The feauture was added in https://webrtc-review.googlesource.com/c/src/+/291119 in order to ensure RTX packet is part of BWE even before the RTP stream is known.
However, it cause an issue if media is signaled with an SSRC that has this RTX SSRC.
Since BWE is now notified about received packets before demuxing to the correct receive stream, it is not necessary to demux RTX packets before the media SSRC is known.
Note that WebRTC require at least one negotiated SSRC/MID before RTCP feedback can be sent. Ie, for BWE to work, at least one media SSRC must be known after this cl. It can either be unsignaled or signaled.
BWE tested with BweRampupWithInitialProbeTest.
Bug: webrtc:14795, webrtc:14817, b/320258158
Change-Id: Icf2c67bedc352720bf846b9ee38d509346af36f2
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/340141
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Per Kjellander <perkj@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#41785}
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