Frontend hot path (player.js, background.js):
- visualizer rAF: drop per-frame getComputedStyle('--accent') (cached on
applyAccentColor), build canvas LinearGradient once per accent change
instead of 32× per frame, batch all bars into a single beginPath/fill
- FPS-gate canvas redraw via frequencyDataVersion so 60-144 Hz monitors
stop re-rendering identical frames produced at 30 Hz on the backend
- editorial spectrum bars: replace style.height (layout) with
transform: scaleY (compositor-only); cache bar refs, pre-compute
per-bar gain/range, dedup writes at 1/1000 quantization
- coalesce VU needle into the visualizer rAF; cache vuNeedle ref;
dedup angle writes at 0.1°
- updateUI: status-payload fingerprint short-circuits the redundant
status_update broadcasts that fire during a track change
- swapArtworkSrc: only force layout reflow when keyframe is in flight;
drop the ?_=Date.now() cache-buster so identical artwork URLs reuse
the decoded bitmap; mini/glow imgs only re-set src when changed
- drop the fullscreen MutationObserver — fs-bloom-art is mirrored
directly from the artwork-swap path, eliminating the second blur paint
- updateProgress: skip text writes when the rounded second hasn't moved;
POSITION_INTERPOLATION_MS 100 → 250
- background.js: lift resizeBackgroundCanvas out of the rAF body, cache
step, accept new int-scaled wire format
CSS:
- spectrum bars use transform: scaleY(var(--bar-h-scale)) + transition
on transform; will-change updated to transform
- album-art-glow and fs-bloom-art switched to small-source-blur trick
(render at 20-25% size, scale 4-6×, lower blur radius) — visually
equivalent, ~10-25× cheaper repaint on track change
- drop unused transition: filter on .vinyl-stage #album-art
Backend (audio_analyzer.py, websocket_manager.py):
- pre-allocate windowed and cumsum buffers; replace
np.concatenate(([0.0], np.cumsum(...))) with cumsum[0]=0 +
np.cumsum(out=cumsum[1:]); float32 hanning window
- RMS via np.dot(mono, mono) — no astype copy, no ** temp
- int16 wire format (scale=1000) — smaller JSON, no Python float boxing
- versioned data + threading.Event so _audio_broadcast_loop is event-
driven (ev.wait + monotonic seq dedup) instead of polling on a timer
with the always-false `data is _last_data` identity check
ruff clean, pytest 7 passed / 3 numpy-skipped, esbuild bundle 113.6 kB.
- WebGL shader background with flowing waves, radial pulse, and frequency ring arcs
- Reacts to captured audio data (frequency bands + bass) when visualizer is active
- Uses page accent color; adapts to dark/light theme via bg-primary blending
- Toggle button in header toolbar, state persisted in localStorage
- Cached uniform locations and color values to avoid per-frame getComputedStyle calls
- i18n support for EN/RU locales
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
alexei.dolgolyov