can't read with RTMP / LHLS a stream encoded with nvenc: DTS is greater than PTS

[JIEgOKOJI]

Which version are you using?

latest

Which operating system are you using?

• [x] Linux amd64 standard
• [ ] Linux amd64 Docker
• [] Linux arm64 standard
• [ ] Linux arm64 Docker
• [ ] Linux arm7 standard
• [ ] Linux arm7 Docker
• [ ] Linux arm6 standard
• [ ] Linux arm6 Docker
• [x] Windows amd64 standard
• [ ] Windows amd64 Docker (WSL backend)
• [ ] macOS amd64 standard
• [ ] macOS amd64 Docker
• [ ] Other (please describe)

Describe the issue

When using lhls and starting stream from OBS with nvenc encoder. The Muxer crashes with logs " destroyed (muxer error: DTS is greater than PTS)"

Describe how to replicate the issue

1. start the server
2. publish with Obs and nvenc with b-frames
3. read with logs

Did you attach the server logs?

2022/06/13 17:21:30 INF [HLS] [muxer lhls/6] is converting into HLS 2022/06/13 17:21:32 INF [HLS] [muxer lhls/6] destroyed (muxer error: DTS is greater than PTS)

no

Did you attach a network dump?

no

[aler9]

Hello, this is caused by the fact that nvenc doesn't include the max_num_reorder_frames field into the H264 SPS, and therefore the server can't compute the initial offset between PTS and DTS (which is max_num_reorder_frames * 1 / fps). Without this initial offset, it happens that DTS > PTS.

FFmpeg uses an undocumented algorithm that allows to derive max_num_reorder_frames when it is not present, that may be implemented in the server too:

https://github.com/FFmpeg/FFmpeg/blob/c6364b711bad1fe2fbd90e5b2798f87080ddf5ea/libavcodec/h264_ps.c#L587

i need to investigate.

[aler9]

fixed in v0.19.2.

[github-actions[bot]]

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