Replaces Phase 2's hard SFU↔HTTP switching with continuous
playback-rate adaptation in the worklet itself. Speakers / cohosts /
hosts start at 0.5s conversational latency; when the Double Dragon
controller detects upstream instability it raises the target to 4s
and the worklet TIME-STRETCHES playback (≤8% slowdown) to grow its
actual buffer toward the new target — no silence, no clicks, just a
brief ≤1 semitone pitch shift during the adaptation window. When
clean stats return for 30+ seconds, target shrinks back, worklet
speeds up (≤8%), buffer drains naturally.
Listeners are explicitly locked at rate=1.0 via a new 'lock_rate'
port message — music must not be resampled.
Worklet additions:
- cursor (fractional input-sample index)
- stretchFactor / targetStretch (1.0 default; ±8% range cap)
- stretchRampPerBlock = 0.0002 (about 7.5%/sec ramp)
- adaptive rate target driven by buffered/targetSamples ratio
- linear interpolation between adjacent samples for sub-sample reads
Controller changes:
- ddSetTargetForPub(pubHex, sec) posts retarget to the publisher's
worklet
- Auto path now GROWS target on instability, SHRINKS on sustained
clean — no startStream/stopStream involvement
- DD_BASE_TARGET_SEC = 0.5 (conversational)
- DD_MAX_TARGET_SEC = 4.0 (full wiggle cushion)
- Manual HTTP toggle still respected (state goes manual-on/off,
controller hands off)
Trade-offs documented:
- Linear interpolation (not WSOLA grain processing). Brief pitch
shift during adaptation but minimal artifacts at ≤8% rate change.
- Phase 4 (pitch-preserving WSOLA via grain processing) deferred —
call when current shift is audible enough to upgrade.
End user behavior:
- Calm room: speaker latency stays at 0.5s, conversation feels natural
- Host wiggles: speaker's buffer grows over ~10s to 4s, listener hears
a brief slowdown, then continuous cushion absorbs subsequent wiggles
- After 30s of clean: buffer shrinks back over ~10s, latency returns
Russell Ballestrini
05064a487e