Audio NACK was advertised in preferStereoOpus(). Chrome receivers will
request retransmits when they see rtcp-fb:nack on the Opus PT, but
Firefox senders never reply (Mozilla never shipped the responder side).
Chrome's jitter buffer waits for recovery that never arrives, then
skips — audibly choppy in mixed Firefox→Chrome rooms.
useinbandfec + 700ms playoutDelayHint already cover the loss case
without protocol churn. Comment block warns future code not to re-add
audio NACK without verifying both sides actually implement it for the
negotiated PT.
Keeps: 510k Opus ceiling, fullband pin, cbr=0, maxptime=120, speaker
picker — none of those are the choppy source.
Russell Ballestrini
873591e87d