avcodec.h

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

    /**
     * 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_AAC_MAIN 0
#define FF_PROFILE_AAC_LOW  1
#define FF_PROFILE_AAC_SSR  2
#define FF_PROFILE_AAC_LTP  3

    /**
     * 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
     * or other things are used.
     * - 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;

    /**
     * constant rate factor - quality-based VBR - values ~correspond to qps
     * - encoding: Set by user.
     * - decoding: unused
     */
    float crf;

    /**
     * constant quantization parameter rate control method
     * - encoding: Set by user.
     * - decoding: unused
     */
    int cqp;

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

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

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

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

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

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

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

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

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

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

    /**
     * Audio cutoff bandwidth (0 means "automatic"), currently used only by FAAC.
     * - 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

    /**
     * Sets whether to use LPC mode - used by FLAC encoder.
     * - encoding: Set by user.
     * - decoding: unused
     */
    int use_lpc;

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

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

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

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

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

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

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

    /**
     * Decoder should decode to this many channels if it can (0 for default)
     * - encoding: unused
     * - decoding: Set by user.
     */
    int request_channels;
} AVCodecContext;

/**
 * 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 CodecType 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,
                  uint8_t *buf, int buf_size);
    int capabilities;
    struct AVCodec *next;
    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 terminanted by -1
} AVCodec;

/**
 * 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;

/**
 * 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.
 */
#define AVPALETTE_SIZE 1024
#define AVPALETTE_COUNT 256
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;

typedef struct AVSubtitleRect {
    uint16_t x;
    uint16_t y;
    uint16_t w;
    uint16_t h;
    uint16_t nb_colors;
    int linesize;
    uint32_t *rgba_palette;
    uint8_t *bitmap;
} 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 */
    uint32_t num_rects;
    AVSubti