tor-browser

avcodec.h (108136B)

---

/*
* 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/channel_layout.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_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"

#include "codec_desc.h"
#include "codec_par.h"
#endif

struct AVCodecParameters;

/**
* @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
*/
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)
/**
* Request the encoder to output reconstructed frames, i.e.\ frames that would
* be produced by decoding the encoded bitstream. 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.
*
* @note
* Each reconstructed frame returned by the encoder corresponds to the last
* encoded packet, i.e. the frames are returned in coded order rather than
* presentation order.
*
* @note
* Frame parameters (like pixel format or dimensions) do not have to match the
* AVCodecContext values. Make sure to use the values from the returned frame.
*/
#define AV_CODEC_FLAG_RECON_FRAME     (1 <<  6)
/**
* @par decoding
* Request the decoder to propagate each packet's 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)

/**
* Decoding only.
* Do not apply picture enhancement layers, export them instead.
*/
#define AV_CODEC_EXPORT_DATA_ENHANCEMENTS (1 << 4)

/**
* 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)

/**
* 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;

   /**
    * 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;

   /**
    * Out-of-band global headers that may be used by some codecs.
    *
    * - decoding: Should be set by the caller when available (typically from a
    *   demuxer) before opening the decoder; some decoders require this to be
    *   set and will fail to initialize otherwise.
    *
    *   The array must be allocated with the av_malloc() family of functions;
    *   allocated size must be at least AV_INPUT_BUFFER_PADDING_SIZE bytes
    *   larger than extradata_size.
    *
    * - encoding: May be set by the encoder in avcodec_open2() (possibly
    *   depending on whether the AV_CODEC_FLAG_GLOBAL_HEADER flag is set).
    *
    * After being set, the array is owned by the codec and freed in
    * avcodec_free_context().
    */
   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;

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

   /**
    * - 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;

   /**
    * 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;

   /**
    * 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;

   /**
    * 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;

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

   /**
    * 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 to override the default output color range value,
    *   If not specified, libavcodec sets the color range depending on the
    *   output format.
    * - decoding: Set by libavcodec, can be set by the user to propagate the
    *   color range to components reading from the decoder context.
    */
   enum AVColorRange color_range;

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

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

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

   /**
    * 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;

   /**
    * 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)

   /**
    * 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;

   /**
    * 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;

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

   /**
    * 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;

   /**
    * 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;

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

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

   /**
    * 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;

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

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

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

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

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

   /**
    * 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;

   /* 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;

   /**
    * 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;

   /**
    * 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;

   /**
    * 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;

   /**
    * 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;

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

   /**
    * 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().
    *   Decoders will generally initialize the whole buffer before it is output
    *   but it can in rare error conditions happen that uninitialized data is passed
    *   through. \important The buffers returned by get_buffer* should thus not contain sensitive
    *   data.
    *
    * 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 */
   /**
    * 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

   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: May be set by libavcodec.
    */
   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;

   /**
    * 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;

   /**
    * 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;

   /**
    * 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.  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;

   /**
    * 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
#define FF_DCT_NEON    7

   /**
    * 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
#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;

   /**
    * 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);

   /**
    * profile
    * - encoding: Set by user.
    * - decoding: Set by libavcodec.
    * See the AV_PROFILE_* defines in defs.h.
    */
    int profile;

   /**
    * Encoding level descriptor.
    * - encoding: Set by user, corresponds to a specific level defined by the
    *   codec, usually corresponding to the profile level, if not specified it
    *   is set to AV_LEVEL_UNKNOWN.
    * - decoding: Set by libavcodec.
    * See AV_LEVEL_* in defs.h.
    */
    int level;

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

   /**
    * 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;

   /**
    * 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 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;

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

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

   /**
    * 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

   /**
    * 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: May be set by the caller before avcodec_open2() to an array
    *   allocated with the av_malloc() family of functions.
    * - decoding: May be set by libavcodec in avcodec_open2().
    *
    * After being set, the array is owned by the codec and freed in
    * avcodec_free_context().
    */
   int subtitle_header_size;
   uint8_t *subtitle_header;

   /**
    * 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;

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

   /**
    * 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;

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

   /**
    * 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;

   /**
    * 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;

   /**
    * 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);

   /**
    * 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;

   /**
    * Decoding only. May be set by the caller before avcodec_open2() to an
    * av_malloc()'ed array (or via AVOptions). Owned and freed by the decoder
    * afterwards.
    *
    * Side data attached to decoded frames may come from several sources:
    * 1. coded_side_data, which the decoder will for certain types translate
    *    from packet-type to frame-type and attach to frames;
    * 2. side data attached to an AVPacket sent for decoding (same
    *    considerations as above);
    * 3. extracted from the coded bytestream.
    * The first two cases are supplied by the caller and typically come from a
    * container.
    *
    * This array configures decoder behaviour in cases when side data of the
    * same type is present both in the coded bytestream and in the
    * user-supplied side data (items 1. and 2. above). In all cases, at most
    * one instance of each side data type will be attached to output frames. By
    * default it will be the bytestream side data. Adding an
    * AVPacketSideDataType value to this array will flip the preference for
    * this type, thus making the decoder prefer user-supplied side data over
    * bytestream. In case side data of the same type is present both in
    * coded_data and attacked to a packet, the packet instance always has
    * priority.
    *
    * The array may also contain a single -1, in which case the preference is
    * switched for all side data types.
    */
   int        *side_data_prefer_packet;
   /**
    * Number of entries in side_data_prefer_packet.
    */
   unsigned nb_side_data_prefer_packet;

   /**
    * Array containing static side data, such as HDR10 CLL / MDCV structures.
    * Side data entries should be allocated by usage of helpers defined in
    * libavutil/frame.h.
    *
    * - encoding: may be set by user before calling avcodec_open2() for
    *             encoder configuration. Afterwards owned and freed by the
    *             encoder.
    * - decoding: may be set by libavcodec in avcodec_open2().
    */
   AVFrameSideData  **decoded_side_data;
   int             nb_decoded_side_data;
} 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;
} 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];

   int flags;
   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;
} 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(struct 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 struct 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.
*
* Depending on the codec, you might need to set options in the codec context
* also for decoding (e.g. width, height, or the pixel or audio sample format in
* the case the information is not available in the bitstream, as when decoding
* raw audio or video).
*
* Options in the codec context can be set either by setting them in the options
* AVDictionary, or by setting the values in the context itself, directly or by
* using the av_opt_set() API before calling this function.
*
* Example:
* @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
*
* In the case AVCodecParameters are available (e.g. when demuxing a stream
* using libavformat, and accessing the AVStream contained in the demuxer), the
* codec parameters can be copied to the codec context using
* avcodec_parameters_to_context(), as in the following example:
*
* @code
* AVStream *stream = ...;
* context = avcodec_alloc_context3(codec);
* if (avcodec_parameters_to_context(context, stream->codecpar) < 0)
*     exit(1);
* if (avcodec_open2(context, codec, NULL) < 0)
*     exit(1);
* @endcode
*
* @note Always call this function before using decoding routines (such as
* @ref avcodec_receive_frame()).
*
* @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, which are set on top of the options already set in
*                avctx, can be NULL. On return this object will be filled with
*                options that were not found in the avctx codec context.
*
* @return zero on success, a negative value on error
* @see avcodec_alloc_context3(), avcodec_find_decoder(), avcodec_find_encoder(),
*      av_dict_set(), av_opt_set(), av_opt_find(), avcodec_parameters_to_context()
*/
int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options);

/**
* 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]);

/**
* 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
* @ref 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
*                          @ref AV_CODEC_FLAG_RECON_FRAME flag enabled
* @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);

enum AVCodecConfig {
   AV_CODEC_CONFIG_PIX_FORMAT,     ///< AVPixelFormat, terminated by AV_PIX_FMT_NONE
   AV_CODEC_CONFIG_FRAME_RATE,     ///< AVRational, terminated by {0, 0}
   AV_CODEC_CONFIG_SAMPLE_RATE,    ///< int, terminated by 0
   AV_CODEC_CONFIG_SAMPLE_FORMAT,  ///< AVSampleFormat, terminated by AV_SAMPLE_FMT_NONE
   AV_CODEC_CONFIG_CHANNEL_LAYOUT, ///< AVChannelLayout, terminated by {0}
   AV_CODEC_CONFIG_COLOR_RANGE,    ///< AVColorRange, terminated by AVCOL_RANGE_UNSPECIFIED
   AV_CODEC_CONFIG_COLOR_SPACE,    ///< AVColorSpace, terminated by AVCOL_SPC_UNSPECIFIED
};

/**
* Retrieve a list of all supported values for a given configuration type.
*
* @param avctx An optional context to use. Values such as
*              `strict_std_compliance` may affect the result. If NULL,
*              default values are used.
* @param codec The codec to query, or NULL to use avctx->codec.
* @param config The configuration to query.
* @param flags Currently unused; should be set to zero.
* @param out_configs On success, set to a list of configurations, terminated
*                    by a config-specific terminator, or NULL if all
*                    possible values are supported.
* @param out_num_configs On success, set to the number of elements in
                         *out_configs, excluding the terminator. Optional.
*/
int avcodec_get_supported_config(const AVCodecContext *avctx,
                                const AVCodec *codec, enum AVCodecConfig config,
                                unsigned flags, const void **out_configs,
                                int *out_num_configs);



/**
* @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 reused 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),
* 0 otherwise.
*/
int avcodec_is_open(AVCodecContext *s);

/**
* @}
*/

#endif /* AVCODEC_AVCODEC_H */