Opus channel count is wrongly set in MPEG-TS and fMP4 based protocols

[aler9]

Which version are you using?

v1.8.1

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
• [ ] Windows amd64 standard
• [ ] Windows amd64 Docker (WSL backend)
• [ ] macOS amd64 standard
• [ ] macOS amd64 Docker
• [ ] Other (please describe)

Describe the issue

Discussed in #3353

Opus streams with a channel count > 3 cannot be streamed correctly, since the channel count is always set to either 1 or 2 due to a RTSP limitation.

Describe how to replicate the issue

N/A

Did you attach the server logs?

no

Did you attach a network dump?

no

[aler9]

additional infos: multichannel Opus streams can be streamed with RTSP (and probably Chrome WebRTC) through a custom RTP format created by Google and documented here:

https://webrtc-review.googlesource.com/c/src/+/129768 https://gstreamer.freedesktop.org/documentation/rtp/rtpopuspay.html?gi-language=c https://issues.webrtc.org/issues/42233792

[aler9]

TODO

• [X] Support multichannel Opus in RTSP (https://github.com/bluenviron/gortsplib/pull/572)
• [X] Support routing multichannel Opus between RTSP, SRT, HLS, UDP and recording in MPEG-TS and fMP4 (https://github.com/bluenviron/mediamtx/pull/3368)
• [ ] Support multichannel Opus in WebRTC

[aler9]

WebRTC issue moved in #3371

[github-actions[bot]]

This issue is mentioned in release v1.8.2 🚀 Check out the entire changelog by clicking here