Question on remb option for Firefox

Hi Jitsi Team,

I made recently some tests on low upload connection with Firefox (ADSL type network with 800-900 kbits in upload). And Firefox video doesn’t work well in this situation.
The sending bandwidth always try to ramp up over the network limit.
Every 10-20 seconds video freeze and the target bitrate decrease but after it restarts to increase over the network limit.
Sending bitrate never stabilizes.

I know that Firefox didn’t support yet transport-cc for bandwidth estimation but it supports remb.
By default remb is disabled in JItsi-Meet configuration.
After enable it in config.js ( enableRemb=true ) , Firefox find a valid sending bandwidth and doesn’t try to use too much bandwidth.

There is any reason or risk to enable remb and transport-cc in Jisti-Meet configuration ? (Remb will be used by firefox and transport-cc by Chrome)

Regards,
Damien

Hi Damien,

Are you using jitsi-videobridge2 or the old bridge (jitsi-videobridge)?

In the new bridge we haven’t implemented support for REMBs yet, therefore we don’t have a working solution for cases such as the one that you’re testing. It’s on our backlog and we’re happy to review or even guide contributions in that area.

The old bridge supports REMBs, as you’ve already found out, but this activates a very old version of the BWE in Chrome that isn’t as performant as the old version and it’s not recommended (there’s been multiple iterations over the years in Chrome’s BWE; unfortunately I’m not aware of any recent measurement studies to link here).

I don’t know remember what would happen if you enable both REMB and TCC. I believe in that case you get the best from both worlds, because REMBs will work for Firefox and Chrome will prefer TCC over REMBs. At least that was the intention when I was implementing this. I can check if this is the case if you want, but please keep in mind that the old bridge is in maintenance mode since a while now and the new bridge is the way forward.

Cheers,
George

Hi Georges,

Many thanks for your detailed response.
I’am using the old videobridge for my test so REMB works fine.

I’ll look at REMB code implementation and see if I can work on porting it to the new videobridge.

Regards,
Damien

Hi @Damien_FETIS, I just wanted to provide a short update this thread, we’ve done some work recently to bring back support for rembs in the new bridge. Let us know if you experience any regression, in case you get a chance to test it.

Hello @gpolitis,

we using jitsi-videobridge2 (3928), is it recommended to enable or disable TCC?

  disableSimulcast: false,
  enableRemb: true,
  enableTcc: true,
  enableLipSync: false,
  disableRtx: false,
  enableRtpStats: false,