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AAC Encode

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17 Feb 2012CPOL3 min read 66.8K   5K   27  
Raw Audio data is encoded to AAC compression using ffmmpeg library.
/*
 * copyright (c) 2001 Fabrice Bellard
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#ifndef AVCODEC_AVCODEC_H
#define AVCODEC_AVCODEC_H

/**
 * @file
 * external API header
 */

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

#include "libavcodec/version.h"

/**
 * 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. Give it a value which when taken as ASCII is recognized uniquely by a human as this specific codec.
 *    This ensures that 2 forks can independantly add CodecIDs without producing conflicts.
 */
enum CodecID {
    CODEC_ID_NONE,

    /* video codecs */
    CODEC_ID_MPEG1VIDEO,
    CODEC_ID_MPEG2VIDEO, ///< preferred ID for MPEG-1/2 video decoding
    CODEC_ID_MPEG2VIDEO_XVMC,
    CODEC_ID_H261,
    CODEC_ID_H263,
    CODEC_ID_RV10,
    CODEC_ID_RV20,
    CODEC_ID_MJPEG,
    CODEC_ID_MJPEGB,
    CODEC_ID_LJPEG,
    CODEC_ID_SP5X,
    CODEC_ID_JPEGLS,
    CODEC_ID_MPEG4,
    CODEC_ID_RAWVIDEO,
    CODEC_ID_MSMPEG4V1,
    CODEC_ID_MSMPEG4V2,
    CODEC_ID_MSMPEG4V3,
    CODEC_ID_WMV1,
    CODEC_ID_WMV2,
    CODEC_ID_H263P,
    CODEC_ID_H263I,
    CODEC_ID_FLV1,
    CODEC_ID_SVQ1,
    CODEC_ID_SVQ3,
    CODEC_ID_DVVIDEO,
    CODEC_ID_HUFFYUV,
    CODEC_ID_CYUV,
    CODEC_ID_H264,
    CODEC_ID_INDEO3,
    CODEC_ID_VP3,
    CODEC_ID_THEORA,
    CODEC_ID_ASV1,
    CODEC_ID_ASV2,
    CODEC_ID_FFV1,
    CODEC_ID_4XM,
    CODEC_ID_VCR1,
    CODEC_ID_CLJR,
    CODEC_ID_MDEC,
    CODEC_ID_ROQ,
    CODEC_ID_INTERPLAY_VIDEO,
    CODEC_ID_XAN_WC3,
    CODEC_ID_XAN_WC4,
    CODEC_ID_RPZA,
    CODEC_ID_CINEPAK,
    CODEC_ID_WS_VQA,
    CODEC_ID_MSRLE,
    CODEC_ID_MSVIDEO1,
    CODEC_ID_IDCIN,
    CODEC_ID_8BPS,
    CODEC_ID_SMC,
    CODEC_ID_FLIC,
    CODEC_ID_TRUEMOTION1,
    CODEC_ID_VMDVIDEO,
    CODEC_ID_MSZH,
    CODEC_ID_ZLIB,
    CODEC_ID_QTRLE,
    CODEC_ID_SNOW,
    CODEC_ID_TSCC,
    CODEC_ID_ULTI,
    CODEC_ID_QDRAW,
    CODEC_ID_VIXL,
    CODEC_ID_QPEG,
    CODEC_ID_PNG,
    CODEC_ID_PPM,
    CODEC_ID_PBM,
    CODEC_ID_PGM,
    CODEC_ID_PGMYUV,
    CODEC_ID_PAM,
    CODEC_ID_FFVHUFF,
    CODEC_ID_RV30,
    CODEC_ID_RV40,
    CODEC_ID_VC1,
    CODEC_ID_WMV3,
    CODEC_ID_LOCO,
    CODEC_ID_WNV1,
    CODEC_ID_AASC,
    CODEC_ID_INDEO2,
    CODEC_ID_FRAPS,
    CODEC_ID_TRUEMOTION2,
    CODEC_ID_BMP,
    CODEC_ID_CSCD,
    CODEC_ID_MMVIDEO,
    CODEC_ID_ZMBV,
    CODEC_ID_AVS,
    CODEC_ID_SMACKVIDEO,
    CODEC_ID_NUV,
    CODEC_ID_KMVC,
    CODEC_ID_FLASHSV,
    CODEC_ID_CAVS,
    CODEC_ID_JPEG2000,
    CODEC_ID_VMNC,
    CODEC_ID_VP5,
    CODEC_ID_VP6,
    CODEC_ID_VP6F,
    CODEC_ID_TARGA,
    CODEC_ID_DSICINVIDEO,
    CODEC_ID_TIERTEXSEQVIDEO,
    CODEC_ID_TIFF,
    CODEC_ID_GIF,
#if LIBAVCODEC_VERSION_MAJOR == 53
    CODEC_ID_FFH264,
#endif
    CODEC_ID_DXA,
    CODEC_ID_DNXHD,
    CODEC_ID_THP,
    CODEC_ID_SGI,
    CODEC_ID_C93,
    CODEC_ID_BETHSOFTVID,
    CODEC_ID_PTX,
    CODEC_ID_TXD,
    CODEC_ID_VP6A,
    CODEC_ID_AMV,
    CODEC_ID_VB,
    CODEC_ID_PCX,
    CODEC_ID_SUNRAST,
    CODEC_ID_INDEO4,
    CODEC_ID_INDEO5,
    CODEC_ID_MIMIC,
    CODEC_ID_RL2,
#if LIBAVCODEC_VERSION_MAJOR == 53
    CODEC_ID_8SVX_EXP,
    CODEC_ID_8SVX_FIB,
#endif
    CODEC_ID_ESCAPE124,
    CODEC_ID_DIRAC,
    CODEC_ID_BFI,
    CODEC_ID_CMV,
    CODEC_ID_MOTIONPIXELS,
    CODEC_ID_TGV,
    CODEC_ID_TGQ,
    CODEC_ID_TQI,
    CODEC_ID_AURA,
    CODEC_ID_AURA2,
    CODEC_ID_V210X,
    CODEC_ID_TMV,
    CODEC_ID_V210,
    CODEC_ID_DPX,
    CODEC_ID_MAD,
    CODEC_ID_FRWU,
    CODEC_ID_FLASHSV2,
    CODEC_ID_CDGRAPHICS,
    CODEC_ID_R210,
    CODEC_ID_ANM,
    CODEC_ID_BINKVIDEO,
    CODEC_ID_IFF_ILBM,
    CODEC_ID_IFF_BYTERUN1,
    CODEC_ID_KGV1,
    CODEC_ID_YOP,
    CODEC_ID_VP8,
    CODEC_ID_PICTOR,
    CODEC_ID_ANSI,
    CODEC_ID_A64_MULTI,
    CODEC_ID_A64_MULTI5,
    CODEC_ID_R10K,
    CODEC_ID_MXPEG,
    CODEC_ID_LAGARITH,
    CODEC_ID_PRORES,
    CODEC_ID_JV,
    CODEC_ID_DFA,
    CODEC_ID_WMV3IMAGE,
    CODEC_ID_VC1IMAGE,
#if LIBAVCODEC_VERSION_MAJOR == 53
    CODEC_ID_G723_1_DEPRECATED,
    CODEC_ID_G729_DEPRECATED,
#endif
    CODEC_ID_UTVIDEO_DEPRECATED,
    CODEC_ID_BMV_VIDEO,
    CODEC_ID_VBLE,
    CODEC_ID_UTVIDEO = 0x800,

    CODEC_ID_G2M        = MKBETAG( 0 ,'G','2','M'),

    /* various PCM "codecs" */
    CODEC_ID_FIRST_AUDIO = 0x10000,     ///< A dummy id pointing at the start of audio codecs
    CODEC_ID_PCM_S16LE = 0x10000,
    CODEC_ID_PCM_S16BE,
    CODEC_ID_PCM_U16LE,
    CODEC_ID_PCM_U16BE,
    CODEC_ID_PCM_S8,
    CODEC_ID_PCM_U8,
    CODEC_ID_PCM_MULAW,
    CODEC_ID_PCM_ALAW,
    CODEC_ID_PCM_S32LE,
    CODEC_ID_PCM_S32BE,
    CODEC_ID_PCM_U32LE,
    CODEC_ID_PCM_U32BE,
    CODEC_ID_PCM_S24LE,
    CODEC_ID_PCM_S24BE,
    CODEC_ID_PCM_U24LE,
    CODEC_ID_PCM_U24BE,
    CODEC_ID_PCM_S24DAUD,
    CODEC_ID_PCM_ZORK,
    CODEC_ID_PCM_S16LE_PLANAR,
    CODEC_ID_PCM_DVD,
    CODEC_ID_PCM_F32BE,
    CODEC_ID_PCM_F32LE,
    CODEC_ID_PCM_F64BE,
    CODEC_ID_PCM_F64LE,
    CODEC_ID_PCM_BLURAY,
    CODEC_ID_PCM_LXF,
    CODEC_ID_S302M,
    CODEC_ID_PCM_S8_PLANAR,

    /* various ADPCM codecs */
    CODEC_ID_ADPCM_IMA_QT = 0x11000,
    CODEC_ID_ADPCM_IMA_WAV,
    CODEC_ID_ADPCM_IMA_DK3,
    CODEC_ID_ADPCM_IMA_DK4,
    CODEC_ID_ADPCM_IMA_WS,
    CODEC_ID_ADPCM_IMA_SMJPEG,
    CODEC_ID_ADPCM_MS,
    CODEC_ID_ADPCM_4XM,
    CODEC_ID_ADPCM_XA,
    CODEC_ID_ADPCM_ADX,
    CODEC_ID_ADPCM_EA,
    CODEC_ID_ADPCM_G726,
    CODEC_ID_ADPCM_CT,
    CODEC_ID_ADPCM_SWF,
    CODEC_ID_ADPCM_YAMAHA,
    CODEC_ID_ADPCM_SBPRO_4,
    CODEC_ID_ADPCM_SBPRO_3,
    CODEC_ID_ADPCM_SBPRO_2,
    CODEC_ID_ADPCM_THP,
    CODEC_ID_ADPCM_IMA_AMV,
    CODEC_ID_ADPCM_EA_R1,
    CODEC_ID_ADPCM_EA_R3,
    CODEC_ID_ADPCM_EA_R2,
    CODEC_ID_ADPCM_IMA_EA_SEAD,
    CODEC_ID_ADPCM_IMA_EA_EACS,
    CODEC_ID_ADPCM_EA_XAS,
    CODEC_ID_ADPCM_EA_MAXIS_XA,
    CODEC_ID_ADPCM_IMA_ISS,
    CODEC_ID_ADPCM_G722,

    /* AMR */
    CODEC_ID_AMR_NB = 0x12000,
    CODEC_ID_AMR_WB,

    /* RealAudio codecs*/
    CODEC_ID_RA_144 = 0x13000,
    CODEC_ID_RA_288,

    /* various DPCM codecs */
    CODEC_ID_ROQ_DPCM = 0x14000,
    CODEC_ID_INTERPLAY_DPCM,
    CODEC_ID_XAN_DPCM,
    CODEC_ID_SOL_DPCM,

    /* audio codecs */
    CODEC_ID_MP2 = 0x15000,
    CODEC_ID_MP3, ///< preferred ID for decoding MPEG audio layer 1, 2 or 3
    CODEC_ID_AAC,
    CODEC_ID_AC3,
    CODEC_ID_DTS,
    CODEC_ID_VORBIS,
    CODEC_ID_DVAUDIO,
    CODEC_ID_WMAV1,
    CODEC_ID_WMAV2,
    CODEC_ID_MACE3,
    CODEC_ID_MACE6,
    CODEC_ID_VMDAUDIO,
#if LIBAVCODEC_VERSION_MAJOR == 53
    CODEC_ID_SONIC,
    CODEC_ID_SONIC_LS,
#endif
    CODEC_ID_FLAC,
    CODEC_ID_MP3ADU,
    CODEC_ID_MP3ON4,
    CODEC_ID_SHORTEN,
    CODEC_ID_ALAC,
    CODEC_ID_WESTWOOD_SND1,
    CODEC_ID_GSM, ///< as in Berlin toast format
    CODEC_ID_QDM2,
    CODEC_ID_COOK,
    CODEC_ID_TRUESPEECH,
    CODEC_ID_TTA,
    CODEC_ID_SMACKAUDIO,
    CODEC_ID_QCELP,
    CODEC_ID_WAVPACK,
    CODEC_ID_DSICINAUDIO,
    CODEC_ID_IMC,
    CODEC_ID_MUSEPACK7,
    CODEC_ID_MLP,
    CODEC_ID_GSM_MS, /* as found in WAV */
    CODEC_ID_ATRAC3,
    CODEC_ID_VOXWARE,
    CODEC_ID_APE,
    CODEC_ID_NELLYMOSER,
    CODEC_ID_MUSEPACK8,
    CODEC_ID_SPEEX,
    CODEC_ID_WMAVOICE,
    CODEC_ID_WMAPRO,
    CODEC_ID_WMALOSSLESS,
    CODEC_ID_ATRAC3P,
    CODEC_ID_EAC3,
    CODEC_ID_SIPR,
    CODEC_ID_MP1,
    CODEC_ID_TWINVQ,
    CODEC_ID_TRUEHD,
    CODEC_ID_MP4ALS,
    CODEC_ID_ATRAC1,
    CODEC_ID_BINKAUDIO_RDFT,
    CODEC_ID_BINKAUDIO_DCT,
    CODEC_ID_AAC_LATM,
    CODEC_ID_QDMC,
    CODEC_ID_CELT,
#if LIBAVCODEC_VERSION_MAJOR > 53
    CODEC_ID_G723_1_DEPRECATED,
    CODEC_ID_G729_DEPRECATED,
    CODEC_ID_8SVX_EXP,
    CODEC_ID_8SVX_FIB,
#endif
    CODEC_ID_BMV_AUDIO,
    CODEC_ID_G729 = 0x15800,
    CODEC_ID_G723_1= 0x15801,
    CODEC_ID_8SVX_RAW   = MKBETAG('8','S','V','X'),

    /* subtitle codecs */
    CODEC_ID_FIRST_SUBTITLE = 0x17000,          ///< A dummy ID pointing at the start of subtitle codecs.
    CODEC_ID_DVD_SUBTITLE = 0x17000,
    CODEC_ID_DVB_SUBTITLE,
    CODEC_ID_TEXT,  ///< raw UTF-8 text
    CODEC_ID_XSUB,
    CODEC_ID_SSA,
    CODEC_ID_MOV_TEXT,
    CODEC_ID_HDMV_PGS_SUBTITLE,
    CODEC_ID_DVB_TELETEXT,
    CODEC_ID_SRT,
    CODEC_ID_MICRODVD   = MKBETAG('m','D','V','D'),

    /* other specific kind of codecs (generally used for attachments) */
    CODEC_ID_FIRST_UNKNOWN = 0x18000,           ///< A dummy ID pointing at the start of various fake codecs.
    CODEC_ID_TTF = 0x18000,
    CODEC_ID_BINTEXT    = MKBETAG('B','T','X','T'),
    CODEC_ID_XBIN       = MKBETAG('X','B','I','N'),
    CODEC_ID_IDF        = MKBETAG( 0 ,'I','D','F'),

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

    CODEC_ID_MPEG2TS = 0x20000, /**< _FAKE_ codec to indicate a raw MPEG-2 TS
                                * stream (only used by libavformat) */
    CODEC_ID_MPEG4SYSTEMS = 0x20001, /**< _FAKE_ codec to indicate a MPEG-4 Systems
                                * stream (only used by libavformat) */
    CODEC_ID_FFMETADATA = 0x21000,   ///< Dummy codec for streams containing only metadata information.
};

#if FF_API_OLD_SAMPLE_FMT
#define SampleFormat AVSampleFormat

#define SAMPLE_FMT_NONE AV_SAMPLE_FMT_NONE
#define SAMPLE_FMT_U8   AV_SAMPLE_FMT_U8
#define SAMPLE_FMT_S16  AV_SAMPLE_FMT_S16
#define SAMPLE_FMT_S32  AV_SAMPLE_FMT_S32
#define SAMPLE_FMT_FLT  AV_SAMPLE_FMT_FLT
#define SAMPLE_FMT_DBL  AV_SAMPLE_FMT_DBL
#define SAMPLE_FMT_NB   AV_SAMPLE_FMT_NB
#endif

#if FF_API_OLD_AUDIOCONVERT
#include "libavutil/audioconvert.h"

/* Audio channel masks */
#define CH_FRONT_LEFT            AV_CH_FRONT_LEFT
#define CH_FRONT_RIGHT           AV_CH_FRONT_RIGHT
#define CH_FRONT_CENTER          AV_CH_FRONT_CENTER
#define CH_LOW_FREQUENCY         AV_CH_LOW_FREQUENCY
#define CH_BACK_LEFT             AV_CH_BACK_LEFT
#define CH_BACK_RIGHT            AV_CH_BACK_RIGHT
#define CH_FRONT_LEFT_OF_CENTER  AV_CH_FRONT_LEFT_OF_CENTER
#define CH_FRONT_RIGHT_OF_CENTER AV_CH_FRONT_RIGHT_OF_CENTER
#define CH_BACK_CENTER           AV_CH_BACK_CENTER
#define CH_SIDE_LEFT             AV_CH_SIDE_LEFT
#define CH_SIDE_RIGHT            AV_CH_SIDE_RIGHT
#define CH_TOP_CENTER            AV_CH_TOP_CENTER
#define CH_TOP_FRONT_LEFT        AV_CH_TOP_FRONT_LEFT
#define CH_TOP_FRONT_CENTER      AV_CH_TOP_FRONT_CENTER
#define CH_TOP_FRONT_RIGHT       AV_CH_TOP_FRONT_RIGHT
#define CH_TOP_BACK_LEFT         AV_CH_TOP_BACK_LEFT
#define CH_TOP_BACK_CENTER       AV_CH_TOP_BACK_CENTER
#define CH_TOP_BACK_RIGHT        AV_CH_TOP_BACK_RIGHT
#define CH_STEREO_LEFT           AV_CH_STEREO_LEFT
#define CH_STEREO_RIGHT          AV_CH_STEREO_RIGHT

/** Channel mask value used for AVCodecContext.request_channel_layout
    to indicate that the user requests the channel order of the decoder output
    to be the native codec channel order. */
#define CH_LAYOUT_NATIVE         AV_CH_LAYOUT_NATIVE

/* Audio channel convenience macros */
#define CH_LAYOUT_MONO           AV_CH_LAYOUT_MONO
#define CH_LAYOUT_STEREO         AV_CH_LAYOUT_STEREO
#define CH_LAYOUT_2_1            AV_CH_LAYOUT_2_1
#define CH_LAYOUT_SURROUND       AV_CH_LAYOUT_SURROUND
#define CH_LAYOUT_4POINT0        AV_CH_LAYOUT_4POINT0
#define CH_LAYOUT_2_2            AV_CH_LAYOUT_2_2
#define CH_LAYOUT_QUAD           AV_CH_LAYOUT_QUAD
#define CH_LAYOUT_5POINT0        AV_CH_LAYOUT_5POINT0
#define CH_LAYOUT_5POINT1        AV_CH_LAYOUT_5POINT1
#define CH_LAYOUT_5POINT0_BACK   AV_CH_LAYOUT_5POINT0_BACK
#define CH_LAYOUT_5POINT1_BACK   AV_CH_LAYOUT_5POINT1_BACK
#define CH_LAYOUT_7POINT0        AV_CH_LAYOUT_7POINT0
#define CH_LAYOUT_7POINT1        AV_CH_LAYOUT_7POINT1
#define CH_LAYOUT_7POINT1_WIDE   AV_CH_LAYOUT_7POINT1_WIDE
#define CH_LAYOUT_STEREO_DOWNMIX AV_CH_LAYOUT_STEREO_DOWNMIX
#endif

/* in bytes */
#define AVCODEC_MAX_AUDIO_FRAME_SIZE 192000 // 1 second of 48khz 32bit audio

/**
 * 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 16

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


/**
 * 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_ITER,        ///< iterative search
    ME_TESA,        ///< transformed exhaustive search algorithm
};

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_YCGCO      =8,
    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
};

#if FF_API_FLAC_GLOBAL_OPTS
/**
 * LPC analysis type
 */
enum AVLPCType {
    AV_LPC_TYPE_DEFAULT     = -1, ///< use the codec default LPC type
    AV_LPC_TYPE_NONE        =  0, ///< do not use LPC prediction or use all zero coefficients
    AV_LPC_TYPE_FIXED       =  1, ///< fixed LPC coefficients
    AV_LPC_TYPE_LEVINSON    =  2, ///< Levinson-Durbin recursion
    AV_LPC_TYPE_CHOLESKY    =  3, ///< Cholesky factorization
    AV_LPC_TYPE_NB              , ///< Not part of ABI
};
#endif

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
};

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.
*/

#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_CBP_RD         0x04000000 ///< Use rate distortion optimization for cbp.
#define CODEC_FLAG_QP_RD          0x08000000 ///< Use rate distortion optimization for qp selectioon.
#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_STRICT_GOP    0x00000002 ///< Strictly enforce GOP size.
#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_SKIP_RD       0x00004000 ///< RD optimal MB level residual skipping
#define CODEC_FLAG2_CHUNKS        0x00008000 ///< Input bitstream might be truncated at a packet boundaries instead of only at frame boundaries.
#define CODEC_FLAG2_SHOW_ALL      0x00400000 ///< Show all frames before the first keyframe
/**
 * @defgroup deprecated_flags Deprecated codec flags
 * Use corresponding private codec options instead.
 * @{
 */
#if FF_API_MPEGVIDEO_GLOBAL_OPTS
#define CODEC_FLAG_OBMC           0x00000001 ///< OBMC
#define CODEC_FLAG_H263P_AIV      0x00000008 ///< H.263 alternative inter VLC
#define CODEC_FLAG_PART   0x0080  ///< Use data partitioning.
#define CODEC_FLAG_ALT_SCAN       0x00100000 ///< Use alternate scan.
#define CODEC_FLAG_H263P_UMV      0x02000000 ///< unlimited motion vector
#define CODEC_FLAG_H263P_SLICE_STRUCT 0x10000000
#define CODEC_FLAG_SVCD_SCAN_OFFSET 0x40000000 ///< Will reserve space for SVCD scan offset user data.
#define CODEC_FLAG2_INTRA_VLC     0x00000800 ///< Use MPEG-2 intra VLC table.
#define CODEC_FLAG2_DROP_FRAME_TIMECODE 0x00002000 ///< timecode is in drop frame format.
#define CODEC_FLAG2_NON_LINEAR_QUANT 0x00010000 ///< Use MPEG-2 nonlinear quantizer.
#endif
#if FF_API_MJPEG_GLOBAL_OPTS
#define CODEC_FLAG_EXTERN_HUFF     0x1000   ///< Use external Huffman table (for MJPEG).
#endif
#if FF_API_X264_GLOBAL_OPTS
#define CODEC_FLAG2_BPYRAMID      0x00000010 ///< H.264 allow B-frames to be used as references.
#define CODEC_FLAG2_WPRED         0x00000020 ///< H.264 weighted biprediction for B-frames
#define CODEC_FLAG2_MIXED_REFS    0x00000040 ///< H.264 one reference per partition, as opposed to one reference per macroblock
#define CODEC_FLAG2_8X8DCT        0x00000080 ///< H.264 high profile 8x8 transform
#define CODEC_FLAG2_FASTPSKIP     0x00000100 ///< H.264 fast pskip
#define CODEC_FLAG2_AUD           0x00000200 ///< H.264 access unit delimiters
#define CODEC_FLAG2_BRDO          0x00000400 ///< B-frame rate-distortion optimization
#define CODEC_FLAG2_MBTREE        0x00040000 ///< Use macroblock tree ratecontrol (x264 only)
#define CODEC_FLAG2_PSY           0x00080000 ///< Use psycho visual optimizations.
#define CODEC_FLAG2_SSIM          0x00100000 ///< Compute SSIM during encoding, error[] values are undefined.
#define CODEC_FLAG2_INTRA_REFRESH 0x00200000 ///< Use periodic insertion of intra blocks instead of keyframes.
#endif
#if FF_API_SNOW_GLOBAL_OPTS
#define CODEC_FLAG2_MEMC_ONLY     0x00001000 ///< Only do ME/MC (I frames -> ref, P frame -> ME+MC).
#endif
#if FF_API_LAME_GLOBAL_OPTS
#define CODEC_FLAG2_BIT_RESERVOIR 0x00020000 ///< Use a bit reservoir when encoding if possible
#endif
/**
 * @}
 */

/* 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
#if FF_API_PARSE_FRAME
/* If 'parse_only' field is true, then avcodec_parse_frame() can be used. */
#define CODEC_CAP_PARSE_ONLY      0x0004
#endif
#define CODEC_CAP_TRUNCATED       0x0008
/* Codec can export data for HW decoding (XvMC). */
#define CODEC_CAP_HWACCEL         0x0010
/**
 * Codec has a nonzero 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. If this is not set, the codec is guaranteed to never be fed
 * with NULL data.
 */
#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 is lossless.
 */
#define CODEC_CAP_LOSSLESS         0x80000000

//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

#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.

#if FF_API_OLD_FF_PICT_TYPES
/* DEPRECATED, directly use the AV_PICTURE_TYPE_* enum values */
#define FF_I_TYPE  AV_PICTURE_TYPE_I  ///< Intra
#define FF_P_TYPE  AV_PICTURE_TYPE_P  ///< Predicted
#define FF_B_TYPE  AV_PICTURE_TYPE_B  ///< Bi-dir predicted
#define FF_S_TYPE  AV_PICTURE_TYPE_S  ///< S(GMC)-VOP MPEG4
#define FF_SI_TYPE AV_PICTURE_TYPE_SI ///< Switching Intra
#define FF_SP_TYPE AV_PICTURE_TYPE_SP ///< Switching Predicted
#define FF_BI_TYPE AV_PICTURE_TYPE_BI
#endif

#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).

enum AVPacketSideDataType {
    AV_PKT_DATA_PALETTE,
};

typedef struct AVPacket {
    /**
     * 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;
    void  (*destruct)(struct AVPacket *);
    void  *priv;
    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

/**
 * Audio Video Frame.
 * New fields can be added to the end of AVFRAME with minor version
 * bumps. Removal, reordering and changes to existing fields require
 * a major version bump.
 * sizeof(AVFrame) must not be used outside libav*.
 */
typedef struct AVFrame {
    /**
     * pointer to the picture planes.
     * This might be different from the first allocated byte
     * - encoding:
     * - decoding:
     */
    uint8_t *data[4];
    int linesize[4];
    /**
     * pointer to the first allocated byte of the picture. Can be used in get_buffer/release_buffer.
     * This isn't used by libavcodec unless the default get/release_buffer() is used.
     * - encoding:
     * - decoding:
     */
    uint8_t *base[4];
    /**
     * 1 -> keyframe, 0-> not
     * - encoding: Set by libavcodec.
     * - decoding: Set by libavcodec.
     */
    int key_frame;

    /**
     * Picture type of the frame, see ?_TYPE below.
     * - encoding: Set by libavcodec. for coded_picture (and set by user for input).
     * - decoding: Set by libavcodec.
     */
    enum AVPictureType pict_type;

    /**
     * presentation timestamp in time_base units (time when frame should be shown to user)
     * If AV_NOPTS_VALUE then frame_rate = 1/time_base will be assumed.
     * - encoding: MUST be set by user.
     * - decoding: Set by libavcodec.
     */
    int64_t pts;

    /**
     * picture number in bitstream order
     * - encoding: set by
     * - decoding: Set by libavcodec.
     */
    int coded_picture_number;
    /**
     * picture number in display order
     * - encoding: set by
     * - decoding: Set by libavcodec.
     */
    int display_picture_number;

    /**
     * quality (between 1 (good) and FF_LAMBDA_MAX (bad))
     * - encoding: Set by libavcodec. for coded_picture (and set by user for input).
     * - decoding: Set by libavcodec.
     */
    int quality;

    /**
     * buffer age (1->was last buffer and dint change, 2->..., ...).
     * Set to INT_MAX if the buffer has not been used yet.
     * - encoding: unused
     * - decoding: MUST be set by get_buffer().
     */
    int age;

    /**
     * is this picture used as reference
     * The values for this are the same as the MpegEncContext.picture_structure
     * variable, that is 1->top field, 2->bottom field, 3->frame/both fields.
     * Set to 4 for delayed, non-reference frames.
     * - encoding: unused
     * - decoding: Set by libavcodec. (before get_buffer() call)).
     */
    int reference;

    /**
     * QP table
     * - encoding: unused
     * - decoding: Set by libavcodec.
     */
    int8_t *qscale_table;
    /**
     * QP store stride
     * - encoding: unused
     * - decoding: Set by libavcodec.
     */
    int qstride;

    /**
     * mbskip_table[mb]>=1 if MB didn't change
     * stride= mb_width = (width+15)>>4
     * - encoding: unused
     * - decoding: Set by libavcodec.
     */
    uint8_t *mbskip_table;

    /**
     * motion vector table
     * @code
     * example:
     * int mv_sample_log2= 4 - motion_subsample_log2;
     * int mb_width= (width+15)>>4;
     * int mv_stride= (mb_width << mv_sample_log2) + 1;
     * motion_val[direction][x + y*mv_stride][0->mv_x, 1->mv_y];
     * @endcode
     * - encoding: Set by user.
     * - decoding: Set by libavcodec.
     */
    int16_t (*motion_val[2])[2];

    /**
     * macroblock type table
     * mb_type_base + mb_width + 2
     * - encoding: Set by user.
     * - decoding: Set by libavcodec.
     */
    uint32_t *mb_type;

    /**
     * log2 of the size of the block which a single vector in motion_val represents:
     * (4->16x16, 3->8x8, 2-> 4x4, 1-> 2x2)
     * - encoding: unused
     * - decoding: Set by libavcodec.
     */
    uint8_t motion_subsample_log2;

    /**
     * for some private data of the user
     * - encoding: unused
     * - decoding: Set by user.
     */
    void *opaque;

    /**
     * error
     * - encoding: Set by libavcodec. if flags&CODEC_FLAG_PSNR.
     * - decoding: unused
     */
    uint64_t error[4];

    /**
     * type of the buffer (to keep track of who has to deallocate data[*])
     * - encoding: Set by the one who allocates it.
     * - decoding: Set by the one who allocates it.
     * Note: User allocated (direct rendering) & internal buffers cannot coexist currently.
     */
    int type;

    /**
     * When decoding, this signals how much the picture must be delayed.
     * extra_delay = repeat_pict / (2*fps)
     * - encoding: unused
     * - decoding: Set by libavcodec.
     */
    int repeat_pict;

    /**
     *
     */
    int qscale_type;

    /**
     * The content of the picture is interlaced.
     * - encoding: Set by user.
     * - decoding: Set by libavcodec. (default 0)
     */
    int interlaced_frame;

    /**
     * If the content is interlaced, is top field displayed first.
     * - encoding: Set by user.
     * - decoding: Set by libavcodec.
     */
    int top_field_first;

    /**
     * Pan scan.
     * - encoding: Set by user.
     * - decoding: Set by libavcodec.
     */
    AVPanScan *pan_scan;

    /**
     * Tell user application that palette has changed from previous frame.
     * - encoding: ??? (no palette-enabled encoder yet)
     * - decoding: Set by libavcodec. (default 0).
     */
    int palette_has_changed;

    /**
     * codec suggestion on buffer type if != 0
     * - encoding: unused
     * - decoding: Set by libavcodec. (before get_buffer() call)).
     */
    int buffer_hints;

    /**
     * DCT coefficients
     * - encoding: unused
     * - decoding: Set by libavcodec.
     */
    short *dct_coeff;

    /**
     * motion reference frame index
     * the order in which these are stored can depend on the codec.
     * - encoding: Set by user.
     * - decoding: Set by libavcodec.
     */
    int8_t *ref_index[2];

    /**
     * reordered opaque 64bit (generally an integer or a double precision float
     * PTS but can be anything).
     * The user sets AVCodecContext.reordered_opaque to represent the input at
     * that time,
     * the decoder reorders values as needed and sets AVFrame.reordered_opaque
     * to exactly one of the values provided by the user through AVCodecContext.reordered_opaque
     * @deprecated in favor of pkt_pts
     * - encoding: unused
     * - decoding: Read by user.
     */
    int64_t reordered_opaque;

    /**
     * hardware accelerator private data (FFmpeg-allocated)
     * - encoding: unused
     * - decoding: Set by libavcodec
     */
    void *hwaccel_picture_private;

    /**
     * reordered pts from the last AVPacket that has been input into the decoder
     * - encoding: unused
     * - decoding: Read by user.
     */
    int64_t pkt_pts;

    /**
     * dts from the last AVPacket that has been input into the decoder
     * - encoding: unused
     * - decoding: Read by user.
     */
    int64_t pkt_dts;

    /**
     * the AVCodecContext which ff_thread_get_buffer() was last called on
     * - encoding: Set by libavcodec.
     * - decoding: Set by libavcodec.
     */
    struct AVCodecContext *owner;

    /**
     * used by multithreading to store frame-specific info
     * - encoding: Set by libavcodec.
     * - decoding: Set by libavcodec.
     */
    void *thread_opaque;

    /**
     * frame timestamp estimated using various heuristics, in stream time base
     * - encoding: unused
     * - decoding: set by libavcodec, read by user.
     */
    int64_t best_effort_timestamp;

    /**
     * reordered pos from the last AVPacket that has been input into the decoder
     * - encoding: unused
     * - decoding: Read by user.
     */
    int64_t pkt_pos;

    /**
     * reordered sample aspect ratio for the video frame, 0/1 if unknown\unspecified
     * - encoding: unused
     * - decoding: Read by user.
     */
    AVRational sample_aspect_ratio;

    /**
     * width and height of the video frame
     * - encoding: unused
     * - decoding: Read by user.
     */
    int width, height;

    /**
     * format of the frame, -1 if unknown or unset
     * It should be cast to the corresponding enum (enum PixelFormat
     * for video, enum AVSampleFormat for audio)
     * - encoding: unused
     * - decoding: Read by user.
     */
    int format;

} AVFrame;

struct AVCodecInternal;

/**
 * main external API structure.
 * New fields can be added to the end with minor version bumps.
 * Removal, reordering and changes to existing fields require a major
 * version bump.
 * Please use AVOptions (av_opt* / av_set/get*()) to access these fields from user
 * applications.
 * sizeof(AVCodecContext) must not be used outside libav*.
 */
typedef struct AVCodecContext {
    /**
     * information on struct for av_log
     * - set by avcodec_alloc_context
     */
    const AVClass *av_class;
    /**
     * 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;

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

    /**
     * Some codecs need additional format info. It is stored here.
     * If any muxer uses this then ALL demuxers/parsers AND encoders for the
     * specific codec MUST set it correctly otherwise stream copy breaks.
     * In general use of this field by muxers is not recommanded.
     * - encoding: Set by libavcodec.
     * - decoding: Set by libavcodec. (FIXME: Is this OK?)
     */
    int sub_id;

    /**
     * Motion estimation algorithm used for video coding.
     * 1 (zero), 2 (full), 3 (log), 4 (phods), 5 (epzs), 6 (x1), 7 (hex),
     * 8 (umh), 9 (iter), 10 (tesa) [7, 8, 10 are x264 specific, 9 is snow specific]
     * - encoding: MUST be set by user.
     * - decoding: unused
     */
    int me_method;

    /**
     * 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;

    /* video only */
    /**
     * picture width / height.
     * - encoding: MUST be set by user.
     * - decoding: Set by libavcodec.
     * Note: For compatibility it is possible to set this instead of
     * coded_width/height before decoding.
     */
    int width, 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 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 PixelFormat pix_fmt;

    /**
     * If non NULL, 'draw_horiz_band' is called by the libavcodec
     * decoder to draw a horizontal band. It improves cache usage. Not
     * all codecs can do that. You must check the codec capabilities
     * beforehand.
     * When multithreading is used, it may be called from multiple threads
     * at the same time; threads might draw different parts of the same AVFrame,
     * or multiple AVFrames, and there is no guarantee that slices will be drawn
     * in order.
     * The function is also used by hardware acceleration APIs.
     * It is called at least once during frame decoding to pass
     * the data needed for hardware render.
     * In that mode instead of pixel data, AVFrame points to
     * a structure specific to the acceleration API. The application
     * reads the structure and can change some fields to indicate progress
     * or mark state.
     * - encoding: unused
     * - decoding: Set by user.
     * @param height the height of the slice
     * @param y the y position of the slice
     * @param type 1->top field, 2->bottom field, 3->frame
     * @param offset offset into the AVFrame.data from which the slice should be read
     */
    void (*draw_horiz_band)(struct AVCodecContext *s,
                            const AVFrame *src, int offset[4],
                            int y, int type, int height);

    /* 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. */
    /**
     * Samples per packet, initialized when calling 'init'.
     */
    int frame_size;
    int frame_number;   ///< audio or video frame number

    /**
     * Encoding: Number of frames delay there will be from the encoder input to
     *           the decoder output. (we assume the decoder matches the spec)
     * Decoding: Number of frames delay in addition to what a standard decoder
     *           as specified in the spec would produce.
     * - encoding: Set by libavcodec.
     * - decoding: Set by libavcodec.
     */
    int delay;

    /* - 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;

    /**
     * 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;

    struct AVCodec *codec;

    void *priv_data;

    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.  */


    /* 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);

    /* 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;

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

    char codec_name[32];
    enum AVMediaType codec_type; /* see AVMEDIA_TYPE_xxx */
    enum CodecID codec_id; /* see 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;

    /**
     * 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
//#define FF_BUG_FAKE_SCALABILITY 16 //Autodetection should work 100%.

    /**
     * luma single coefficient elimination threshold
     * - encoding: Set by user.
     * - decoding: unused
     */
    int luma_elim_threshold;

    /**
     * chroma single coeff elimination threshold
     * - encoding: Set by user.
     * - decoding: unused
     */
    int chroma_elim_threshold;

    /**
     * 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.

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

#if FF_API_ER
    /**
     * Error recognition; higher values will detect more errors but may
     * misdetect some more or less valid parts as errors.
     * - encoding: unused
     * - decoding: Set by user.
     */
    attribute_deprecated int error_recognition;
#define FF_ER_CAREFUL         1
#define FF_ER_COMPLIANT       2
#define FF_ER_AGGRESSIVE      3
#define FF_ER_VERY_AGGRESSIVE 4
#define FF_ER_EXPLODE         5
#endif /* FF_API_ER */

    /**
     * Called at the beginning of each frame to get a buffer for it.
     * 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 CODEC_CAP_DR1 is not set then get_buffer() must call
     * avcodec_default_get_buffer() instead of providing buffers allocated by
     * some other means.
     * 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.
     * - encoding: unused
     * - decoding: Set by libavcodec, user can override.
     */
    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.
     */
    void (*release_buffer)(struct AVCodecContext *c, AVFrame *pic);

    /**
     * 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;

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

#if FF_API_PARSE_FRAME
    /**
     * If true, only parsing is done. The frame data is returned.
     * Only MPEG audio decoders support this now.
     * - encoding: unused
     * - decoding: Set by user
     */
    attribute_deprecated int parse_only;
#endif

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

    /**
     * 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;

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

    float rc_qmod_amp;
    int rc_qmod_freq;

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

    /**
     * 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;

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

    /**
     * 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;

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

    /**
     * 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_MLIB    4
#define FF_DCT_ALTIVEC 5
#define FF_DCT_FAAN    6

    /**
     * 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;

    /**
     * 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_LIBMPEG2MMX   4
#define FF_IDCT_PS2           5
#define FF_IDCT_MLIB          6
#define FF_IDCT_ARM           7
#define FF_IDCT_ALTIVEC       8
#define FF_IDCT_SH4           9
#define FF_IDCT_SIMPLEARM     10
#define FF_IDCT_H264          11
#define FF_IDCT_VP3           12
#define FF_IDCT_IPP           13
#define FF_IDCT_XVIDMMX       14
#define FF_IDCT_CAVS          15
#define FF_IDCT_SIMPLEARMV5TE 16
#define FF_IDCT_SIMPLEARMV6   17
#define FF_IDCT_SIMPLEVIS     18
#define FF_IDCT_WMV2          19
#define FF_IDCT_FAAN          20
#define FF_IDCT_EA            21
#define FF_IDCT_SIMPLENEON    22
#define FF_IDCT_SIMPLEALPHA   23
#define FF_IDCT_BINK          24

    /**
     * slice count
     * - encoding: Set by libavcodec.
     * - decoding: Set by user (or 0).
     */
    int slice_count;
    /**
     * slice offsets in the frame in bytes
     * - encoding: Set/allocated by libavcodec.
     * - decoding: Set/allocated by user (or NULL).
     */
    int *slice_offset;

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

    /**
     * dsp_mask could be add used to disable unwanted CPU features
     * CPU features (i.e. MMX, SSE. ...)
     *
     * With the FORCE flag you may instead enable given CPU features.
     * (Dangerous: Usable in case of misdetection, improper usage however will
     * result into program crash.)
     */
    unsigned dsp_mask;

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

    /**
     * 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

    /**
     * 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;

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

    /**
     * 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
     * - encoding: Set by libavcodec if flags&CODEC_FLAG_PSNR.
     * - decoding: unused
     */
    uint64_t error[4];

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

    /**
     * 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 PixelFormat (*get_format)(struct AVCodecContext *s, const enum PixelFormat * fmt);

    /**
     * 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;

    /**
     * color table ID
     * - encoding: unused
     * - decoding: Which clrtable should be used for 8bit RGB images.
     *             Tables have to be stored somewhere. FIXME
     */
    int color_table_id;

#if FF_API_INTERNAL_CONTEXT
    /**
     * internal_buffer count
     * Don't touch, used by libavcodec default_get_buffer().
     * @deprecated this field was moved to an internal context
     */
    attribute_deprecated int internal_buffer_count;

    /**
     * internal_buffers
     * Don't touch, used by libavcodec default_get_buffer().
     * @deprecated this field was moved to an internal context
     */
    attribute_deprecated void *internal_buffer;
#endif

    /**
     * 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;

#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;
#if 0
    /**
     *
     * - encoding: unused
     * - decoding: Set by user.
     */
    uint8_t * (*realloc)(struct AVCodecContext *s, uint8_t *buf, int buf_size);
#endif

    /**
     * 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;

    /**
     * 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;

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

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

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

#if FF_API_PALETTE_CONTROL
    /**
     * palette control structure
     * - encoding: ??? (no palette-enabled encoder yet)
     * - decoding: Set by user.
     */
    struct AVPaletteControl *palctrl;
#endif

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

    /**
     * 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.
     */
    int (*reget_buffer)(struct AVCodecContext *c, AVFrame *pic);

    /**
     * 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;

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

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

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

#if FF_API_ANTIALIAS_ALGO
    /**
     * MP3 antialias algorithm, see FF_AA_* below.
     * - encoding: unused
     * - decoding: Set by user.
     */
    attribute_deprecated int antialias_algo;
#define FF_AA_AUTO    0
#define FF_AA_FASTINT 1 //not implemented yet
#define FF_AA_INT     2
#define FF_AA_FLOAT   3
#endif

    /**
     * quantizer noise shaping
     * - encoding: Set by user.
     * - decoding: unused
     */
    int quantizer_noise_shaping;

    /**
     * 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;

    /**
     * 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);

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

    /**
     * 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;

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

    /**
     * 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;

    /**
     * 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_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

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

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

    /**
     * Bitstream width / height, may be different from width/height if lowres enabled.
     * - encoding: unused
     * - decoding: Set by user before init if known. Codec should override / dynamically change if needed.
     */
    int coded_width, coded_height;

    /**
     * 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;

    /**
     * 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: 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;

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

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

#if FF_API_X264_GLOBAL_OPTS
    /**
     * constant rate factor - quality-based VBR - values ~correspond to qps
     * - encoding: Set by user.
     * - decoding: unused
     *   @deprecated use 'crf' libx264 private option
     */
    attribute_deprecated float crf;

    /**
     * constant quantization parameter rate control method
     * - encoding: Set by user.
     * - decoding: unused
     *   @deprecated use 'cqp' libx264 private option
     */
    attribute_deprecated int cqp;
#endif

    /**
     * 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;

#if FF_API_X264_GLOBAL_OPTS
    /**
     * Influences how often B-frames are used.
     * - encoding: Set by user.
     * - decoding: unused
     */
    attribute_deprecated int bframebias;
#endif

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

#if FF_API_X264_GLOBAL_OPTS
    /**
     * Reduce fluctuations in qp (before curve compression).
     * - encoding: Set by user.
     * - decoding: unused
     */
    attribute_deprecated float complexityblur;

    /**
     * in-loop deblocking filter alphac0 parameter
     * alpha is in the range -6...6
     * - encoding: Set by user.
     * - decoding: unused
     */
    attribute_deprecated int deblockalpha;

    /**
     * in-loop deblocking filter beta parameter
     * beta is in the range -6...6
     * - encoding: Set by user.
     * - decoding: unused
     */
    attribute_deprecated int deblockbeta;

    /**
     * macroblock subpartition sizes to consider - p8x8, p4x4, b8x8, i8x8, i4x4
     * - encoding: Set by user.
     * - decoding: unused
     */
    attribute_deprecated int partitions;
#define X264_PART_I4X4 0x001  /* Analyze i4x4 */
#define X264_PART_I8X8 0x002  /* Analyze i8x8 (requires 8x8 transform) */
#define X264_PART_P8X8 0x010  /* Analyze p16x8, p8x16 and p8x8 */
#define X264_PART_P4X4 0x020  /* Analyze p8x4, p4x8, p4x4 */
#define X264_PART_B8X8 0x100  /* Analyze b16x8, b8x16 and b8x8 */

    /**
     * direct MV prediction mode - 0 (none), 1 (spatial), 2 (temporal), 3 (auto)
     * - encoding: Set by user.
     * - decoding: unused
     */
    attribute_deprecated int directpred;
#endif

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

    /**
     * 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;

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

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

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

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

#if FF_API_FLAC_GLOBAL_OPTS
    /**
     * @name FLAC options
     * @deprecated Use FLAC encoder private options instead.
     * @{
     */

    /**
     * LPC coefficient precision - used by FLAC encoder
     * - encoding: Set by user.
     * - decoding: unused
     */
    attribute_deprecated int lpc_coeff_precision;

    /**
     * search method for selecting prediction order
     * - encoding: Set by user.
     * - decoding: unused
     */
    attribute_deprecated int prediction_order_method;

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

    /**
     * - encoding: Set by user.
     * - decoding: unused
     */
    attribute_deprecated int max_partition_order;
    /**
     * @}
     */
#endif

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

#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

#if FF_API_DRC_SCALE
    /**
     * Percentage of dynamic range compression to be applied by the decoder.
     * The default value is 1.0, corresponding to full compression.
     * - encoding: unused
     * - decoding: Set by user.
     * @deprecated use AC3 decoder private option instead.
     */
    attribute_deprecated float drc_scale;
#endif

    /**
     * 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;

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

    /**
     * Audio channel layout.
     * - encoding: set by user.
     * - decoding: set by user, may be overwritten by libavcodec.
     */
    int64_t channel_layout;

    /**
     * Request decoder to use this channel layout if it can (0 for default)
     * - encoding: unused
     * - decoding: Set by user.
     */
    int64_t request_channel_layout;

    /**
     * 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;

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

    /**
     * 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;

    /**
     * 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 FFmpeg cannot instantiate itself. Please refer to the
     * FFmpeg 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;

    /**
     * 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;

    /**
     * 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);

#if FF_API_X264_GLOBAL_OPTS
    /**
     * explicit P-frame weighted prediction analysis method
     * 0: off
     * 1: fast blind weighting (one reference duplicate with -1 offset)
     * 2: smart weighting (full fade detection analysis)
     * - encoding: Set by user.
     * - decoding: unused
     */
    attribute_deprecated int weighted_p_pred;

    /**
     * AQ mode
     * 0: Disabled
     * 1: Variance AQ (complexity mask)
     * 2: Auto-variance AQ (experimental)
     * - encoding: Set by user
     * - decoding: unused
     */
    attribute_deprecated int aq_mode;

    /**
     * AQ strength
     * Reduces blocking and blurring in flat and textured areas.
     * - encoding: Set by user
     * - decoding: unused
     */
    attribute_deprecated float aq_strength;

    /**
     * PSY RD
     * Strength of psychovisual optimization
     * - encoding: Set by user
     * - decoding: unused
     */
    attribute_deprecated float psy_rd;

    /**
     * PSY trellis
     * Strength of psychovisual optimization
     * - encoding: Set by user
     * - decoding: unused
     */
    attribute_deprecated float psy_trellis;

    /**
     * RC lookahead
     * Number of frames for frametype and ratecontrol lookahead
     * - encoding: Set by user
     * - decoding: unused
     */
    attribute_deprecated int rc_lookahead;

    /**
     * Constant rate factor maximum
     * With CRF encoding mode and VBV restrictions enabled, prevents quality from being worse
     * than crf_max, even if doing so would violate VBV restrictions.
     * - encoding: Set by user.
     * - decoding: unused
     */
    attribute_deprecated float crf_max;
#endif

    int log_level_offset;

#if FF_API_FLAC_GLOBAL_OPTS
    /**
     * Determines which LPC analysis algorithm to use.
     * - encoding: Set by user
     * - decoding: unused
     */
    attribute_deprecated enum AVLPCType lpc_type;

    /**
     * Number of passes to use for Cholesky factorization during LPC analysis
     * - encoding: Set by user
     * - decoding: unused
     */
    attribute_deprecated int lpc_passes;
#endif

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

    /**
     * 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_open())
     * - decoding: Set/allocated/freed by libavcodec (by avcodec_open())
     */
    uint8_t *subtitle_header;
    int subtitle_header_size;

    /**
     * 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;

#if FF_API_INTERNAL_CONTEXT
    /**
     * Whether this is a copy of the context which had init() called on it.
     * This is used by multithreading - shared tables and picture pointers
     * should be freed from the original context only.
     * - encoding: Set by libavcodec.
     * - decoding: Set by libavcodec.
     *
     * @deprecated this field has been moved to an internal context
     */
    attribute_deprecated int is_copy;
#endif

    /**
     * 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
     * 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;

    /**
     * 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;

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

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

    /**
     * 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)

#define AV_EF_CAREFUL    (1<<16)
#define AV_EF_COMPLIANT  (1<<17)
#define AV_EF_AGGRESSIVE (1<<18)

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

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

} AVCodecContext;

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

typedef struct AVCodecDefault AVCodecDefault;

/**
 * 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;
    enum AVMediaType type;
    enum CodecID id;
    int priv_data_size;
    int (*init)(AVCodecContext *);
    int (*encode)(AVCodecContext *, uint8_t *buf, int buf_size, void *data);
    int (*close)(AVCodecContext *);
    int (*decode)(AVCodecContext *, void *outdata, int *outdata_size, AVPacket *avpkt);
    /**
     * Codec capabilities.
     * see CODEC_CAP_*
     */
    int capabilities;
    struct AVCodec *next;
    /**
     * Flush buffers.
     * Will be called when seeking
     */
    void (*flush)(AVCodecContext *);
    const AVRational *supported_framerates; ///< array of supported framerates, or NULL if any, array is terminated by {0,0}
    const enum PixelFormat *pix_fmts;       ///< array of supported pixel formats, or NULL if unknown, array is terminated by -1
    /**
     * 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;
    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 int64_t *channel_layouts;         ///< array of support channel layouts, or NULL if unknown. array is terminated by 0
    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}

    /**
     * @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);
} 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 CODEC_ID_xxx
     */
    enum CodecID id;

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

/**
 * four components are given, that's all.
 * the last component is alpha
 */
typedef struct AVPicture {
    uint8_t *data[4];
    int linesize[4];       ///< number of bytes per line
} AVPicture;

#define AVPALETTE_SIZE 1024
#define AVPALETTE_COUNT 256
#if FF_API_PALETTE_CONTROL
/**
 * AVPaletteControl
 * This structure defines a method for communicating palette changes
 * between and demuxer and a decoder.
 *
 * @deprecated Use AVPacket to send palette changes instead.
 * This is totally broken.
 */
typedef struct AVPaletteControl {

    /* Demuxer sets this to 1 to indicate the palette has changed;
     * decoder resets to 0. */
    int palette_changed;

    /* 4-byte ARGB palette entries, stored in native byte order; note that
     * the individual palette components should be on a 8-bit scale; if
     * the palette data comes from an IBM VGA native format, the component
     * data is probably 6 bits in size and needs to be scaled. */
    unsigned int palette[AVPALETTE_COUNT];

} AVPaletteControl attribute_deprecated;
#endif

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,
};

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;
} 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;

/* packet functions */

/**
 * @deprecated use NULL instead
 */
attribute_deprecated void av_destruct_packet_nofree(AVPacket *pkt);

/**
 * Default packet destructor.
 */
void av_destruct_packet(AVPacket *pkt);

/**
 * Initialize optional fields of a packet with default values.
 *
 * @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);

/**
 * @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);

/**
 * 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);

int av_packet_merge_side_data(AVPacket *pkt);

int av_packet_split_side_data(AVPacket *pkt);


/* resample.c */

struct ReSampleContext;
struct AVResampleContext;

typedef struct ReSampleContext ReSampleContext;

/**
 *  Initialize audio resampling context.
 *
 * @param output_channels  number of output channels
 * @param input_channels   number of input channels
 * @param output_rate      output sample rate
 * @param input_rate       input sample rate
 * @param sample_fmt_out   requested output sample format
 * @param sample_fmt_in    input sample format
 * @param filter_length    length of each FIR filter in the filterbank relative to the cutoff frequency
 * @param log2_phase_count log2 of the number of entries in the polyphase filterbank
 * @param linear           if 1 then the used FIR filter will be linearly interpolated
                           between the 2 closest, if 0 the closest will be used
 * @param cutoff           cutoff frequency, 1.0 corresponds to half the output sampling rate
 * @return allocated ReSampleContext, NULL if error occured
 */
ReSampleContext *av_audio_resample_init(int output_channels, int input_channels,
                                        int output_rate, int input_rate,
                                        enum AVSampleFormat sample_fmt_out,
                                        enum AVSampleFormat sample_fmt_in,
                                        int filter_length, int log2_phase_count,
                                        int linear, double cutoff);

int audio_resample(ReSampleContext *s, short *output, short *input, int nb_samples);

/**
 * Free resample context.
 *
 * @param s a non-NULL pointer to a resample context previously
 *          created with av_audio_resample_init()
 */
void audio_resample_close(ReSampleContext *s);


/**
 * Initialize an audio resampler.
 * Note, if either rate is not an integer then simply scale both rates up so they are.
 * @param filter_length length of each FIR filter in the filterbank relative to the cutoff freq
 * @param log2_phase_count log2 of the number of entries in the polyphase filterbank
 * @param linear If 1 then the used FIR filter will be linearly interpolated
                 between the 2 closest, if 0 the closest will be used
 * @param cutoff cutoff frequency, 1.0 corresponds to half the output sampling rate
 */
struct AVResampleContext *av_resample_init(int out_rate, int in_rate, int filter_length, int log2_phase_count, int linear, double cutoff);

/**
 * Resample an array of samples using a previously configured context.
 * @param src an array of unconsumed samples
 * @param consumed the number of samples of src which have been consumed are returned here
 * @param src_size the number of unconsumed samples available
 * @param dst_size the amount of space in samples available in dst
 * @param update_ctx If this is 0 then the context will not be modified, that way several channels can be resampled with the same context.
 * @return the number of samples written in dst or -1 if an error occurred
 */
int av_resample(struct AVResampleContext *c, short *dst, short *src, int *consumed, int src_size, int dst_size, int update_ctx);


/**
 * Compensate samplerate/timestamp drift. The compensation is done by changing
 * the resampler parameters, so no audible clicks or similar distortions occur
 * @param compensation_distance distance in output samples over which the compensation should be performed
 * @param sample_delta number of output samples which should be output less
 *
 * example: av_resample_compensate(c, 10, 500)
 * here instead of 510 samples only 500 samples would be output
 *
 * note, due to rounding the actual compensation might be slightly different,
 * especially if the compensation_distance is large and the in_rate used during init is small
 */
void av_resample_compensate(struct AVResampleContext *c, int sample_delta, int compensation_distance);
void av_resample_close(struct AVResampleContext *c);

/**
 * Allocate memory for a picture.  Call avpicture_free() to free it.
 *
 * @see avpicture_fill()
 *
 * @param picture the picture to be filled in
 * @param pix_fmt the format of the picture
 * @param width the width of the picture
 * @param height the height of the picture
 * @return zero if successful, a negative value if not
 */
int avpicture_alloc(AVPicture *picture, enum PixelFormat pix_fmt, int width, int height);

/**
 * Free a picture previously allocated by avpicture_alloc().
 * The data buffer used by the AVPicture is freed, but the AVPicture structure
 * itself is not.
 *
 * @param picture the AVPicture to be freed
 */
void avpicture_free(AVPicture *picture);

/**
 * Fill in the AVPicture fields.
 * The fields of the given AVPicture are filled in by using the 'ptr' address
 * which points to the image data buffer. Depending on the specified picture
 * format, one or multiple image data pointers and line sizes will be set.
 * If a planar format is specified, several pointers will be set pointing to
 * the different picture planes and the line sizes of the different planes
 * will be stored in the lines_sizes array.
 * Call with ptr == NULL to get the required size for the ptr buffer.
 *
 * To allocate the buffer and fill in the AVPicture fields in one call,
 * use avpicture_alloc().
 *
 * @param picture AVPicture whose fields are to be filled in
 * @param ptr Buffer which will contain or contains the actual image data
 * @param pix_fmt The format in which the picture data is stored.
 * @param width the width of the image in pixels
 * @param height the height of the image in pixels
 * @return size of the image data in bytes
 */
int avpicture_fill(AVPicture *picture, uint8_t *ptr,
                   enum PixelFormat pix_fmt, int width, int height);

/**
 * Copy pixel data from an AVPicture into a buffer.
 * The data is stored compactly, without any gaps for alignment or padding
 * which may be applied by avpicture_fill().
 *
 * @see avpicture_get_size()
 *
 * @param[in] src AVPicture containing image data
 * @param[in] pix_fmt The format in which the picture data is stored.
 * @param[in] width the width of the image in pixels.
 * @param[in] height the height of the image in pixels.
 * @param[out] dest A buffer into which picture data will be copied.
 * @param[in] dest_size The size of 'dest'.
 * @return The number of bytes written to dest, or a negative value (error code) on error.
 */
int avpicture_layout(const AVPicture* src, enum PixelFormat pix_fmt, int width, int height,
                     unsigned char *dest, int dest_size);

/**
 * Calculate the size in bytes that a picture of the given width and height
 * would occupy if stored in the given picture format.
 * Note that this returns the size of a compact representation as generated
 * by avpicture_layout(), which can be smaller than the size required for e.g.
 * avpicture_fill().
 *
 * @param pix_fmt the given picture format
 * @param width the width of the image
 * @param height the height of the image
 * @return Image data size in bytes or -1 on error (e.g. too large dimensions).
 */
int avpicture_get_size(enum PixelFormat pix_fmt, int width, int height);
void avcodec_get_chroma_sub_sample(enum PixelFormat pix_fmt, int *h_shift, int *v_shift);

/**
 * Get the name of a codec.
 * @return  a static string identifying the codec; never NULL
 */
const char *avcodec_get_name(enum CodecID id);

#if FF_API_GET_PIX_FMT_NAME
/**
 * Return the short name for a pixel format.
 *
 * \see av_get_pix_fmt(), av_get_pix_fmt_string().
 * @deprecated Deprecated in favor of av_get_pix_fmt_name().
 */
attribute_deprecated
const char *avcodec_get_pix_fmt_name(enum PixelFormat pix_fmt);
#endif

void avcodec_set_dimensions(AVCodecContext *s, int width, int height);

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

/**
 * Put a string representing the codec tag codec_tag in buf.
 *
 * @param buf_size size in bytes of buf
 * @return the length of the string that would have been generated if
 * enough space had been available, excluding the trailing null
 */
size_t av_get_codec_tag_string(char *buf, size_t buf_size, unsigned int codec_tag);

#define FF_LOSS_RESOLUTION  0x0001 /**< loss due to resolution change */
#define FF_LOSS_DEPTH       0x0002 /**< loss due to color depth change */
#define FF_LOSS_COLORSPACE  0x0004 /**< loss due to color space conversion */
#define FF_LOSS_ALPHA       0x0008 /**< loss of alpha bits */
#define FF_LOSS_COLORQUANT  0x0010 /**< loss due to color quantization */
#define FF_LOSS_CHROMA      0x0020 /**< loss of chroma (e.g. RGB to gray conversion) */

/**
 * Compute what kind of losses will occur when converting from one specific
 * pixel format to another.
 * When converting from one pixel format to another, information loss may occur.
 * For example, when converting from RGB24 to GRAY, the color information will
 * be lost. Similarly, other losses occur when converting from some formats to
 * other formats. These losses can involve loss of chroma, but also loss of
 * resolution, loss of color depth, loss due to the color space conversion, loss
 * of the alpha bits or loss due to color quantization.
 * avcodec_get_fix_fmt_loss() informs you about the various types of losses
 * which will occur when converting from one pixel format to another.
 *
 * @param[in] dst_pix_fmt destination pixel format
 * @param[in] src_pix_fmt source pixel format
 * @param[in] has_alpha Whether the source pixel format alpha channel is used.
 * @return Combination of flags informing you what kind of losses will occur
 * (maximum loss for an invalid dst_pix_fmt).
 */
int avcodec_get_pix_fmt_loss(enum PixelFormat dst_pix_fmt, enum PixelFormat src_pix_fmt,
                             int has_alpha);

/**
 * Find the best pixel format to convert to given a certain source pixel
 * format.  When converting from one pixel format to another, information loss
 * may occur.  For example, when converting from RGB24 to GRAY, the color
 * information will be lost. Similarly, other losses occur when converting from
 * some formats to other formats. avcodec_find_best_pix_fmt() searches which of
 * the given pixel formats should be used to suffer the least amount of loss.
 * The pixel formats from which it chooses one, are determined by the
 * pix_fmt_mask parameter.
 *
 * Note, only the first 64 pixel formats will fit in pix_fmt_mask.
 *
 * @code
 * src_pix_fmt = PIX_FMT_YUV420P;
 * pix_fmt_mask = (1 << PIX_FMT_YUV422P) | (1 << PIX_FMT_RGB24);
 * dst_pix_fmt = avcodec_find_best_pix_fmt(pix_fmt_mask, src_pix_fmt, alpha, &loss);
 * @endcode
 *
 * @param[in] pix_fmt_mask bitmask determining which pixel format to choose from
 * @param[in] src_pix_fmt source pixel format
 * @param[in] has_alpha Whether the source pixel format alpha channel is used.
 * @param[out] loss_ptr Combination of flags informing you what kind of losses will occur.
 * @return The best pixel format to convert to or -1 if none was found.
 */
enum PixelFormat avcodec_find_best_pix_fmt(int64_t pix_fmt_mask, enum PixelFormat src_pix_fmt,
                              int has_alpha, int *loss_ptr);

/**
 * Find the best pixel format to convert to given a certain source pixel
 * format and a selection of two destination pixel formats. When converting from
 * one pixel format to another, information loss may occur.  For example, when converting
 * from RGB24 to GRAY, the color information will be lost. Similarly, other losses occur when
 * converting from some formats to other formats. avcodec_find_best_pix_fmt2() selects which of
 * the given pixel formats should be used to suffer the least amount of loss.
 *
 * If one of the destination formats is PIX_FMT_NONE the other pixel format (if valid) will be
 * returned.
 *
 * @code
 * src_pix_fmt = PIX_FMT_YUV420P;
 * dst_pix_fmt1= PIX_FMT_RGB24;
 * dst_pix_fmt2= PIX_FMT_GRAY8;
 * dst_pix_fmt3= PIX_FMT_RGB8;
 * loss= FF_LOSS_CHROMA; // don't care about chroma loss, so chroma loss will be ignored.
 * dst_pix_fmt = avcodec_find_best_pix_fmt2(dst_pix_fmt1, dst_pix_fmt2, src_pix_fmt, alpha, &loss);
 * dst_pix_fmt = avcodec_find_best_pix_fmt2(dst_pix_fmt, dst_pix_fmt3, src_pix_fmt, alpha, &loss);
 * @endcode
 *
 * @param[in] dst_pix_fmt1 One of the two destination pixel formats to choose from
 * @param[in] dst_pix_fmt2 The other of the two destination pixel formats to choose from
 * @param[in] src_pix_fmt Source pixel format
 * @param[in] has_alpha Whether the source pixel format alpha channel is used.
 * @param[in, out] loss_ptr Combination of loss flags. In: selects which of the losses to ignore, i.e.
 *                               NULL or value of zero means we care about all losses. Out: the loss
 *                               that occurs when converting from src to selected dst pixel format.
 * @return The best pixel format to convert to or -1 if none was found.
 */
enum PixelFormat avcodec_find_best_pix_fmt2(enum PixelFormat dst_pix_fmt1, enum PixelFormat dst_pix_fmt2,
                                            enum PixelFormat src_pix_fmt, int has_alpha, int *loss_ptr);

#if FF_API_GET_ALPHA_INFO
#define FF_ALPHA_TRANSP       0x0001 /* image has some totally transparent pixels */
#define FF_ALPHA_SEMI_TRANSP  0x0002 /* image has some transparent pixels */

/**
 * Tell if an image really has transparent alpha values.
 * @return ored mask of FF_ALPHA_xxx constants
 */
attribute_deprecated
int img_get_alpha_info(const AVPicture *src,
                       enum PixelFormat pix_fmt, int width, int height);
#endif

/* deinterlace a picture */
/* deinterlace - if not supported return -1 */
int avpicture_deinterlace(AVPicture *dst, const AVPicture *src,
                          enum PixelFormat pix_fmt, int width, int height);

/* external high level API */

/**
 * 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(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);

#if FF_API_AVCODEC_INIT
/**
 * @deprecated this function is called automatically from avcodec_register()
 * and avcodec_register_all(), there is no need to call it manually
 */
attribute_deprecated
void avcodec_init(void);
#endif

/**
 * 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);

/**
 * Find a registered encoder with a matching codec ID.
 *
 * @param id CodecID of the requested encoder
 * @return An encoder if one was found, NULL otherwise.
 */
AVCodec *avcodec_find_encoder(enum CodecID id);

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

/**
 * Find a registered decoder with a matching codec ID.
 *
 * @param id CodecID of the requested decoder
 * @return A decoder if one was found, NULL otherwise.
 */
AVCodec *avcodec_find_decoder(enum CodecID 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);
void avcodec_string(char *buf, int buf_size, AVCodecContext *enc, int encode);

/**
 * Return a name for the specified profile, if available.
 *
 * @param codec the codec that is searched for the given profile
 * @param profile the profile value for which a name is requested
 * @return A name for the profile if found, NULL otherwise.
 */
const char *av_get_profile_name(const AVCodec *codec, int profile);

#if FF_API_ALLOC_CONTEXT
/**
 * Set the fields of the given AVCodecContext to default values.
 *
 * @param s The AVCodecContext of which the fields should be set to default values.
 * @deprecated use avcodec_get_context_defaults3
 */
attribute_deprecated
void avcodec_get_context_defaults(AVCodecContext *s);

/** THIS FUNCTION IS NOT YET PART OF THE PUBLIC API!
 *  we WILL change its arguments and name a few times! */
attribute_deprecated
void avcodec_get_context_defaults2(AVCodecContext *s, enum AVMediaType);
#endif

/**
 * 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, AVCodec *codec);

#if FF_API_ALLOC_CONTEXT
/**
 * Allocate an AVCodecContext and set its fields to default values.  The
 * resulting struct can be deallocated by simply calling av_free().
 *
 * @return An AVCodecContext filled with default values or NULL on failure.
 * @see avcodec_get_context_defaults
 *
 * @deprecated use avcodec_alloc_context3()
 */
attribute_deprecated
AVCodecContext *avcodec_alloc_context(void);

/** THIS FUNCTION IS NOT YET PART OF THE PUBLIC API!
 *  we WILL change its arguments and name a few times! */
attribute_deprecated
AVCodecContext *avcodec_alloc_context2(enum AVMediaType);
#endif

/**
 * Allocate an AVCodecContext and set its fields to default values.  The
 * resulting struct can be deallocated by simply calling av_free().
 *
 * @param codec if non-NULL, allocate private data and initialize defaults
 *              for the given codec. It is illegal to then call avcodec_open()
 *              with a different codec.
 *
 * @return An AVCodecContext filled with default values or NULL on failure.
 * @see avcodec_get_context_defaults
 */
AVCodecContext *avcodec_alloc_context3(AVCodec *codec);

/**
 * 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_open() 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);

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

/**
 * Allocate an AVFrame and set its fields to default values.  The resulting
 * struct can be deallocated by simply calling av_free().
 *
 * @return An AVFrame filled with default values or NULL on failure.
 * @see avcodec_get_frame_defaults
 */
AVFrame *avcodec_alloc_frame(void);

int avcodec_default_get_buffer(AVCodecContext *s, AVFrame *pic);
void avcodec_default_release_buffer(AVCodecContext *s, AVFrame *pic);
int avcodec_default_reget_buffer(AVCodecContext *s, AVFrame *pic);

/**
 * 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[4]);

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

#if FF_API_THREAD_INIT
/**
 * @deprecated Set s->thread_count before calling avcodec_open() instead of calling this.
 */
attribute_deprecated
int avcodec_thread_init(AVCodecContext *s, int thread_count);
#endif

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

#if FF_API_AVCODEC_OPEN
/**
 * Initialize the AVCodecContext to use the given AVCodec. Prior to using this
 * function the context has to be allocated.
 *
 * 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();
 * codec = avcodec_find_decoder(CODEC_ID_H264);
 * if (!codec)
 *     exit(1);
 *
 * context = avcodec_alloc_context3(codec);
 *
 * if (avcodec_open(context, codec) < 0)
 *     exit(1);
 * @endcode
 *
 * @param avctx The context which will be set up to use the given codec.
 * @param codec The codec to use within the context.
 * @return zero on success, a negative value on error
 * @see avcodec_alloc_context3, avcodec_find_decoder, avcodec_find_encoder, avcodec_close
 *
 * @deprecated use avcodec_open2
 */
attribute_deprecated
int avcodec_open(AVCodecContext *avctx, AVCodec *codec);
#endif

/**
 * Initialize the AVCodecContext to use the given AVCodec. Prior to using this
 * function the context has to be allocated with avcodec_alloc_context().
 *
 * 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(CODEC_ID_H264);
 * if (!codec)
 *     exit(1);
 *
 * context = avcodec_alloc_context();
 *
 * if (avcodec_open(context, codec, opts) < 0)
 *     exit(1);
 * @endcode
 *
 * @param avctx The context to initialize.
 * @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, AVCodec *codec, AVDictionary **options);

/**
 * Decode the audio frame of size avpkt->size from avpkt->data into samples.
 * Some decoders may support multiple frames in a single AVPacket, such
 * decoders would then just decode the first frame. In this case,
 * avcodec_decode_audio3 has to be called again with an AVPacket that contains
 * the remaining data in order to decode the second frame etc.
 * If no frame
 * could be outputted, frame_size_ptr is zero. Otherwise, it is the
 * decompressed frame size in bytes.
 *
 * @warning You must set frame_size_ptr to the allocated size of the
 * output buffer before calling avcodec_decode_audio3().
 *
 * @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 avpkt->data 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 and output buffer
 * samples. 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 and
 * samples should be 16 byte aligned unless the CPU doesn't need it
 * (AltiVec and SSE do).
 *
 * @note Codecs which have the CODEC_CAP_DELAY capability set have a delay
 * between input and output, these need to be fed with avpkt->data=NULL,
 * avpkt->size=0 at the end to return the remaining frames.
 *
 * @param avctx the codec context
 * @param[out] samples the output buffer, sample type in avctx->sample_fmt
 * @param[in,out] frame_size_ptr the output buffer size in bytes
 * @param[in] avpkt The input AVPacket containing the input buffer.
 *            You can create such packet with av_init_packet() and by then setting
 *            data and size, some decoders might in addition need other fields.
 *            All decoders are designed to use the least fields possible though.
 * @return On error a negative value is returned, otherwise the number of bytes
 * used or zero if no frame data was decompressed (used) from the input AVPacket.
 */
int avcodec_decode_audio3(AVCodecContext *avctx, int16_t *samples,
                         int *frame_size_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
 * between input and output, these need to be fed with avpkt->data=NULL,
 * avpkt->size=0 at the end to return the remaining frames.
 *
 * @param avctx the codec context
 * @param[out] picture The AVFrame in which the decoded video frame will be stored.
 *             Use avcodec_alloc_frame to get an AVFrame, the codec will
 *             allocate memory for the actual bitmap.
 *             with default get/release_buffer(), the decoder frees/reuses the bitmap as it sees fit.
 *             with overridden get/release_buffer() (needs CODEC_CAP_DR1) the user decides into what buffer the decoder
 *                   decodes and the decoder tells the user once it does not need the data anymore,
 *                   the user app can at this point free/reuse/keep the memory as it sees fit.
 *
 * @param[in] avpkt The input AVpacket containing the input buffer.
 *            You can create such packet with av_init_packet() and by then setting
 *            data and size, some decoders might in addition need other fields like
 *            flags&AV_PKT_FLAG_KEY. All decoders are designed to use the least
 *            fields possible.
 * @param[in,out] got_picture_ptr Zero if no frame could be decompressed, otherwise, it is nonzero.
 * @return On error a negative value is returned, otherwise the number of bytes
 * used or zero if no frame could be decompressed.
 */
int avcodec_decode_video2(AVCodecContext *avctx, AVFrame *picture,
                         int *got_picture_ptr,
                         AVPacket *avpkt);

/**
 * Decode a subtitle message.
 * Return a negative value on error, otherwise return the number of bytes used.
 * If no subtitle could be decompressed, got_sub_ptr is zero.
 * Otherwise, the subtitle is stored in *sub.
 * Note that CODEC_CAP_DR1 is not available for subtitle codecs. This is for
 * simplicity, because the performance difference is expect to be negligible
 * and reusing a get_buffer written for video codecs would probably perform badly
 * due to a potentially very different allocation pattern.
 *
 * @param avctx the codec context
 * @param[out] sub The AVSubtitle in which the decoded subtitle will be stored, must be
                   freed with avsubtitle_free if *got_sub_ptr is set.
 * @param[in,out] got_sub_ptr Zero if no subtitle could be decompressed, otherwise, it is nonzero.
 * @param[in] avpkt The input AVPacket containing the input buffer.
 */
int avcodec_decode_subtitle2(AVCodecContext *avctx, AVSubtitle *sub,
                            int *got_sub_ptr,
                            AVPacket *avpkt);

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

/**
 * Encode an audio frame from samples into buf.
 *
 * @note The output buffer should be at least FF_MIN_BUFFER_SIZE bytes large.
 * However, for PCM audio the user will know how much space is needed
 * because it depends on the value passed in buf_size as described
 * below. In that case a lower value can be used.
 *
 * @param avctx the codec context
 * @param[out] buf the output buffer
 * @param[in] buf_size the output buffer size
 * @param[in] samples the input buffer containing the samples
 * The number of samples read from this buffer is frame_size*channels,
 * both of which are defined in avctx.
 * For PCM audio the number of samples read from samples is equal to
 * buf_size * input_sample_size / output_sample_size.
 * @return On error a negative value is returned, on success zero or the number
 * of bytes used to encode the data read from the input buffer.
 */
int avcodec_encode_audio(AVCodecContext *avctx, uint8_t *buf, int buf_size,
                         const short *samples);

/**
 * Encode a video frame from pict into buf.
 * The input picture should be
 * stored using a specific format, namely avctx.pix_fmt.
 *
 * @param avctx the codec context
 * @param[out] buf the output buffer for the bitstream of encoded frame
 * @param[in] buf_size the size of the output buffer in bytes
 * @param[in] pict the input picture to encode
 * @return On error a negative value is returned, on success zero or the number
 * of bytes used from the output buffer.
 */
int avcodec_encode_video(AVCodecContext *avctx, uint8_t *buf, int buf_size,
                         const AVFrame *pict);
int avcodec_encode_subtitle(AVCodecContext *avctx, uint8_t *buf, int buf_size,
                            const AVSubtitle *sub);

int avcodec_close(AVCodecContext *avctx);

/**
 * 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);

/**
 * Flush buffers, should be called when seeking or when switching to a different stream.
 */
void avcodec_flush_buffers(AVCodecContext *avctx);

void avcodec_default_free_buffers(AVCodecContext *s);

/* misc useful functions */

#if FF_API_OLD_FF_PICT_TYPES
/**
 * Return a single letter to describe the given picture type pict_type.
 *
 * @param[in] pict_type the picture type
 * @return A single character representing the picture type.
 * @deprecated Use av_get_picture_type_char() instead.
 */
attribute_deprecated
char av_get_pict_type_char(int pict_type);
#endif

/**
 * Return codec bits per sample.
 *
 * @param[in] codec_id the codec
 * @return Number of bits per sample or zero if unknown for the given codec.
 */
int av_get_bits_per_sample(enum CodecID codec_id);

#if FF_API_OLD_SAMPLE_FMT
/**
 * @deprecated Use av_get_bytes_per_sample() instead.
 */
attribute_deprecated
int av_get_bits_per_sample_format(enum AVSampleFormat sample_fmt);
#endif

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

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

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

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

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

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

    /**
     * Time difference in stream 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 frame.
     * 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;

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

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

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

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

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

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

typedef struct AVCodecParser {
    int codec_ids[5]; /* several codec IDs are permitted */
    int priv_data_size;
    int (*parser_init)(AVCodecParserContext *s);
    int (*parser_parse)(AVCodecParserContext *s,
                        AVCodecContext *avctx,
                        const uint8_t **poutbuf, int *poutbuf_size,
                        const uint8_t *buf, int buf_size);
    void (*parser_close)(AVCodecParserContext *s);
    int (*split)(AVCodecContext *avctx, const uint8_t *buf, int buf_size);
    struct AVCodecParser *next;
} AVCodecParser;

AVCodecParser *av_parser_next(AVCodecParser *c);

void av_register_codec_parser(AVCodecParser *parser);
AVCodecParserContext *av_parser_init(int codec_id);

/**
 * Parse a packet.
 *
 * @param s             parser context.
 * @param avctx         codec context.
 * @param poutbuf       set to pointer to parsed buffer or NULL if not yet finished.
 * @param poutbuf_size  set to size of parsed buffer or zero if not yet finished.
 * @param buf           input buffer.
 * @param buf_size      input length, to signal EOF, this should be 0 (so that the last frame can be output).
 * @param pts           input presentation timestamp.
 * @param dts           input decoding timestamp.
 * @param pos           input byte position in stream.
 * @return the number of bytes of the input bitstream used.
 *
 * Example:
 * @code
 *   while(in_len){
 *       len = av_parser_parse2(myparser, AVCodecContext, &data, &size,
 *                                        in_data, in_len,
 *                                        pts, dts, pos);
 *       in_data += len;
 *       in_len  -= len;
 *
 *       if(size)
 *          decode_frame(data, size);
 *   }
 * @endcode
 */
int av_parser_parse2(AVCodecParserContext *s,
                     AVCodecContext *avctx,
                     uint8_t **poutbuf, int *poutbuf_size,
                     const uint8_t *buf, int buf_size,
                     int64_t pts, int64_t dts,
                     int64_t pos);

int av_parser_change(AVCodecParserContext *s,
                     AVCodecContext *avctx,
                     uint8_t **poutbuf, int *poutbuf_size,
                     const uint8_t *buf, int buf_size, int keyframe);
void av_parser_close(AVCodecParserContext *s);


typedef struct AVBitStreamFilterContext {
    void *priv_data;
    struct AVBitStreamFilter *filter;
    AVCodecParserContext *parser;
    struct AVBitStreamFilterContext *next;
} AVBitStreamFilterContext;


typedef struct AVBitStreamFilter {
    const char *name;
    int priv_data_size;
    int (*filter)(AVBitStreamFilterContext *bsfc,
                  AVCodecContext *avctx, const char *args,
                  uint8_t **poutbuf, int *poutbuf_size,
                  const uint8_t *buf, int buf_size, int keyframe);
    void (*close)(AVBitStreamFilterContext *bsfc);
    struct AVBitStreamFilter *next;
} AVBitStreamFilter;

void av_register_bitstream_filter(AVBitStreamFilter *bsf);
AVBitStreamFilterContext *av_bitstream_filter_init(const char *name);
int av_bitstream_filter_filter(AVBitStreamFilterContext *bsfc,
                               AVCodecContext *avctx, const char *args,
                               uint8_t **poutbuf, int *poutbuf_size,
                               const uint8_t *buf, int buf_size, int keyframe);
void av_bitstream_filter_close(AVBitStreamFilterContext *bsf);

AVBitStreamFilter *av_bitstream_filter_next(AVBitStreamFilter *f);

/* memory */

/**
 * Reallocate the given block if it is not large enough, otherwise do nothing.
 *
 * @see av_realloc
 */
void *av_fast_realloc(void *ptr, unsigned int *size, size_t min_size);

/**
 * Allocate a buffer, reusing the given one if large enough.
 *
 * Contrary to av_fast_realloc the current buffer contents might not be
 * preserved and on error the old buffer is freed, thus no special
 * handling to avoid memleaks is necessary.
 *
 * @param ptr pointer to pointer to already allocated buffer, overwritten with pointer to new buffer
 * @param size size of the buffer *ptr points to
 * @param min_size minimum size of *ptr buffer after returning, *ptr will be NULL and
 *                 *size 0 if an error occurred.
 */
void av_fast_malloc(void *ptr, unsigned int *size, size_t min_size);

/**
 * Copy image src to dst. Wraps av_picture_data_copy() above.
 */
void av_picture_copy(AVPicture *dst, const AVPicture *src,
                     enum PixelFormat pix_fmt, int width, int height);

/**
 * Crop image top and left side.
 */
int av_picture_crop(AVPicture *dst, const AVPicture *src,
                    enum PixelFormat pix_fmt, int top_band, int left_band);

/**
 * Pad image.
 */
int av_picture_pad(AVPicture *dst, const AVPicture *src, int height, int width, enum PixelFormat pix_fmt,
            int padtop, int padbottom, int padleft, int padright, int *color);

/**
 * Encode extradata length to a buffer. Used by xiph codecs.
 *
 * @param s buffer to write to; must be at least (v/255+1) bytes long
 * @param v size of extradata in bytes
 * @return number of bytes written to the buffer.
 */
unsigned int av_xiphlacing(unsigned char *s, unsigned int v);

/**
 * Logs a generic warning message about a missing feature. This function is
 * intended to be used internally by FFmpeg (libavcodec, libavformat, etc.)
 * only, and would normally not be used by applications.
 * @param[in] avc a pointer to an arbitrary struct of which the first field is
 * a pointer to an AVClass struct
 * @param[in] feature string containing the name of the missing feature
 * @param[in] want_sample indicates if samples are wanted which exhibit this feature.
 * If want_sample is non-zero, additional verbage will be added to the log
 * message which tells the user how to report samples to the development
 * mailing list.
 */
void av_log_missing_feature(void *avc, const char *feature, int want_sample);

/**
 * Log a generic warning message asking for a sample. This function is
 * intended to be used internally by FFmpeg (libavcodec, libavformat, etc.)
 * only, and would normally not be used by applications.
 * @param[in] avc a pointer to an arbitrary struct of which the first field is
 * a pointer to an AVClass struct
 * @param[in] msg string containing an optional message, or NULL if no message
 */
void av_log_ask_for_sample(void *avc, const char *msg, ...) av_printf_format(2, 3);

/**
 * Register the hardware accelerator hwaccel.
 */
void av_register_hwaccel(AVHWAccel *hwaccel);

/**
 * If hwaccel is NULL, returns the first registered hardware accelerator,
 * if hwaccel is non-NULL, returns the next registered hardware accelerator
 * after hwaccel, or NULL if hwaccel is the last one.
 */
AVHWAccel *av_hwaccel_next(AVHWAccel *hwaccel);


/**
 * Lock operation used by lockmgr
 */
enum AVLockOp {
  AV_LOCK_CREATE,  ///< Create a mutex
  AV_LOCK_OBTAIN,  ///< Lock the mutex
  AV_LOCK_RELEASE, ///< Unlock the mutex
  AV_LOCK_DESTROY, ///< Free mutex resources
};

/**
 * Register a user provided lock manager supporting the operations
 * specified by AVLockOp. mutex points to a (void *) where the
 * lockmgr should store/get a pointer to a user allocated mutex. It's
 * NULL upon AV_LOCK_CREATE and != NULL for all other ops.
 *
 * @param cb User defined callback. Note: FFmpeg may invoke calls to this
 *           callback during the call to av_lockmgr_register().
 *           Thus, the application must be prepared to handle that.
 *           If cb is set to NULL the lockmgr will be unregistered.
 *           Also note that during unregistration the previously registered
 *           lockmgr callback may also be invoked.
 */
int av_lockmgr_register(int (*cb)(void **mutex, enum AVLockOp op));

/**
 * Get the type of the given codec.
 */
enum AVMediaType avcodec_get_type(enum CodecID codec_id);

/**
 * 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);

#endif /* AVCODEC_AVCODEC_H */

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Written By
Software Developer (Senior) 3k Techonologies
United States United States
Suresh Potluri has worked in Windows device drivers, Solid experience in NDIS Layer, developed many NDIS Miniport drivers. Extensive experience in developing NDIS miniport drivers, building WHQL/DTM setup, clearing all WHQL/DTM tests, and subsequently getting device signature/logo process for the developed drivers. He also was also solely responsible for debugging traps and blue screens for a number of years.
he also worked on many PCI based boards, developed Board support packages, Vx-Works firmware for Power PC, firmware for ARM based boards for Wireless LAN devices.

he is interested in Embedded, NDIS, MPEG.

Previously worked in Tandberg TV, Sunnyvale, Chlesio Communications, Sunnyvale, Hellosoft, Hyderabad.

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