FFMPEG结构体分析：AVCodec

AVCodec是存储编解码器信息的结构体

每一个编解码器对应一个该结构体【AVCodec】，查看一下ffmpeg的源代码，我们可以看一下H.264解码器的结构体如下所示（h264.c）：

H.264解码器的结构体

AVCodec ff_h264_decoder = {
    .name           = "h264",
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = CODEC_ID_H264, //wgj 注意：此处其他类型的解码器的值也不同 
    .priv_data_size = sizeof(H264Context),
    .init           = ff_h264_decode_init,
    .close          = ff_h264_decode_end,
    .decode         = decode_frame,
    .capabilities   = /*CODEC_CAP_DRAW_HORIZ_BAND |*/ CODEC_CAP_DR1 | CODEC_CAP_DELAY |
                      CODEC_CAP_SLICE_THREADS | CODEC_CAP_FRAME_THREADS,
    .flush= flush_dpb,
    .long_name = NULL_IF_CONFIG_SMALL("H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10"),
    .init_thread_copy      = ONLY_IF_THREADS_ENABLED(decode_init_thread_copy),
    .update_thread_context = ONLY_IF_THREADS_ENABLED(decode_update_thread_context),
    .profiles = NULL_IF_CONFIG_SMALL(profiles),
    .priv_class     = &h264_class,
};

JPEG2000解码器结构体（j2kdec.c）

AVCodec ff_jpeg2000_decoder = {
    .name           = "j2k",
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = CODEC_ID_JPEG2000,
    .priv_data_size = sizeof(J2kDecoderContext),
    .init           = j2kdec_init,
    .close          = decode_end,
    .decode         = decode_frame,
    .capabilities = CODEC_CAP_EXPERIMENTAL,
    .long_name = NULL_IF_CONFIG_SMALL("JPEG 2000"),
    .pix_fmts =
        (const enum PixelFormat[]) {PIX_FMT_GRAY8, PIX_FMT_RGB24, PIX_FMT_NONE}
};