Codec headroom (Tier 1):
- Opus 256 kbps → 510 kbps (spec ceiling) at every music-mode site:
mic publish (SFU + mesh), screen audio, game-share audio. Both
SDP maxaveragebitrate and RTP-level encodings[0].maxBitrate raised.
- Pin Opus fullband: maxplaybackrate=48000, sprop-maxcapturerate=48000
so BWE pressure can't opportunistically narrow to 16/24 kHz.
- cbr=0 explicit (VBR — Opus only spends what it needs).
Loss resilience (Tier 2):
- Audio NACK feedback (a=rtcp-fb:<opus_pt> nack) injected after Opus
rtpmap. Reactive packet recovery, near-zero overhead, ignored by
browsers that don't honor it.
- a=maxptime:120 in music mode advertises tolerance for larger frames
from peers (more encode context = cleaner music at same bitrate).
Playback chain (Tier 3):
- New speaker output selector (setSinkId) so listeners can route peer
audio to studio monitors / external DAC. Hidden on Safari (no
setSinkId on HTMLMediaElement). Persists to localStorage; applied
to every remote <audio> on creation and on user switch.
Live sessions need leave+enter to pick up the new SDP (per CLAUDE.md —
existing RTCPeerConnections are locked to whatever was negotiated at
creation time).
make stamp updates web/zebra-spaces.html footer date + hashes.
Russell Ballestrini
23a4649b37