srs/trunk/doc
OSSRS-AI 6e93dd73b5
AI: WebRTC: Support optional msid attribute per RFC 8830. v7.0.126 (#4570) (#4572)
Fix issue #4570 by supporting optional `msid` attribute in WebRTC SDP
negotiation, enabling compatibility with libdatachannel and other
clients that don't include msid information.

SRS failed to negotiate WebRTC connections from libdatachannel clients
because:
- libdatachannel SDP lacks `a=ssrc:XX msid:stream_id track_id`
attributes
- SRS required msid information to create track descriptions
- According to RFC 8830, the msid attribute and its appdata (track_id)
are **optional**

If diligently look at the SDP generated by libdatachannel:

```
a=ssrc:42 cname:video-send
a=ssrc:43 cname:audio-send
```

It's deliberately missing the `a=ssrc:XX msid:stream_id track_id` line,
comparing that with this one:

```
a=ssrc:42 cname:video-send
a=ssrc:42 msid:stream_id video_track_id
a=ssrc:43 cname:audio-send  
a=ssrc:43 msid:stream_id audio_track_id
```

In such a situation, to keep compatible with libdatachannel, if no msid
line in sdp, SRS comprehensively and consistently uses:

* app/stream as stream_id, such as live/livestream
* type=video|audio, cname, and ssrc as track_id, such as
track-video-video-send-43
2025-11-11 10:22:31 -05:00
..
Architecture.md GB28181: Fix bug for parsing GB to RTC. 2022-10-07 19:47:34 +08:00
CHANGELOG.md AI: WebRTC: Support optional msid attribute per RFC 8830. v7.0.126 (#4570) (#4572) 2025-11-11 10:22:31 -05:00
Dockers.md Use new cache image name. v6.0.86 (#3815) 2023-10-08 07:43:14 -05:00
Features.md AI: Remove cygwin64, always enable WebRTC, and enforce C++98 compatibility. v7.0.60 (#4447) 2025-08-21 10:03:38 -06:00
ffmpeg-logo.png support ffmpeg filter 2013-12-01 10:54:41 +08:00
ffmpeg-min.png add drawtext filter sample 2013-12-01 12:04:00 +08:00
PERFORMANCE.md Improve README and documents with AI. v5.0.153. v6.0.43 (#3538) 2023-05-12 17:18:30 +08:00
README.md Micro changes and refines. 2022-09-30 17:57:48 +08:00
readme.txt Move doc 2020-01-26 11:14:18 +08:00
Resources.md Merge 4.0release, migrate to new website. 2022-07-31 18:34:18 +08:00
source.200kbps.768x320.flv update readme, add hls(audio-only) support to readme. update sample flv from h264+mp3 to h264+aac 2014-03-21 11:38:02 +08:00
source.flv SquashSRS4: Support RTC2RTMP. 2021-05-01 22:15:57 +08:00
srs-logo.ico Windows: Support cygwin pipline and packager. v5.0.89 (#3257) 2022-11-20 15:02:08 +08:00
srs-logo.png remove the libfreetype for it fullfill with bugs and always cause build failed. 0.9.139 2014-06-29 10:43:53 +08:00