Incorrect forwarding Firefox video stream with DD header

[bukharin]

Description

Starting jitsi/lib-jitsi-meet@7d484a8 you are enable AV1/VP9 outbound video streams in Firefox 136+ but it seems works buggy now.

Current behavior

In my test scenario I have 3 participants

• Firefox 137 sends 720p AV1 stream
• 1 Chrome ask 720p stream from Firefox
• 1 Chrome ask 180p stream from Firefox

Actual behaivour: both Chrome clients receives 720p from Firefox. Picture for explanation

Reproduces on meet.jit.si. Same behaivour for VP8 Firefox stream.

Also I suppose that forwarding this Firefox stream JVB starts to incorrectly calculate for downlink bandwidth of Chrome clients, because Firefox stream may switch to inactive state quickly.

Expected Behavior

Should works like Chromium

[JonathanLennox]

I can reproduce, but it's a client problem, not a videobridge probem - Firefox is encoding AV1 non-scalably, as a single 720p layer, so there's nothing the JVB can do to scale it down. I'll raise this with the client team.