Chrome111 handler

[ibc]

The new Chrome111 handler uses scalabilityMode when in Chrome/Chromium/Edge >= M111 (which supports encpding.scalabilityMode), meaning that finally we can decide desired number of spatial and temporal layers.

• Tested in Canary M112.
• See diff between Chrome111 and Chrome74 here: https://www.diffchecker.com/tIkXlhzv/

Some references:

• Available scalabilityMode in libwebrtc for VP8: https://webrtc.googlesource.com/src/+/a1a7c638ece600a0d9e2a1f7d77e1a9050737e90/modules/video_coding/codecs/vp8/vp8_scalability.h
• Available scalabilityMode in libwebrtc for VP9 and H264: https://webrtc.googlesource.com/src/+/ecfe8da46b22883363a66d0909d7d2246cb13c48/modules/video_coding/svc/create_scalability_structure.cc
• See new query params in mediasoup-demo: https://github.com/versatica/mediasoup-demo/#configuration-via-query-parameters
• Thanks @thebongy for documenting this in fix(svc): simulcast/svc broken on M111 because S1T2 is not valid for VP8, use L1T2 instead #247.

Issues

NOTE: These issues are not necessarily intended for this PR.

ISSUE 1: If the user creates a VP8 producer with 3 encodings but do not include scalabilityMode into them, then Chrome will select 'L3T3' but we will signal "1 spatial and 1 temporal layer" to mediasoup, so consumers will just receive the temporal layer 0 of each simulcast stream.

• UPDATE: Fixed in ae22bd9

ISSUE 2: We must allow creation of a SimulcastConsumer in mediasoup side (instead of SingleConsumer) when the producer RtpParameters have a single encoding with scalabilityMode other than 'L1T1'.

• Of course, in the future we should just merge all XxxxxConsumer classes into one as discussed some time ago.
• UPDATE: PR done in mediasoup: Allow simulcast with a single encoding (and N temporal layers) mediasoup#1013

ISSUE 3: User may pass different scalabilityMode for each encoding in simulcast (it works). Problem is that in mediasoup land we assume that number of temporal layers is the same for all the simulcast streams. In fact AFAIR we read it from the first encoding.

• UPDATE: Fixed here: b9435d1

ISSUE 4: There are no temporal layers when using H264 simulcast, but it doesn't even work using Chrome74 handler in Chrome or Canary old or latest versions. ¯_(ツ)_/¯

ISSUE 5: Screen sharing with VP9 (with or without SVC) does not work in Canary M111. No idea. It wouldn't be the first time something similar happens in Canary last version.

[jmillan]

👍

[ibc]

Released in mediasoup-client 3.6.80

[Rush]

ISSUE 5: Screen sharing with VP9 (with our without SVC) does not work in Canary M111. No idea. It wouldn't be the first time something similar happens in Canary last version.

Did anybody figure out a fix? It seems it does work if I do not include any scalabilityMode but how to make it work with scalabilityMode?

[ibc]

Did anybody figure out a fix? It seems it does work if I do not include any scalabilityMode but how to make it work with scalabilityMode?

Please report the issue in libwebrtc project if you wish. Let's not use this PR as a forum.