ffmpeg rtp 流错误 : RTP: dropping old packet received too late

Question

我像这样通过 ffmpeg 开始视频传输:

ffmpeg -f video4linux2 -i /dev/video0 -vcodec libx264 -preset ultrafast -crf 20 -tune zerolatency -s 800x600 -r 25 -b:v 0.9M -sdp_file video.sdp -f rtp rtp://192.168.10.24:5010    

我这样重现:

ffplay -protocol_whitelist file,udp,rtp video.sdp    

一切正常。然后我中断传输，几秒钟后我恢复。 ffplay 不会立即开始重现但会出现错误:

....
[sdp @ 0x6ebf80] RTP: dropping old packet received too lateB f=1/1
    Last message repeated 14 times
[sdp @ 0x6ebf80] RTP: dropping old packet received too lateB f=1/1
    Last message repeated 33 times
[sdp @ 0x6ebf80] RTP: dropping old packet received too lateB f=1/1
    Last message repeated 41 times
[sdp @ 0x6ebf80] RTP: dropping old packet received too lateB f=1/1
    Last message repeated 49 times
[sdp @ 0x6ebf80] RTP: dropping old packet received too lateB f=1/1
    Last message repeated 33 times
[sdp @ 0x6ebf80] RTP: dropping old packet received too lateB f=1/1
    Last message repeated 27 times
[sdp @ 0x6ebf80] RTP: dropping old packet received too lateB f=1/1
    Last message repeated 14 times
[sdp @ 0x6ebf80] RTP: dropping old packet received too lateB f=1/1
    Last message repeated 48 times
[sdp @ 0x6ebf80] RTP: dropping old packet received too lateB f=1/1
    Last message repeated 34 times
......    

一段时间后，播放恢复了，但是太长了。当传入流被暂停时，有没有办法消除或最小化这种性质的错误的发生，可以选择还是其他？阅读手册 ffmpeg 没什么值得的，这没有 naryl .... ((((

Answer 1

好的，所以我遇到了同样的问题并花了一个小时的时间。深入研究ffmpeg代码；在 libavformat/rtpdec.c

    if ((s->seq == 0 && !s->queue) || s->queue_size <= 1) {
    /* First packet, or no reordering */
    return rtp_parse_packet_internal(s, pkt, buf, len);
} else {
    uint16_t seq = AV_RB16(buf + 2);
    int16_t diff = seq - s->seq;
    if (diff < 0) {
        /* Packet older than the previously emitted one, drop */
        av_log(s->ic, AV_LOG_WARNING,
               "RTP: dropping old packet received too late\n");
        return -1;
    } else if (diff <= 1) {

它谈到没有重新排序。所以我跟进了 queue_size 并且在 libavformat/rtsp.c 中谈到了 reordering_queue_size 并且在文档 https://ffmpeg.org/ffmpeg-protocols.html#rtsp 中显示

-reorder_queue_size

    Set number of packets to buffer for handling of reordered packets.

这不是明确的，但如果您添加 -reorder_queue_size 0 它会解决问题，因为它会停止对数据包进行排序。我验证并解决了我的问题。我可以中断源...并在 2 分钟后重新启动，它就可以正常工作

主要是因为是 udp 和实时我不需要任何命令，它应该只播放通过的内容

希望这也能解决您的问题