avcodec.h

ffmpeg源码分析

    enum CodecType codec_type; /* see CODEC_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 workaround some encoder bugs
     * - encoding: set by user, if not then the default based on codec_id will be used
     * - decoding: set by user, will be converted to upper case by lavc during init
     */
    unsigned int codec_tag;

    /**
     * workaround 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 ///< workaround various bugs in microsofts broken decoders
//#define FF_BUG_FAKE_SCALABILITY 16 //autodetection should work 100%

    /**
     * luma single coeff 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 std (MPEG4, ...).
     * - encoding: set by user
     * - decoding: unused
     */
    int strict_std_compliance;
#define FF_COMPLIANCE_VERY_STRICT   2 ///< strictly conform to a 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_INOFFICIAL   -1 ///< allow inofficial extensions
#define FF_COMPLIANCE_EXPERIMENTAL -2 ///< allow non standarized experimental things

    /**
     * qscale offset 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_offset;

    /**
     * error resilience higher values will detect more errors but may missdetect
     * some more or less valid parts as errors.
     * - encoding: unused
     * - decoding: set by user
     */
    int error_resilience;
#define FF_ER_CAREFUL         1
#define FF_ER_COMPLIANT       2
#define FF_ER_AGGRESSIVE      3
#define FF_ER_VERY_AGGRESSIVE 4

    /**
     * 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 lavc
     * avcodec_align_dimensions() should be used to find the required width and
     * height, as they normally need to be rounded up to the next multiple of 16
     * - encoding: unused
     * - decoding: set by lavc, user can override
     */
    int (*get_buffer)(struct AVCodecContext *c, AVFrame *pic);

    /**
     * called to release buffers which where allocated with get_buffer.
     * a released buffer can be reused in get_buffer()
     * pic.data[*] must be set to NULL
     * - encoding: unused
     * - decoding: set by lavc, user can override
     */
    void (*release_buffer)(struct AVCodecContext *c, AVFrame *pic);

    /**
     * if 1 the stream has a 1 frame delay during decoding.
     * - encoding: set by lavc
     * - decoding: set by lavc
     */
    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;

    int parse_only; /* - decoding only: if true, only parsing is done
                       (function avcodec_parse_frame()). The frame
                       data is returned. Only MPEG codecs support this now. */

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

    /**
     * pass1 encoding statistics output buffer.
     * - encoding: set by lavc
     * - 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
     */
    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;


    /* for binary compatibility */
    int unused;

    /**
     * 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

    /**
     * slice count.
     * - encoding: set by lavc
     * - decoding: set by user (or 0)
     */
    int slice_count;
    /**
     * slice offsets in the frame in bytes.
     * - encoding: set/allocated by lavc
     * - 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 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;
#define FF_MM_FORCE    0x80000000 /* force usage of selected flags (OR) */
    /* lower 16 bits - CPU features */
#ifdef HAVE_MMX
#define FF_MM_MMX      0x0001 /* standard MMX */
#define FF_MM_3DNOW    0x0004 /* AMD 3DNOW */
#define FF_MM_MMXEXT   0x0002 /* SSE integer functions or AMD MMX ext */
#define FF_MM_SSE      0x0008 /* SSE functions */
#define FF_MM_SSE2     0x0010 /* PIV SSE2 functions */
#define FF_MM_3DNOWEXT 0x0020 /* AMD 3DNowExt */
#endif /* HAVE_MMX */
#ifdef HAVE_IWMMXT
#define FF_MM_IWMMXT   0x0100 /* XScale IWMMXT */
#endif /* HAVE_IWMMXT */

    /**
     * bits per sample/pixel from the demuxer (needed for huffyuv).
     * - encoding: set by lavc
     * - decoding: set by user
     */
     int bits_per_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).
     * numerator and denominator must be relative prime and smaller then 256 for some video standards
     * - encoding: set by user.
     * - decoding: set by lavc.
     */
    AVRational sample_aspect_ratio;

    /**
     * the picture in the bitstream.
     * - encoding: set by lavc
     * - decoding: set by lavc
     */
    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

    /**
     * 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 lavc if flags&CODEC_FLAG_PSNR
     * - decoding: unused
     */
    uint64_t error[4];

    /**
     * minimum MB quantizer.
     * - encoding: unused
     * - decoding: unused
     */
    int mb_qmin;

    /**
     * maximum MB quantizer.
     * - encoding: unused
     * - decoding: unused
     */
    int mb_qmax;

    /**
     * motion estimation compare function.
     * - encoding: set by user.
     * - decoding: unused
     */
    int me_cmp;
    /**
     * subpixel motion estimation compare function.
     * - encoding: set by user.
     * - decoding: unused
     */
    int me_sub_cmp;
    /**
     * macroblock compare function (not supported yet).
     * - encoding: set by user.
     * - decoding: unused
     */
    int mb_cmp;
    /**
     * interlaced dct compare 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
     */