Libavformat 记录 RTP 流太快（FPS 太高）

Question

我正在尝试使用 libavformat 录制 RTP 流，但是录制视频的 FPS 高得离谱，我得到数千 FPS，如果不是一万。我尝试将 FPS 设置为 30 进行以下修改：

AVFormatContext *src; // Assume src is set here to demuxer's context
AVStream *source_stream = src->streams[i];
AVStream *dest_stream = avformat_new_stream(dest, NULL); // dest is muxer's context here
const AVCodec *pCodec = avcodec_find_decoder(source_stream->codecpar->codec_id);
AVCodecContext *avctx = avcodec_alloc_context3(pCodec);
avctx->time_base = av_make_q(1, 30000);
avcodec_parameters_to_context(avctx, source_stream->codecpar);
avcodec_parameters_from_context(dest_stream->codecpar, avctx);
dest_stream->sample_aspect_ratio = source_stream->sample_aspect_ratio;
dest_stream->time_base = avctx->time_base;
dest_stream->avg_frame_rate = av_make_q(30, 1);
dest_stream->r_frame_rate = source_stream->r_frame_rate;
dest_stream->disposition = source_stream->disposition;

然后，在记录阶段，我在读取新数据包时执行以下操作：

packet->pts = av_rescale_q(packet->pts, src_stream->time_base, dest_stream->time_base);
packet->dts = av_rescale_q(packet->dts, src_stream->time_base, dest_stream->time_base);
packet->duration = dest_stream->time_base.den / dest_stream->time_base.num / dest_stream->avg_frame_rate.num * dest_stream->avg_frame_rate.den;
av_interleaved_write_frame(dest, packet);

我得到的错误日志如下，以重复的方式：

[mp4 @ 0x7fc514001d00] Application provided duration: ... / timestamp: ... is out of range for mov/mp4 format
[mp4 @ 0x7fc514001d00] pts has no value

我使用的libav版本如下：

ffmpeg version 4.3.3 Copyright (c) 2000-2021 the FFmpeg developers
  built with gcc 7 (Ubuntu 7.2.0-8ubuntu3)
  configuration:
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100

P.S: 升级 ffmpeg 版本无效。

Answer 1

我按照提到的进行了以下修改here，现在可以正常工作了：

packet.pts = av_rescale_q_rnd(packet.pts, in_stream->time_base, out_stream->time_base, AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX);
packet.dts = av_rescale_q_rnd(packet.dts, in_stream->time_base, out_stream->time_base, AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX);
packet.duration = av_rescale_q(packet.duration, in_stream->time_base, out_stream->time_base);
// https://ffmpeg.org/doxygen/trunk/structAVPacket.html#ab5793d8195cf4789dfb3913b7a693903
packet.pos = -1;

Libavformat 记录 RTP 流太快（FPS 太高）

Libavformat records RTP stream too fast (too high FPS)

video

ffmpeg

rtp

libav

libavformat