

  /**
   * temporary complexity masking (0-> disabled)
   * - encoding: Set by user.
   * - decoding: unused
   */
  float temporal_cplx_masking;

  /**
   * spatial complexity masking (0-> disabled)
   * - encoding: Set by user.
   * - decoding: unused
   */
  float spatial_cplx_masking;

  /**
   * p block masking (0-> disabled)
   * - encoding: Set by user.
   * - decoding: unused
   */
  float p_masking;

  /**
   * darkness masking (0-> disabled)
   * - encoding: Set by user.
   * - decoding: unused
   */
  float dark_masking;

  /**
   * slice count
   * - encoding: Set by libavcodec.
   * - decoding: Set by user (or 0).
   */
  int slice_count;

  /**
   * slice offsets in the frame in bytes
   * - encoding: Set/allocated by libavcodec.
   * - decoding: Set/allocated by user (or NULL).
   */
  int* slice_offset;

  /**
   * sample aspect ratio (0 if unknown)
   * That is the width of a pixel divided by the height of the pixel.
   * Numerator and denominator must be relatively prime and smaller than 256 for
   * some video standards.
   * - encoding: Set by user.
   * - decoding: Set by libavcodec.
   */
  AVRational sample_aspect_ratio;

  /**
   * motion estimation comparison function
   * - encoding: Set by user.
   * - decoding: unused
   */
  int me_cmp;
  /**
   * subpixel motion estimation comparison function
   * - encoding: Set by user.
   * - decoding: unused
   */
  int me_sub_cmp;
  /**
   * macroblock comparison function (not supported yet)
   * - encoding: Set by user.
   * - decoding: unused
   */
  int mb_cmp;
  /**
   * interlaced DCT comparison function
   * - encoding: Set by user.
   * - decoding: unused
   */
  int ildct_cmp;
#define FF_CMP_SAD 0
#define FF_CMP_SSE 1
#define FF_CMP_SATD 2
#define FF_CMP_DCT 3
#define FF_CMP_PSNR 4
#define FF_CMP_BIT 5
#define FF_CMP_RD 6
#define FF_CMP_ZERO 7
#define FF_CMP_VSAD 8
#define FF_CMP_VSSE 9
#define FF_CMP_NSSE 10
#define FF_CMP_W53 11
#define FF_CMP_W97 12
#define FF_CMP_DCTMAX 13
#define FF_CMP_DCT264 14
#define FF_CMP_MEDIAN_SAD 15
#define FF_CMP_CHROMA 256

  /**
   * ME diamond size & shape
   * - encoding: Set by user.
   * - decoding: unused
   */
  int dia_size;

  /**
   * amount of previous MV predictors (2a+1 x 2a+1 square)
   * - encoding: Set by user.
   * - decoding: unused
   */
  int last_predictor_count;

  /**
   * motion estimation prepass comparison function
   * - encoding: Set by user.
   * - decoding: unused
   */
  int me_pre_cmp;

  /**
   * ME prepass diamond size & shape
   * - encoding: Set by user.
   * - decoding: unused
   */
  int pre_dia_size;

  /**
   * subpel ME quality
   * - encoding: Set by user.
   * - decoding: unused
   */
  int me_subpel_quality;

  /**
   * maximum motion estimation search range in subpel units
   * If 0 then no limit.
   *
   * - encoding: Set by user.
   * - decoding: unused
   */
  int me_range;

  /**
   * slice flags
   * - encoding: unused
   * - decoding: Set by user.
   */
  int slice_flags;
#define SLICE_FLAG_CODED_ORDER \
  0x0001  ///< draw_horiz_band() is called in coded order instead of display
#define SLICE_FLAG_ALLOW_FIELD \
  0x0002  ///< allow draw_horiz_band() with field slices (MPEG-2 field pics)
#define SLICE_FLAG_ALLOW_PLANE \
  0x0004  ///< allow draw_horiz_band() with 1 component at a time (SVQ1)

  /**
   * macroblock decision mode
   * - encoding: Set by user.
   * - decoding: unused
   */
  int mb_decision;
#define FF_MB_DECISION_SIMPLE 0  ///< uses mb_cmp
#define FF_MB_DECISION_BITS 1  ///< chooses the one which needs the fewest bits
#define FF_MB_DECISION_RD 2    ///< rate distortion

  /**
   * custom intra quantization matrix
   * Must be allocated with the av_malloc() family of functions, and will be
   * freed in avcodec_free_context().
   * - encoding: Set/allocated by user, freed by libavcodec. Can be NULL.
   * - decoding: Set/allocated/freed by libavcodec.
   */
  uint16_t* intra_matrix;

  /**
   * custom inter quantization matrix
   * Must be allocated with the av_malloc() family of functions, and will be
   * freed in avcodec_free_context().
   * - encoding: Set/allocated by user, freed by libavcodec. Can be NULL.
   * - decoding: Set/allocated/freed by libavcodec.
   */
  uint16_t* inter_matrix;

  /**
   * precision of the intra DC coefficient - 8
   * - encoding: Set by user.
   * - decoding: Set by libavcodec
   */
  int intra_dc_precision;

  /**
   * Number of macroblock rows at the top which are skipped.
   * - encoding: unused
   * - decoding: Set by user.
   */
  int skip_top;

  /**
   * Number of macroblock rows at the bottom which are skipped.
   * - encoding: unused
   * - decoding: Set by user.
   */
  int skip_bottom;

  /**
   * minimum MB Lagrange multiplier
   * - encoding: Set by user.
   * - decoding: unused
   */
  int mb_lmin;

  /**
   * maximum MB Lagrange multiplier
   * - encoding: Set by user.
   * - decoding: unused
   */
  int mb_lmax;

  /**
   * - encoding: Set by user.
   * - decoding: unused
   */
  int bidir_refine;

  /**
   * minimum GOP size
   * - encoding: Set by user.
   * - decoding: unused
   */
  int keyint_min;

  /**
   * number of reference frames
   * - encoding: Set by user.
   * - decoding: Set by lavc.
   */
  int refs;

  /**
   * Note: Value depends upon the compare function used for fullpel ME.
   * - encoding: Set by user.
   * - decoding: unused
   */
  int mv0_threshold;

  /**
   * Chromaticity coordinates of the source primaries.
   * - encoding: Set by user
   * - decoding: Set by libavcodec
   */
  enum AVColorPrimaries color_primaries;

  /**
   * Color Transfer Characteristic.
   * - encoding: Set by user
   * - decoding: Set by libavcodec
   */
  enum AVColorTransferCharacteristic color_trc;

  /**
   * YUV colorspace type.
   * - encoding: Set by user
   * - decoding: Set by libavcodec
   */
  enum AVColorSpace colorspace;

  /**
   * MPEG vs JPEG YUV range.
   * - encoding: Set by user
   * - decoding: Set by libavcodec
   */
  enum AVColorRange color_range;

  /**
   * This defines the location of chroma samples.
   * - encoding: Set by user
   * - decoding: Set by libavcodec
   */
  enum AVChromaLocation chroma_sample_location;

  /**
   * Number of slices.
   * Indicates number of picture subdivisions. Used for parallelized
   * decoding.
   * - encoding: Set by user
   * - decoding: unused
   */
  int slices;

  /** Field order
   * - encoding: set by libavcodec
   * - decoding: Set by user.
   */
  enum AVFieldOrder field_order;

  /* audio only */
  int sample_rate;  ///< samples per second

#if FF_API_OLD_CHANNEL_LAYOUT
  /**
   * number of audio channels
   * @deprecated use ch_layout.nb_channels
   */
  attribute_deprecated int channels;
#endif

  /**
   * audio sample format
   * - encoding: Set by user.
   * - decoding: Set by libavcodec.
   */
  enum AVSampleFormat sample_fmt;  ///< sample format

  /* The following data should not be initialized. */
  /**
   * Number of samples per channel in an audio frame.
   *
   * - encoding: set by libavcodec in avcodec_open2(). Each submitted frame
   *   except the last must contain exactly frame_size samples per channel.
   *   May be 0 when the codec has AV_CODEC_CAP_VARIABLE_FRAME_SIZE set, then
   * the frame size is not restricted.
   * - decoding: may be set by some decoders to indicate constant frame size
   */
  int frame_size;

#if FF_API_AVCTX_FRAME_NUMBER
  /**
   * Frame counter, set by libavcodec.
   *
   * - decoding: total number of frames returned from the decoder so far.
   * - encoding: total number of frames passed to the encoder so far.
   *
   *   @note the counter is not incremented if encoding/decoding resulted in
   *   an error.
   *   @deprecated use frame_num instead
   */
  attribute_deprecated int frame_number;
#endif

  /**
   * number of bytes per packet if constant and known or 0
   * Used by some WAV based audio codecs.
   */
  int block_align;

  /**
   * Audio cutoff bandwidth (0 means "automatic")
   * - encoding: Set by user.
   * - decoding: unused
   */
  int cutoff;

#if FF_API_OLD_CHANNEL_LAYOUT
  /**
   * Audio channel layout.
   * - encoding: set by user.
   * - decoding: set by user, may be overwritten by libavcodec.
   * @deprecated use ch_layout
   */
  attribute_deprecated uint64_t channel_layout;

  /**
   * Request decoder to use this channel layout if it can (0 for default)
   * - encoding: unused
   * - decoding: Set by user.
   * @deprecated use "downmix" codec private option
   */
  attribute_deprecated uint64_t request_channel_layout;
#endif

  /**
   * Type of service that the audio stream conveys.
   * - encoding: Set by user.
   * - decoding: Set by libavcodec.
   */
  enum AVAudioServiceType audio_service_type;

  /**
   * desired sample format
   * - encoding: Not used.
   * - decoding: Set by user.
   * Decoder will decode to this format if it can.
   */
  enum AVSampleFormat request_sample_fmt;

  /**
   * This callback is called at the beginning of each frame to get data
   * buffer(s) for it. There may be one contiguous buffer for all the data or
   * there may be a buffer per each data plane or anything in between. What
   * this means is, you may set however many entries in buf[] you feel
   * necessary. Each buffer must be reference-counted using the AVBuffer API
   * (see description of buf[] below).
   *
   * The following fields will be set in the frame before this callback is
   * called:
   * - format
   * - width, height (video only)
   * - sample_rate, channel_layout, nb_samples (audio only)
   * Their values may differ from the corresponding values in
   * AVCodecContext. This callback must use the frame values, not the codec
   * context values, to calculate the required buffer size.
   *
   * This callback must fill the following fields in the frame:
   * - data[]
   * - linesize[]
   * - extended_data:
   *   * if the data is planar audio with more than 8 channels, then this
   *     callback must allocate and fill extended_data to contain all pointers
   *     to all data planes. data[] must hold as many pointers as it can.
   *     extended_data must be allocated with av_malloc() and will be freed in
   *     av_frame_unref().
   *   * otherwise extended_data must point to data
   * - buf[] must contain one or more pointers to AVBufferRef structures. Each
   * of the frame's data and extended_data pointers must be contained in these.
   * That is, one AVBufferRef for each allocated chunk of memory, not
   * necessarily one AVBufferRef per data[] entry. See: av_buffer_create(),
   * av_buffer_alloc(), and av_buffer_ref().
   * - extended_buf and nb_extended_buf must be allocated with av_malloc() by
   *   this callback and filled with the extra buffers if there are more
   *   buffers than buf[] can hold. extended_buf will be freed in
   *   av_frame_unref().
   *
   * If AV_CODEC_CAP_DR1 is not set then get_buffer2() must call
   * avcodec_default_get_buffer2() instead of providing buffers allocated by
   * some other means.
   *
   * Each data plane must be aligned to the maximum required by the target
   * CPU.
   *
   * @see avcodec_default_get_buffer2()
   *
   * Video:
   *
   * If AV_GET_BUFFER_FLAG_REF is set in flags then the frame may be reused
   * (read and/or written to if it is writable) later by libavcodec.
   *
   * avcodec_align_dimensions2() should be used to find the required width and
   * height, as they normally need to be rounded up to the next multiple of 16.
   *
   * Some decoders do not support linesizes changing between frames.
   *
   * If frame multithreading is used, this callback may be called from a
   * different thread, but not from more than one at once. Does not need to be
   * reentrant.
   *
   * @see avcodec_align_dimensions2()
   *
   * Audio:
   *
   * Decoders request a buffer of a particular size by setting
   * AVFrame.nb_samples prior to calling get_buffer2(). The decoder may,
   * however, utilize only part of the buffer by setting AVFrame.nb_samples
   * to a smaller value in the output frame.
   *
   * As a convenience, av_samples_get_buffer_size() and
   * av_samples_fill_arrays() in libavutil may be used by custom get_buffer2()
   * functions to find the required data size and to fill data pointers and
   * linesize. In AVFrame.linesize, only linesize[0] may be set for audio
   * since all planes must be the same size.
   *
   * @see av_samples_get_buffer_size(), av_samples_fill_arrays()
   *
   * - encoding: unused
   * - decoding: Set by libavcodec, user can override.
   */
  int (*get_buffer2)(struct AVCodecContext* s, AVFrame* frame, int flags);

  /* - encoding parameters */
  float qcompress;  ///< amount of qscale change between easy & hard scenes
                    ///< (0.0-1.0)
  float qblur;      ///< amount of qscale smoothing over time (0.0-1.0)

  /**
   * minimum quantizer
   * - encoding: Set by user.
   * - decoding: unused
   */
  int qmin;

  /**
   * maximum quantizer
   * - encoding: Set by user.
   * - decoding: unused
   */
  int qmax;

  /**
   * maximum quantizer difference between frames
   * - encoding: Set by user.
   * - decoding: unused
   */
  int max_qdiff;

  /**
   * decoder bitstream buffer size
   * - encoding: Set by user.
   * - decoding: unused
   */
  int rc_buffer_size;

  /**
   * ratecontrol override, see RcOverride
   * - encoding: Allocated/set/freed by user.
   * - decoding: unused
   */
  int rc_override_count;
  RcOverride* rc_override;

  /**
   * maximum bitrate
   * - encoding: Set by user.
   * - decoding: Set by user, may be overwritten by libavcodec.
   */
  int64_t rc_max_rate;

  /**
   * minimum bitrate
   * - encoding: Set by user.
   * - decoding: unused
   */
  int64_t rc_min_rate;

  /**
   * Ratecontrol attempt to use, at maximum, <value> of what can be used without
   * an underflow.
   * - encoding: Set by user.
   * - decoding: unused.
   */
  float rc_max_available_vbv_use;

  /**
   * Ratecontrol attempt to use, at least, <value> times the amount needed to
   * prevent a vbv overflow.
   * - encoding: Set by user.
   * - decoding: unused.
   */
  float rc_min_vbv_overflow_use;

  /**
   * Number of bits which should be loaded into the rc buffer before decoding
   * starts.
   * - encoding: Set by user.
   * - decoding: unused
   */
  int rc_initial_buffer_occupancy;

  /**
   * trellis RD quantization
   * - encoding: Set by user.
   * - decoding: unused
   */
  int trellis;

  /**
   * pass1 encoding statistics output buffer
   * - encoding: Set by libavcodec.
   * - decoding: unused
   */
  char* stats_out;

  /**
   * pass2 encoding statistics input buffer
   * Concatenated stuff from stats_out of pass1 should be placed here.
   * - encoding: Allocated/set/freed by user.
   * - decoding: unused
   */
  char* stats_in;

  /**
   * Work around bugs in encoders which sometimes cannot be detected
   * automatically.
   * - encoding: Set by user
   * - decoding: Set by user
   */
  int workaround_bugs;
#define FF_BUG_AUTODETECT 1  ///< autodetection
#define FF_BUG_XVID_ILACE 4
#define FF_BUG_UMP4 8
#define FF_BUG_NO_PADDING 16
#define FF_BUG_AMV 32
#define FF_BUG_QPEL_CHROMA 64
#define FF_BUG_STD_QPEL 128
#define FF_BUG_QPEL_CHROMA2 256
#define FF_BUG_DIRECT_BLOCKSIZE 512
#define FF_BUG_EDGE 1024
#define FF_BUG_HPEL_CHROMA 2048
#define FF_BUG_DC_CLIP 4096
#define FF_BUG_MS \
  8192  ///< Work around various bugs in Microsoft's broken decoders.
#define FF_BUG_TRUNCATED 16384
#define FF_BUG_IEDGE 32768

  /**
   * strictly follow the standard (MPEG-4, ...).
   * - encoding: Set by user.
   * - decoding: Set by user.
   * Setting this to STRICT or higher means the encoder and decoder will
   * generally do stupid things, whereas setting it to unofficial or lower
   * will mean the encoder might produce output that is not supported by all
   * spec-compliant decoders. Decoders don't differentiate between normal,
   * unofficial and experimental (that is, they always try to decode things
   * when they can) unless they are explicitly asked to behave stupidly
   * (=strictly conform to the specs)
   * This may only be set to one of the FF_COMPLIANCE_* values in defs.h.
   */
  int strict_std_compliance;

  /**
   * error concealment flags
   * - encoding: unused
   * - decoding: Set by user.
   */
  int error_concealment;
#define FF_EC_GUESS_MVS 1
#define FF_EC_DEBLOCK 2
#define FF_EC_FAVOR_INTER 256

  /**
   * debug
   * - encoding: Set by user.
   * - decoding: Set by user.
   */
  int debug;
#define FF_DEBUG_PICT_INFO 1
#define FF_DEBUG_RC 2
#define FF_DEBUG_BITSTREAM 4
#define FF_DEBUG_MB_TYPE 8
#define FF_DEBUG_QP 16
#define FF_DEBUG_DCT_COEFF 0x00000040
#define FF_DEBUG_SKIP 0x00000080
#define FF_DEBUG_STARTCODE 0x00000100
#define FF_DEBUG_ER 0x00000400
#define FF_DEBUG_MMCO 0x00000800
#define FF_DEBUG_BUGS 0x00001000
#define FF_DEBUG_BUFFERS 0x00008000
#define FF_DEBUG_THREADS 0x00010000
#define FF_DEBUG_GREEN_MD 0x00800000
#define FF_DEBUG_NOMC 0x01000000

  /**
   * Error recognition; may misdetect some more or less valid parts as errors.
   * This is a bitfield of the AV_EF_* values defined in defs.h.
   *
   * - encoding: Set by user.
   * - decoding: Set by user.
   */
  int err_recognition;

#if FF_API_REORDERED_OPAQUE
  /**
   * opaque 64-bit number (generally a PTS) that will be reordered and
   * output in AVFrame.reordered_opaque
   * - encoding: Set by libavcodec to the reordered_opaque of the input
   *             frame corresponding to the last returned packet. Only
   *             supported by encoders with the
   *             AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE capability.
   * - decoding: Set by user.
   *
   * @deprecated Use AV_CODEC_FLAG_COPY_OPAQUE instead
   */
  attribute_deprecated int64_t reordered_opaque;
#endif

  /**
   * Hardware accelerator in use
   * - encoding: unused.
   * - decoding: Set by libavcodec
   */
  const struct AVHWAccel* hwaccel;

  /**
   * Legacy hardware accelerator context.
   *
   * For some hardware acceleration methods, the caller may use this field to
   * signal hwaccel-specific data to the codec. The struct pointed to by this
   * pointer is hwaccel-dependent and defined in the respective header. Please
   * refer to the FFmpeg HW accelerator documentation to know how to fill
   * this.
   *
   * In most cases this field is optional - the necessary information may also
   * be provided to libavcodec through @ref hw_frames_ctx or @ref
   * hw_device_ctx (see avcodec_get_hw_config()). However, in some cases it
   * may be the only method of signalling some (optional) information.
   *
   * The struct and its contents are owned by the caller.
   *
   * - encoding: May be set by the caller before avcodec_open2(). Must remain
   *             valid until avcodec_free_context().
   * - decoding: May be set by the caller in the get_format() callback.
   *             Must remain valid until the next get_format() call,
   *             or avcodec_free_context() (whichever comes first).
   */
  void* hwaccel_context;

  /**
   * error
   * - encoding: Set by libavcodec if flags & AV_CODEC_FLAG_PSNR.
   * - decoding: unused
   */
  uint64_t error[AV_NUM_DATA_POINTERS];

  /**
   * DCT algorithm, see FF_DCT_* below
   * - encoding: Set by user.
   * - decoding: unused
   */
  int dct_algo;
#define FF_DCT_AUTO 0
#define FF_DCT_FASTINT 1
#define FF_DCT_INT 2
#define FF_DCT_MMX 3
#define FF_DCT_ALTIVEC 5
#define FF_DCT_FAAN 6

  /**
   * IDCT algorithm, see FF_IDCT_* below.
   * - encoding: Set by user.
   * - decoding: Set by user.
   */
  int idct_algo;
#define FF_IDCT_AUTO 0
#define FF_IDCT_INT 1
#define FF_IDCT_SIMPLE 2
#define FF_IDCT_SIMPLEMMX 3
#define FF_IDCT_ARM 7
#define FF_IDCT_ALTIVEC 8
#define FF_IDCT_SIMPLEARM 10
#define FF_IDCT_XVID 14
#define FF_IDCT_SIMPLEARMV5TE 16
#define FF_IDCT_SIMPLEARMV6 17
#define FF_IDCT_FAAN 20
#define FF_IDCT_SIMPLENEON 22
#if FF_API_IDCT_NONE
// formerly used by xvmc
#  define FF_IDCT_NONE 24
#endif
#define FF_IDCT_SIMPLEAUTO 128

  /**
   * bits per sample/pixel from the demuxer (needed for huffyuv).
   * - encoding: Set by libavcodec.
   * - decoding: Set by user.
   */
  int bits_per_coded_sample;

  /**
   * Bits per sample/pixel of internal libavcodec pixel/sample format.
   * - encoding: set by user.
   * - decoding: set by libavcodec.
   */
  int bits_per_raw_sample;

  /**
   * low resolution decoding, 1-> 1/2 size, 2->1/4 size
   * - encoding: unused
   * - decoding: Set by user.
   */
  int lowres;

  /**
   * thread count
   * is used to decide how many independent tasks should be passed to execute()
   * - encoding: Set by user.
   * - decoding: Set by user.
   */
  int thread_count;

  /**
   * Which multithreading methods to use.
   * Use of FF_THREAD_FRAME will increase decoding delay by one frame per
   * thread, so clients which cannot provide future frames should not use it.
   *
   * - encoding: Set by user, otherwise the default is used.
   * - decoding: Set by user, otherwise the default is used.
   */
  int thread_type;
#define FF_THREAD_FRAME 1  ///< Decode more than one frame at once
#define FF_THREAD_SLICE \
  2  ///< Decode more than one part of a single frame at once

  /**
   * Which multithreading methods are in use by the codec.
   * - encoding: Set by libavcodec.
   * - decoding: Set by libavcodec.
   */
  int active_thread_type;

  /**
   * The codec may call this to execute several independent things.
   * It will return only after finishing all tasks.
   * The user may replace this with some multithreaded implementation,
   * the default implementation will execute the parts serially.
   * @param count the number of things to execute
   * - encoding: Set by libavcodec, user can override.
   * - decoding: Set by libavcodec, user can override.
   */
  int (*execute)(struct AVCodecContext* c,
                 int (*func)(struct AVCodecContext* c2, void* arg), void* arg2,
                 int* ret, int count, int size);

  /**
   * The codec may call this to execute several independent things.
   * It will return only after finishing all tasks.
   * The user may replace this with some multithreaded implementation,
   * the default implementation will execute the parts serially.
   * @param c context passed also to func
   * @param count the number of things to execute
   * @param arg2 argument passed unchanged to func
   * @param ret return values of executed functions, must have space for "count"
   * values. May be NULL.
   * @param func function that will be called count times, with jobnr from 0 to
   * count-1. threadnr will be in the range 0 to c->thread_count-1 < MAX_THREADS
   * and so that no two instances of func executing at the same time will have
   * the same threadnr.
   * @return always 0 currently, but code should handle a future improvement
   * where when any call to func returns < 0 no further calls to func may be
   * done and < 0 is returned.
   * - encoding: Set by libavcodec, user can override.
   * - decoding: Set by libavcodec, user can override.
   */
  int (*execute2)(struct AVCodecContext* c,
                  int (*func)(struct AVCodecContext* c2, void* arg, int jobnr,
                              int threadnr),
                  void* arg2, int* ret, int count);

  /**
   * noise vs. sse weight for the nsse comparison function
   * - encoding: Set by user.
   * - decoding: unused
   */
  int nsse_weight;

  /**
   * profile
   * - encoding: Set by user.
   * - decoding: Set by libavcodec.
   */
  int profile;
#define FF_PROFILE_UNKNOWN -99
#define FF_PROFILE_RESERVED -100

#define FF_PROFILE_AAC_MAIN 0
#define FF_PROFILE_AAC_LOW 1
#define FF_PROFILE_AAC_SSR 2
#define FF_PROFILE_AAC_LTP 3
#define FF_PROFILE_AAC_HE 4
#define FF_PROFILE_AAC_HE_V2 28
#define FF_PROFILE_AAC_LD 22
#define FF_PROFILE_AAC_ELD 38
#define FF_PROFILE_MPEG2_AAC_LOW 128
#define FF_PROFILE_MPEG2_AAC_HE 131

#define FF_PROFILE_DNXHD 0
#define FF_PROFILE_DNXHR_LB 1
#define FF_PROFILE_DNXHR_SQ 2
#define FF_PROFILE_DNXHR_HQ 3
#define FF_PROFILE_DNXHR_HQX 4
#define FF_PROFILE_DNXHR_444 5

#define FF_PROFILE_DTS 20
#define FF_PROFILE_DTS_ES 30
#define FF_PROFILE_DTS_96_24 40
#define FF_PROFILE_DTS_HD_HRA 50
#define FF_PROFILE_DTS_HD_MA 60
#define FF_PROFILE_DTS_EXPRESS 70

#define FF_PROFILE_MPEG2_422 0
#define FF_PROFILE_MPEG2_HIGH 1
#define FF_PROFILE_MPEG2_SS 2
#define FF_PROFILE_MPEG2_SNR_SCALABLE 3
#define FF_PROFILE_MPEG2_MAIN 4
#define FF_PROFILE_MPEG2_SIMPLE 5

#define FF_PROFILE_H264_CONSTRAINED (1 << 9)  // 8+1; constraint_set1_flag
#define FF_PROFILE_H264_INTRA (1 << 11)       // 8+3; constraint_set3_flag

#define FF_PROFILE_H264_BASELINE 66
#define FF_PROFILE_H264_CONSTRAINED_BASELINE (66 | FF_PROFILE_H264_CONSTRAINED)
#define FF_PROFILE_H264_MAIN 77
#define FF_PROFILE_H264_EXTENDED 88
#define FF_PROFILE_H264_HIGH 100
#define FF_PROFILE_H264_HIGH_10 110
#define FF_PROFILE_H264_HIGH_10_INTRA (110 | FF_PROFILE_H264_INTRA)
#define FF_PROFILE_H264_MULTIVIEW_HIGH 118
#define FF_PROFILE_H264_HIGH_422 122
#define FF_PROFILE_H264_HIGH_422_INTRA (122 | FF_PROFILE_H264_INTRA)
#define FF_PROFILE_H264_STEREO_HIGH 128
#define FF_PROFILE_H264_HIGH_444 144
#define FF_PROFILE_H264_HIGH_444_PREDICTIVE 244
#define FF_PROFILE_H264_HIGH_444_INTRA (244 | FF_PROFILE_H264_INTRA)
#define FF_PROFILE_H264_CAVLC_444 44

#define FF_PROFILE_VC1_SIMPLE 0
#define FF_PROFILE_VC1_MAIN 1
#define FF_PROFILE_VC1_COMPLEX 2
#define FF_PROFILE_VC1_ADVANCED 3

#define FF_PROFILE_MPEG4_SIMPLE 0
#define FF_PROFILE_MPEG4_SIMPLE_SCALABLE 1
#define FF_PROFILE_MPEG4_CORE 2
#define FF_PROFILE_MPEG4_MAIN 3
#define FF_PROFILE_MPEG4_N_BIT 4
#define FF_PROFILE_MPEG4_SCALABLE_TEXTURE 5
#define FF_PROFILE_MPEG4_SIMPLE_FACE_ANIMATION 6
#define FF_PROFILE_MPEG4_BASIC_ANIMATED_TEXTURE 7
#define FF_PROFILE_MPEG4_HYBRID 8
#define FF_PROFILE_MPEG4_ADVANCED_REAL_TIME 9
#define FF_PROFILE_MPEG4_CORE_SCALABLE 10
#define FF_PROFILE_MPEG4_ADVANCED_CODING 11
#define FF_PROFILE_MPEG4_ADVANCED_CORE 12
#define FF_PROFILE_MPEG4_ADVANCED_SCALABLE_TEXTURE 13
#define FF_PROFILE_MPEG4_SIMPLE_STUDIO 14
#define FF_PROFILE_MPEG4_ADVANCED_SIMPLE 15

#define FF_PROFILE_JPEG2000_CSTREAM_RESTRICTION_0 1
#define FF_PROFILE_JPEG2000_CSTREAM_RESTRICTION_1 2
#define FF_PROFILE_JPEG2000_CSTREAM_NO_RESTRICTION 32768
#define FF_PROFILE_JPEG2000_DCINEMA_2K 3
#define FF_PROFILE_JPEG2000_DCINEMA_4K 4

#define FF_PROFILE_VP9_0 0
#define FF_PROFILE_VP9_1 1
#define FF_PROFILE_VP9_2 2
#define FF_PROFILE_VP9_3 3

#define FF_PROFILE_HEVC_MAIN 1
#define FF_PROFILE_HEVC_MAIN_10 2
#define FF_PROFILE_HEVC_MAIN_STILL_PICTURE 3
#define FF_PROFILE_HEVC_REXT 4
#define FF_PROFILE_HEVC_SCC 9

#define FF_PROFILE_VVC_MAIN_10 1
#define FF_PROFILE_VVC_MAIN_10_444 33

#define FF_PROFILE_AV1_MAIN 0
#define FF_PROFILE_AV1_HIGH 1
#define FF_PROFILE_AV1_PROFESSIONAL 2

#define FF_PROFILE_MJPEG_HUFFMAN_BASELINE_DCT 0xc0
#define FF_PROFILE_MJPEG_HUFFMAN_EXTENDED_SEQUENTIAL_DCT 0xc1
#define FF_PROFILE_MJPEG_HUFFMAN_PROGRESSIVE_DCT 0xc2
#define FF_PROFILE_MJPEG_HUFFMAN_LOSSLESS 0xc3
#define FF_PROFILE_MJPEG_JPEG_LS 0xf7

#define FF_PROFILE_SBC_MSBC 1

#define FF_PROFILE_PRORES_PROXY 0
#define FF_PROFILE_PRORES_LT 1
#define FF_PROFILE_PRORES_STANDARD 2
#define FF_PROFILE_PRORES_HQ 3
#define FF_PROFILE_PRORES_4444 4
#define FF_PROFILE_PRORES_XQ 5

#define FF_PROFILE_ARIB_PROFILE_A 0
#define FF_PROFILE_ARIB_PROFILE_C 1

#define FF_PROFILE_KLVA_SYNC 0
#define FF_PROFILE_KLVA_ASYNC 1

  /**
   * level
   * - encoding: Set by user.
   * - decoding: Set by libavcodec.
   */
  int level;
#define FF_LEVEL_UNKNOWN -99

  /**
   * Skip loop filtering for selected frames.
   * - encoding: unused
   * - decoding: Set by user.
   */
  enum AVDiscard skip_loop_filter;

  /**
   * Skip IDCT/dequantization for selected frames.
   * - encoding: unused
   * - decoding: Set by user.
   */
  enum AVDiscard skip_idct;

  /**
   * Skip decoding for selected frames.
   * - encoding: unused
   * - decoding: Set by user.
   */
  enum AVDiscard skip_frame;

  /**
   * Header containing style information for text subtitles.
   * For SUBTITLE_ASS subtitle type, it should contain the whole ASS
   * [Script Info] and [V4+ Styles] section, plus the [Events] line and
   * the Format line following. It shouldn't include any Dialogue line.
   * - encoding: Set/allocated/freed by user (before avcodec_open2())
   * - decoding: Set/allocated/freed by libavcodec (by avcodec_open2())
   */
  uint8_t* subtitle_header;
  int subtitle_header_size;

  /**
   * Audio only. The number of "priming" samples (padding) inserted by the
   * encoder at the beginning of the audio. I.e. this number of leading
   * decoded samples must be discarded by the caller to get the original audio
   * without leading padding.
   *
   * - decoding: unused
   * - encoding: Set by libavcodec. The timestamps on the output packets are
   *             adjusted by the encoder so that they always refer to the
   *             first sample of the data actually contained in the packet,
   *             including any added padding.  E.g. if the timebase is
   *             1/samplerate and the timestamp of the first input sample is
   *             0, the timestamp of the first output packet will be
   *             -initial_padding.
   */
  int initial_padding;

  /**
   * - decoding: For codecs that store a framerate value in the compressed
   *             bitstream, the decoder may export it here. { 0, 1} when
   *             unknown.
   * - encoding: May be used to signal the framerate of CFR content to an
   *             encoder.
   */
  AVRational framerate;

  /**
   * Nominal unaccelerated pixel format, see AV_PIX_FMT_xxx.
   * - encoding: unused.
   * - decoding: Set by libavcodec before calling get_format()
   */
  enum AVPixelFormat sw_pix_fmt;

  /**
   * Timebase in which pkt_dts/pts and AVPacket.dts/pts are.
   * - encoding unused.
   * - decoding set by user.
   */
  AVRational pkt_timebase;

  /**
   * AVCodecDescriptor
   * - encoding: unused.
   * - decoding: set by libavcodec.
   */
  const AVCodecDescriptor* codec_descriptor;

  /**
   * Current statistics for PTS correction.
   * - decoding: maintained and used by libavcodec, not intended to be used by
   * user apps
   * - encoding: unused
   */
  int64_t
      pts_correction_num_faulty_pts;  /// Number of incorrect PTS values so far
  int64_t
      pts_correction_num_faulty_dts;  /// Number of incorrect DTS values so far
  int64_t pts_correction_last_pts;    /// PTS of the last frame
  int64_t pts_correction_last_dts;    /// DTS of the last frame

  /**
   * Character encoding of the input subtitles file.
   * - decoding: set by user
   * - encoding: unused
   */
  char* sub_charenc;

  /**
   * Subtitles character encoding mode. Formats or codecs might be adjusting
   * this setting (if they are doing the conversion themselves for instance).
   * - decoding: set by libavcodec
   * - encoding: unused
   */
  int sub_charenc_mode;
#define FF_SUB_CHARENC_MODE_DO_NOTHING \
  -1  ///< do nothing (demuxer outputs a stream supposed to be already in UTF-8,
      ///< or the codec is bitmap for instance)
#define FF_SUB_CHARENC_MODE_AUTOMATIC \
  0  ///< libavcodec will select the mode itself
#define FF_SUB_CHARENC_MODE_PRE_DECODER \
  1  ///< the AVPacket data needs to be recoded to UTF-8 before being fed to the
     ///< decoder, requires iconv
#define FF_SUB_CHARENC_MODE_IGNORE \
  2  ///< neither convert the subtitles, nor check them for valid UTF-8

  /**
   * Skip processing alpha if supported by codec.
   * Note that if the format uses pre-multiplied alpha (common with VP6,
   * and recommended due to better video quality/compression)
   * the image will look as if alpha-blended onto a black background.
   * However for formats that do not use pre-multiplied alpha
   * there might be serious artefacts (though e.g. libswscale currently
   * assumes pre-multiplied alpha anyway).
   *
   * - decoding: set by user
   * - encoding: unused
   */
  int skip_alpha;

  /**
   * Number of samples to skip after a discontinuity
   * - decoding: unused
   * - encoding: set by libavcodec
   */
  int seek_preroll;

  /**
   * custom intra quantization matrix
   * - encoding: Set by user, can be NULL.
   * - decoding: unused.
   */
  uint16_t* chroma_intra_matrix;

  /**
   * dump format separator.
   * can be ", " or "\n      " or anything else
   * - encoding: Set by user.
   * - decoding: Set by user.
   */
  uint8_t* dump_separator;

  /**
   * ',' separated list of allowed decoders.
   * If NULL then all are allowed
   * - encoding: unused
   * - decoding: set by user
   */
  char* codec_whitelist;

  /**
   * Properties of the stream that gets decoded
   * - encoding: unused
   * - decoding: set by libavcodec
   */
  unsigned properties;
#define FF_CODEC_PROPERTY_LOSSLESS 0x00000001
#define FF_CODEC_PROPERTY_CLOSED_CAPTIONS 0x00000002
#define FF_CODEC_PROPERTY_FILM_GRAIN 0x00000004

  /**
   * Additional data associated with the entire coded stream.
   *
   * - decoding: unused
   * - encoding: may be set by libavcodec after avcodec_open2().
   */
  AVPacketSideData* coded_side_data;
  int nb_coded_side_data;

  /**
   * A reference to the AVHWFramesContext describing the input (for encoding)
   * or output (decoding) frames. The reference is set by the caller and
   * afterwards owned (and freed) by libavcodec - it should never be read by
   * the caller after being set.
   *
   * - decoding: This field should be set by the caller from the get_format()
   *             callback. The previous reference (if any) will always be
   *             unreffed by libavcodec before the get_format() call.
   *
   *             If the default get_buffer2() is used with a hwaccel pixel
   *             format, then this AVHWFramesContext will be used for
   *             allocating the frame buffers.
   *
   * - encoding: For hardware encoders configured to use a hwaccel pixel
   *             format, this field should be set by the caller to a reference
   *             to the AVHWFramesContext describing input frames.
   *             AVHWFramesContext.format must be equal to
   *             AVCodecContext.pix_fmt.
   *
   *             This field should be set before avcodec_open2() is called.
   */
  AVBufferRef* hw_frames_ctx;

  /**
   * Audio only. The amount of padding (in samples) appended by the encoder to
   * the end of the audio. I.e. this number of decoded samples must be
   * discarded by the caller from the end of the stream to get the original
   * audio without any trailing padding.
   *
   * - decoding: unused
   * - encoding: unused
   */
  int trailing_padding;

  /**
   * The number of pixels per image to maximally accept.
   *
   * - decoding: set by user
   * - encoding: set by user
   */
  int64_t max_pixels;

  /**
   * A reference to the AVHWDeviceContext describing the device which will
   * be used by a hardware encoder/decoder.  The reference is set by the
   * caller and afterwards owned (and freed) by libavcodec.
   *
   * This should be used if either the codec device does not require
   * hardware frames or any that are used are to be allocated internally by
   * libavcodec.  If the user wishes to supply any of the frames used as
   * encoder input or decoder output then hw_frames_ctx should be used
   * instead.  When hw_frames_ctx is set in get_format() for a decoder, this
   * field will be ignored while decoding the associated stream segment, but
   * may again be used on a following one after another get_format() call.
   *
   * For both encoders and decoders this field should be set before
   * avcodec_open2() is called and must not be written to thereafter.
   *
   * Note that some decoders may require this field to be set initially in
   * order to support hw_frames_ctx at all - in that case, all frames
   * contexts used must be created on the same device.
   */
  AVBufferRef* hw_device_ctx;

  /**
   * Bit set of AV_HWACCEL_FLAG_* flags, which affect hardware accelerated
   * decoding (if active).
   * - encoding: unused
   * - decoding: Set by user (either before avcodec_open2(), or in the
   *             AVCodecContext.get_format callback)
   */
  int hwaccel_flags;

  /**
   * Video decoding only. Certain video codecs support cropping, meaning that
   * only a sub-rectangle of the decoded frame is intended for display.  This
   * option controls how cropping is handled by libavcodec.
   *
   * When set to 1 (the default), libavcodec will apply cropping internally.
   * I.e. it will modify the output frame width/height fields and offset the
   * data pointers (only by as much as possible while preserving alignment, or
   * by the full amount if the AV_CODEC_FLAG_UNALIGNED flag is set) so that
   * the frames output by the decoder refer only to the cropped area. The
   * crop_* fields of the output frames will be zero.
   *
   * When set to 0, the width/height fields of the output frames will be set
   * to the coded dimensions and the crop_* fields will describe the cropping
   * rectangle. Applying the cropping is left to the caller.
   *
   * @warning When hardware acceleration with opaque output frames is used,
   * libavcodec is unable to apply cropping from the top/left border.
   *
   * @note when this option is set to zero, the width/height fields of the
   * AVCodecContext and output AVFrames have different meanings. The codec
   * context fields store display dimensions (with the coded dimensions in
   * coded_width/height), while the frame fields store the coded dimensions
   * (with the display dimensions being determined by the crop_* fields).
   */
  int apply_cropping;

  /*
   * Video decoding only.  Sets the number of extra hardware frames which
   * the decoder will allocate for use by the caller.  This must be set
   * before avcodec_open2() is called.
   *
   * Some hardware decoders require all frames that they will use for
   * output to be defined in advance before decoding starts.  For such
   * decoders, the hardware frame pool must therefore be of a fixed size.
   * The extra frames set here are on top of any number that the decoder
   * needs internally in order to operate normally (for example, frames
   * used as reference pictures).
   */
  int extra_hw_frames;

  /**
   * The percentage of damaged samples to discard a frame.
   *
   * - decoding: set by user
   * - encoding: unused
   */
  int discard_damaged_percentage;

  /**
   * The number of samples per frame to maximally accept.
   *
   * - decoding: set by user
   * - encoding: set by user
   */
  int64_t max_samples;

  /**
   * Bit set of AV_CODEC_EXPORT_DATA_* flags, which affects the kind of
   * metadata exported in frame, packet, or coded stream side data by
   * decoders and encoders.
   *
   * - decoding: set by user
   * - encoding: set by user
   */
  int export_side_data;

  /**
   * This callback is called at the beginning of each packet to get a data
   * buffer for it.
   *
   * The following field will be set in the packet before this callback is
   * called:
   * - size
   * This callback must use the above value to calculate the required buffer
   * size, which must padded by at least AV_INPUT_BUFFER_PADDING_SIZE bytes.
   *
   * In some specific cases, the encoder may not use the entire buffer allocated
   * by this callback. This will be reflected in the size value in the packet
   * once returned by avcodec_receive_packet().
   *
   * This callback must fill the following fields in the packet:
   * - data: alignment requirements for AVPacket apply, if any. Some
   * architectures and encoders may benefit from having aligned data.
   * - buf: must contain a pointer to an AVBufferRef structure. The packet's
   *   data pointer must be contained in it. See: av_buffer_create(),
   * av_buffer_alloc(), and av_buffer_ref().
   *
   * If AV_CODEC_CAP_DR1 is not set then get_encode_buffer() must call
   * avcodec_default_get_encode_buffer() instead of providing a buffer allocated
   * by some other means.
   *
   * The flags field may contain a combination of AV_GET_ENCODE_BUFFER_FLAG_
   * flags. They may be used for example to hint what use the buffer may get
   * after being created. Implementations of this callback may ignore flags they
   * don't understand. If AV_GET_ENCODE_BUFFER_FLAG_REF is set in flags then the
   * packet may be reused (read and/or written to if it is writable) later by
   * libavcodec.
   *
   * This callback must be thread-safe, as when frame threading is used, it may
   * be called from multiple threads simultaneously.
   *
   * @see avcodec_default_get_encode_buffer()
   *
   * - encoding: Set by libavcodec, user can override.
   * - decoding: unused
   */
  int (*get_encode_buffer)(struct AVCodecContext* s, AVPacket* pkt, int flags);

  /**
   * Audio channel layout.
   * - encoding: must be set by the caller, to one of AVCodec.ch_layouts.
   * - decoding: may be set by the caller if known e.g. from the container.
   *             The decoder can then override during decoding as needed.
   */
  AVChannelLayout ch_layout;

  /**
   * Frame counter, set by libavcodec.
   *
   * - decoding: total number of frames returned from the decoder so far.
   * - encoding: total number of frames passed to the encoder so far.
   *
   *   @note the counter is not incremented if encoding/decoding resulted in
   *   an error.
   */
  int64_t frame_num;
} AVCodecContext;

/**
 * @defgroup lavc_hwaccel AVHWAccel
 *
 * @note  Nothing in this structure should be accessed by the user.  At some
 *        point in future it will not be externally visible at all.
 *
 * @{
 */
typedef struct AVHWAccel {
  /**
   * Name of the hardware accelerated codec.
   * The name is globally unique among encoders and among decoders (but an
   * encoder and a decoder can share the same name).
   */
  const char* name;

  /**
   * Type of codec implemented by the hardware accelerator.
   *
   * See AVMEDIA_TYPE_xxx
   */
  enum AVMediaType type;

  /**
   * Codec implemented by the hardware accelerator.
   *
   * See AV_CODEC_ID_xxx
   */
  enum AVCodecID id;

  /**
   * Supported pixel format.
   *
   * Only hardware accelerated formats are supported here.
   */
  enum AVPixelFormat pix_fmt;

  /**
   * Hardware accelerated codec capabilities.
   * see AV_HWACCEL_CODEC_CAP_*
   */
  int capabilities;

  /*****************************************************************
   * No fields below this line are part of the public API. They
   * may not be used outside of libavcodec and can be changed and
   * removed at will.
   * New public fields should be added right above.
   *****************************************************************
   */

  /**
   * Allocate a custom buffer
   */
  int (*alloc_frame)(AVCodecContext* avctx, AVFrame* frame);

  /**
   * Called at the beginning of each frame or field picture.
   *
   * Meaningful frame information (codec specific) is guaranteed to
   * be parsed at this point. This function is mandatory.
   *
   * Note that buf can be NULL along with buf_size set to 0.
   * Otherwise, this means the whole frame is available at this point.
   *
   * @param avctx the codec context
   * @param buf the frame data buffer base
   * @param buf_size the size of the frame in bytes
   * @return zero if successful, a negative value otherwise
   */
  int (*start_frame)(AVCodecContext* avctx, const uint8_t* buf,
                     uint32_t buf_size);

  /**
   * Callback for parameter data (SPS/PPS/VPS etc).
   *
   * Useful for hardware decoders which keep persistent state about the
   * video parameters, and need to receive any changes to update that state.
   *
   * @param avctx the codec context
   * @param type the nal unit type
   * @param buf the nal unit data buffer
   * @param buf_size the size of the nal unit in bytes
   * @return zero if successful, a negative value otherwise
   */
  int (*decode_params)(AVCodecContext* avctx, int type, const uint8_t* buf,
                       uint32_t buf_size);

  /**
   * Callback for each slice.
   *
   * Meaningful slice information (codec specific) is guaranteed to
   * be parsed at this point. This function is mandatory.
   *
   * @param avctx the codec context
   * @param buf the slice data buffer base
   * @param buf_size the size of the slice in bytes
   * @return zero if successful, a negative value otherwise
   */
  int (*decode_slice)(AVCodecContext* avctx, const uint8_t* buf,
                      uint32_t buf_size);

  /**
   * Called at the end of each frame or field picture.
   *
   * The whole picture is parsed at this point and can now be sent
   * to the hardware accelerator. This function is mandatory.
   *
   * @param avctx the codec context
   * @return zero if successful, a negative value otherwise
   */
  int (*end_frame)(AVCodecContext* avctx);

  /**
   * Size of per-frame hardware accelerator private data.
   *
   * Private data is allocated with av_mallocz() before
   * AVCodecContext.get_buffer() and deallocated after
   * AVCodecContext.release_buffer().
   */
  int frame_priv_data_size;

  /**
   * Initialize the hwaccel private data.
   *
   * This will be called from ff_get_format(), after hwaccel and
   * hwaccel_context are set and the hwaccel private data in AVCodecInternal
   * is allocated.
   */
  int (*init)(AVCodecContext* avctx);

  /**
   * Uninitialize the hwaccel private data.
   *
   * This will be called from get_format() or avcodec_close(), after hwaccel
   * and hwaccel_context are already uninitialized.
   */
  int (*uninit)(AVCodecContext* avctx);

  /**
   * Size of the private data to allocate in
   * AVCodecInternal.hwaccel_priv_data.
   */
  int priv_data_size;

  /**
   * Internal hwaccel capabilities.
   */
  int caps_internal;

  /**
   * Fill the given hw_frames context with current codec parameters. Called
   * from get_format. Refer to avcodec_get_hw_frames_parameters() for
   * details.
   *
   * This CAN be called before AVHWAccel.init is called, and you must assume
   * that avctx->hwaccel_priv_data is invalid.
   */
  int (*frame_params)(AVCodecContext* avctx, AVBufferRef* hw_frames_ctx);
} AVHWAccel;

/**
 * HWAccel is experimental and is thus avoided in favor of non experimental
 * codecs
 */
#define AV_HWACCEL_CODEC_CAP_EXPERIMENTAL 0x0200

/**
 * Hardware acceleration should be used for decoding even if the codec level
 * used is unknown or higher than the maximum supported level reported by the
 * hardware driver.
 *
 * It's generally a good idea to pass this flag unless you have a specific
 * reason not to, as hardware tends to under-report supported levels.
 */
#define AV_HWACCEL_FLAG_IGNORE_LEVEL (1 << 0)

/**
 * Hardware acceleration can output YUV pixel formats with a different chroma
 * sampling than 4:2:0 and/or other than 8 bits per component.
 */
#define AV_HWACCEL_FLAG_ALLOW_HIGH_DEPTH (1 << 1)

/**
 * Hardware acceleration should still be attempted for decoding when the
 * codec profile does not match the reported capabilities of the hardware.
 *
 * For example, this can be used to try to decode baseline profile H.264
 * streams in hardware - it will often succeed, because many streams marked
 * as baseline profile actually conform to constrained baseline profile.
 *
 * @warning If the stream is actually not supported then the behaviour is
 *          undefined, and may include returning entirely incorrect output
 *          while indicating success.
 */
#define AV_HWACCEL_FLAG_ALLOW_PROFILE_MISMATCH (1 << 2)

/**
 * Some hardware decoders (namely nvdec) can either output direct decoder
 * surfaces, or make an on-device copy and return said copy.
 * There is a hard limit on how many decoder surfaces there can be, and it
 * cannot be accurately guessed ahead of time.
 * For some processing chains, this can be okay, but others will run into the
 * limit and in turn produce very confusing errors that require fine tuning of
 * more or less obscure options by the user, or in extreme cases cannot be
 * resolved at all without inserting an avfilter that forces a copy.
 *
 * Thus, the hwaccel will by default make a copy for safety and resilience.
 * If a users really wants to minimize the amount of copies, they can set this
 * flag and ensure their processing chain does not exhaust the surface pool.
 */
#define AV_HWACCEL_FLAG_UNSAFE_OUTPUT (1 << 3)

/**
 * @}
 */

enum AVSubtitleType {
  SUBTITLE_NONE,

  SUBTITLE_BITMAP,  ///< A bitmap, pict will be set

  /**
   * Plain text, the text field must be set by the decoder and is
   * authoritative. ass and pict fields may contain approximations.
   */
  SUBTITLE_TEXT,

  /**
   * Formatted text, the ass field must be set by the decoder and is
   * authoritative. pict and text fields may contain approximations.
   */
  SUBTITLE_ASS,
};

#define AV_SUBTITLE_FLAG_FORCED 0x00000001

typedef struct AVSubtitleRect {
  int x;          ///< top left corner  of pict, undefined when pict is not set
  int y;          ///< top left corner  of pict, undefined when pict is not set
  int w;          ///< width            of pict, undefined when pict is not set
  int h;          ///< height           of pict, undefined when pict is not set
  int nb_colors;  ///< number of colors in pict, undefined when pict is not set

  /**
   * data+linesize for the bitmap of this subtitle.
   * Can be set for text/ass as well once they are rendered.
   */
  uint8_t* data[4];
  int linesize[4];

  enum AVSubtitleType type;

  char* text;  ///< 0 terminated plain UTF-8 text

  /**
   * 0 terminated ASS/SSA compatible event line.
   * The presentation of this is unaffected by the other values in this
   * struct.
   */
  char* ass;

  int flags;
} AVSubtitleRect;

typedef struct AVSubtitle {
  uint16_t format;             /* 0 = graphics */
  uint32_t start_display_time; /* relative to packet pts, in ms */
  uint32_t end_display_time;   /* relative to packet pts, in ms */
  unsigned num_rects;
  AVSubtitleRect** rects;
  int64_t pts;  ///< Same as packet pts, in AV_TIME_BASE
} AVSubtitle;

/**
 * Return the LIBAVCODEC_VERSION_INT constant.
 */
unsigned avcodec_version(void);

/**
 * Return the libavcodec build-time configuration.
 */
const char* avcodec_configuration(void);

/**
 * Return the libavcodec license.
 */
const char* avcodec_license(void);

/**
 * Allocate an AVCodecContext and set its fields to default values. The
 * resulting struct should be freed with avcodec_free_context().
 *
 * @param codec if non-NULL, allocate private data and initialize defaults
 *              for the given codec. It is illegal to then call avcodec_open2()
 *              with a different codec.
 *              If NULL, then the codec-specific defaults won't be initialized,
 *              which may result in suboptimal default settings (this is
 *              important mainly for encoders, e.g. libx264).
 *
 * @return An AVCodecContext filled with default values or NULL on failure.
 */
AVCodecContext* avcodec_alloc_context3(const AVCodec* codec);

/**
 * Free the codec context and everything associated with it and write NULL to
 * the provided pointer.
 */
void avcodec_free_context(AVCodecContext** avctx);

/**
 * Get the AVClass for AVCodecContext. It can be used in combination with
 * AV_OPT_SEARCH_FAKE_OBJ for examining options.
 *
 * @see av_opt_find().
 */
const AVClass* avcodec_get_class(void);

/**
 * Get the AVClass for AVSubtitleRect. It can be used in combination with
 * AV_OPT_SEARCH_FAKE_OBJ for examining options.
 *
 * @see av_opt_find().
 */
const AVClass* avcodec_get_subtitle_rect_class(void);

/**
 * Fill the parameters struct based on the values from the supplied codec
 * context. Any allocated fields in par are freed and replaced with duplicates
 * of the corresponding fields in codec.
 *
 * @return >= 0 on success, a negative AVERROR code on failure
 */
int avcodec_parameters_from_context(AVCodecParameters* par,
                                    const AVCodecContext* codec);

/**
 * Fill the codec context based on the values from the supplied codec
 * parameters. Any allocated fields in codec that have a corresponding field in
 * par are freed and replaced with duplicates of the corresponding field in par.
 * Fields in codec that do not have a counterpart in par are not touched.
 *
 * @return >= 0 on success, a negative AVERROR code on failure.
 */
int avcodec_parameters_to_context(AVCodecContext* codec,
                                  const AVCodecParameters* par);

/**
 * Initialize the AVCodecContext to use the given AVCodec. Prior to using this
 * function the context has to be allocated with avcodec_alloc_context3().
 *
 * The functions avcodec_find_decoder_by_name(), avcodec_find_encoder_by_name(),
 * avcodec_find_decoder() and avcodec_find_encoder() provide an easy way for
 * retrieving a codec.
 *
 * @note Always call this function before using decoding routines (such as
 * @ref avcodec_receive_frame()).
 *
 * @code
 * av_dict_set(&opts, "b", "2.5M", 0);
 * codec = avcodec_find_decoder(AV_CODEC_ID_H264);
 * if (!codec)
 *     exit(1);
 *
 * context = avcodec_alloc_context3(codec);
 *
 * if (avcodec_open2(context, codec, opts) < 0)
 *     exit(1);
 * @endcode
 *
 * @param avctx The context to initialize.
 * @param codec The codec to open this context for. If a non-NULL codec has been
 *              previously passed to avcodec_alloc_context3() or
 *              for this context, then this parameter MUST be either NULL or
 *              equal to the previously passed codec.
 * @param options A dictionary filled with AVCodecContext and codec-private
 * options. On return this object will be filled with options that were not
 * found.
 *
 * @return zero on success, a negative value on error
 * @see avcodec_alloc_context3(), avcodec_find_decoder(),
 * avcodec_find_encoder(), av_dict_set(), av_opt_find().
 */
int avcodec_open2(AVCodecContext* avctx, const AVCodec* codec,
                  AVDictionary** options);

/**
 * Close a given AVCodecContext and free all the data associated with it
 * (but not the AVCodecContext itself).
 *
 * Calling this function on an AVCodecContext that hasn't been opened will free
 * the codec-specific data allocated in avcodec_alloc_context3() with a non-NULL
 * codec. Subsequent calls will do nothing.
 *
 * @note Do not use this function. Use avcodec_free_context() to destroy a
 * codec context (either open or closed). Opening and closing a codec context
 * multiple times is not supported anymore -- use multiple codec contexts
 * instead.
 */
int avcodec_close(AVCodecContext* avctx);

/**
 * Free all allocated data in the given subtitle struct.
 *
 * @param sub AVSubtitle to free.
 */
void avsubtitle_free(AVSubtitle* sub);

/**
 * @}
 */

/**
 * @addtogroup lavc_decoding
 * @{
 */

/**
 * The default callback for AVCodecContext.get_buffer2(). It is made public so
 * it can be called by custom get_buffer2() implementations for decoders without
 * AV_CODEC_CAP_DR1 set.
 */
int avcodec_default_get_buffer2(AVCodecContext* s, AVFrame* frame, int flags);

/**
 * The default callback for AVCodecContext.get_encode_buffer(). It is made
 * public so it can be called by custom get_encode_buffer() implementations for
 * encoders without AV_CODEC_CAP_DR1 set.
 */
int avcodec_default_get_encode_buffer(AVCodecContext* s, AVPacket* pkt,
                                      int flags);

/**
 * Modify width and height values so that they will result in a memory
 * buffer that is acceptable for the codec if you do not use any horizontal
 * padding.
 *
 * May only be used if a codec with AV_CODEC_CAP_DR1 has been opened.
 */
void avcodec_align_dimensions(AVCodecContext* s, int* width, int* height);

/**
 * Modify width and height values so that they will result in a memory
 * buffer that is acceptable for the codec if you also ensure that all
 * line sizes are a multiple of the respective linesize_align[i].
 *
 * May only be used if a codec with AV_CODEC_CAP_DR1 has been opened.
 */
void avcodec_align_dimensions2(AVCodecContext* s, int* width, int* height,
                               int linesize_align[AV_NUM_DATA_POINTERS]);

#ifdef FF_API_AVCODEC_CHROMA_POS
/**
 * Converts AVChromaLocation to swscale x/y chroma position.
 *
 * The positions represent the chroma (0,0) position in a coordinates system
 * with luma (0,0) representing the origin and luma(1,1) representing 256,256
 *
 * @param xpos  horizontal chroma sample position
 * @param ypos  vertical   chroma sample position
 * @deprecated Use av_chroma_location_enum_to_pos() instead.
 */
attribute_deprecated int avcodec_enum_to_chroma_pos(int* xpos, int* ypos,
                                                    enum AVChromaLocation pos);

/**
 * Converts swscale x/y chroma position to AVChromaLocation.
 *
 * The positions represent the chroma (0,0) position in a coordinates system
 * with luma (0,0) representing the origin and luma(1,1) representing 256,256
 *
 * @param xpos  horizontal chroma sample position
 * @param ypos  vertical   chroma sample position
 * @deprecated Use av_chroma_location_pos_to_enum() instead.
 */
attribute_deprecated enum AVChromaLocation avcodec_chroma_pos_to_enum(int xpos,
                                                                      int ypos);
#endif

/**
 * Decode a subtitle message.
 * Return a negative value on error, otherwise return the number of bytes used.
 * If no subtitle could be decompressed, got_sub_ptr is zero.
 * Otherwise, the subtitle is stored in *sub.
 * Note that AV_CODEC_CAP_DR1 is not available for subtitle codecs. This is for
 * simplicity, because the performance difference is expected to be negligible
 * and reusing a get_buffer written for video codecs would probably perform
 * badly due to a potentially very different allocation pattern.
 *
 * Some decoders (those marked with AV_CODEC_CAP_DELAY) have a delay between
 * input and output. This means that for some packets they will not immediately
 * produce decoded output and need to be flushed at the end of decoding to get
 * all the decoded data. Flushing is done by calling this function with packets
 * with avpkt->data set to NULL and avpkt->size set to 0 until it stops
 * returning subtitles. It is safe to flush even those decoders that are not
 * marked with AV_CODEC_CAP_DELAY, then no subtitles will be returned.
 *
 * @note The AVCodecContext MUST have been opened with @ref avcodec_open2()
 * before packets may be fed to the decoder.
 *
 * @param avctx the codec context
 * @param[out] sub The preallocated AVSubtitle in which the decoded subtitle
 * will be stored, must be freed with avsubtitle_free if *got_sub_ptr is set.
 * @param[in,out] got_sub_ptr Zero if no subtitle could be decompressed,
 * otherwise, it is nonzero.
 * @param[in] avpkt The input AVPacket containing the input buffer.
 */
int avcodec_decode_subtitle2(AVCodecContext* avctx, AVSubtitle* sub,
                             int* got_sub_ptr, const AVPacket* avpkt);

/**
 * Supply raw packet data as input to a decoder.
 *
 * Internally, this call will copy relevant AVCodecContext fields, which can
 * influence decoding per-packet, and apply them when the packet is actually
 * decoded. (For example AVCodecContext.skip_frame, which might direct the
 * decoder to drop the frame contained by the packet sent with this function.)
 *
 * @warning The input buffer, avpkt->data must be AV_INPUT_BUFFER_PADDING_SIZE
 *          larger than the actual read bytes because some optimized bitstream
 *          readers read 32 or 64 bits at once and could read over the end.
 *
 * @note The AVCodecContext MUST have been opened with @ref avcodec_open2()
 *       before packets may be fed to the decoder.
 *
 * @param avctx codec context
 * @param[in] avpkt The input AVPacket. Usually, this will be a single video
 *                  frame, or several complete audio frames.
 *                  Ownership of the packet remains with the caller, and the
 *                  decoder will not write to the packet. The decoder may create
 *                  a reference to the packet data (or copy it if the packet is
 *                  not reference-counted).
 *                  Unlike with older APIs, the packet is always fully consumed,
 *                  and if it contains multiple frames (e.g. some audio codecs),
 *                  will require you to call avcodec_receive_frame() multiple
 *                  times afterwards before you can send a new packet.
 *                  It can be NULL (or an AVPacket with data set to NULL and
 *                  size set to 0); in this case, it is considered a flush
 *                  packet, which signals the end of the stream. Sending the
 *                  first flush packet will return success. Subsequent ones are
 *                  unnecessary and will return AVERROR_EOF. If the decoder
 *                  still has frames buffered, it will return them after sending
 *                  a flush packet.
 *
 * @retval 0                 success
 * @retval AVERROR(EAGAIN)   input is not accepted in the current state - user
 *                           must read output with avcodec_receive_frame() (once
 *                           all output is read, the packet should be resent,
 *                           and the call will not fail with EAGAIN).
 * @retval AVERROR_EOF       the decoder has been flushed, and no new packets
 * can be sent to it (also returned if more than 1 flush packet is sent)
 * @retval AVERROR(EINVAL)   codec not opened, it is an encoder, or requires
 * flush
 * @retval AVERROR(ENOMEM)   failed to add packet to internal queue, or similar
 * @retval "another negative error code" legitimate decoding errors
 */
int avcodec_send_packet(AVCodecContext* avctx, const AVPacket* avpkt);

/**
 * Return decoded output data from a decoder or encoder (when the
 * AV_CODEC_FLAG_RECON_FRAME flag is used).
 *
 * @param avctx codec context
 * @param frame This will be set to a reference-counted video or audio
 *              frame (depending on the decoder type) allocated by the
 *              codec. Note that the function will always call
 *              av_frame_unref(frame) before doing anything else.
 *
 * @retval 0                success, a frame was returned
 * @retval AVERROR(EAGAIN)  output is not available in this state - user must
 *                          try to send new input
 * @retval AVERROR_EOF      the codec has been fully flushed, and there will be
 *                          no more output frames
 * @retval AVERROR(EINVAL)  codec not opened, or it is an encoder without the
 *                          AV_CODEC_FLAG_RECON_FRAME flag enabled
 * @retval AVERROR_INPUT_CHANGED current decoded frame has changed parameters
 * with respect to first decoded frame. Applicable when flag
 *                          AV_CODEC_FLAG_DROPCHANGED is set.
 * @retval "other negative error code" legitimate decoding errors
 */
int avcodec_receive_frame(AVCodecContext* avctx, AVFrame* frame);

/**
 * Supply a raw video or audio frame to the encoder. Use
 * avcodec_receive_packet() to retrieve buffered output packets.
 *
 * @param avctx     codec context
 * @param[in] frame AVFrame containing the raw audio or video frame to be
 * encoded. Ownership of the frame remains with the caller, and the encoder will
 * not write to the frame. The encoder may create a reference to the frame data
 * (or copy it if the frame is not reference-counted). It can be NULL, in which
 * case it is considered a flush packet.  This signals the end of the stream. If
 * the encoder still has packets buffered, it will return them after this call.
 * Once flushing mode has been entered, additional flush packets are ignored,
 * and sending frames will return AVERROR_EOF.
 *
 *                  For audio:
 *                  If AV_CODEC_CAP_VARIABLE_FRAME_SIZE is set, then each frame
 *                  can have any number of samples.
 *                  If it is not set, frame->nb_samples must be equal to
 *                  avctx->frame_size for all frames except the last.
 *                  The final frame may be smaller than avctx->frame_size.
 * @retval 0                 success
 * @retval AVERROR(EAGAIN)   input is not accepted in the current state - user
 * must read output with avcodec_receive_packet() (once all output is read, the
 * packet should be resent, and the call will not fail with EAGAIN).
 * @retval AVERROR_EOF       the encoder has been flushed, and no new frames can
 *                           be sent to it
 * @retval AVERROR(EINVAL)   codec not opened, it is a decoder, or requires
 * flush
 * @retval AVERROR(ENOMEM)   failed to add packet to internal queue, or similar
 * @retval "another negative error code" legitimate encoding errors
 */
int avcodec_send_frame(AVCodecContext* avctx, const AVFrame* frame);

/**
 * Read encoded data from the encoder.
 *
 * @param avctx codec context
 * @param avpkt This will be set to a reference-counted packet allocated by the
 *              encoder. Note that the function will always call
 *              av_packet_unref(avpkt) before doing anything else.
 * @retval 0               success
 * @retval AVERROR(EAGAIN) output is not available in the current state - user
 * must try to send input
 * @retval AVERROR_EOF     the encoder has been fully flushed, and there will be
 * no more output packets
 * @retval AVERROR(EINVAL) codec not opened, or it is a decoder
 * @retval "another negative error code" legitimate encoding errors
 */
int avcodec_receive_packet(AVCodecContext* avctx, AVPacket* avpkt);

/**
 * Create and return a AVHWFramesContext with values adequate for hardware
 * decoding. This is meant to get called from the get_format callback, and is
 * a helper for preparing a AVHWFramesContext for AVCodecContext.hw_frames_ctx.
 * This API is for decoding with certain hardware acceleration modes/APIs only.
 *
 * The returned AVHWFramesContext is not initialized. The caller must do this
 * with av_hwframe_ctx_init().
 *
 * Calling this function is not a requirement, but makes it simpler to avoid
 * codec or hardware API specific details when manually allocating frames.
 *
 * Alternatively to this, an API user can set AVCodecContext.hw_device_ctx,
 * which sets up AVCodecContext.hw_frames_ctx fully automatically, and makes
 * it unnecessary to call this function or having to care about
 * AVHWFramesContext initialization at all.
 *
 * There are a number of requirements for calling this function:
 *
 * - It must be called from get_format with the same avctx parameter that was
 *   passed to get_format. Calling it outside of get_format is not allowed, and
 *   can trigger undefined behavior.
 * - The function is not always supported (see description of return values).
 *   Even if this function returns successfully, hwaccel initialization could
 *   fail later. (The degree to which implementations check whether the stream
 *   is actually supported varies. Some do this check only after the user's
 *   get_format callback returns.)
 * - The hw_pix_fmt must be one of the choices suggested by get_format. If the
 *   user decides to use a AVHWFramesContext prepared with this API function,
 *   the user must return the same hw_pix_fmt from get_format.
 * - The device_ref passed to this function must support the given hw_pix_fmt.
 * - After calling this API function, it is the user's responsibility to
 *   initialize the AVHWFramesContext (returned by the out_frames_ref
 * parameter), and to set AVCodecContext.hw_frames_ctx to it. If done, this must
 * be done before returning from get_format (this is implied by the normal
 *   AVCodecContext.hw_frames_ctx API rules).
 * - The AVHWFramesContext parameters may change every time time get_format is
 *   called. Also, AVCodecContext.hw_frames_ctx is reset before get_format. So
 *   you are inherently required to go through this process again on every
 *   get_format call.
 * - It is perfectly possible to call this function without actually using
 *   the resulting AVHWFramesContext. One use-case might be trying to reuse a
 *   previously initialized AVHWFramesContext, and calling this API function
 *   only to test whether the required frame parameters have changed.
 * - Fields that use dynamically allocated values of any kind must not be set
 *   by the user unless setting them is explicitly allowed by the documentation.
 *   If the user sets AVHWFramesContext.free and AVHWFramesContext.user_opaque,
 *   the new free callback must call the potentially set previous free callback.
 *   This API call may set any dynamically allocated fields, including the free
 *   callback.
 *
 * The function will set at least the following fields on AVHWFramesContext
 * (potentially more, depending on hwaccel API):
 *
 * - All fields set by av_hwframe_ctx_alloc().
 * - Set the format field to hw_pix_fmt.
 * - Set the sw_format field to the most suited and most versatile format. (An
 *   implication is that this will prefer generic formats over opaque formats
 *   with arbitrary restrictions, if possible.)
 * - Set the width/height fields to the coded frame size, rounded up to the
 *   API-specific minimum alignment.
 * - Only _if_ the hwaccel requires a pre-allocated pool: set the
 * initial_pool_size field to the number of maximum reference surfaces possible
 * with the codec, plus 1 surface for the user to work (meaning the user can
 * safely reference at most 1 decoded surface at a time), plus additional
 * buffering introduced by frame threading. If the hwaccel does not require
 * pre-allocation, the field is left to 0, and the decoder will allocate new
 * surfaces on demand during decoding.
 * - Possibly AVHWFramesContext.hwctx fields, depending on the underlying
 *   hardware API.
 *
 * Essentially, out_frames_ref returns the same as av_hwframe_ctx_alloc(), but
 * with basic frame parameters set.
 *
 * The function is stateless, and does not change the AVCodecContext or the
 * device_ref AVHWDeviceContext.
 *
 * @param avctx The context which is currently calling get_format, and which
 *              implicitly contains all state needed for filling the returned
 *              AVHWFramesContext properly.
 * @param device_ref A reference to the AVHWDeviceContext describing the device
 *                   which will be used by the hardware decoder.
 * @param hw_pix_fmt The hwaccel format you are going to return from get_format.
 * @param out_frames_ref On success, set to a reference to an _uninitialized_
 *                       AVHWFramesContext, created from the given device_ref.
 *                       Fields will be set to values required for decoding.
 *                       Not changed if an error is returned.
 * @return zero on success, a negative value on error. The following error codes
 *         have special semantics:
 *      AVERROR(ENOENT): the decoder does not support this functionality. Setup
 *                       is always manual, or it is a decoder which does not
 *                       support setting AVCodecContext.hw_frames_ctx at all,
 *                       or it is a software format.
 *      AVERROR(EINVAL): it is known that hardware decoding is not supported for
 *                       this configuration, or the device_ref is not supported
 *                       for the hwaccel referenced by hw_pix_fmt.
 */
int avcodec_get_hw_frames_parameters(AVCodecContext* avctx,
                                     AVBufferRef* device_ref,
                                     enum AVPixelFormat hw_pix_fmt,
                                     AVBufferRef** out_frames_ref);

/**
 * @defgroup lavc_parsing Frame parsing
 * @{
 */

enum AVPictureStructure {
  AV_PICTURE_STRUCTURE_UNKNOWN,       ///< unknown
  AV_PICTURE_STRUCTURE_TOP_FIELD,     ///< coded as top field
  AV_PICTURE_STRUCTURE_BOTTOM_FIELD,  ///< coded as bottom field
  AV_PICTURE_STRUCTURE_FRAME,         ///< coded as frame
};

typedef struct AVCodecParserContext {
  void* priv_data;
  const struct AVCodecParser* parser;
  int64_t frame_offset;      /* offset of the current frame */
  int64_t cur_offset;        /* current offset
                                (incremented by each av_parser_parse()) */
  int64_t next_frame_offset; /* offset of the next frame */
  /* video info */
  int pict_type; /* XXX: Put it back in AVCodecContext. */
  /**
   * This field is used for proper frame duration computation in lavf.
   * It signals, how much longer the frame duration of the current frame
   * is compared to normal frame duration.
   *
   * frame_duration = (1 + repeat_pict) * time_base
   *
   * It is used by codecs like H.264 to display telecined material.
   */
  int repeat_pict; /* XXX: Put it back in AVCodecContext. */
  int64_t pts;     /* pts of the current frame */
  int64_t dts;     /* dts of the current frame */

  /* private data */
  int64_t last_pts;
  int64_t last_dts;
  int fetch_timestamp;

#define AV_PARSER_PTS_NB 4
  int cur_frame_start_index;
  int64_t cur_frame_offset[AV_PARSER_PTS_NB];
  int64_t cur_frame_pts[AV_PARSER_PTS_NB];
  int64_t cur_frame_dts[AV_PARSER_PTS_NB];

  int flags;
#define PARSER_FLAG_COMPLETE_FRAMES 0x0001
#define PARSER_FLAG_ONCE 0x0002
/// Set if the parser has a valid file offset
#define PARSER_FLAG_FETCHED_OFFSET 0x0004
#define PARSER_FLAG_USE_CODEC_TS 0x1000

  int64_t offset;  ///< byte offset from starting packet start
  int64_t cur_frame_end[AV_PARSER_PTS_NB];

  /**
   * Set by parser to 1 for key frames and 0 for non-key frames.
   * It is initialized to -1, so if the parser doesn't set this flag,
   * old-style fallback using AV_PICTURE_TYPE_I picture type as key frames
   * will be used.
   */
  int key_frame;

  // Timestamp generation support:
  /**
   * Synchronization point for start of timestamp generation.
   *
   * Set to >0 for sync point, 0 for no sync point and <0 for undefined
   * (default).
   *
   * For example, this corresponds to presence of H.264 buffering period
   * SEI message.
   */
  int dts_sync_point;

  /**
   * Offset of the current timestamp against last timestamp sync point in
   * units of AVCodecContext.time_base.
   *
   * Set to INT_MIN when dts_sync_point unused. Otherwise, it must
   * contain a valid timestamp offset.
   *
   * Note that the timestamp of sync point has usually a nonzero
   * dts_ref_dts_delta, which refers to the previous sync point. Offset of
   * the next frame after timestamp sync point will be usually 1.
   *
   * For example, this corresponds to H.264 cpb_removal_delay.
   */
  int dts_ref_dts_delta;

  /**
   * Presentation delay of current frame in units of AVCodecContext.time_base.
   *
   * Set to INT_MIN when dts_sync_point unused. Otherwise, it must
   * contain valid non-negative timestamp delta (presentation time of a frame
   * must not lie in the past).
   *
   * This delay represents the difference between decoding and presentation
   * time of the frame.
   *
   * For example, this corresponds to H.264 dpb_output_delay.
   */
  int pts_dts_delta;

  /**
   * Position of the packet in file.
   *
   * Analogous to cur_frame_pts/dts
   */
  int64_t cur_frame_pos[AV_PARSER_PTS_NB];

  /**
   * Byte position of currently parsed frame in stream.
   */
  int64_t pos;

  /**
   * Previous frame byte position.
   */
  int64_t last_pos;

  /**
   * Duration of the current frame.
   * For audio, this is in units of 1 / AVCodecContext.sample_rate.
   * For all other types, this is in units of AVCodecContext.time_base.
   */
  int duration;

  enum AVFieldOrder field_order;

  /**
   * Indicate whether a picture is coded as a frame, top field or bottom field.
   *
   * For example, H.264 field_pic_flag equal to 0 corresponds to
   * AV_PICTURE_STRUCTURE_FRAME. An H.264 picture with field_pic_flag
   * equal to 1 and bottom_field_flag equal to 0 corresponds to
   * AV_PICTURE_STRUCTURE_TOP_FIELD.
   */
  enum AVPictureStructure picture_structure;

  /**
   * Picture number incremented in presentation or output order.
   * This field may be reinitialized at the first picture of a new sequence.
   *
   * For example, this corresponds to H.264 PicOrderCnt.
   */
  int output_picture_number;

  /**
   * Dimensions of the decoded video intended for presentation.
   */
  int width;
  int height;

  /**
   * Dimensions of the coded video.
   */
  int coded_width;
  int coded_height;

  /**
   * The format of the coded data, corresponds to enum AVPixelFormat for video
   * and for enum AVSampleFormat for audio.
   *
   * Note that a decoder can have considerable freedom in how exactly it
   * decodes the data, so the format reported here might be different from the
   * one returned by a decoder.
   */
  int format;
} AVCodecParserContext;

typedef struct AVCodecParser {
  int codec_ids[7]; /* several codec IDs are permitted */
  int priv_data_size;
  int (*parser_init)(AVCodecParserContext* s);
  /* This callback never returns an error, a negative value means that
   * the frame start was in a previous packet. */
  int (*parser_parse)(AVCodecParserContext* s, AVCodecContext* avctx,
                      const uint8_t** poutbuf, int* poutbuf_size,
                      const uint8_t* buf, int buf_size);
  void (*parser_close)(AVCodecParserContext* s);
  int (*split)(AVCodecContext* avctx, const uint8_t* buf, int buf_size);
} AVCodecParser;

/**
 * Iterate over all registered codec parsers.
 *
 * @param opaque a pointer where libavcodec will store the iteration state. Must
 *               point to NULL to start the iteration.
 *
 * @return the next registered codec parser or NULL when the iteration is
 *         finished
 */
const AVCodecParser* av_parser_iterate(void** opaque);

AVCodecParserContext* av_parser_init(int codec_id);

/**
 * Parse a packet.
 *
 * @param s             parser context.
 * @param avctx         codec context.
 * @param poutbuf       set to pointer to parsed buffer or NULL if not yet
 finished.
 * @param poutbuf_size  set to size of parsed buffer or zero if not yet
 finished.
 * @param buf           input buffer.
 * @param buf_size      buffer size in bytes without the padding. I.e. the full
 buffer size is assumed to be buf_size + AV_INPUT_BUFFER_PADDING_SIZE. To signal
 EOF, this should be 0 (so that the last frame can be output).
 * @param pts           input presentation timestamp.
 * @param dts           input decoding timestamp.
 * @param pos           input byte position in stream.
 * @return the number of bytes of the input bitstream used.
 *
 * Example:
 * @code
 *   while(in_len){
 *       len = av_parser_parse2(myparser, AVCodecContext, &data, &size,
 *                                        in_data, in_len,
 *                                        pts, dts, pos);
 *       in_data += len;
 *       in_len  -= len;
 *
 *       if(size)
 *          decode_frame(data, size);
 *   }
 * @endcode
 */
int av_parser_parse2(AVCodecParserContext* s, AVCodecContext* avctx,
                     uint8_t** poutbuf, int* poutbuf_size, const uint8_t* buf,
                     int buf_size, int64_t pts, int64_t dts, int64_t pos);

void av_parser_close(AVCodecParserContext* s);

/**
 * @}
 * @}
 */

/**
 * @addtogroup lavc_encoding
 * @{
 */

int avcodec_encode_subtitle(AVCodecContext* avctx, uint8_t* buf, int buf_size,
                            const AVSubtitle* sub);

/**
 * @}
 */

/**
 * @defgroup lavc_misc Utility functions
 * @ingroup libavc
 *
 * Miscellaneous utility functions related to both encoding and decoding
 * (or neither).
 * @{
 */

/**
 * @defgroup lavc_misc_pixfmt Pixel formats
 *
 * Functions for working with pixel formats.
 * @{
 */

/**
 * Return a value representing the fourCC code associated to the
 * pixel format pix_fmt, or 0 if no associated fourCC code can be
 * found.
 */
unsigned int avcodec_pix_fmt_to_codec_tag(enum AVPixelFormat pix_fmt);

/**
 * Find the best pixel format to convert to given a certain source pixel
 * format.  When converting from one pixel format to another, information loss
 * may occur.  For example, when converting from RGB24 to GRAY, the color
 * information will be lost. Similarly, other losses occur when converting from
 * some formats to other formats. avcodec_find_best_pix_fmt_of_2() searches
 * which of the given pixel formats should be used to suffer the least amount of
 * loss. The pixel formats from which it chooses one, are determined by the
 * pix_fmt_list parameter.
 *
 *
 * @param[in] pix_fmt_list AV_PIX_FMT_NONE terminated array of pixel formats to
 * choose from
 * @param[in] src_pix_fmt source pixel format
 * @param[in] has_alpha Whether the source pixel format alpha channel is used.
 * @param[out] loss_ptr Combination of flags informing you what kind of losses
 * will occur.
 * @return The best pixel format to convert to or -1 if none was found.
 */
enum AVPixelFormat avcodec_find_best_pix_fmt_of_list(
    const enum AVPixelFormat* pix_fmt_list, enum AVPixelFormat src_pix_fmt,
    int has_alpha, int* loss_ptr);

enum AVPixelFormat avcodec_default_get_format(struct AVCodecContext* s,
                                              const enum AVPixelFormat* fmt);

/**
 * @}
 */

void avcodec_string(char* buf, int buf_size, AVCodecContext* enc, int encode);

int avcodec_default_execute(AVCodecContext* c,
                            int (*func)(AVCodecContext* c2, void* arg2),
                            void* arg, int* ret, int count, int size);
int avcodec_default_execute2(AVCodecContext* c,
                             int (*func)(AVCodecContext* c2, void* arg2, int,
                                         int),
                             void* arg, int* ret, int count);
// FIXME func typedef

/**
 * Fill AVFrame audio data and linesize pointers.
 *
 * The buffer buf must be a preallocated buffer with a size big enough
 * to contain the specified samples amount. The filled AVFrame data
 * pointers will point to this buffer.
 *
 * AVFrame extended_data channel pointers are allocated if necessary for
 * planar audio.
 *
 * @param frame       the AVFrame
 *                    frame->nb_samples must be set prior to calling the
 *                    function. This function fills in frame->data,
 *                    frame->extended_data, frame->linesize[0].
 * @param nb_channels channel count
 * @param sample_fmt  sample format
 * @param buf         buffer to use for frame data
 * @param buf_size    size of buffer
 * @param align       plane size sample alignment (0 = default)
 * @return            >=0 on success, negative error code on failure
 * @todo return the size in bytes required to store the samples in
 * case of success, at the next libavutil bump
 */
int avcodec_fill_audio_frame(AVFrame* frame, int nb_channels,
                             enum AVSampleFormat sample_fmt, const uint8_t* buf,
                             int buf_size, int align);

/**
 * Reset the internal codec state / flush internal buffers. Should be called
 * e.g. when seeking or when switching to a different stream.
 *
 * @note for decoders, this function just releases any references the decoder
 * might keep internally, but the caller's references remain valid.
 *
 * @note for encoders, this function will only do something if the encoder
 * declares support for AV_CODEC_CAP_ENCODER_FLUSH. When called, the encoder
 * will drain any remaining packets, and can then be re-used for a different
 * stream (as opposed to sending a null frame which will leave the encoder
 * in a permanent EOF state after draining). This can be desirable if the
 * cost of tearing down and replacing the encoder instance is high.
 */
void avcodec_flush_buffers(AVCodecContext* avctx);

/**
 * Return audio frame duration.
 *
 * @param avctx        codec context
 * @param frame_bytes  size of the frame, or 0 if unknown
 * @return             frame duration, in samples, if known. 0 if not able to
 *                     determine.
 */
int av_get_audio_frame_duration(AVCodecContext* avctx, int frame_bytes);

/* memory */

/**
 * Same behaviour av_fast_malloc but the buffer has additional
 * AV_INPUT_BUFFER_PADDING_SIZE at the end which will always be 0.
 *
 * In addition the whole buffer will initially and after resizes
 * be 0-initialized so that no uninitialized data will ever appear.
 */
void av_fast_padded_malloc(void* ptr, unsigned int* size, size_t min_size);

/**
 * Same behaviour av_fast_padded_malloc except that buffer will always
 * be 0-initialized after call.
 */
void av_fast_padded_mallocz(void* ptr, unsigned int* size, size_t min_size);

/**
 * @return a positive value if s is open (i.e. avcodec_open2() was called on it
 * with no corresponding avcodec_close()), 0 otherwise.
 */
int avcodec_is_open(AVCodecContext* s);

/**
 * @}
 */

#endif /* AVCODEC_AVCODEC_H */