avcodec: doxy: Clarify what get_buffer2 must fill in buf[]

[libav.git] / libavcodec / avcodec.h

/*
 * copyright (c) 2001 Fabrice Bellard
 *
 * This file is part of Libav.
 *
 * Libav 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.
 *
 * Libav 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 Libav; 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
 * external API header
 */

#include <errno.h>
#include "libavutil/samplefmt.h"
#include "libavutil/avutil.h"
#include "libavutil/buffer.h"
#include "libavutil/cpu.h"
#include "libavutil/dict.h"
#include "libavutil/frame.h"
#include "libavutil/log.h"
#include "libavutil/pixfmt.h"
#include "libavutil/rational.h"

#include "libavcodec/version.h"
/**
 * @defgroup libavc 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
 * @{
 * @}
 * @}
 *
 */

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


/**
 * Identify the syntax and semantics of the bitstream.
 * The principle is roughly:
 * Two decoders with the same ID can decode the same streams.
 * Two encoders with the same ID can encode compatible streams.
 * There may be slight deviations from the principle due to implementation
 * details.
 *
 * If you add a codec ID to this list, add it so that
 * 1. no value of a existing codec ID changes (that would break ABI),
 * 2. it is as close as possible to similar codecs.
 *
 * After adding new codec IDs, do not forget to add an entry to the codec
 * descriptor list and bump libavcodec minor version.
 */
enum AVCodecID {
    AV_CODEC_ID_NONE,

    /* video codecs */
    AV_CODEC_ID_MPEG1VIDEO,
    AV_CODEC_ID_MPEG2VIDEO, ///< preferred ID for MPEG-1/2 video decoding
    AV_CODEC_ID_MPEG2VIDEO_XVMC,
    AV_CODEC_ID_H261,
    AV_CODEC_ID_H263,
    AV_CODEC_ID_RV10,
    AV_CODEC_ID_RV20,
    AV_CODEC_ID_MJPEG,
    AV_CODEC_ID_MJPEGB,
    AV_CODEC_ID_LJPEG,
    AV_CODEC_ID_SP5X,
    AV_CODEC_ID_JPEGLS,
    AV_CODEC_ID_MPEG4,
    AV_CODEC_ID_RAWVIDEO,
    AV_CODEC_ID_MSMPEG4V1,
    AV_CODEC_ID_MSMPEG4V2,
    AV_CODEC_ID_MSMPEG4V3,
    AV_CODEC_ID_WMV1,
    AV_CODEC_ID_WMV2,
    AV_CODEC_ID_H263P,
    AV_CODEC_ID_H263I,
    AV_CODEC_ID_FLV1,
    AV_CODEC_ID_SVQ1,
    AV_CODEC_ID_SVQ3,
    AV_CODEC_ID_DVVIDEO,
    AV_CODEC_ID_HUFFYUV,
    AV_CODEC_ID_CYUV,
    AV_CODEC_ID_H264,
    AV_CODEC_ID_INDEO3,
    AV_CODEC_ID_VP3,
    AV_CODEC_ID_THEORA,
    AV_CODEC_ID_ASV1,
    AV_CODEC_ID_ASV2,
    AV_CODEC_ID_FFV1,
    AV_CODEC_ID_4XM,
    AV_CODEC_ID_VCR1,
    AV_CODEC_ID_CLJR,
    AV_CODEC_ID_MDEC,
    AV_CODEC_ID_ROQ,
    AV_CODEC_ID_INTERPLAY_VIDEO,
    AV_CODEC_ID_XAN_WC3,
    AV_CODEC_ID_XAN_WC4,
    AV_CODEC_ID_RPZA,
    AV_CODEC_ID_CINEPAK,
    AV_CODEC_ID_WS_VQA,
    AV_CODEC_ID_MSRLE,
    AV_CODEC_ID_MSVIDEO1,
    AV_CODEC_ID_IDCIN,
    AV_CODEC_ID_8BPS,
    AV_CODEC_ID_SMC,
    AV_CODEC_ID_FLIC,
    AV_CODEC_ID_TRUEMOTION1,
    AV_CODEC_ID_VMDVIDEO,
    AV_CODEC_ID_MSZH,
    AV_CODEC_ID_ZLIB,
    AV_CODEC_ID_QTRLE,
    AV_CODEC_ID_TSCC,
    AV_CODEC_ID_ULTI,
    AV_CODEC_ID_QDRAW,
    AV_CODEC_ID_VIXL,
    AV_CODEC_ID_QPEG,
    AV_CODEC_ID_PNG,
    AV_CODEC_ID_PPM,
    AV_CODEC_ID_PBM,
    AV_CODEC_ID_PGM,
    AV_CODEC_ID_PGMYUV,
    AV_CODEC_ID_PAM,
    AV_CODEC_ID_FFVHUFF,
    AV_CODEC_ID_RV30,
    AV_CODEC_ID_RV40,
    AV_CODEC_ID_VC1,
    AV_CODEC_ID_WMV3,
    AV_CODEC_ID_LOCO,
    AV_CODEC_ID_WNV1,
    AV_CODEC_ID_AASC,
    AV_CODEC_ID_INDEO2,
    AV_CODEC_ID_FRAPS,
    AV_CODEC_ID_TRUEMOTION2,
    AV_CODEC_ID_BMP,
    AV_CODEC_ID_CSCD,
    AV_CODEC_ID_MMVIDEO,
    AV_CODEC_ID_ZMBV,
    AV_CODEC_ID_AVS,
    AV_CODEC_ID_SMACKVIDEO,
    AV_CODEC_ID_NUV,
    AV_CODEC_ID_KMVC,
    AV_CODEC_ID_FLASHSV,
    AV_CODEC_ID_CAVS,
    AV_CODEC_ID_JPEG2000,
    AV_CODEC_ID_VMNC,
    AV_CODEC_ID_VP5,
    AV_CODEC_ID_VP6,
    AV_CODEC_ID_VP6F,
    AV_CODEC_ID_TARGA,
    AV_CODEC_ID_DSICINVIDEO,
    AV_CODEC_ID_TIERTEXSEQVIDEO,
    AV_CODEC_ID_TIFF,
    AV_CODEC_ID_GIF,
    AV_CODEC_ID_DXA,
    AV_CODEC_ID_DNXHD,
    AV_CODEC_ID_THP,
    AV_CODEC_ID_SGI,
    AV_CODEC_ID_C93,
    AV_CODEC_ID_BETHSOFTVID,
    AV_CODEC_ID_PTX,
    AV_CODEC_ID_TXD,
    AV_CODEC_ID_VP6A,
    AV_CODEC_ID_AMV,
    AV_CODEC_ID_VB,
    AV_CODEC_ID_PCX,
    AV_CODEC_ID_SUNRAST,
    AV_CODEC_ID_INDEO4,
    AV_CODEC_ID_INDEO5,
    AV_CODEC_ID_MIMIC,
    AV_CODEC_ID_RL2,
    AV_CODEC_ID_ESCAPE124,
    AV_CODEC_ID_DIRAC,
    AV_CODEC_ID_BFI,
    AV_CODEC_ID_CMV,
    AV_CODEC_ID_MOTIONPIXELS,
    AV_CODEC_ID_TGV,
    AV_CODEC_ID_TGQ,
    AV_CODEC_ID_TQI,
    AV_CODEC_ID_AURA,
    AV_CODEC_ID_AURA2,
    AV_CODEC_ID_V210X,
    AV_CODEC_ID_TMV,
    AV_CODEC_ID_V210,
    AV_CODEC_ID_DPX,
    AV_CODEC_ID_MAD,
    AV_CODEC_ID_FRWU,
    AV_CODEC_ID_FLASHSV2,
    AV_CODEC_ID_CDGRAPHICS,
    AV_CODEC_ID_R210,
    AV_CODEC_ID_ANM,
    AV_CODEC_ID_BINKVIDEO,
    AV_CODEC_ID_IFF_ILBM,
    AV_CODEC_ID_IFF_BYTERUN1,
    AV_CODEC_ID_KGV1,
    AV_CODEC_ID_YOP,
    AV_CODEC_ID_VP8,
    AV_CODEC_ID_PICTOR,
    AV_CODEC_ID_ANSI,
    AV_CODEC_ID_A64_MULTI,
    AV_CODEC_ID_A64_MULTI5,
    AV_CODEC_ID_R10K,
    AV_CODEC_ID_MXPEG,
    AV_CODEC_ID_LAGARITH,
    AV_CODEC_ID_PRORES,
    AV_CODEC_ID_JV,
    AV_CODEC_ID_DFA,
    AV_CODEC_ID_WMV3IMAGE,
    AV_CODEC_ID_VC1IMAGE,
    AV_CODEC_ID_UTVIDEO,
    AV_CODEC_ID_BMV_VIDEO,
    AV_CODEC_ID_VBLE,
    AV_CODEC_ID_DXTORY,
    AV_CODEC_ID_V410,
    AV_CODEC_ID_XWD,
    AV_CODEC_ID_CDXL,
    AV_CODEC_ID_XBM,
    AV_CODEC_ID_ZEROCODEC,
    AV_CODEC_ID_MSS1,
    AV_CODEC_ID_MSA1,
    AV_CODEC_ID_TSCC2,
    AV_CODEC_ID_MTS2,
    AV_CODEC_ID_CLLC,
    AV_CODEC_ID_MSS2,
    AV_CODEC_ID_VP9,

    /* various PCM "codecs" */
    AV_CODEC_ID_FIRST_AUDIO = 0x10000,     ///< A dummy id pointing at the start of audio codecs
    AV_CODEC_ID_PCM_S16LE = 0x10000,
    AV_CODEC_ID_PCM_S16BE,
    AV_CODEC_ID_PCM_U16LE,
    AV_CODEC_ID_PCM_U16BE,
    AV_CODEC_ID_PCM_S8,
    AV_CODEC_ID_PCM_U8,
    AV_CODEC_ID_PCM_MULAW,
    AV_CODEC_ID_PCM_ALAW,
    AV_CODEC_ID_PCM_S32LE,
    AV_CODEC_ID_PCM_S32BE,
    AV_CODEC_ID_PCM_U32LE,
    AV_CODEC_ID_PCM_U32BE,
    AV_CODEC_ID_PCM_S24LE,
    AV_CODEC_ID_PCM_S24BE,
    AV_CODEC_ID_PCM_U24LE,
    AV_CODEC_ID_PCM_U24BE,
    AV_CODEC_ID_PCM_S24DAUD,
    AV_CODEC_ID_PCM_ZORK,
    AV_CODEC_ID_PCM_S16LE_PLANAR,
    AV_CODEC_ID_PCM_DVD,
    AV_CODEC_ID_PCM_F32BE,
    AV_CODEC_ID_PCM_F32LE,
    AV_CODEC_ID_PCM_F64BE,
    AV_CODEC_ID_PCM_F64LE,
    AV_CODEC_ID_PCM_BLURAY,
    AV_CODEC_ID_PCM_LXF,
    AV_CODEC_ID_S302M,
    AV_CODEC_ID_PCM_S8_PLANAR,

    /* various ADPCM codecs */
    AV_CODEC_ID_ADPCM_IMA_QT = 0x11000,
    AV_CODEC_ID_ADPCM_IMA_WAV,
    AV_CODEC_ID_ADPCM_IMA_DK3,
    AV_CODEC_ID_ADPCM_IMA_DK4,
    AV_CODEC_ID_ADPCM_IMA_WS,
    AV_CODEC_ID_ADPCM_IMA_SMJPEG,
    AV_CODEC_ID_ADPCM_MS,
    AV_CODEC_ID_ADPCM_4XM,
    AV_CODEC_ID_ADPCM_XA,
    AV_CODEC_ID_ADPCM_ADX,
    AV_CODEC_ID_ADPCM_EA,
    AV_CODEC_ID_ADPCM_G726,
    AV_CODEC_ID_ADPCM_CT,
    AV_CODEC_ID_ADPCM_SWF,
    AV_CODEC_ID_ADPCM_YAMAHA,
    AV_CODEC_ID_ADPCM_SBPRO_4,
    AV_CODEC_ID_ADPCM_SBPRO_3,
    AV_CODEC_ID_ADPCM_SBPRO_2,
    AV_CODEC_ID_ADPCM_THP,
    AV_CODEC_ID_ADPCM_IMA_AMV,
    AV_CODEC_ID_ADPCM_EA_R1,
    AV_CODEC_ID_ADPCM_EA_R3,
    AV_CODEC_ID_ADPCM_EA_R2,
    AV_CODEC_ID_ADPCM_IMA_EA_SEAD,
    AV_CODEC_ID_ADPCM_IMA_EA_EACS,
    AV_CODEC_ID_ADPCM_EA_XAS,
    AV_CODEC_ID_ADPCM_EA_MAXIS_XA,
    AV_CODEC_ID_ADPCM_IMA_ISS,
    AV_CODEC_ID_ADPCM_G722,
    AV_CODEC_ID_ADPCM_IMA_APC,

    /* AMR */
    AV_CODEC_ID_AMR_NB = 0x12000,
    AV_CODEC_ID_AMR_WB,

    /* RealAudio codecs*/
    AV_CODEC_ID_RA_144 = 0x13000,
    AV_CODEC_ID_RA_288,

    /* various DPCM codecs */
    AV_CODEC_ID_ROQ_DPCM = 0x14000,
    AV_CODEC_ID_INTERPLAY_DPCM,
    AV_CODEC_ID_XAN_DPCM,
    AV_CODEC_ID_SOL_DPCM,

    /* audio codecs */
    AV_CODEC_ID_MP2 = 0x15000,
    AV_CODEC_ID_MP3, ///< preferred ID for decoding MPEG audio layer 1, 2 or 3
    AV_CODEC_ID_AAC,
    AV_CODEC_ID_AC3,
    AV_CODEC_ID_DTS,
    AV_CODEC_ID_VORBIS,
    AV_CODEC_ID_DVAUDIO,
    AV_CODEC_ID_WMAV1,
    AV_CODEC_ID_WMAV2,
    AV_CODEC_ID_MACE3,
    AV_CODEC_ID_MACE6,
    AV_CODEC_ID_VMDAUDIO,
    AV_CODEC_ID_FLAC,
    AV_CODEC_ID_MP3ADU,
    AV_CODEC_ID_MP3ON4,
    AV_CODEC_ID_SHORTEN,
    AV_CODEC_ID_ALAC,
    AV_CODEC_ID_WESTWOOD_SND1,
    AV_CODEC_ID_GSM, ///< as in Berlin toast format
    AV_CODEC_ID_QDM2,
    AV_CODEC_ID_COOK,
    AV_CODEC_ID_TRUESPEECH,
    AV_CODEC_ID_TTA,
    AV_CODEC_ID_SMACKAUDIO,
    AV_CODEC_ID_QCELP,
    AV_CODEC_ID_WAVPACK,
    AV_CODEC_ID_DSICINAUDIO,
    AV_CODEC_ID_IMC,
    AV_CODEC_ID_MUSEPACK7,
    AV_CODEC_ID_MLP,
    AV_CODEC_ID_GSM_MS, /* as found in WAV */
    AV_CODEC_ID_ATRAC3,
    AV_CODEC_ID_VOXWARE,
    AV_CODEC_ID_APE,
    AV_CODEC_ID_NELLYMOSER,
    AV_CODEC_ID_MUSEPACK8,
    AV_CODEC_ID_SPEEX,
    AV_CODEC_ID_WMAVOICE,
    AV_CODEC_ID_WMAPRO,
    AV_CODEC_ID_WMALOSSLESS,
    AV_CODEC_ID_ATRAC3P,
    AV_CODEC_ID_EAC3,
    AV_CODEC_ID_SIPR,
    AV_CODEC_ID_MP1,
    AV_CODEC_ID_TWINVQ,
    AV_CODEC_ID_TRUEHD,
    AV_CODEC_ID_MP4ALS,
    AV_CODEC_ID_ATRAC1,
    AV_CODEC_ID_BINKAUDIO_RDFT,
    AV_CODEC_ID_BINKAUDIO_DCT,
    AV_CODEC_ID_AAC_LATM,
    AV_CODEC_ID_QDMC,
    AV_CODEC_ID_CELT,
    AV_CODEC_ID_G723_1,
    AV_CODEC_ID_G729,
    AV_CODEC_ID_8SVX_EXP,
    AV_CODEC_ID_8SVX_FIB,
    AV_CODEC_ID_BMV_AUDIO,
    AV_CODEC_ID_RALF,
    AV_CODEC_ID_IAC,
    AV_CODEC_ID_ILBC,
    AV_CODEC_ID_OPUS,
    AV_CODEC_ID_COMFORT_NOISE,
    AV_CODEC_ID_TAK,

    /* subtitle codecs */
    AV_CODEC_ID_FIRST_SUBTITLE = 0x17000,          ///< A dummy ID pointing at the start of subtitle codecs.
    AV_CODEC_ID_DVD_SUBTITLE = 0x17000,
    AV_CODEC_ID_DVB_SUBTITLE,
    AV_CODEC_ID_TEXT,  ///< raw UTF-8 text
    AV_CODEC_ID_XSUB,
    AV_CODEC_ID_SSA,
    AV_CODEC_ID_MOV_TEXT,
    AV_CODEC_ID_HDMV_PGS_SUBTITLE,
    AV_CODEC_ID_DVB_TELETEXT,
    AV_CODEC_ID_SRT,

    /* other specific kind of codecs (generally used for attachments) */
    AV_CODEC_ID_FIRST_UNKNOWN = 0x18000,           ///< A dummy ID pointing at the start of various fake codecs.
    AV_CODEC_ID_TTF = 0x18000,

    AV_CODEC_ID_PROBE = 0x19000, ///< codec_id is not known (like AV_CODEC_ID_NONE) but lavf should attempt to identify it

    AV_CODEC_ID_MPEG2TS = 0x20000, /**< _FAKE_ codec to indicate a raw MPEG-2 TS
                                * stream (only used by libavformat) */
    AV_CODEC_ID_MPEG4SYSTEMS = 0x20001, /**< _FAKE_ codec to indicate a MPEG-4 Systems
                                * stream (only used by libavformat) */
    AV_CODEC_ID_FFMETADATA = 0x21000,   ///< Dummy codec for streams containing only metadata information.
};

/**
 * This struct describes the properties of a single codec described by an
 * AVCodecID.
 * @see avcodec_get_descriptor()
 */
typedef struct AVCodecDescriptor {
    enum AVCodecID     id;
    enum AVMediaType type;
    /**
     * Name of the codec described by this descriptor. It is non-empty and
     * unique for each codec descriptor. It should contain alphanumeric
     * characters and '_' only.
     */
    const char      *name;
    /**
     * A more descriptive name for this codec. May be NULL.
     */
    const char *long_name;
    /**
     * Codec properties, a combination of AV_CODEC_PROP_* flags.
     */
    int             props;
} AVCodecDescriptor;

/**
 * Codec uses only intra compression.
 * Video codecs only.
 */
#define AV_CODEC_PROP_INTRA_ONLY    (1 << 0)
/**
 * Codec supports lossy compression. Audio and video codecs only.
 * @note a codec may support both lossy and lossless
 * compression modes
 */
#define AV_CODEC_PROP_LOSSY         (1 << 1)
/**
 * Codec supports lossless compression. Audio and video codecs only.
 */
#define AV_CODEC_PROP_LOSSLESS      (1 << 2)

/**
 * @ingroup lavc_decoding
 * Required number of additionally allocated bytes at the end of the input bitstream for decoding.
 * This is mainly needed because some optimized bitstream readers read
 * 32 or 64 bit at once and could read over the end.<br>
 * Note: If the first 23 bits of the additional bytes are not 0, then damaged
 * MPEG bitstreams could cause overread and segfault.
 */
#define FF_INPUT_BUFFER_PADDING_SIZE 8

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


/**
 * @ingroup lavc_encoding
 * motion estimation type.
 */
enum Motion_Est_ID {
    ME_ZERO = 1,    ///< no search, that is use 0,0 vector whenever one is needed
    ME_FULL,
    ME_LOG,
    ME_PHODS,
    ME_EPZS,        ///< enhanced predictive zonal search
    ME_X1,          ///< reserved for experiments
    ME_HEX,         ///< hexagon based search
    ME_UMH,         ///< uneven multi-hexagon search
    ME_TESA,        ///< transformed exhaustive search algorithm
};

/**
 * @ingroup lavc_decoding
 */
enum AVDiscard{
    /* We leave some space between them for extensions (drop some
     * keyframes for intra-only or drop just some bidir frames). */
    AVDISCARD_NONE    =-16, ///< discard nothing
    AVDISCARD_DEFAULT =  0, ///< discard useless packets like 0 size packets in avi
    AVDISCARD_NONREF  =  8, ///< discard all non reference
    AVDISCARD_BIDIR   = 16, ///< discard all bidirectional frames
    AVDISCARD_NONKEY  = 32, ///< discard all frames except keyframes
    AVDISCARD_ALL     = 48, ///< discard all
};

enum AVColorPrimaries{
    AVCOL_PRI_BT709       = 1, ///< also ITU-R BT1361 / IEC 61966-2-4 / SMPTE RP177 Annex B
    AVCOL_PRI_UNSPECIFIED = 2,
    AVCOL_PRI_BT470M      = 4,
    AVCOL_PRI_BT470BG     = 5, ///< also ITU-R BT601-6 625 / ITU-R BT1358 625 / ITU-R BT1700 625 PAL & SECAM
    AVCOL_PRI_SMPTE170M   = 6, ///< also ITU-R BT601-6 525 / ITU-R BT1358 525 / ITU-R BT1700 NTSC
    AVCOL_PRI_SMPTE240M   = 7, ///< functionally identical to above
    AVCOL_PRI_FILM        = 8,
    AVCOL_PRI_NB             , ///< Not part of ABI
};

enum AVColorTransferCharacteristic{
    AVCOL_TRC_BT709       = 1, ///< also ITU-R BT1361
    AVCOL_TRC_UNSPECIFIED = 2,
    AVCOL_TRC_GAMMA22     = 4, ///< also ITU-R BT470M / ITU-R BT1700 625 PAL & SECAM
    AVCOL_TRC_GAMMA28     = 5, ///< also ITU-R BT470BG
    AVCOL_TRC_SMPTE240M   = 7,
    AVCOL_TRC_NB             , ///< Not part of ABI
};

enum AVColorSpace{
    AVCOL_SPC_RGB         = 0,
    AVCOL_SPC_BT709       = 1, ///< also ITU-R BT1361 / IEC 61966-2-4 xvYCC709 / SMPTE RP177 Annex B
    AVCOL_SPC_UNSPECIFIED = 2,
    AVCOL_SPC_FCC         = 4,
    AVCOL_SPC_BT470BG     = 5, ///< also ITU-R BT601-6 625 / ITU-R BT1358 625 / ITU-R BT1700 625 PAL & SECAM / IEC 61966-2-4 xvYCC601
    AVCOL_SPC_SMPTE170M   = 6, ///< also ITU-R BT601-6 525 / ITU-R BT1358 525 / ITU-R BT1700 NTSC / functionally identical to above
    AVCOL_SPC_SMPTE240M   = 7,
    AVCOL_SPC_YCOCG       = 8, ///< Used by Dirac / VC-2 and H.264 FRext, see ITU-T SG16
    AVCOL_SPC_NB             , ///< Not part of ABI
};

enum AVColorRange{
    AVCOL_RANGE_UNSPECIFIED = 0,
    AVCOL_RANGE_MPEG        = 1, ///< the normal 219*2^(n-8) "MPEG" YUV ranges
    AVCOL_RANGE_JPEG        = 2, ///< the normal     2^n-1   "JPEG" YUV ranges
    AVCOL_RANGE_NB             , ///< Not part of ABI
};

/**
 *  X   X      3 4 X      X are luma samples,
 *             1 2        1-6 are possible chroma positions
 *  X   X      5 6 X      0 is undefined/unknown position
 */
enum AVChromaLocation{
    AVCHROMA_LOC_UNSPECIFIED = 0,
    AVCHROMA_LOC_LEFT        = 1, ///< mpeg2/4, h264 default
    AVCHROMA_LOC_CENTER      = 2, ///< mpeg1, jpeg, h263
    AVCHROMA_LOC_TOPLEFT     = 3, ///< DV
    AVCHROMA_LOC_TOP         = 4,
    AVCHROMA_LOC_BOTTOMLEFT  = 5,
    AVCHROMA_LOC_BOTTOM      = 6,
    AVCHROMA_LOC_NB             , ///< Not part of ABI
};

enum AVAudioServiceType {
    AV_AUDIO_SERVICE_TYPE_MAIN              = 0,
    AV_AUDIO_SERVICE_TYPE_EFFECTS           = 1,
    AV_AUDIO_SERVICE_TYPE_VISUALLY_IMPAIRED = 2,
    AV_AUDIO_SERVICE_TYPE_HEARING_IMPAIRED  = 3,
    AV_AUDIO_SERVICE_TYPE_DIALOGUE          = 4,
    AV_AUDIO_SERVICE_TYPE_COMMENTARY        = 5,
    AV_AUDIO_SERVICE_TYPE_EMERGENCY         = 6,
    AV_AUDIO_SERVICE_TYPE_VOICE_OVER        = 7,
    AV_AUDIO_SERVICE_TYPE_KARAOKE           = 8,
    AV_AUDIO_SERVICE_TYPE_NB                   , ///< Not part of ABI
};

/**
 * @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;

#define FF_MAX_B_FRAMES 16

/* 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 CODEC_FLAG_UNALIGNED 0x0001
#define CODEC_FLAG_QSCALE 0x0002  ///< Use fixed qscale.
#define CODEC_FLAG_4MV    0x0004  ///< 4 MV per MB allowed / advanced prediction for H.263.
#define CODEC_FLAG_QPEL   0x0010  ///< Use qpel MC.
#define CODEC_FLAG_GMC    0x0020  ///< Use GMC.
#define CODEC_FLAG_MV0    0x0040  ///< Always try a MB with MV=<0,0>.
/**
 * The parent program guarantees that the input for B-frames containing
 * streams is not written to for at least s->max_b_frames+1 frames, if
 * this is not set the input will be copied.
 */
#define CODEC_FLAG_INPUT_PRESERVED 0x0100
#define CODEC_FLAG_PASS1           0x0200   ///< Use internal 2pass ratecontrol in first pass mode.
#define CODEC_FLAG_PASS2           0x0400   ///< Use internal 2pass ratecontrol in second pass mode.
#define CODEC_FLAG_GRAY            0x2000   ///< Only decode/encode grayscale.
#define CODEC_FLAG_EMU_EDGE        0x4000   ///< Don't draw edges.
#define CODEC_FLAG_PSNR            0x8000   ///< error[?] variables will be set during encoding.
#define CODEC_FLAG_TRUNCATED       0x00010000 /** Input bitstream might be truncated at a random
                                                  location instead of only at frame boundaries. */
#define CODEC_FLAG_NORMALIZE_AQP  0x00020000 ///< Normalize adaptive quantization.
#define CODEC_FLAG_INTERLACED_DCT 0x00040000 ///< Use interlaced DCT.
#define CODEC_FLAG_LOW_DELAY      0x00080000 ///< Force low delay.
#define CODEC_FLAG_GLOBAL_HEADER  0x00400000 ///< Place global headers in extradata instead of every keyframe.
#define CODEC_FLAG_BITEXACT       0x00800000 ///< Use only bitexact stuff (except (I)DCT).
/* Fx : Flag for h263+ extra options */
#define CODEC_FLAG_AC_PRED        0x01000000 ///< H.263 advanced intra coding / MPEG-4 AC prediction
#define CODEC_FLAG_LOOP_FILTER    0x00000800 ///< loop filter
#define CODEC_FLAG_INTERLACED_ME  0x20000000 ///< interlaced motion estimation
#define CODEC_FLAG_CLOSED_GOP     0x80000000
#define CODEC_FLAG2_FAST          0x00000001 ///< Allow non spec compliant speedup tricks.
#define CODEC_FLAG2_NO_OUTPUT     0x00000004 ///< Skip bitstream encoding.
#define CODEC_FLAG2_LOCAL_HEADER  0x00000008 ///< Place global headers at every keyframe instead of in extradata.
#define CODEC_FLAG2_IGNORE_CROP   0x00010000 ///< Discard cropping information from SPS.

#define CODEC_FLAG2_CHUNKS        0x00008000 ///< Input bitstream might be truncated at a packet boundaries instead of only at frame boundaries.

/* Unsupported options :
 *              Syntax Arithmetic coding (SAC)
 *              Reference Picture Selection
 *              Independent Segment Decoding */
/* /Fx */
/* codec capabilities */

#define CODEC_CAP_DRAW_HORIZ_BAND 0x0001 ///< Decoder can use draw_horiz_band callback.
/**
 * Codec uses get_buffer() for allocating buffers and supports custom allocators.
 * If not set, it might not use get_buffer() at all or use operations that
 * assume the buffer was allocated by avcodec_default_get_buffer.
 */
#define CODEC_CAP_DR1             0x0002
#define CODEC_CAP_TRUNCATED       0x0008
/* Codec can export data for HW decoding (XvMC). */
#define CODEC_CAP_HWACCEL         0x0010
/**
 * Encoder or decoder requires flushing with NULL input at the end in order to
 * give the complete and correct output.
 *
 * NOTE: If this flag is not set, the codec is guaranteed to never be fed with
 *       with NULL data. The user can still send NULL data to the public encode
 *       or decode function, but libavcodec will not pass it along to the codec
 *       unless this flag is set.
 *
 * Decoders:
 * The decoder has a non-zero delay and needs to be fed with avpkt->data=NULL,
 * avpkt->size=0 at the end to get the delayed data until the decoder no longer
 * returns frames.
 *
 * Encoders:
 * The encoder needs to be fed with NULL data at the end of encoding until the
 * encoder no longer returns data.
 *
 * NOTE: For encoders implementing the AVCodec.encode2() function, setting this
 *       flag also means that the encoder must set the pts and duration for
 *       each output packet. If this flag is not set, the pts and duration will
 *       be determined by libavcodec from the input frame.
 */
#define CODEC_CAP_DELAY           0x0020
/**
 * Codec can be fed a final frame with a smaller size.
 * This can be used to prevent truncation of the last audio samples.
 */
#define CODEC_CAP_SMALL_LAST_FRAME 0x0040
/**
 * Codec can export data for HW decoding (VDPAU).
 */
#define CODEC_CAP_HWACCEL_VDPAU    0x0080
/**
 * Codec can output multiple frames per AVPacket
 * Normally demuxers return one frame at a time, demuxers which do not do
 * are connected to a parser to split what they return into proper frames.
 * This flag is reserved to the very rare category of codecs which have a
 * bitstream that cannot be split into frames without timeconsuming
 * operations like full decoding. Demuxers carring such bitstreams thus
 * may return multiple frames in a packet. This has many disadvantages like
 * prohibiting stream copy in many cases thus it should only be considered
 * as a last resort.
 */
#define CODEC_CAP_SUBFRAMES        0x0100
/**
 * Codec is experimental and is thus avoided in favor of non experimental
 * encoders
 */
#define CODEC_CAP_EXPERIMENTAL     0x0200
/**
 * Codec should fill in channel configuration and samplerate instead of container
 */
#define CODEC_CAP_CHANNEL_CONF     0x0400
/**
 * Codec is able to deal with negative linesizes
 */
#define CODEC_CAP_NEG_LINESIZES    0x0800
/**
 * Codec supports frame-level multithreading.
 */
#define CODEC_CAP_FRAME_THREADS    0x1000
/**
 * Codec supports slice-based (or partition-based) multithreading.
 */
#define CODEC_CAP_SLICE_THREADS    0x2000
/**
 * Codec supports changed parameters at any point.
 */
#define CODEC_CAP_PARAM_CHANGE     0x4000
/**
 * Codec supports avctx->thread_count == 0 (auto).
 */
#define CODEC_CAP_AUTO_THREADS     0x8000
/**
 * Audio encoder supports receiving a different number of samples in each call.
 */
#define CODEC_CAP_VARIABLE_FRAME_SIZE 0x10000

//The following defines may change, don't expect compatibility if you use them.
#define MB_TYPE_INTRA4x4   0x0001
#define MB_TYPE_INTRA16x16 0x0002 //FIXME H.264-specific
#define MB_TYPE_INTRA_PCM  0x0004 //FIXME H.264-specific
#define MB_TYPE_16x16      0x0008
#define MB_TYPE_16x8       0x0010
#define MB_TYPE_8x16       0x0020
#define MB_TYPE_8x8        0x0040
#define MB_TYPE_INTERLACED 0x0080
#define MB_TYPE_DIRECT2    0x0100 //FIXME
#define MB_TYPE_ACPRED     0x0200
#define MB_TYPE_GMC        0x0400
#define MB_TYPE_SKIP       0x0800
#define MB_TYPE_P0L0       0x1000
#define MB_TYPE_P1L0       0x2000
#define MB_TYPE_P0L1       0x4000
#define MB_TYPE_P1L1       0x8000
#define MB_TYPE_L0         (MB_TYPE_P0L0 | MB_TYPE_P1L0)
#define MB_TYPE_L1         (MB_TYPE_P0L1 | MB_TYPE_P1L1)
#define MB_TYPE_L0L1       (MB_TYPE_L0   | MB_TYPE_L1)
#define MB_TYPE_QUANT      0x00010000
#define MB_TYPE_CBP        0x00020000
//Note bits 24-31 are reserved for codec specific use (h264 ref0, mpeg1 0mv, ...)

/**
 * Pan Scan area.
 * This specifies the area which should be displayed.
 * Note there may be multiple such areas for one frame.
 */
typedef struct AVPanScan{
    /**
     * id
     * - encoding: Set by user.
     * - decoding: Set by libavcodec.
     */
    int id;

    /**
     * width and height in 1/16 pel
     * - encoding: Set by user.
     * - decoding: Set by libavcodec.
     */
    int width;
    int height;

    /**
     * position of the top left corner in 1/16 pel for up to 3 fields/frames
     * - encoding: Set by user.
     * - decoding: Set by libavcodec.
     */
    int16_t position[3][2];
}AVPanScan;

#define FF_QSCALE_TYPE_MPEG1 0
#define FF_QSCALE_TYPE_MPEG2 1
#define FF_QSCALE_TYPE_H264  2
#define FF_QSCALE_TYPE_VP56  3

#if FF_API_GET_BUFFER
#define FF_BUFFER_TYPE_INTERNAL 1
#define FF_BUFFER_TYPE_USER     2 ///< direct rendering buffers (image is (de)allocated by user)
#define FF_BUFFER_TYPE_SHARED   4 ///< Buffer from somewhere else; don't deallocate image (data/base), all other tables are not shared.
#define FF_BUFFER_TYPE_COPY     8 ///< Just a (modified) copy of some other buffer, don't deallocate anything.

#define FF_BUFFER_HINTS_VALID    0x01 // Buffer hints value is meaningful (if 0 ignore).
#define FF_BUFFER_HINTS_READABLE 0x02 // Codec will read from buffer.
#define FF_BUFFER_HINTS_PRESERVE 0x04 // User must not alter buffer content.
#define FF_BUFFER_HINTS_REUSABLE 0x08 // Codec will reuse the buffer (update).
#endif

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

/**
 * @defgroup lavc_packet AVPacket
 *
 * Types and functions for working with AVPacket.
 * @{
 */
enum AVPacketSideDataType {
    AV_PKT_DATA_PALETTE,
    AV_PKT_DATA_NEW_EXTRADATA,

    /**
     * An AV_PKT_DATA_PARAM_CHANGE side data packet is laid out as follows:
     * @code
     * u32le param_flags
     * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_COUNT)
     *     s32le channel_count
     * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_LAYOUT)
     *     u64le channel_layout
     * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_SAMPLE_RATE)
     *     s32le sample_rate
     * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_DIMENSIONS)
     *     s32le width
     *     s32le height
     * @endcode
     */
    AV_PKT_DATA_PARAM_CHANGE,

    /**
     * An AV_PKT_DATA_H263_MB_INFO side data packet contains a number of
     * structures with info about macroblocks relevant to splitting the
     * packet into smaller packets on macroblock edges (e.g. as for RFC 2190).
     * That is, it does not necessarily contain info about all macroblocks,
     * as long as the distance between macroblocks in the info is smaller
     * than the target payload size.
     * Each MB info structure is 12 bytes, and is laid out as follows:
     * @code
     * u32le bit offset from the start of the packet
     * u8    current quantizer at the start of the macroblock
     * u8    GOB number
     * u16le macroblock address within the GOB
     * u8    horizontal MV predictor
     * u8    vertical MV predictor
     * u8    horizontal MV predictor for block number 3
     * u8    vertical MV predictor for block number 3
     * @endcode
     */
    AV_PKT_DATA_H263_MB_INFO,
};

/**
 * This structure stores compressed data. It is typically exported by demuxers
 * and then passed as input to decoders, or received as output from encoders and
 * then passed to muxers.
 *
 * For video, it should typically contain one compressed frame. For audio it may
 * contain several compressed frames.
 *
 * AVPacket is one of the few structs in Libav, whose size is a part of public
 * ABI. Thus it may be allocated on stack and no new fields can be added to it
 * without libavcodec and libavformat major bump.
 *
 * The semantics of data ownership depends on the buf or destruct (deprecated)
 * fields. If either is set, the packet data is dynamically allocated and is
 * valid indefinitely until av_free_packet() is called (which in turn calls
 * av_buffer_unref()/the destruct callback to free the data). If neither is set,
 * the packet data is typically backed by some static buffer somewhere and is
 * only valid for a limited time (e.g. until the next read call when demuxing).
 *
 * The side data is always allocated with av_malloc() and is freed in
 * av_free_packet().
 */
typedef struct AVPacket {
    /**
     * A reference to the reference-counted buffer where the packet data is
     * stored.
     * May be NULL, then the packet data is not reference-counted.
     */
    AVBufferRef *buf;
    /**
     * Presentation timestamp in AVStream->time_base units; the time at which
     * the decompressed packet will be presented to the user.
     * Can be AV_NOPTS_VALUE if it is not stored in the file.
     * pts MUST be larger or equal to dts as presentation cannot happen before
     * decompression, unless one wants to view hex dumps. Some formats misuse
     * the terms dts and pts/cts to mean something different. Such timestamps
     * must be converted to true pts/dts before they are stored in AVPacket.
     */
    int64_t pts;
    /**
     * Decompression timestamp in AVStream->time_base units; the time at which
     * the packet is decompressed.
     * Can be AV_NOPTS_VALUE if it is not stored in the file.
     */
    int64_t dts;
    uint8_t *data;
    int   size;
    int   stream_index;
    /**
     * A combination of AV_PKT_FLAG values
     */
    int   flags;
    /**
     * Additional packet data that can be provided by the container.
     * Packet can contain several types of side information.
     */
    struct {
        uint8_t *data;
        int      size;
        enum AVPacketSideDataType type;
    } *side_data;
    int side_data_elems;

    /**
     * Duration of this packet in AVStream->time_base units, 0 if unknown.
     * Equals next_pts - this_pts in presentation order.
     */
    int   duration;
#if FF_API_DESTRUCT_PACKET
    attribute_deprecated
    void  (*destruct)(struct AVPacket *);
    attribute_deprecated
    void  *priv;
#endif
    int64_t pos;                            ///< byte position in stream, -1 if unknown

    /**
     * Time difference in AVStream->time_base units from the pts of this
     * packet to the point at which the output from the decoder has converged
     * independent from the availability of previous frames. That is, the
     * frames are virtually identical no matter if decoding started from
     * the very first frame or from this keyframe.
     * Is AV_NOPTS_VALUE if unknown.
     * This field is not the display duration of the current packet.
     * This field has no meaning if the packet does not have AV_PKT_FLAG_KEY
     * set.
     *
     * The purpose of this field is to allow seeking in streams that have no
     * keyframes in the conventional sense. It corresponds to the
     * recovery point SEI in H.264 and match_time_delta in NUT. It is also
     * essential for some types of subtitle streams to ensure that all
     * subtitles are correctly displayed after seeking.
     */
    int64_t convergence_duration;
} AVPacket;
#define AV_PKT_FLAG_KEY     0x0001 ///< The packet contains a keyframe
#define AV_PKT_FLAG_CORRUPT 0x0002 ///< The packet content is corrupted

enum AVSideDataParamChangeFlags {
    AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_COUNT  = 0x0001,
    AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_LAYOUT = 0x0002,
    AV_SIDE_DATA_PARAM_CHANGE_SAMPLE_RATE    = 0x0004,
    AV_SIDE_DATA_PARAM_CHANGE_DIMENSIONS     = 0x0008,
};
/**
 * @}
 */

struct AVCodecInternal;

enum AVFieldOrder {
    AV_FIELD_UNKNOWN,
    AV_FIELD_PROGRESSIVE,
    AV_FIELD_TT,          //< Top coded_first, top displayed first
    AV_FIELD_BB,          //< Bottom coded first, bottom displayed first
    AV_FIELD_TB,          //< Top coded first, bottom displayed first
    AV_FIELD_BT,          //< Bottom coded first, top displayed first
};

/**
 * 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.
 * 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;
    char             codec_name[32];
    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;

    /**
     * fourcc from the AVI stream header (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
     * This is used to work around some encoder bugs.
     * - encoding: unused
     * - decoding: Set by user, will be converted to uppercase by libavcodec during init.
     */
    unsigned int stream_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 libavcodec. 0 or some bitrate if this info is available in the stream.
     */
    int bit_rate;

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

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

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

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

    /**
     * CODEC_FLAG2_*
     * - encoding: Set by user.
     * - decoding: Set by user.
     */
    int flags2;

    /**
     * some codecs need / can use extradata like Huffman tables.
     * mjpeg: Huffman tables
     * rv10: additional flags
     * mpeg4: global headers (they can be in the bitstream or here)
     * The allocated memory should be FF_INPUT_BUFFER_PADDING_SIZE bytes larger
     * than extradata_size to avoid prolems if it is read with the bitstream reader.
     * The bytewise contents of extradata must not depend on the architecture or CPU endianness.
     * - encoding: Set/allocated/freed by libavcodec.
     * - decoding: Set/allocated/freed by user.
     */
    uint8_t *extradata;
    int extradata_size;

    /**
     * This is the fundamental unit of time (in seconds) in terms
     * of which frame timestamps are represented. For fixed-fps content,
     * timebase should be 1/framerate and timestamp increments should be
     * identically 1.
     * - encoding: MUST be set by user.
     * - decoding: Set by libavcodec.
     */
    AVRational time_base;

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

    /**
     * Codec delay.
     *
     * Video:
     *   Number of frames the decoded output will be delayed relative to the
     *   encoded input.
     *
     * Audio:
     *   For encoding, this is the number of "priming" samples added to the
     *   beginning of the stream. The decoded output will be delayed by this
     *   many samples relative to the input to the encoder. Note that this
     *   field is purely informational and does not directly affect the pts
     *   output by the encoder, which should always be based on the actual
     *   presentation time, including any delay.
     *   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.
     * - 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.
     */
    int width, height;

    /**
     * Bitstream width / height, may be different from width/height e.g. when
     * the decoded frame is cropped before being output.
     * - 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.
     */
    int coded_width, coded_height;

#define FF_ASPECT_EXTENDED 15

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

    /**
     * Pixel format, see AV_PIX_FMT_xxx.
     * May be set by the demuxer if known from headers.
     * May be overriden by the decoder if it knows better.
     * - encoding: Set by user.
     * - decoding: Set by user if known, overridden by libavcodec if known
     */
    enum AVPixelFormat pix_fmt;

    /**
     * Motion estimation algorithm used for video coding.
     * 1 (zero), 2 (full), 3 (log), 4 (phods), 5 (epzs), 6 (x1), 7 (hex),
     * 8 (umh), 10 (tesa) [7, 8, 10 are x264 specific]
     * - encoding: MUST be set by user.
     * - decoding: unused
     */
    int me_method;

    /**
     * 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 pixelFormat
     * @param fmt is the list of formats which are supported by the codec,
     * it is terminated by -1 as 0 is a valid format, the formats are ordered by quality.
     * The first is always the native one.
     * @return the chosen format
     * - encoding: unused
     * - decoding: Set by user, if not set the native format will be chosen.
     */
    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;

    /** obsolete FIXME remove */
    int rc_strategy;
#define FF_RC_STRATEGY_XVID 1

    int b_frame_strategy;

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

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

    /**
     * 0-> h263 quant 1-> mpeg quant
     * - encoding: Set by user.
     * - decoding: unused
     */
    int mpeg_quant;

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

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

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

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

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

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

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

    /**
     * slice count
     * - encoding: Set by libavcodec.
     * - decoding: Set by user (or 0).
     */
    int slice_count;
    /**
     * prediction method (needed for huffyuv)
     * - encoding: Set by user.
     * - decoding: unused
     */
     int prediction_method;
#define FF_PRED_LEFT   0
#define FF_PRED_PLANE  1
#define FF_PRED_MEDIAN 2

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

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

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

    /**
     * prepass for motion estimation
     * - encoding: Set by user.
     * - decoding: unused
     */
    int pre_me;

    /**
     * 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;

    /**
     * DTG active format information (additional aspect ratio
     * information only used in DVB MPEG-2 transport streams)
     * 0 if not set.
     *
     * - encoding: unused
     * - decoding: Set by decoder.
     */
    int dtg_active_format;
#define FF_DTG_AFD_SAME         8
#define FF_DTG_AFD_4_3          9
#define FF_DTG_AFD_16_9         10
#define FF_DTG_AFD_14_9         11
#define FF_DTG_AFD_4_3_SP_14_9  13
#define FF_DTG_AFD_16_9_SP_14_9 14
#define FF_DTG_AFD_SP_4_3       15

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

    /**
     * intra quantizer bias
     * - encoding: Set by user.
     * - decoding: unused
     */
    int intra_quant_bias;
#define FF_DEFAULT_QUANT_BIAS 999999

    /**
     * inter quantizer bias
     * - encoding: Set by user.
     * - decoding: unused
     */
    int inter_quant_bias;

    /**
     * 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 (MPEG2 field pics)
#define SLICE_FLAG_ALLOW_PLANE    0x0004 ///< allow draw_horiz_band() with 1 component at a time (SVQ1)

    /**
     * XVideo Motion Acceleration
     * - encoding: forbidden
     * - decoding: set by decoder
     */
    int xvmc_acceleration;

    /**
     * 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
     * - encoding: Set by user, can be NULL.
     * - decoding: Set by libavcodec.
     */
    uint16_t *intra_matrix;

    /**
     * custom inter quantization matrix
     * - encoding: Set by user, can be NULL.
     * - decoding: Set by libavcodec.
     */
    uint16_t *inter_matrix;

    /**
     * scene change detection threshold
     * 0 is default, larger means fewer detected scene changes.
     * - encoding: Set by user.
     * - decoding: unused
     */
    int scenechange_threshold;

    /**
     * noise reduction strength
     * - encoding: Set by user.
     * - decoding: unused
     */
    int noise_reduction;

    /**
     * Motion estimation threshold below which no motion estimation is
     * performed, but instead the user specified motion vectors are used.
     *
     * - encoding: Set by user.
     * - decoding: unused
     */
    int me_threshold;

    /**
     * Macroblock threshold below which the user specified macroblock types will be used.
     * - encoding: Set by user.
     * - decoding: unused
     */
    int mb_threshold;

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

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

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

    /**
     * Border processing masking, raises the quantizer for mbs on the borders
     * of the picture.
     * - encoding: Set by user.
     * - decoding: unused
     */
    float border_masking;

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

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

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

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

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

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

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

    /**
     * chroma qp offset from luma
     * - encoding: Set by user.
     * - decoding: unused
     */
    int chromaoffset;

    /**
     * Multiplied by qscale for each frame and added to scene_change_score.
     * - encoding: Set by user.
     * - decoding: unused
     */
    int scenechange_factor;

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

    /**
     * Adjust sensitivity of b_frame_strategy 1.
     * - encoding: Set by user.
     * - decoding: unused
     */
    int b_sensitivity;

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

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

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

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

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

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

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

    /* audio only */
    int sample_rate; ///< samples per second
    int channels;    ///< number of audio channels

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

    /* The following data should not be initialized. */
    /**
     * Number of samples per channel in an audio frame.
     *
     * - encoding: set by libavcodec in avcodec_open2(). Each submitted frame
     *   except the last must contain exactly frame_size samples per channel.
     *   May be 0 when the codec has 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;

    /**
     * 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.
     */
    int frame_number;

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

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

#if FF_API_REQUEST_CHANNELS
    /**
     * Decoder should decode to this many channels if it can (0 for default)
     * - encoding: unused
     * - decoding: Set by user.
     * @deprecated Deprecated in favor of request_channel_layout.
     */
    int request_channels;
#endif

    /**
     * Audio channel layout.
     * - encoding: set by user.
     * - decoding: set by libavcodec.
     */
    uint64_t channel_layout;

    /**
     * Request decoder to use this channel layout if it can (0 for default)
     * - encoding: unused
     * - decoding: Set by user.
     */
    uint64_t request_channel_layout;

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

    /**
     * Used to request a sample format from the decoder.
     * - encoding: unused.
     * - decoding: Set by user.
     */
    enum AVSampleFormat request_sample_fmt;

#if FF_API_GET_BUFFER
    /**
     * Called at the beginning of each frame to get a buffer for it.
     *
     * The function will set AVFrame.data[], AVFrame.linesize[].
     * AVFrame.extended_data[] must also be set, but it should be the same as
     * AVFrame.data[] except for planar audio with more channels than can fit
     * in AVFrame.data[]. In that case, AVFrame.data[] shall still contain as
     * many data pointers as it can hold.
     *
     * if CODEC_CAP_DR1 is not set then get_buffer() must call
     * avcodec_default_get_buffer() instead of providing buffers allocated by
     * some other means.
     *
     * AVFrame.data[] should be 32- or 16-byte-aligned unless the CPU doesn't
     * need it. avcodec_default_get_buffer() aligns the output buffer properly,
     * but if get_buffer() is overridden then alignment considerations should
     * be taken into account.
     *
     * @see avcodec_default_get_buffer()
     *
     * Video:
     *
     * If pic.reference is set then the frame will be read 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.
     *
     * If frame multithreading is used and thread_safe_callbacks is set,
     * it may be called from a different thread, but not from more than one at
     * once. Does not need to be reentrant.
     *
     * @see release_buffer(), reget_buffer()
     * @see avcodec_align_dimensions2()
     *
     * Audio:
     *
     * Decoders request a buffer of a particular size by setting
     * AVFrame.nb_samples prior to calling get_buffer(). The decoder may,
     * however, utilize only part of the buffer by setting AVFrame.nb_samples
     * to a smaller value in the output frame.
     *
     * Decoders cannot use the buffer after returning from
     * avcodec_decode_audio4(), so they will not call release_buffer(), as it
     * is assumed to be released immediately upon return. In some rare cases,
     * a decoder may need to call get_buffer() more than once in a single
     * call to avcodec_decode_audio4(). In that case, when get_buffer() is
     * called again after it has already been called once, the previously
     * acquired buffer is assumed to be released at that time and may not be
     * reused by the decoder.
     *
     * As a convenience, av_samples_get_buffer_size() and
     * av_samples_fill_arrays() in libavutil may be used by custom get_buffer()
     * 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.
     *
     * @deprecated use get_buffer2()
     */
    attribute_deprecated
    int (*get_buffer)(struct AVCodecContext *c, AVFrame *pic);

    /**
     * Called to release buffers which were allocated with get_buffer.
     * A released buffer can be reused in get_buffer().
     * pic.data[*] must be set to NULL.
     * May be called from a different thread if frame multithreading is used,
     * but not by more than one thread at once, so does not need to be reentrant.
     * - encoding: unused
     * - decoding: Set by libavcodec, user can override.
     *
     * @deprecated custom freeing callbacks should be set from get_buffer2()
     */
    attribute_deprecated
    void (*release_buffer)(struct AVCodecContext *c, AVFrame *pic);

    /**
     * Called at the beginning of a frame to get cr buffer for it.
     * Buffer type (size, hints) must be the same. libavcodec won't check it.
     * libavcodec will pass previous buffer in pic, function should return
     * same buffer or new buffer with old frame "painted" into it.
     * If pic.data[0] == NULL must behave like get_buffer().
     * if CODEC_CAP_DR1 is not set then reget_buffer() must call
     * avcodec_default_reget_buffer() instead of providing buffers allocated by
     * some other means.
     * - encoding: unused
     * - decoding: Set by libavcodec, user can override.
     */
    attribute_deprecated
    int (*reget_buffer)(struct AVCodecContext *c, AVFrame *pic);
#endif

    /**
     * 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. Each
     * buffer must be reference-counted using the AVBuffer API.
     *
     * 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 exended_data must point to data
     * - buf[] must contain one or more pointers to AVBufferRef structures. Each of
     *   the frame's data and extended_data pointers must be contained in these. That
     *   is, one AVBufferRef for each allocated chunk of memory, not necessarily one
     *   AVBufferRef per data[] entry. See: av_buffer_create(), av_buffer_alloc(),
     *   and av_buffer_ref().
     * - extended_buf and nb_extended_buf must be allocated with av_malloc() by
     *   this callback and filled with the extra buffers if there are more
     *   buffers than buf[] can hold. extended_buf will be freed in
     *   av_frame_unref().
     *
     * If 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.
     *
     * If CODEC_FLAG_EMU_EDGE is not set in s->flags, the buffer must contain an
     * edge of the size returned by avcodec_get_edge_width() on all sides.
     *
     * 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.
     *
     * If frame multithreading is used and thread_safe_callbacks is set,
     * 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);

    /**
     * If non-zero, the decoded audio and video frames returned from
     * avcodec_decode_video2() and avcodec_decode_audio4() are reference-counted
     * and are valid indefinitely. The caller must free them with
     * av_frame_unref() when they are not needed anymore.
     * Otherwise, the decoded frames must not be freed by the caller and are
     * only valid until the next decode call.
     *
     * - encoding: unused
     * - decoding: set by the caller before avcodec_open2().
     */
    int refcounted_frames;

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

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

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

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

    /**
     * ratecontrol qmin qmax limiting method
     * 0-> clipping, 1-> use a nice continuous function to limit qscale wthin qmin/qmax.
     * - encoding: Set by user.
     * - decoding: unused
     */
    float rc_qsquish;

    float rc_qmod_amp;
    int rc_qmod_freq;

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

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

    /**
     * rate control equation
     * - encoding: Set by user
     * - decoding: unused
     */
    const char *rc_eq;

    /**
     * maximum bitrate
     * - encoding: Set by user.
     * - decoding: unused
     */
    int rc_max_rate;

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

    float rc_buffer_aggressivity;

    /**
     * initial complexity for pass1 ratecontrol
     * - encoding: Set by user.
     * - decoding: unused
     */
    float rc_initial_cplx;

    /**
     * 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;

#define FF_CODER_TYPE_VLC       0
#define FF_CODER_TYPE_AC        1
#define FF_CODER_TYPE_RAW       2
#define FF_CODER_TYPE_RLE       3
#define FF_CODER_TYPE_DEFLATE   4
    /**
     * coder type
     * - encoding: Set by user.
     * - decoding: unused
     */
    int coder_type;

    /**
     * context model
     * - encoding: Set by user.
     * - decoding: unused
     */
    int context_model;

    /**
     * minimum Lagrange multipler
     * - encoding: Set by user.
     * - decoding: unused
     */
    int lmin;

    /**
     * maximum Lagrange multipler
     * - encoding: Set by user.
     * - decoding: unused
     */
    int lmax;

    /**
     * frame skip threshold
     * - encoding: Set by user.
     * - decoding: unused
     */
    int frame_skip_threshold;

    /**
     * frame skip factor
     * - encoding: Set by user.
     * - decoding: unused
     */
    int frame_skip_factor;

    /**
     * frame skip exponent
     * - encoding: Set by user.
     * - decoding: unused
     */
    int frame_skip_exp;

    /**
     * frame skip comparison function
     * - encoding: Set by user.
     * - decoding: unused
     */
    int frame_skip_cmp;

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

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

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

    /**
     * GOP timecode frame start number, in non drop frame format
     * - encoding: Set by user.
     * - decoding: unused
     */
    int64_t timecode_frame_start;

    /* The RTP callback: This function is called    */
    /* every time the encoder has a packet to send. */
    /* It depends on the encoder if the data starts */
    /* with a Start Code (it should). H.263 does.   */
    /* mb_nb contains the number of macroblocks     */
    /* encoded in the RTP payload.                  */
    void (*rtp_callback)(struct AVCodecContext *avctx, void *data, int size, int mb_nb);

    int rtp_payload_size;   /* The size of the RTP payload: the coder will  */
                            /* do its best to deliver a chunk with size     */
                            /* below rtp_payload_size, the chunk will start */
                            /* with a start code on some codecs like H.263. */
                            /* This doesn't take account of any particular  */
                            /* headers inside the transmitted RTP payload.  */

    /* statistics, used for 2-pass encoding */
    int mv_bits;
    int header_bits;
    int i_tex_bits;
    int p_tex_bits;
    int i_count;
    int p_count;
    int skip_count;
    int misc_bits;

    /**
     * number of bits used for the previously encoded frame
     * - encoding: Set by libavcodec.
     * - decoding: unused
     */
    int frame_bits;

    /**
     * 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_OLD_MSMPEG4      2
#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_AC_VLC           0  ///< Will be removed, libavcodec can now handle these non-compliant files by default.
#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

    /**
     * strictly follow the standard (MPEG4, ...).
     * - 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)
     */
    int strict_std_compliance;
#define FF_COMPLIANCE_VERY_STRICT   2 ///< Strictly conform to an older more strict version of the spec or reference software.
#define FF_COMPLIANCE_STRICT        1 ///< Strictly conform to all the things in the spec no matter what consequences.
#define FF_COMPLIANCE_NORMAL        0
#define FF_COMPLIANCE_UNOFFICIAL   -1 ///< Allow unofficial extensions
#define FF_COMPLIANCE_EXPERIMENTAL -2 ///< Allow nonstandardized experimental things.

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

    /**
     * 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_MV          32
#define FF_DEBUG_DCT_COEFF   0x00000040
#define FF_DEBUG_SKIP        0x00000080
#define FF_DEBUG_STARTCODE   0x00000100
#define FF_DEBUG_PTS         0x00000200
#define FF_DEBUG_ER          0x00000400
#define FF_DEBUG_MMCO        0x00000800
#define FF_DEBUG_BUGS        0x00001000
#define FF_DEBUG_VIS_QP      0x00002000
#define FF_DEBUG_VIS_MB_TYPE 0x00004000
#define FF_DEBUG_BUFFERS     0x00008000
#define FF_DEBUG_THREADS     0x00010000

    /**
     * debug
     * - encoding: Set by user.
     * - decoding: Set by user.
     */
    int debug_mv;
#define FF_DEBUG_VIS_MV_P_FOR  0x00000001 //visualize forward predicted MVs of P frames
#define FF_DEBUG_VIS_MV_B_FOR  0x00000002 //visualize forward predicted MVs of B frames
#define FF_DEBUG_VIS_MV_B_BACK 0x00000004 //visualize backward predicted MVs of B frames

    /**
     * Error recognition; may misdetect some more or less valid parts as errors.
     * - encoding: unused
     * - decoding: Set by user.
     */
    int err_recognition;
#define AV_EF_CRCCHECK  (1<<0)
#define AV_EF_BITSTREAM (1<<1)
#define AV_EF_BUFFER    (1<<2)
#define AV_EF_EXPLODE   (1<<3)

    /**
     * opaque 64bit number (generally a PTS) that will be reordered and
     * output in AVFrame.reordered_opaque
     * @deprecated in favor of pkt_pts
     * - encoding: unused
     * - decoding: Set by user.
     */
    int64_t reordered_opaque;

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

    /**
     * Hardware accelerator context.
     * For some hardware accelerators, a global context needs to be
     * provided by the user. In that case, this holds display-dependent
     * data Libav cannot instantiate itself. Please refer to the
     * Libav HW accelerator documentation to know how to fill this
     * is. e.g. for VA API, this is a struct vaapi_context.
     * - encoding: unused
     * - decoding: Set by user
     */
    void *hwaccel_context;

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

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

    /**
     * IDCT algorithm, see FF_IDCT_* below.
     * - encoding: Set by user.
     * - decoding: Set by user.
     */
    int idct_algo;
#define FF_IDCT_AUTO          0
#define FF_IDCT_INT           1
#define FF_IDCT_SIMPLE        2
#define FF_IDCT_SIMPLEMMX     3
#define FF_IDCT_ARM           7
#define FF_IDCT_ALTIVEC       8
#define FF_IDCT_SH4           9
#define FF_IDCT_SIMPLEARM     10
#define FF_IDCT_IPP           13
#define FF_IDCT_XVIDMMX       14
#define FF_IDCT_SIMPLEARMV5TE 16
#define FF_IDCT_SIMPLEARMV6   17
#define FF_IDCT_SIMPLEVIS     18
#define FF_IDCT_FAAN          20
#define FF_IDCT_SIMPLENEON    22
#define FF_IDCT_SIMPLEALPHA   23

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

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

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

    /**
     * the picture in the bitstream
     * - encoding: Set by libavcodec.
     * - decoding: Set by libavcodec.
     */
    AVFrame *coded_frame;

    /**
     * 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;

    /**
     * Set by the client if its custom get_buffer() callback can be called
     * synchronously from another thread, which allows faster multithreaded decoding.
     * draw_horiz_band() will be called from other threads regardless of this setting.
     * Ignored if the default get_buffer() is used.
     * - encoding: Set by user.
     * - decoding: Set by user.
     */
    int thread_safe_callbacks;

    /**
     * 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.
     * Also see avcodec_thread_init and e.g. the --enable-pthread configure option.
     * @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);

    /**
     * thread opaque
     * Can be used by execute() to store some per AVCodecContext stuff.
     * - encoding: set by execute()
     * - decoding: set by execute()
     */
    void *thread_opaque;

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

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

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

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

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

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

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

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

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

#define FF_PROFILE_JPEG2000_CSTREAM_RESTRICTION_0   0
#define FF_PROFILE_JPEG2000_CSTREAM_RESTRICTION_1   1
#define FF_PROFILE_JPEG2000_CSTREAM_NO_RESTRICTION  2
#define FF_PROFILE_JPEG2000_DCINEMA_2K              3
#define FF_PROFILE_JPEG2000_DCINEMA_4K              4

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

    /**
     *
     * - encoding: unused
     * - decoding: Set by user.
     */
    enum AVDiscard skip_loop_filter;

    /**
     *
     * - encoding: unused
     * - decoding: Set by user.
     */
    enum AVDiscard skip_idct;

    /**
     *
     * - encoding: unused
     * - decoding: Set by user.
     */
    enum AVDiscard skip_frame;

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

    /**
     * Simulates errors in the bitstream to test error concealment.
     * - encoding: Set by user.
     * - decoding: unused
     */
    int error_rate;

    /**
     * Current packet as passed into the decoder, to avoid having
     * to pass the packet into every function. Currently only valid
     * inside lavc and get/release_buffer callbacks.
     * - decoding: set by avcodec_decode_*, read by get_buffer() for setting pkt_pts
     * - encoding: unused
     */
    AVPacket *pkt;

    /**
     * VBV delay coded in the last frame (in periods of a 27 MHz clock).
     * Used for compliant TS muxing.
     * - encoding: Set by libavcodec.
     * - decoding: unused.
     */
    uint64_t vbv_delay;
} AVCodecContext;

/**
 * AVProfile.
 */
typedef struct AVProfile {
    int profile;
    const char *name; ///< short name for the profile
} AVProfile;

typedef struct AVCodecDefault AVCodecDefault;

struct AVSubtitle;

/**
 * AVCodec.
 */
typedef struct AVCodec {
    /**
     * Name of the codec implementation.
     * The name is globally unique among encoders and among decoders (but an
     * encoder and a decoder can share the same name).
     * This is the primary way to find a codec from the user perspective.
     */
    const char *name;
    /**
     * Descriptive name for the codec, meant to be more human readable than name.
     * You should use the NULL_IF_CONFIG_SMALL() macro to define it.
     */
    const char *long_name;
    enum AVMediaType type;
    enum AVCodecID id;
    /**
     * Codec capabilities.
     * see CODEC_CAP_*
     */
    int capabilities;
    const AVRational *supported_framerates; ///< array of supported framerates, or NULL if any, array is terminated by {0,0}
    const enum AVPixelFormat *pix_fmts;     ///< array of supported pixel formats, or NULL if unknown, array is terminated by -1
    const int *supported_samplerates;       ///< array of supported audio samplerates, or NULL if unknown, array is terminated by 0
    const enum AVSampleFormat *sample_fmts; ///< array of supported sample formats, or NULL if unknown, array is terminated by -1
    const uint64_t *channel_layouts;         ///< array of support channel layouts, or NULL if unknown. array is terminated by 0
    attribute_deprecated uint8_t max_lowres; ///< maximum value for lowres supported by the decoder
    const AVClass *priv_class;              ///< AVClass for the private context
    const AVProfile *profiles;              ///< array of recognized profiles, or NULL if unknown, array is terminated by {FF_PROFILE_UNKNOWN}

    /*****************************************************************
     * No fields below this line are part of the public API. They
     * may not be used outside of libavcodec and can be changed and
     * removed at will.
     * New public fields should be added right above.
     *****************************************************************
     */
    int priv_data_size;
    struct AVCodec *next;
    /**
     * @name Frame-level threading support functions
     * @{
     */
    /**
     * If defined, called on thread contexts when they are created.
     * If the codec allocates writable tables in init(), re-allocate them here.
     * priv_data will be set to a copy of the original.
     */
    int (*init_thread_copy)(AVCodecContext *);
    /**
     * Copy necessary context variables from a previous thread context to the current one.
     * If not defined, the next thread will start automatically; otherwise, the codec
     * must call ff_thread_finish_setup().
     *
     * dst and src will (rarely) point to the same context, in which case memcpy should be skipped.
     */
    int (*update_thread_context)(AVCodecContext *dst, const AVCodecContext *src);
    /** @} */

    /**
     * Private codec-specific defaults.
     */
    const AVCodecDefault *defaults;

    /**
     * Initialize codec static data, called from avcodec_register().
     */
    void (*init_static_data)(struct AVCodec *codec);

    int (*init)(AVCodecContext *);
    int (*encode_sub)(AVCodecContext *, uint8_t *buf, int buf_size,
                      const struct AVSubtitle *sub);
    /**
     * Encode data to an AVPacket.
     *
     * @param      avctx          codec context
     * @param      avpkt          output AVPacket (may contain a user-provided buffer)
     * @param[in]  frame          AVFrame containing the raw data to be encoded
     * @param[out] got_packet_ptr encoder sets to 0 or 1 to indicate that a
     *                            non-empty packet was returned in avpkt.
     * @return 0 on success, negative error code on failure
     */
    int (*encode2)(AVCodecContext *avctx, AVPacket *avpkt, const AVFrame *frame,
                   int *got_packet_ptr);
    int (*decode)(AVCodecContext *, void *outdata, int *outdata_size, AVPacket *avpkt);
    int (*close)(AVCodecContext *);
    /**
     * Flush buffers.
     * Will be called when seeking
     */
    void (*flush)(AVCodecContext *);
} AVCodec;

/**
 * AVHWAccel.
 */
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 FF_HWACCEL_CODEC_CAP_*
     */
    int capabilities;

    struct AVHWAccel *next;

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

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

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

    /**
     * Size of HW accelerator private data.
     *
     * Private data is allocated with av_mallocz() before
     * AVCodecContext.get_buffer() and deallocated after
     * AVCodecContext.release_buffer().
     */
    int priv_data_size;
} AVHWAccel;

/**
 * @defgroup lavc_picture AVPicture
 *
 * Functions for working with AVPicture
 * @{
 */

/**
 * four components are given, that's all.
 * the last component is alpha
 */
typedef struct AVPicture {
    uint8_t *data[AV_NUM_DATA_POINTERS];
    int linesize[AV_NUM_DATA_POINTERS];     ///< number of bytes per line
} AVPicture;

/**
 * @}
 */

#define AVPALETTE_SIZE 1024
#define AVPALETTE_COUNT 256

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 where rendered
     */
    AVPicture pict;
    enum AVSubtitleType type;

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

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

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

/**
 * If c is NULL, returns the first registered codec,
 * if c is non-NULL, returns the next registered codec after c,
 * or NULL if c is the last one.
 */
AVCodec *av_codec_next(const AVCodec *c);

/**
 * 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);

/**
 * Register the codec codec and initialize libavcodec.
 *
 * @warning either this function or avcodec_register_all() must be called
 * before any other libavcodec functions.
 *
 * @see avcodec_register_all()
 */
void avcodec_register(AVCodec *codec);

/**
 * Register all the codecs, parsers and bitstream filters which were enabled at
 * configuration time. If you do not call this function you can select exactly
 * which formats you want to support, by using the individual registration
 * functions.
 *
 * @see avcodec_register
 * @see av_register_codec_parser
 * @see av_register_bitstream_filter
 */
void avcodec_register_all(void);

/**
 * Allocate an AVCodecContext and set its fields to default values.  The
 * resulting struct can be deallocated by calling avcodec_close() on it followed
 * by av_free().
 *
 * @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.
 * @see avcodec_get_context_defaults
 */
AVCodecContext *avcodec_alloc_context3(const AVCodec *codec);

/**
 * Set the fields of the given AVCodecContext to default values corresponding
 * to the given codec (defaults may be codec-dependent).
 *
 * Do not call this function if a non-NULL codec has been passed
 * to avcodec_alloc_context3() that allocated this AVCodecContext.
 * If codec is non-NULL, it is illegal to call avcodec_open2() with a
 * different codec on this AVCodecContext.
 */
int avcodec_get_context_defaults3(AVCodecContext *s, const AVCodec *codec);

/**
 * 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);

/**
 * Copy the settings of the source AVCodecContext into the destination
 * AVCodecContext. The resulting destination codec context will be
 * unopened, i.e. you are required to call avcodec_open2() before you
 * can use this AVCodecContext to decode/encode video/audio data.
 *
 * @param dest target codec context, should be initialized with
 *             avcodec_alloc_context3(), but otherwise uninitialized
 * @param src source codec context
 * @return AVERROR() on error (e.g. memory allocation error), 0 on success
 */
int avcodec_copy_context(AVCodecContext *dest, const AVCodecContext *src);

/**
 * Allocate an AVFrame and set its fields to default values.  The resulting
 * struct must be freed using avcodec_free_frame().
 *
 * @return An AVFrame filled with default values or NULL on failure.
 * @see avcodec_get_frame_defaults
 */
AVFrame *avcodec_alloc_frame(void);

/**
 * Set the fields of the given AVFrame to default values.
 *
 * @param frame The AVFrame of which the fields should be set to default values.
 */
void avcodec_get_frame_defaults(AVFrame *frame);

/**
 * Free the frame and any dynamically allocated objects in it,
 * e.g. extended_data.
 *
 * @param frame frame to be freed. The pointer will be set to NULL.
 *
 * @warning this function does NOT free the data buffers themselves
 * (it does not know how, since they might have been allocated with
 *  a custom get_buffer()).
 */
void avcodec_free_frame(AVFrame **frame);

/**
 * 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.
 *
 * @warning This function is not thread safe!
 *
 * @code
 * avcodec_register_all();
 * av_dict_set(&opts, "b", "2.5M", 0);
 * codec = avcodec_find_decoder(AV_CODEC_ID_H264);
 * if (!codec)
 *     exit(1);
 *
 * context = avcodec_alloc_context3(codec);
 *
 * if (avcodec_open2(context, codec, opts) < 0)
 *     exit(1);
 * @endcode
 *
 * @param avctx The context to initialize.
 * @param codec The codec to open this context for. If a non-NULL codec has been
 *              previously passed to avcodec_alloc_context3() or
 *              avcodec_get_context_defaults3() for this context, then this
 *              parameter MUST be either NULL or equal to the previously passed
 *              codec.
 * @param options A dictionary filled with AVCodecContext and codec-private options.
 *                On return this object will be filled with options that were not found.
 *
 * @return zero on success, a negative value on error
 * @see avcodec_alloc_context3(), avcodec_find_decoder(), avcodec_find_encoder(),
 *      av_dict_set(), av_opt_find().
 */
int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options);

/**
 * Close a given AVCodecContext and free all the data associated with it
 * (but not the AVCodecContext itself).
 *
 * Calling this function on an AVCodecContext that hasn't been opened will free
 * the codec-specific data allocated in avcodec_alloc_context3() /
 * avcodec_get_context_defaults3() with a non-NULL codec. Subsequent calls will
 * do nothing.
 */
int avcodec_close(AVCodecContext *avctx);

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

/**
 * @}
 */

/**
 * @addtogroup lavc_packet
 * @{
 */

#if FF_API_DESTRUCT_PACKET
/**
 * Default packet destructor.
 * @deprecated use the AVBuffer API instead
 */
attribute_deprecated
void av_destruct_packet(AVPacket *pkt);
#endif

/**
 * Initialize optional fields of a packet with default values.
 *
 * Note, this does not touch the data and size members, which have to be
 * initialized separately.
 *
 * @param pkt packet
 */
void av_init_packet(AVPacket *pkt);

/**
 * Allocate the payload of a packet and initialize its fields with
 * default values.
 *
 * @param pkt packet
 * @param size wanted payload size
 * @return 0 if OK, AVERROR_xxx otherwise
 */
int av_new_packet(AVPacket *pkt, int size);

/**
 * Reduce packet size, correctly zeroing padding
 *
 * @param pkt packet
 * @param size new size
 */
void av_shrink_packet(AVPacket *pkt, int size);

/**
 * Increase packet size, correctly zeroing padding
 *
 * @param pkt packet
 * @param grow_by number of bytes by which to increase the size of the packet
 */
int av_grow_packet(AVPacket *pkt, int grow_by);

/**
 * Initialize a reference-counted packet from av_malloc()ed data.
 *
 * @param pkt packet to be initialized. This function will set the data, size,
 *        buf and destruct fields, all others are left untouched.
 * @param data Data allocated by av_malloc() to be used as packet data. If this
 *        function returns successfully, the data is owned by the underlying AVBuffer.
 *        The caller may not access the data through other means.
 * @param size size of data in bytes, without the padding. I.e. the full buffer
 *        size is assumed to be size + FF_INPUT_BUFFER_PADDING_SIZE.
 *
 * @return 0 on success, a negative AVERROR on error
 */
int av_packet_from_data(AVPacket *pkt, uint8_t *data, int size);

/**
 * @warning This is a hack - the packet memory allocation stuff is broken. The
 * packet is allocated if it was not really allocated.
 */
int av_dup_packet(AVPacket *pkt);

/**
 * Free a packet.
 *
 * @param pkt packet to free
 */
void av_free_packet(AVPacket *pkt);

/**
 * Allocate new information of a packet.
 *
 * @param pkt packet
 * @param type side information type
 * @param size side information size
 * @return pointer to fresh allocated data or NULL otherwise
 */
uint8_t* av_packet_new_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
                                 int size);

/**
 * Shrink the already allocated side data buffer
 *
 * @param pkt packet
 * @param type side information type
 * @param size new side information size
 * @return 0 on success, < 0 on failure
 */
int av_packet_shrink_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
                               int size);

/**
 * Get side information from packet.
 *
 * @param pkt packet
 * @param type desired side information type
 * @param size pointer for side information size to store (optional)
 * @return pointer to data if present or NULL otherwise
 */
uint8_t* av_packet_get_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
                                 int *size);

/**
 * @}
 */

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

/**
 * Find a registered decoder with a matching codec ID.
 *
 * @param id AVCodecID of the requested decoder
 * @return A decoder if one was found, NULL otherwise.
 */
AVCodec *avcodec_find_decoder(enum AVCodecID id);

/**
 * Find a registered decoder with the specified name.
 *
 * @param name name of the requested decoder
 * @return A decoder if one was found, NULL otherwise.
 */
AVCodec *avcodec_find_decoder_by_name(const char *name);

#if FF_API_GET_BUFFER
attribute_deprecated int avcodec_default_get_buffer(AVCodecContext *s, AVFrame *pic);
attribute_deprecated void avcodec_default_release_buffer(AVCodecContext *s, AVFrame *pic);
attribute_deprecated int avcodec_default_reget_buffer(AVCodecContext *s, AVFrame *pic);
#endif

/**
 * The default callback for AVCodecContext.get_buffer2(). It is made public so
 * it can be called by custom get_buffer2() implementations for decoders without
 * CODEC_CAP_DR1 set.
 */
int avcodec_default_get_buffer2(AVCodecContext *s, AVFrame *frame, int flags);

/**
 * Return the amount of padding in pixels which the get_buffer callback must
 * provide around the edge of the image for codecs which do not have the
 * CODEC_FLAG_EMU_EDGE flag.
 *
 * @return Required padding in pixels.
 */
unsigned avcodec_get_edge_width(void);

/**
 * 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 CODEC_CAP_DR1 has been opened.
 * If CODEC_FLAG_EMU_EDGE is not set, the dimensions must have been increased
 * according to avcodec_get_edge_width() before.
 */
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 CODEC_CAP_DR1 has been opened.
 * If CODEC_FLAG_EMU_EDGE is not set, the dimensions must have been increased
 * according to avcodec_get_edge_width() before.
 */
void avcodec_align_dimensions2(AVCodecContext *s, int *width, int *height,
                               int linesize_align[AV_NUM_DATA_POINTERS]);

/**
 * Decode the audio frame of size avpkt->size from avpkt->data into frame.
 *
 * Some decoders may support multiple frames in a single AVPacket. Such
 * decoders would then just decode the first frame. In this case,
 * avcodec_decode_audio4 has to be called again with an AVPacket containing
 * the remaining data in order to decode the second frame, etc...
 * Even if no frames are returned, the packet needs to be fed to the decoder
 * with remaining data until it is completely consumed or an error occurs.
 *
 * @warning The input buffer, avpkt->data must be FF_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 You might have to align the input buffer. The alignment requirements
 *       depend on the CPU and the decoder.
 *
 * @param      avctx the codec context
 * @param[out] frame The AVFrame in which to store decoded audio samples.
 *                   The decoder will allocate a buffer for the decoded frame by
 *                   calling the AVCodecContext.get_buffer2() callback.
 *                   When AVCodecContext.refcounted_frames is set to 1, the frame is
 *                   reference counted and the returned reference belongs to the
 *                   caller. The caller must release the frame using av_frame_unref()
 *                   when the frame is no longer needed. The caller may safely write
 *                   to the frame if av_frame_is_writable() returns 1.
 *                   When AVCodecContext.refcounted_frames is set to 0, the returned
 *                   reference belongs to the decoder and is valid only until the
 *                   next call to this function or until closing the decoder.
 *                   The caller may not write to it.
 * @param[out] got_frame_ptr Zero if no frame could be decoded, otherwise it is
 *                           non-zero.
 * @param[in]  avpkt The input AVPacket containing the input buffer.
 *                   At least avpkt->data and avpkt->size should be set. Some
 *                   decoders might also require additional fields to be set.
 * @return A negative error code is returned if an error occurred during
 *         decoding, otherwise the number of bytes consumed from the input
 *         AVPacket is returned.
 */
int avcodec_decode_audio4(AVCodecContext *avctx, AVFrame *frame,
                          int *got_frame_ptr, AVPacket *avpkt);

/**
 * Decode the video frame of size avpkt->size from avpkt->data into picture.
 * Some decoders may support multiple frames in a single AVPacket, such
 * decoders would then just decode the first frame.
 *
 * @warning The input buffer must be FF_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.
 *
 * @warning The end of the input buffer buf should be set to 0 to ensure that
 * no overreading happens for damaged MPEG streams.
 *
 * @note You might have to align the input buffer avpkt->data.
 * The alignment requirements depend on the CPU: on some CPUs it isn't
 * necessary at all, on others it won't work at all if not aligned and on others
 * it will work but it will have an impact on performance.
 *
 * In practice, avpkt->data should have 4 byte alignment at minimum.
 *
 * @note Codecs which have the CODEC_CAP_DELAY capability set have a delay