[Galene] Building a streaming gateway for Galène

[Alexandre IOOSS <erdnaxe@crans.org>]

Hello all,

For the past two weeks I have been working on streaming from a
broadcasting software such as OBS-Studio (that uses FFMpeg) to Galène.
This would enable users to use Galène for low-latency video streaming
and as a robust self-hosted Twitch alternative for conferences.

I believe we don't want to have to do any video/audio conversion on the
server side, so I see multiple possibilities to stream to Galène:

0. Using OBS Virtual v4l2 camera, but it is not portable and has audio
sync issues.
1. Streaming to a gateway that will initiate the WebRTC session with Galène.
2. Implement WebRTC support in OBS-Studio as an output plugin.

The point 2 was already tried by
<https://github.com/CoSMoSoftware/OBS-studio-webrtc> but it seems to be
problematic as they are using the WebRTC library from Chromium. I don't
expect this OBS fork to be merged upstream soon.

Last week I tried to implement a gateway using GStreamer webrtcbin
plugin, <https://github.com/erdnaxe/galene-stream>. Although I am able
to stream to Galène, I observe video drops. I am circumventing the issue
by forcing the VP8 encoder to insert a keyframe every 5 frames, but that
seems a terrible hack.

Right now I am a bit lost, I don't know if I should either try to
replace GStreamer webrtcbin with Pion
(https://github.com/pion/example-webrtc-applications/tree/master/gstreamer-send),
or if something is wrong with GStreamer/Galène. Does anyone have advice?

Best regards,

-- 
Alexandre Iooss