ffmpeg 中 rtsp相关源码解析(一)

本是古典何须时尚 2021-05-16 20:36 877阅读 0赞

ffmpeg中与rtsp协议相关的代码位于libavformat中

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMzc2MDI_size_16_color_FFFFFF_t_70][]

libavformat/avformat.h文件中声明 **void****av\_register\_all**(**void**);

函数定义位于libavformat/allformats.c中 **av\_register\_all**调用**register\_all**函数**，**从而对多种muxer和demuxer进行注册

static void register_all(void)
    {
        avcodec_register_all();
    
        /* (de)muxers */
       ...
        REGISTER_MUXDEMUX(RTP,              rtp);
        REGISTER_MUXER   (RTP_MPEGTS,       rtp_mpegts);
        REGISTER_MUXDEMUX(RTSP,             rtsp);
        ...
    }

#define REGISTER_MUXER(X, x)                                            \
        {                                                                   \
            extern AVOutputFormat ff_##x##_muxer;                           \
            if (CONFIG_##X##_MUXER)                                         \
                av_register_output_format(&ff_##x##_muxer);                 \
        }
    
    #define REGISTER_DEMUXER(X, x)                                          \
        {                                                                   \
            extern AVInputFormat ff_##x##_demuxer;                          \
            if (CONFIG_##X##_DEMUXER)                                       \
                av_register_input_format(&ff_##x##_demuxer);                \
        }
    
    #define REGISTER_MUXDEMUX(X, x) REGISTER_MUXER(X, x); REGISTER_DEMUXER(X, x)

代码中可以看到为ff\_rtsp\_muxer和ff\_rtsp\_demuxer进行了注册

ff\_rtsp\_muxer和ff\_rtsp\_demuxer的定义位于 libavformat/rtspenc.c、libavformat/rtspdec.c中，

定义如下：

AVOutputFormat ff_rtsp_muxer = {
        .name              = "rtsp",
        .long_name         = NULL_IF_CONFIG_SMALL("RTSP output"),
        .priv_data_size    = sizeof(RTSPState),
        .audio_codec       = AV_CODEC_ID_AAC,
        .video_codec       = AV_CODEC_ID_MPEG4,
        .write_header      = rtsp_write_header,
        .write_packet      = rtsp_write_packet,
        .write_trailer     = rtsp_write_close,
        .flags             = AVFMT_NOFILE | AVFMT_GLOBALHEADER,
        .priv_class        = &rtsp_muxer_class,
    };
    
    AVInputFormat ff_rtsp_demuxer = {
        .name           = "rtsp",
        .long_name      = NULL_IF_CONFIG_SMALL("RTSP input"),
        .priv_data_size = sizeof(RTSPState),
        .read_probe     = rtsp_probe,
        .read_header    = rtsp_read_header,
        .read_packet    = rtsp_read_packet,
        .read_close     = rtsp_read_close,
        .read_seek      = rtsp_read_seek,
        .flags          = AVFMT_NOFILE,
        .read_play      = rtsp_read_play,
        .read_pause     = rtsp_read_pause,
        .priv_class     = &rtsp_demuxer_class,
    };

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTEzMzc2MDI_size_16_color_FFFFFF_t_70]: /images/20210516/c0110c2344744f7bae4b61f020ffb04d.png