Master clock: the selected soundtrack (new GET /api/audio/{id} —
listening-quality stereo AAC, lazily ffmpeg-extracted and cached in
data/work/audio_hq/) plays through WebAudio, and t_global derives from
AudioContext.currentTime. Every <video> is muted picture-only, so hard
seeks and playbackRate corrections are inaudible (the unmuted video
used to warble on every nudge). Graceful fallback to the old
performance.now() clock + <video> audio when a track can't load, with
an in-place upgrade if the decode lands mid-play. Drift is compensated
in the track's playbackRate; _resync() now recomputes from the live
clock since the soundtrack keeps playing while rAF is throttled.
Spatial audio (🎧 3D audio, shown when poses exist): every enabled
camera's track plays through an HRTF PannerNode at its live
reconstructed pose, gains normalized 1/sqrt(N); the listener follows
the viewer camera each frame (free roam, follow-cam, and M9 paths).
Tracks that finish decoding mid-play join the mix in place; toggling,
seeking, rate and enable changes rebuild the graph at the current
t_global with no timeline jump.
The window.__f4d debug hook is now also available in production builds
via localStorage f4dDebug=1 (headless panes throttle rAF; the pump is
the only way to drive the loop there).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
- GET /api/splat serves data/work/splat.ply; manifest reports has_splat
- scene3d: lazy-load @mkkellogg/gaussian-splats-3d DropInViewer when a splat
exists (rigs/anchors/paths overlay as before); point-cloud fallback intact
- scripts/splat_via_modelbeast.sh: train the splat on the MODELBEAST fleet
(colmap_poses -> brush_train via the mb queue) and drop it in place
- docs/modelbeast-crossover.md: full crossover map (fleet compute, volumetric
capture w/ CorridorKey + audio sync, per-moment splats)
Verified in-browser: 32MB room splat rendered via /api/splat with overlays live.
Full frontend built against the synthetic API (no dependence on lanes A/B/D):
M4 — synchronized playback: master clock from performance.now() (never a <video>);
per-video correction via requestVideoFrameCallback (exact mediaTime) with a
currentTime+half-frame fallback — hard-seek >150ms / nudge playbackRate +/-5% 20-150ms /
lock <20ms; out-of-range videos pause+dim; single audio source; dev sync-error overlay.
Timebase mirrors config.py (lib/timebase.js). Verified: seek is exact to 0ms; continuous
inter-video desync 13ms mean / 46ms max.
M5 — 3D viewer: PLY point cloud, per-video camera paths + current-pose frusta, OrbitControls,
snap-to-camera (intrinsics->PerspectiveCamera fov) + free roam. All COLMAP->Three.js via the
frozen lib/pose.js; pose interpolation in lib/poseTrack.js (slerp+lerp of contract inputs).
M6 — anchor overlays: letterbox-correct per-video canvas; anchors projected via pose.js;
behind-camera cull. Projection agrees with an independent pinhole to 1.45e-13 px.
Timeline — colored event markers + legend, hover tooltip, click-to-jump; draggable scrubber.
Phase-3 seams (annotate.js M8, camPath.js M9) left as stubs. No frozen files edited; no new
deps; no change requests.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
