[置顶] FFmpeg总结（五）AV系列结构体之AVCodec、AVCodecParameters、AVCodecParser、AVCodecParserContext、AVCodecDescriptor
AVCodec： 编解码器结构体
位于libavcodec/avcodec.h中
typedef struct AVCodec {
const char *name; // codec的名字，保持全局唯一，标识名
const char *long_name; // codec的名字，全名
enum AVMediaType type; // Media类型，是视频，音频，还是字幕
enum AVCodecID id;
int capabilities; // codec的容量，参考 AV_CODEC_CAP_*
const AVRational *supported_framerates; //支持的帧率,如果是null，返回是{0，0}
const enum AVPixelFormat *pix_fmts; //支持的像素格式,如果是null或unknown，返回-1
const int *supported_samplerates; //支持的采样率，如果是null或unknown，返回0
const enum AVSampleFormat *sample_fmts; //支持的采样率，如果是null，返回-1
const uint64_t *channel_layouts; //支持的声道数， 如果是null，返回0
uint8_t max_lowres; //解码器支持的最大lowres
const AVClass *priv_class; //定义AVClass 成员变量
const AVProfile *profiles; //定义AVProfile 成员变量
/***************************************************************** * No fields below this line are part of the public API. They * may not be used outside of libavcodec and can be changed and * removed at will. * New public fields should be added right above. ***************************************************************** */
int priv_data_size;
struct AVCodec *next;
/** * @name Frame-level threading support functions * @{ */
/** * If defined, called on thread contexts when they are created. * If the codec allocates writable tables in init(), re-allocate them here. * priv_data will be set to a copy of the original. */
int (*init_thread_copy)(AVCodecContext *);
/** * Copy necessary context variables from a previous thread context to the current one. * If not defined, the next thread will start automatically; otherwise, the codec * must call ff_thread_finish_setup(). * * dst and src will (rarely) point to the same context, in which case memcpy should be skipped. */
int (*update_thread_context)(AVCodecContext *dst, const AVCodecContext *src);
/** @} */
/** * Private codec-specific defaults. */
const AVCodecDefault *defaults;
/** * Initialize codec static data, called from avcodec_register(). */
void (*init_static_data)(struct AVCodec *codec);
int (*init)(AVCodecContext *);
int (*encode_sub)(AVCodecContext *, uint8_t *buf, int buf_size,
const struct AVSubtitle *sub);
/** * Encode data to an AVPacket. * * @param avctx codec context * @param avpkt output AVPacket (may contain a user-provided buffer) * @param[in] frame AVFrame containing the raw data to be encoded * @param[out] got_packet_ptr encoder sets to 0 or 1 to indicate that a * non-empty packet was returned in avpkt. * @return 0 on success, negative error code on failure */
int (*encode2)(AVCodecContext *avctx, AVPacket *avpkt, const AVFrame *frame,
int *got_packet_ptr);
int (*decode)(AVCodecContext *, void *outdata, int *outdata_size, AVPacket *avpkt);
int (*close)(AVCodecContext *);
/** * Decode/encode API with decoupled packet/frame dataflow. The API is the * same as the avcodec_ prefixed APIs (avcodec_send_frame() etc.), except * that: * - never called if the codec is closed or the wrong type, * - AVPacket parameter change side data is applied right before calling * AVCodec->send_packet, * - if AV_CODEC_CAP_DELAY is not set, drain packets or frames are never sent, * - only one drain packet is ever passed down (until the next flush()), * - a drain AVPacket is always NULL (no need to check for avpkt->size). */
int (*send_frame)(AVCodecContext *avctx, const AVFrame *frame);
int (*send_packet)(AVCodecContext *avctx, const AVPacket *avpkt);
int (*receive_frame)(AVCodecContext *avctx, AVFrame *frame);
int (*receive_packet)(AVCodecContext *avctx, AVPacket *avpkt);
/** * Flush buffers. * Will be called when seeking */
void (*flush)(AVCodecContext *);
/** * Internal codec capabilities. * See FF_CODEC_CAP_* in internal.h */
int caps_internal;
} AVCodec;AVCodecParameters:描述一个解码后的流的属性
sizeof(AVCodecParameters),并不是public的api, 这个结构必须通过avcodec_parameters_alloc()分配空间，通过avcodec_parameters_free()释放空间。
typedef struct AVCodecParameters {
/** * General type of the encoded data. */
enum AVMediaType codec_type;
/** * Specific type of the encoded data (the codec used). */
enum AVCodecID codec_id;
/** * Additional information about the codec (corresponds to the AVI FOURCC). */
uint32_t codec_tag;
/** * Extra binary data needed for initializing the decoder, codec-dependent. * * Must be allocated with av_malloc() and will be freed by * avcodec_parameters_free(). The allocated size of extradata must be at * least extradata_size + AV_INPUT_BUFFER_PADDING_SIZE, with the padding * bytes zeroed. */
uint8_t *extradata;
/** * Size of the extradata content in bytes. */
int extradata_size;
/** * - video: the pixel format, the value corresponds to enum AVPixelFormat. * - audio: the sample format, the value corresponds to enum AVSampleFormat. */
int format;
/** * The average bitrate of the encoded data (in bits per second). */
int64_t bit_rate;
/** * The number of bits per sample in the codedwords. * * This is basically the bitrate per sample. It is mandatory for a bunch of * formats to actually decode them. It's the number of bits for one sample in * the actual coded bitstream. * * This could be for example 4 for ADPCM * For PCM formats this matches bits_per_raw_sample * Can be 0 */
int bits_per_coded_sample;
/** * This is the number of valid bits in each output sample. If the * sample format has more bits, the least significant bits are additional * padding bits, which are always 0. Use right shifts to reduce the sample * to its actual size. For example, audio formats with 24 bit samples will * have bits_per_raw_sample set to 24, and format set to AV_SAMPLE_FMT_S32. * To get the original sample use "(int32_t)sample >> 8"." * * For ADPCM this might be 12 or 16 or similar * Can be 0 */
int bits_per_raw_sample;
/** * Codec-specific bitstream restrictions that the stream conforms to. */
int profile;
int level;
/** * Video only. The dimensions of the video frame in pixels. */
int width;
int height;
/** * Video only. The aspect ratio (width / height) which a single pixel * should have when displayed. * * When the aspect ratio is unknown / undefined, the numerator should be * set to 0 (the denominator may have any value). */
AVRational sample_aspect_ratio;
/** * Video only. The order of the fields in interlaced video. */
enum AVFieldOrder field_order;
/** * Video only. Additional colorspace characteristics. */
enum AVColorRange color_range;
enum AVColorPrimaries color_primaries;
enum AVColorTransferCharacteristic color_trc;
enum AVColorSpace color_space;
enum AVChromaLocation chroma_location;
/** * Video only. Number of delayed frames. */
int video_delay;
/** * Audio only. The channel layout bitmask. May be 0 if the channel layout is * unknown or unspecified, otherwise the number of bits set must be equal to * the channels field. */
uint64_t channel_layout;
/** * Audio only. The number of audio channels. */
int channels;
/** * Audio only. The number of audio samples per second. */
int sample_rate;
/** * Audio only. The number of bytes per coded audio frame, required by some * formats. * * Corresponds to nBlockAlign in WAVEFORMATEX. */
int block_align;
/** * Audio only. Audio frame size, if known. Required by some formats to be static. */
int frame_size;
/** * Audio only. The amount of padding (in samples) inserted by the encoder at * the beginning of the audio. I.e. this number of leading decoded samples * must be discarded by the caller to get the original audio without leading * padding. */
int initial_padding;
/** * Audio only. The amount of padding (in samples) appended by the encoder to * the end of the audio. I.e. this number of decoded samples must be * discarded by the caller from the end of the stream to get the original * audio without any trailing padding. */
int trailing_padding;
/** * Audio only. Number of samples to skip after a discontinuity. */
int seek_preroll;
} AVCodecParameters;AVCodecParser
typedef struct AVCodecParser {
int codec_ids[5]; /* several codec IDs are permitted */
int priv_data_size;
int (*parser_init)(AVCodecParserContext *s);
/* This callback never returns an error, a negative value means that * the frame start was in a previous packet. */
int (*parser_parse)(AVCodecParserContext *s,
AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size);
void (*parser_close)(AVCodecParserContext *s);
int (*split)(AVCodecContext *avctx, const uint8_t *buf, int buf_size);
struct AVCodecParser *next;
} AVCodecParser;AVCodecParserContext ：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
#define PARSER_FLAG_USE_CODEC_TS 0x1000
int64_t offset; ///< byte offset from starting packet start
int64_t cur_frame_end[AV_PARSER_PTS_NB];
/** * Set by parser to 1 for key frames and 0 for non-key frames. * It is initialized to -1, so if the parser doesn't set this flag, * old-style fallback using AV_PICTURE_TYPE_I picture type as key frames * will be used. */
int key_frame;
#if FF_API_CONVERGENCE_DURATION
/** * @deprecated unused */
attribute_deprecated
int64_t convergence_duration;
#endif
// Timestamp generation support:
/** * Synchronization point for start of timestamp generation. * * Set to >0 for sync point, 0 for no sync point and <0 for undefined * (default). * * For example, this corresponds to presence of H.264 buffering period * SEI message. */
int dts_sync_point;
/** * Offset of the current timestamp against last timestamp sync point in * units of AVCodecContext.time_base. * * Set to INT_MIN when dts_sync_point unused. Otherwise, it must * contain a valid timestamp offset. * * Note that the timestamp of sync point has usually a nonzero * dts_ref_dts_delta, which refers to the previous sync point. Offset of * the next frame after timestamp sync point will be usually 1. * * For example, this corresponds to H.264 cpb_removal_delay. */
int dts_ref_dts_delta;
/** * Presentation delay of current frame in units of AVCodecContext.time_base. * * Set to INT_MIN when dts_sync_point unused. Otherwise, it must * contain valid non-negative timestamp delta (presentation time of a frame * must not lie in the past). * * This delay represents the difference between decoding and presentation * time of the frame. * * For example, this corresponds to H.264 dpb_output_delay. */
int pts_dts_delta;
/** * Position of the packet in file. * * Analogous to cur_frame_pts/dts */
int64_t cur_frame_pos[AV_PARSER_PTS_NB];
/** * Byte position of currently parsed frame in stream. */
int64_t pos;
/** * Previous frame byte position. */
int64_t last_pos;
/** * Duration of the current frame. * For audio, this is in units of 1 / AVCodecContext.sample_rate. * For all other types, this is in units of AVCodecContext.time_base. */
int duration;
enum AVFieldOrder field_order;
/** * Indicate whether a picture is coded as a frame, top field or bottom field. * * For example, H.264 field_pic_flag equal to 0 corresponds to * AV_PICTURE_STRUCTURE_FRAME. An H.264 picture with field_pic_flag * equal to 1 and bottom_field_flag equal to 0 corresponds to * AV_PICTURE_STRUCTURE_TOP_FIELD. */
enum AVPictureStructure picture_structure;
/** * Picture number incremented in presentation or output order. * This field may be reinitialized at the first picture of a new sequence. * * For example, this corresponds to H.264 PicOrderCnt. */
int output_picture_number;
/** * Dimensions of the decoded video intended for presentation. */
int width;
int height;
/** * Dimensions of the coded video. */
int coded_width;
int coded_height;
/** * The format of the coded data, corresponds to enum AVPixelFormat for video * and for enum AVSampleFormat for audio. * * Note that a decoder can have considerable freedom in how exactly it * decodes the data, so the format reported here might be different from the * one returned by a decoder. */
int format;
} AVCodecParserContext;AVCodecDescriptor:描述单个解码器的属性，单个解码器被描述是通过AVCodecID
typedef struct AVCodecDescriptor {
enum AVCodecID id;
enum AVMediaType type;
const char *name;
const char *long_name;
/** * Codec properties, a combination of AV_CODEC_PROP_* flags. */
int props;
/** * MIME type(s) associated with the codec. * May be NULL; if not, a NULL-terminated array of MIME types. * The first item is always non-NULL and is the preferred MIME type. */
const char *const *mime_types;
/** * If non-NULL, an array of profiles recognized for this codec. * Terminated with FF_PROFILE_UNKNOWN. */
const struct AVProfile *profiles;
} AVCodecDescriptor;AVCodecID:枚举出FFmpeg所有解码器id
enum AVCodecID {
AV_CODEC_ID_NONE,
/* video codecs */
AV_CODEC_ID_MPEG1VIDEO,
AV_CODEC_ID_MPEG2VIDEO, ///< preferred ID for MPEG-1/2 video decoding
#if FF_API_XVMC
AV_CODEC_ID_MPEG2VIDEO_XVMC,
#endif /* FF_API_XVMC */
AV_CODEC_ID_H261,
AV_CODEC_ID_H263,
AV_CODEC_ID_RV10,
AV_CODEC_ID_RV20,
AV_CODEC_ID_MJPEG,
AV_CODEC_ID_MJPEGB,
AV_CODEC_ID_LJPEG,
AV_CODEC_ID_SP5X,
AV_CODEC_ID_JPEGLS,
AV_CODEC_ID_MPEG4,
AV_CODEC_ID_RAWVIDEO,
AV_CODEC_ID_MSMPEG4V1,
AV_CODEC_ID_MSMPEG4V2,
AV_CODEC_ID_MSMPEG4V3,
AV_CODEC_ID_WMV1,
AV_CODEC_ID_WMV2,
AV_CODEC_ID_H263P,
AV_CODEC_ID_H263I,
AV_CODEC_ID_FLV1,
AV_CODEC_ID_SVQ1,
AV_CODEC_ID_SVQ3,
AV_CODEC_ID_DVVIDEO,
AV_CODEC_ID_HUFFYUV,
AV_CODEC_ID_CYUV,
AV_CODEC_ID_H264,
AV_CODEC_ID_INDEO3,
AV_CODEC_ID_VP3,
AV_CODEC_ID_THEORA,
AV_CODEC_ID_ASV1,
AV_CODEC_ID_ASV2,
AV_CODEC_ID_FFV1,
AV_CODEC_ID_4XM,
AV_CODEC_ID_VCR1,
AV_CODEC_ID_CLJR,
AV_CODEC_ID_MDEC,
AV_CODEC_ID_ROQ,
AV_CODEC_ID_INTERPLAY_VIDEO,
AV_CODEC_ID_XAN_WC3,
AV_CODEC_ID_XAN_WC4,
AV_CODEC_ID_RPZA,
AV_CODEC_ID_CINEPAK,
AV_CODEC_ID_WS_VQA,
AV_CODEC_ID_MSRLE,
AV_CODEC_ID_MSVIDEO1,
AV_CODEC_ID_IDCIN,
AV_CODEC_ID_8BPS,
AV_CODEC_ID_SMC,
AV_CODEC_ID_FLIC,
AV_CODEC_ID_TRUEMOTION1,
AV_CODEC_ID_VMDVIDEO,
AV_CODEC_ID_MSZH,
AV_CODEC_ID_ZLIB,
AV_CODEC_ID_QTRLE,
AV_CODEC_ID_TSCC,
AV_CODEC_ID_ULTI,
AV_CODEC_ID_QDRAW,
AV_CODEC_ID_VIXL,
AV_CODEC_ID_QPEG,
AV_CODEC_ID_PNG,
AV_CODEC_ID_PPM,
AV_CODEC_ID_PBM,
AV_CODEC_ID_PGM,
AV_CODEC_ID_PGMYUV,
AV_CODEC_ID_PAM,
AV_CODEC_ID_FFVHUFF,
AV_CODEC_ID_RV30,
AV_CODEC_ID_RV40,
AV_CODEC_ID_VC1,
AV_CODEC_ID_WMV3,
AV_CODEC_ID_LOCO,
AV_CODEC_ID_WNV1,
AV_CODEC_ID_AASC,
AV_CODEC_ID_INDEO2,
AV_CODEC_ID_FRAPS,
AV_CODEC_ID_TRUEMOTION2,
AV_CODEC_ID_BMP,
AV_CODEC_ID_CSCD,
AV_CODEC_ID_MMVIDEO,
AV_CODEC_ID_ZMBV,
AV_CODEC_ID_AVS,
AV_CODEC_ID_SMACKVIDEO,
AV_CODEC_ID_NUV,
AV_CODEC_ID_KMVC,
AV_CODEC_ID_FLASHSV,
AV_CODEC_ID_CAVS,
AV_CODEC_ID_JPEG2000,
AV_CODEC_ID_VMNC,
AV_CODEC_ID_VP5,
AV_CODEC_ID_VP6,
AV_CODEC_ID_VP6F,
AV_CODEC_ID_TARGA,
AV_CODEC_ID_DSICINVIDEO,
AV_CODEC_ID_TIERTEXSEQVIDEO,
AV_CODEC_ID_TIFF,
AV_CODEC_ID_GIF,
AV_CODEC_ID_DXA,
AV_CODEC_ID_DNXHD,
AV_CODEC_ID_THP,
AV_CODEC_ID_SGI,
AV_CODEC_ID_C93,
AV_CODEC_ID_BETHSOFTVID,
AV_CODEC_ID_PTX,
AV_CODEC_ID_TXD,
AV_CODEC_ID_VP6A,
AV_CODEC_ID_AMV,
AV_CODEC_ID_VB,
AV_CODEC_ID_PCX,
AV_CODEC_ID_SUNRAST,
AV_CODEC_ID_INDEO4,
AV_CODEC_ID_INDEO5,
AV_CODEC_ID_MIMIC,
AV_CODEC_ID_RL2,
AV_CODEC_ID_ESCAPE124,
AV_CODEC_ID_DIRAC,
AV_CODEC_ID_BFI,
AV_CODEC_ID_CMV,
AV_CODEC_ID_MOTIONPIXELS,
AV_CODEC_ID_TGV,
AV_CODEC_ID_TGQ,
AV_CODEC_ID_TQI,
AV_CODEC_ID_AURA,
AV_CODEC_ID_AURA2,
AV_CODEC_ID_V210X,
AV_CODEC_ID_TMV,
AV_CODEC_ID_V210,
AV_CODEC_ID_DPX,
AV_CODEC_ID_MAD,
AV_CODEC_ID_FRWU,
AV_CODEC_ID_FLASHSV2,
AV_CODEC_ID_CDGRAPHICS,
AV_CODEC_ID_R210,
AV_CODEC_ID_ANM,
AV_CODEC_ID_BINKVIDEO,
AV_CODEC_ID_IFF_ILBM,
#define AV_CODEC_ID_IFF_BYTERUN1 AV_CODEC_ID_IFF_ILBM
AV_CODEC_ID_KGV1,
AV_CODEC_ID_YOP,
AV_CODEC_ID_VP8,
AV_CODEC_ID_PICTOR,
AV_CODEC_ID_ANSI,
AV_CODEC_ID_A64_MULTI,
AV_CODEC_ID_A64_MULTI5,
AV_CODEC_ID_R10K,
AV_CODEC_ID_MXPEG,
AV_CODEC_ID_LAGARITH,
AV_CODEC_ID_PRORES,
AV_CODEC_ID_JV,
AV_CODEC_ID_DFA,
AV_CODEC_ID_WMV3IMAGE,
AV_CODEC_ID_VC1IMAGE,
AV_CODEC_ID_UTVIDEO,
AV_CODEC_ID_BMV_VIDEO,
AV_CODEC_ID_VBLE,
AV_CODEC_ID_DXTORY,
AV_CODEC_ID_V410,
AV_CODEC_ID_XWD,
AV_CODEC_ID_CDXL,
AV_CODEC_ID_XBM,
AV_CODEC_ID_ZEROCODEC,
AV_CODEC_ID_MSS1,
AV_CODEC_ID_MSA1,
AV_CODEC_ID_TSCC2,
AV_CODEC_ID_MTS2,
AV_CODEC_ID_CLLC,
AV_CODEC_ID_MSS2,
AV_CODEC_ID_VP9,
AV_CODEC_ID_AIC,
AV_CODEC_ID_ESCAPE130,
AV_CODEC_ID_G2M,
AV_CODEC_ID_WEBP,
AV_CODEC_ID_HNM4_VIDEO,
AV_CODEC_ID_HEVC,
#define AV_CODEC_ID_H265 AV_CODEC_ID_HEVC
AV_CODEC_ID_FIC,
AV_CODEC_ID_ALIAS_PIX,
AV_CODEC_ID_BRENDER_PIX,
AV_CODEC_ID_PAF_VIDEO,
AV_CODEC_ID_EXR,
AV_CODEC_ID_VP7,
AV_CODEC_ID_SANM,
AV_CODEC_ID_SGIRLE,
AV_CODEC_ID_MVC1,
AV_CODEC_ID_MVC2,
AV_CODEC_ID_HQX,
AV_CODEC_ID_TDSC,
AV_CODEC_ID_HQ_HQA,
AV_CODEC_ID_HAP,
AV_CODEC_ID_DDS,
AV_CODEC_ID_DXV,
AV_CODEC_ID_SCREENPRESSO,
AV_CODEC_ID_RSCC,
AV_CODEC_ID_Y41P = 0x8000,
AV_CODEC_ID_AVRP,
AV_CODEC_ID_012V,
AV_CODEC_ID_AVUI,
AV_CODEC_ID_AYUV,
AV_CODEC_ID_TARGA_Y216,
AV_CODEC_ID_V308,
AV_CODEC_ID_V408,
AV_CODEC_ID_YUV4,
AV_CODEC_ID_AVRN,
AV_CODEC_ID_CPIA,
AV_CODEC_ID_XFACE,
AV_CODEC_ID_SNOW,
AV_CODEC_ID_SMVJPEG,
AV_CODEC_ID_APNG,
AV_CODEC_ID_DAALA,
AV_CODEC_ID_CFHD,
AV_CODEC_ID_TRUEMOTION2RT,
AV_CODEC_ID_M101,
AV_CODEC_ID_MAGICYUV,
AV_CODEC_ID_SHEERVIDEO,
AV_CODEC_ID_YLC,
/* various PCM "codecs" */
AV_CODEC_ID_FIRST_AUDIO = 0x10000, ///< A dummy id pointing at the start of audio codecs
AV_CODEC_ID_PCM_S16LE = 0x10000,
AV_CODEC_ID_PCM_S16BE,
AV_CODEC_ID_PCM_U16LE,
AV_CODEC_ID_PCM_U16BE,
AV_CODEC_ID_PCM_S8,
AV_CODEC_ID_PCM_U8,
AV_CODEC_ID_PCM_MULAW,
AV_CODEC_ID_PCM_ALAW,
AV_CODEC_ID_PCM_S32LE,
AV_CODEC_ID_PCM_S32BE,
AV_CODEC_ID_PCM_U32LE,
AV_CODEC_ID_PCM_U32BE,
AV_CODEC_ID_PCM_S24LE,
AV_CODEC_ID_PCM_S24BE,
AV_CODEC_ID_PCM_U24LE,
AV_CODEC_ID_PCM_U24BE,
AV_CODEC_ID_PCM_S24DAUD,
AV_CODEC_ID_PCM_ZORK,
AV_CODEC_ID_PCM_S16LE_PLANAR,
AV_CODEC_ID_PCM_DVD,
AV_CODEC_ID_PCM_F32BE,
AV_CODEC_ID_PCM_F32LE,
AV_CODEC_ID_PCM_F64BE,
AV_CODEC_ID_PCM_F64LE,
AV_CODEC_ID_PCM_BLURAY,
AV_CODEC_ID_PCM_LXF,
AV_CODEC_ID_S302M,
AV_CODEC_ID_PCM_S8_PLANAR,
AV_CODEC_ID_PCM_S24LE_PLANAR,
AV_CODEC_ID_PCM_S32LE_PLANAR,
AV_CODEC_ID_PCM_S16BE_PLANAR,
/* new PCM "codecs" should be added right below this line starting with * an explicit value of for example 0x10800 */
/* various ADPCM codecs */
AV_CODEC_ID_ADPCM_IMA_QT = 0x11000,
AV_CODEC_ID_ADPCM_IMA_WAV,
AV_CODEC_ID_ADPCM_IMA_DK3,
AV_CODEC_ID_ADPCM_IMA_DK4,
AV_CODEC_ID_ADPCM_IMA_WS,
AV_CODEC_ID_ADPCM_IMA_SMJPEG,
AV_CODEC_ID_ADPCM_MS,
AV_CODEC_ID_ADPCM_4XM,
AV_CODEC_ID_ADPCM_XA,
AV_CODEC_ID_ADPCM_ADX,
AV_CODEC_ID_ADPCM_EA,
AV_CODEC_ID_ADPCM_G726,
AV_CODEC_ID_ADPCM_CT,
AV_CODEC_ID_ADPCM_SWF,
AV_CODEC_ID_ADPCM_YAMAHA,
AV_CODEC_ID_ADPCM_SBPRO_4,
AV_CODEC_ID_ADPCM_SBPRO_3,
AV_CODEC_ID_ADPCM_SBPRO_2,
AV_CODEC_ID_ADPCM_THP,
AV_CODEC_ID_ADPCM_IMA_AMV,
AV_CODEC_ID_ADPCM_EA_R1,
AV_CODEC_ID_ADPCM_EA_R3,
AV_CODEC_ID_ADPCM_EA_R2,
AV_CODEC_ID_ADPCM_IMA_EA_SEAD,
AV_CODEC_ID_ADPCM_IMA_EA_EACS,
AV_CODEC_ID_ADPCM_EA_XAS,
AV_CODEC_ID_ADPCM_EA_MAXIS_XA,
AV_CODEC_ID_ADPCM_IMA_ISS,
AV_CODEC_ID_ADPCM_G722,
AV_CODEC_ID_ADPCM_IMA_APC,
AV_CODEC_ID_ADPCM_VIMA,
#if FF_API_VIMA_DECODER
AV_CODEC_ID_VIMA = AV_CODEC_ID_ADPCM_VIMA,
#endif
AV_CODEC_ID_ADPCM_AFC = 0x11800,
AV_CODEC_ID_ADPCM_IMA_OKI,
AV_CODEC_ID_ADPCM_DTK,
AV_CODEC_ID_ADPCM_IMA_RAD,
AV_CODEC_ID_ADPCM_G726LE,
AV_CODEC_ID_ADPCM_THP_LE,
AV_CODEC_ID_ADPCM_PSX,
AV_CODEC_ID_ADPCM_AICA,
AV_CODEC_ID_ADPCM_IMA_DAT4,
AV_CODEC_ID_ADPCM_MTAF,
/* AMR */
AV_CODEC_ID_AMR_NB = 0x12000,
AV_CODEC_ID_AMR_WB,
/* RealAudio codecs*/
AV_CODEC_ID_RA_144 = 0x13000,
AV_CODEC_ID_RA_288,
/* various DPCM codecs */
AV_CODEC_ID_ROQ_DPCM = 0x14000,
AV_CODEC_ID_INTERPLAY_DPCM,
AV_CODEC_ID_XAN_DPCM,
AV_CODEC_ID_SOL_DPCM,
AV_CODEC_ID_SDX2_DPCM = 0x14800,
/* audio codecs */
AV_CODEC_ID_MP2 = 0x15000,
AV_CODEC_ID_MP3, ///< preferred ID for decoding MPEG audio layer 1, 2 or 3
AV_CODEC_ID_AAC,
AV_CODEC_ID_AC3,
AV_CODEC_ID_DTS,
AV_CODEC_ID_VORBIS,
AV_CODEC_ID_DVAUDIO,
AV_CODEC_ID_WMAV1,
AV_CODEC_ID_WMAV2,
AV_CODEC_ID_MACE3,
AV_CODEC_ID_MACE6,
AV_CODEC_ID_VMDAUDIO,
AV_CODEC_ID_FLAC,
AV_CODEC_ID_MP3ADU,
AV_CODEC_ID_MP3ON4,
AV_CODEC_ID_SHORTEN,
AV_CODEC_ID_ALAC,
AV_CODEC_ID_WESTWOOD_SND1,
AV_CODEC_ID_GSM, ///< as in Berlin toast format
AV_CODEC_ID_QDM2,
AV_CODEC_ID_COOK,
AV_CODEC_ID_TRUESPEECH,
AV_CODEC_ID_TTA,
AV_CODEC_ID_SMACKAUDIO,
AV_CODEC_ID_QCELP,
AV_CODEC_ID_WAVPACK,
AV_CODEC_ID_DSICINAUDIO,
AV_CODEC_ID_IMC,
AV_CODEC_ID_MUSEPACK7,
AV_CODEC_ID_MLP,
AV_CODEC_ID_GSM_MS, /* as found in WAV */
AV_CODEC_ID_ATRAC3,
#if FF_API_VOXWARE
AV_CODEC_ID_VOXWARE,
#endif
AV_CODEC_ID_APE,
AV_CODEC_ID_NELLYMOSER,
AV_CODEC_ID_MUSEPACK8,
AV_CODEC_ID_SPEEX,
AV_CODEC_ID_WMAVOICE,
AV_CODEC_ID_WMAPRO,
AV_CODEC_ID_WMALOSSLESS,
AV_CODEC_ID_ATRAC3P,
AV_CODEC_ID_EAC3,
AV_CODEC_ID_SIPR,
AV_CODEC_ID_MP1,
AV_CODEC_ID_TWINVQ,
AV_CODEC_ID_TRUEHD,
AV_CODEC_ID_MP4ALS,
AV_CODEC_ID_ATRAC1,
AV_CODEC_ID_BINKAUDIO_RDFT,
AV_CODEC_ID_BINKAUDIO_DCT,
AV_CODEC_ID_AAC_LATM,
AV_CODEC_ID_QDMC,
AV_CODEC_ID_CELT,
AV_CODEC_ID_G723_1,
AV_CODEC_ID_G729,
AV_CODEC_ID_8SVX_EXP,
AV_CODEC_ID_8SVX_FIB,
AV_CODEC_ID_BMV_AUDIO,
AV_CODEC_ID_RALF,
AV_CODEC_ID_IAC,
AV_CODEC_ID_ILBC,
AV_CODEC_ID_OPUS,
AV_CODEC_ID_COMFORT_NOISE,
AV_CODEC_ID_TAK,
AV_CODEC_ID_METASOUND,
AV_CODEC_ID_PAF_AUDIO,
AV_CODEC_ID_ON2AVC,
AV_CODEC_ID_DSS_SP,
AV_CODEC_ID_FFWAVESYNTH = 0x15800,
AV_CODEC_ID_SONIC,
AV_CODEC_ID_SONIC_LS,
AV_CODEC_ID_EVRC,
AV_CODEC_ID_SMV,
AV_CODEC_ID_DSD_LSBF,
AV_CODEC_ID_DSD_MSBF,
AV_CODEC_ID_DSD_LSBF_PLANAR,
AV_CODEC_ID_DSD_MSBF_PLANAR,
AV_CODEC_ID_4GV,
AV_CODEC_ID_INTERPLAY_ACM,
AV_CODEC_ID_XMA1,
AV_CODEC_ID_XMA2,
AV_CODEC_ID_DST,
/* subtitle codecs */
AV_CODEC_ID_FIRST_SUBTITLE = 0x17000, ///< A dummy ID pointing at the start of subtitle codecs.
AV_CODEC_ID_DVD_SUBTITLE = 0x17000,
AV_CODEC_ID_DVB_SUBTITLE,
AV_CODEC_ID_TEXT, ///< raw UTF-8 text
AV_CODEC_ID_XSUB,
AV_CODEC_ID_SSA,
AV_CODEC_ID_MOV_TEXT,
AV_CODEC_ID_HDMV_PGS_SUBTITLE,
AV_CODEC_ID_DVB_TELETEXT,
AV_CODEC_ID_SRT,
AV_CODEC_ID_MICRODVD = 0x17800,
AV_CODEC_ID_EIA_608,
AV_CODEC_ID_JACOSUB,
AV_CODEC_ID_SAMI,
AV_CODEC_ID_REALTEXT,
AV_CODEC_ID_STL,
AV_CODEC_ID_SUBVIEWER1,
AV_CODEC_ID_SUBVIEWER,
AV_CODEC_ID_SUBRIP,
AV_CODEC_ID_WEBVTT,
AV_CODEC_ID_MPL2,
AV_CODEC_ID_VPLAYER,
AV_CODEC_ID_PJS,
AV_CODEC_ID_ASS,
AV_CODEC_ID_HDMV_TEXT_SUBTITLE,
/* other specific kind of codecs (generally used for attachments) */
AV_CODEC_ID_FIRST_UNKNOWN = 0x18000, ///< A dummy ID pointing at the start of various fake codecs.
AV_CODEC_ID_TTF = 0x18000,
AV_CODEC_ID_BINTEXT = 0x18800,
AV_CODEC_ID_XBIN,
AV_CODEC_ID_IDF,
AV_CODEC_ID_OTF,
AV_CODEC_ID_SMPTE_KLV,
AV_CODEC_ID_DVD_NAV,
AV_CODEC_ID_TIMED_ID3,
AV_CODEC_ID_BIN_DATA,
AV_CODEC_ID_PROBE = 0x19000, ///< codec_id is not known (like AV_CODEC_ID_NONE) but lavf should attempt to identify it
AV_CODEC_ID_MPEG2TS = 0x20000, /**< _FAKE_ codec to indicate a raw MPEG-2 TS * stream (only used by libavformat) */
AV_CODEC_ID_MPEG4SYSTEMS = 0x20001, /**< _FAKE_ codec to indicate a MPEG-4 Systems * stream (only used by libavformat) */
AV_CODEC_ID_FFMETADATA = 0x21000, ///< Dummy codec for streams containing only metadata information.
AV_CODEC_ID_WRAPPED_AVFRAME = 0x21001, ///< Passthrough codec, AVFrames wrapped in AVPacket
};
如我们找一个标准的h.264+aac的解码，h.264解码器在h264.c中的声明如下，注意id(AV_CODEC_ID_H264)对应我们上面AVCodcID中的AV_CODEC_ID_H264。
AVCodec ff_h264_decoder = {
.name = "h264",
.long_name = NULL_IF_CONFIG_SMALL("H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10"),
.type = AVMEDIA_TYPE_VIDEO,
.id = AV_CODEC_ID_H264,
.priv_data_size = sizeof(H264Context),
.init = ff_h264_decode_init,
.close = h264_decode_end,
.decode = h264_decode_frame,
.capabilities = /*AV_CODEC_CAP_DRAW_HORIZ_BAND |*/ AV_CODEC_CAP_DR1 |
AV_CODEC_CAP_DELAY | AV_CODEC_CAP_SLICE_THREADS |
AV_CODEC_CAP_FRAME_THREADS,
.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
.flush = flush_dpb,
.init_thread_copy = ONLY_IF_THREADS_ENABLED(decode_init_thread_copy),
.update_thread_context = ONLY_IF_THREADS_ENABLED(ff_h264_update_thread_context),
.profiles = NULL_IF_CONFIG_SMALL(ff_h264_profiles),
.priv_class = &h264_class,
};aac中解码器声明如下，位于aacdec.c文件中,注意id(AV_CODEC_ID_AAC)与上面上面的AVCodcID中的AV_CODEC_ID_AAC。
AVCodec ff_aac_decoder = {
.name = "aac",
.long_name = NULL_IF_CONFIG_SMALL("AAC (Advanced Audio Coding)"),
.type = AVMEDIA_TYPE_AUDIO,
.id = AV_CODEC_ID_AAC,
.priv_data_size = sizeof(AACContext),
.init = aac_decode_init,
.close = aac_decode_close,
.decode = aac_decode_frame,
.sample_fmts = (const enum AVSampleFormat[]) {
AV_SAMPLE_FMT_FLTP, AV_SAMPLE_FMT_NONE
},
.capabilities = AV_CODEC_CAP_CHANNEL_CONF | AV_CODEC_CAP_DR1,
.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
.channel_layouts = aac_channel_layout,
.flush = flush,
.priv_class = &aac_decoder_class,
.profiles = NULL_IF_CONFIG_SMALL(ff_aac_profiles),
};每一个编解码器对应一个结构体AVCodec