fix(core,player,studio): bound trimmed audio playback to the clip window (#1430)

* fix(player): bound the parent audio proxy to its clip window

When iframe autoplay is blocked, audible playback is promoted to a parent-frame
audio proxy. The proxy read the clip's data-start/data-duration once at adopt
time and mirrorTime() only skipped (never paused) the element outside that
window — so a trimmed/moved music clip kept playing the full source past its
on-timeline end, even though the iframe element was correctly paused.

Fix: the proxy keeps a reference to its source iframe element and re-reads
data-start/data-duration each mirror tick (live trims/moves apply), pauses the
proxy when the playhead leaves [start, start+duration), and resumes it when the
playhead re-enters during parent-owned playback.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Co-authored-by: Miguel Ángel <miguel07alm@protonmail.com>

* fix(core,studio): bound trimmed audio playback to the clip window

Trimmed audio played to the source file's natural end instead of
stopping at the clip edge, on every audio path:

- WebAudio (the audible path in Studio): schedulePlayback now passes
  the clip's data-duration as the third start() arg, so the decoded
  buffer stops at the trimmed edge instead of running to the file end.
- Runtime element gating: the duration resolver caps each clip by its
  own data-duration (min of source length, host window, authored
  duration), so a trimmed <audio>/<video> element pauses at its edge.

Studio trim UX:

- Resize live-patches the media-start/playback-start offset, so a
  start-edge drag trims into the source instead of only repositioning
  the clip.
- AudioWaveform windows the rendered peaks to the trimmed slice so the
  waveform tracks the clip edges.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Co-authored-by: Miguel Ángel <miguel07alm@protonmail.com>

* fix(player,core): gate proxy playback to the live clip window

Review follow-ups on the parent-audio-proxy / WebAudio bound:
- seekAll now re-reads live source bounds (_refreshEntryBounds) before
  gating, so a paused scrub right after a trim/move uses the current clip
  window instead of the adopt-time one.
- playAll and clip adoption only start a proxy when the playhead is inside
  the clip's window (_playEntryIfActive), so bulk starts / promotion no
  longer blip audio for clips outside their window until the next tick.
- The WebAudio buffer is now bounded by the host-composition window too
  (matching resolveDurationSeconds), so a sub-composition-nested clip stops
  at the same edge on the WebAudio and HTMLMedia paths.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Co-authored-by: Miguel Ángel <miguel07alm@protonmail.com>

* fix(core,player): reschedule bounded WebAudio on rate change; guard NaN bounds

A bounded WebAudio source's wall-clock length is baked into start()'s duration
arg (in buffer-sample seconds) at its scheduling rate. Mutating playbackRate in
place on a later rate change does not rescale that bound, so a trimmed clip ends
early (fast) or late (slow). setRate now reports whether the rate changed and
exposes hasBoundedActiveSources(); the runtime stopAll()+reschedules active
clips at the new rate when any bounded source is live. The per-clip schedule
loop is extracted to a shared closure so play() and the rate path agree.

Also guard _refreshEntryBounds against a non-numeric duration attribute parsing
to NaN, which would make every window check false and let the proxy play past
its clip end.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Co-authored-by: Miguel Ángel <miguel07alm@protonmail.com>

---------

Co-authored-by: Miguel Ángel <miguel07alm@protonmail.com>
This commit is contained in:
Vance Ingalls
2026-06-14 17:14:49 -07:00
committed by GitHub
co-authored by Claude Opus 4.8 Miguel Ángel
parent 5c8b637369
commit a95e49dbda
8 changed files with 373 additions and 79 deletions
+76 -32
View File
@@ -1469,10 +1469,18 @@ export function initSandboxRuntimeModular(): void {
Number.isFinite(element.duration) && element.duration > mediaStart
? Math.max(0, element.duration - mediaStart)
: null;
if (sourceDuration != null && hostRemaining != null) {
return Math.min(sourceDuration, hostRemaining);
}
return sourceDuration ?? hostRemaining;
// The element's own data-duration is an explicit clip-length trim
// (the studio writes it when you drag the clip edge). It must bound
// playback so a trimmed track stops at its edge instead of running on
// to the source-file or host-composition end. Absent → no cap (an
// untrimmed clip plays its natural source length).
const ownDuration = Number.parseFloat(element.dataset.duration ?? "");
const explicitDuration =
Number.isFinite(ownDuration) && ownDuration > 0 ? ownDuration : null;
const candidates = [sourceDuration, hostRemaining, explicitDuration].filter(
(value): value is number => value != null,
);
return candidates.length > 0 ? Math.min(...candidates) : null;
},
});
// Attach probed volume keyframes to clips so syncRuntimeMedia can use the
@@ -1760,7 +1768,7 @@ export function initSandboxRuntimeModular(): void {
onSetPlaybackRate: (rate) => {
applyPlaybackRate(rate);
if (state.transportClock) state.transportClock.setRate(state.playbackRate);
webAudio.setRate(state.playbackRate);
applyWebAudioRate();
},
onTick: () => {
if (state.tornDown || !clock.isPlaying()) return;
@@ -2133,6 +2141,67 @@ export function initSandboxRuntimeModular(): void {
};
// Player methods route through the TransportClock.
// Schedule WebAudio playback for every in-window audio clip, bounding each
// buffer to its clip window (own data-duration AND the remaining host
// composition window) so trimmed / sub-composition-nested clips stop at the
// same edge as the HTMLMedia path. Reused by play() and by the rate-change
// handler (a rate change can't rescale a bounded source in place).
const scheduleWebAudioForActiveClips = () => {
const gen = webAudio.startGeneration();
const audioEls = document.querySelectorAll("audio[data-start]");
for (const rawEl of audioEls) {
if (!(rawEl instanceof HTMLMediaElement) || !rawEl.isConnected) continue;
const compStart = Number.parseFloat(rawEl.dataset.start ?? "");
if (!Number.isFinite(compStart)) continue;
const mediaStart =
Number.parseFloat(rawEl.dataset.playbackStart ?? rawEl.dataset.mediaStart ?? "0") || 0;
const volumeAttr = Number.parseFloat(rawEl.dataset.volume ?? "");
const vol = Number.isFinite(volumeAttr) ? volumeAttr : 1;
const durationAttr = Number.parseFloat(rawEl.dataset.duration ?? "");
let clipDuration =
Number.isFinite(durationAttr) && durationAttr > 0 ? durationAttr : Number.POSITIVE_INFINITY;
const compositionRoot = rawEl.closest("[data-composition-id]");
if (compositionRoot) {
const inheritedStart = resolveStartForElement(compositionRoot, 0);
const inheritedDuration = resolveDurationForElement(compositionRoot, {
includeAuthoredTimingAttrs: true,
});
if (inheritedDuration != null && inheritedDuration > 0) {
clipDuration = Math.min(
clipDuration,
Math.max(0, inheritedStart + inheritedDuration - compStart),
);
}
}
void webAudio.decodeAudioElement(rawEl).then((buffer) => {
if (!buffer || !clock.isPlaying()) return;
void webAudio.schedulePlayback(
rawEl,
buffer,
compStart,
mediaStart,
clock.now(),
vol * state.bridgeVolume,
gen,
state.playbackRate,
clipDuration,
);
});
}
};
// Apply a new playback rate to the WebAudio transport. Unbounded sources are
// rescaled in place; but a bounded source's window was baked into start()'s
// duration at its prior rate and can't be rescaled, so when one is active we
// stopAll()+reschedule at the new rate to keep trimmed clips ending on time.
const applyWebAudioRate = () => {
const changed = webAudio.setRate(state.playbackRate);
if (changed && webAudioReady && clock.isPlaying() && webAudio.hasBoundedActiveSources()) {
webAudio.stopAll();
scheduleWebAudioForActiveClips();
}
};
player.play = () => {
const tl = state.capturedTimeline;
if (clock.isPlaying()) return;
@@ -2157,32 +2226,7 @@ export function initSandboxRuntimeModular(): void {
// Schedule audio through WebAudio for sample-accurate timing.
// Falls back to HTMLMediaElement playback if WebAudio isn't ready
// or decoding fails (the syncRuntimeMedia path handles that).
if (webAudioReady) {
const gen = webAudio.startGeneration();
const audioEls = document.querySelectorAll("audio[data-start]");
for (const rawEl of audioEls) {
if (!(rawEl instanceof HTMLMediaElement) || !rawEl.isConnected) continue;
const compStart = Number.parseFloat(rawEl.dataset.start ?? "");
if (!Number.isFinite(compStart)) continue;
const mediaStart =
Number.parseFloat(rawEl.dataset.playbackStart ?? rawEl.dataset.mediaStart ?? "0") || 0;
const volumeAttr = Number.parseFloat(rawEl.dataset.volume ?? "");
const vol = Number.isFinite(volumeAttr) ? volumeAttr : 1;
void webAudio.decodeAudioElement(rawEl).then((buffer) => {
if (!buffer || !clock.isPlaying()) return;
void webAudio.schedulePlayback(
rawEl,
buffer,
compStart,
mediaStart,
clock.now(),
vol * state.bridgeVolume,
gen,
state.playbackRate,
);
});
}
}
if (webAudioReady) scheduleWebAudioForActiveClips();
runAdapters("play");
syncMediaForCurrentState();
postState(true);
@@ -2249,7 +2293,7 @@ export function initSandboxRuntimeModular(): void {
player.setPlaybackRate = (rate: number) => {
applyPlaybackRate(rate);
clock.setRate(state.playbackRate);
webAudio.setRate(state.playbackRate);
applyWebAudioRate();
};
// Sync clock duration from any captured timeline
@@ -171,6 +171,43 @@ describe("WebAudioTransport", () => {
});
});
describe("clip duration bound (trim)", () => {
it("bounds an in-progress clip to its remaining authored window", async () => {
const { transport, mock, gen } = setupTransport(100);
// compStart=5, mediaStart=0, compTime=8 → elapsed=3; clipDuration=10 → 7 left
await transport.schedulePlayback(mockEl, mockBuffer, 5, 0, 8, 1, gen, 1, 10);
expect(mock.startFn).toHaveBeenCalledWith(0, 3, 7);
});
it("bounds a future clip to its full authored window", async () => {
const { transport, mock, gen } = setupTransport(100);
// compStart=10, mediaStart=1.5, compTime=2 → elapsed=-8 → delay 8; clipDuration=4
await transport.schedulePlayback(mockEl, mockBuffer, 10, 1.5, 2, 1, gen, 1, 4);
expect(mock.startFn).toHaveBeenCalledWith(108, 1.5, 4);
});
it("does not schedule a clip whose window has already elapsed", async () => {
const { transport, mock, gen } = setupTransport(100);
// elapsed=15 > clipDuration=10 → nothing to play
const result = await transport.schedulePlayback(mockEl, mockBuffer, 5, 0, 20, 1, gen, 1, 10);
expect(result).toBeNull();
expect(mock.startFn).not.toHaveBeenCalled();
});
it("scales the bound by playback rate (buffer seconds)", async () => {
const { transport, mock, gen } = setupTransport(100);
// rate=2, clipDuration=10 → clipSourceLen=20; elapsed=3 → 17 buffer seconds left
await transport.schedulePlayback(mockEl, mockBuffer, 5, 0, 8, 1, gen, 2, 10);
expect(mock.startFn).toHaveBeenCalledWith(0, 3, 17);
});
it("plays unbounded when clipDuration is omitted (legacy behavior)", async () => {
const { transport, mock, gen } = setupTransport(100);
await transport.schedulePlayback(mockEl, mockBuffer, 5, 0, 8, 1, gen);
expect(mock.startFn).toHaveBeenCalledWith(0, 3);
});
});
describe("playback rate", () => {
it("sets sourceNode.playbackRate.value when rate is provided", async () => {
const { transport, mock, gen } = setupTransport(100);
+65 -7
View File
@@ -5,6 +5,42 @@ function normalizeRate(rate: number): number {
return rate;
}
/**
* Start a buffer source, bounding it to the clip's authored window
* (`data-duration`) so a trimmed clip stops at its edge instead of running the
* buffer to the source file's natural end. `clipSourceLen` is the clip span in
* buffer seconds; the third `start()` arg is the portion to play from the
* offset. An infinite `clipDuration` plays unbounded (legacy behavior).
*
* Returns false when the playhead is already past the clip end (nothing to
* play); the caller should discard the source.
*/
function startBoundedSource(
node: AudioBufferSourceNode,
opts: {
elapsed: number;
mediaStart: number;
scheduledAt: number;
safeRate: number;
clipDuration: number;
},
): boolean {
const { elapsed, mediaStart, scheduledAt, safeRate, clipDuration } = opts;
const hasBound = Number.isFinite(clipDuration) && clipDuration > 0;
const clipSourceLen = clipDuration * safeRate;
if (elapsed >= 0) {
const remaining = clipSourceLen - elapsed;
if (hasBound && remaining <= 0) return false;
if (hasBound) node.start(0, elapsed + mediaStart, remaining);
else node.start(0, elapsed + mediaStart);
return true;
}
const delay = -elapsed / safeRate;
if (hasBound) node.start(scheduledAt + delay, mediaStart, clipSourceLen);
else node.start(scheduledAt + delay, mediaStart);
return true;
}
export type ScheduledSource = {
el: HTMLMediaElement;
sourceNode: AudioBufferSourceNode;
@@ -13,6 +49,10 @@ export type ScheduledSource = {
mediaStart: number;
scheduledAt: number;
priorMuted: boolean;
// The clip had a finite window, so start() was given a fixed duration in
// buffer-sample seconds. That bound can't be rescaled in place on a rate
// change — callers must stopAll()+reschedule (see hasBoundedActiveSources).
bounded: boolean;
};
export class WebAudioTransport {
@@ -92,6 +132,7 @@ export class WebAudioTransport {
volume: number,
generation: number,
rate = 1,
clipDuration = Number.POSITIVE_INFINITY,
): Promise<ScheduledSource | null> {
if (!this._ctx || !this._masterGain) return null;
if (generation !== this._playGeneration) return null;
@@ -119,11 +160,19 @@ export class WebAudioTransport {
this._rateAnchorCtx = scheduledAt;
this._rateAnchorComp = compositionTime;
if (elapsed >= 0) {
sourceNode.start(0, elapsed + mediaStart);
} else {
const delay = -elapsed / safeRate;
sourceNode.start(scheduledAt + delay, mediaStart);
if (
!startBoundedSource(sourceNode, {
elapsed,
mediaStart,
scheduledAt,
safeRate,
clipDuration,
})
) {
// Playhead already past the clip end — discard the nodes we built.
sourceNode.disconnect();
gainNode.disconnect();
return null;
}
const priorMuted = el.muted;
@@ -137,6 +186,7 @@ export class WebAudioTransport {
mediaStart,
scheduledAt,
priorMuted,
bounded: Number.isFinite(clipDuration) && clipDuration > 0,
};
this._activeSources.push(scheduled);
this._paused = false;
@@ -163,9 +213,9 @@ export class WebAudioTransport {
* start in the future keep their original wallclock start time callers
* that need rate-correct future starts should `stopAll()` and reschedule.
*/
setRate(rate: number): void {
setRate(rate: number): boolean {
const safeRate = normalizeRate(rate);
if (safeRate === this._rate) return;
if (safeRate === this._rate) return false;
if (this._ctx && !this._paused) {
this._rateAnchorComp = this.getTime();
this._rateAnchorCtx = this._ctx.currentTime;
@@ -178,6 +228,14 @@ export class WebAudioTransport {
swallow("webAudioTransport.setRate", err);
}
}
return true;
}
// A bounded source's wall-clock duration was baked into start()'s duration
// arg at its original rate; a later rate change can't rescale it in place, so
// the caller must stopAll()+reschedule to keep trimmed clips ending on time.
hasBoundedActiveSources(): boolean {
return this._activeSources.some((s) => s.bounded);
}
stopAll(): void {