FFmpeg4.0.2 over版本av_register_all()流程(二十九)

1.ffmpeg3.4.8中av_register_all()流程.
<1>.ffmpeg-3.4.8/libavformat/allformats.c
void av_register_all(void){
  static AVOnce control = AV_ONCE_INIT;
  ff_thread_once(&control, register_all);
}

static void register_all(void){
    avcodec_register_all();
    //注册所有编解码器、解封装等
    /* (de)muxers */
    REGISTER_MUXER   (A64,              a64);
    REGISTER_DEMUXER (AA,               aa);
    REGISTER_DEMUXER (AAC,              aac);
    REGISTER_MUXDEMUX(AC3,              ac3);
    REGISTER_DEMUXER (ACM,              acm);
    REGISTER_DEMUXER (ACT,              act);
    REGISTER_DEMUXER (ADF,              adf);
    REGISTER_DEMUXER (ADP,              adp);
    REGISTER_DEMUXER (ADS,              ads);
    REGISTER_MUXER   (ADTS,             adts);
    RE