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feat: Implement sequential lookahead preloading for multiple upcoming TTS sentences.

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This commit is contained in:
Richard R 2026-02-22 03:31:03 -07:00
parent 6e442e8dba
commit 49c5b794ea
1 changed files with 64 additions and 36 deletions
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100
src/contexts/TTSContext.tsx
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@ -1519,45 +1519,73 @@ export function TTSProvider({ children }: { children: ReactNode }): ReactElement
}, [activeHowl, isPlaying, currentSentenceAlignment]);
/**
* Preloads the next sentence's audio
* Preloads upcoming sentences sequentially.
* As soon as one preload finishes, the next one starts (up to lookahead window).
*/
const preloadNextAudio = useCallback(async () => {
const preloadNextAudio = useCallback(() => {
const PRELOAD_LOOKAHEAD = 3;
if (isAtLimit) return;
try {
const nextSentence = sentences[currentIndex + 1];
if (nextSentence) {
const nextKey = buildCacheKey(
nextSentence,
voice,
speed,
configTTSProvider,
ttsModel,
);
if (!audioCache.has(nextKey) && !preloadRequests.current.has(nextSentence)) {
// Start preloading but don't wait for it to complete
processSentence(nextSentence, true).catch(error => {
const status = (() => {
if (typeof error === 'object' && error !== null && 'status' in error) {
const maybe = (error as { status?: unknown }).status;
return typeof maybe === 'number' ? maybe : undefined;
}
return undefined;
})();
const code = (() => {
if (typeof error === 'object' && error !== null && 'code' in error) {
const maybe = (error as { code?: unknown }).code;
return typeof maybe === 'string' ? maybe : undefined;
}
return undefined;
})();
// Ignore quota errors during preload
if (!(status === 429 && code === 'USER_DAILY_QUOTA_EXCEEDED')) {
console.error('Error preloading next sentence:', error);
}
});
}
const preloadFromOffset = (offset: number) => {
if (offset > PRELOAD_LOOKAHEAD) return;
const sentenceIndex = currentIndex + offset;
const nextSentence = sentences[sentenceIndex];
if (!nextSentence) return;
const nextKey = buildCacheKey(
nextSentence,
voice,
speed,
configTTSProvider,
ttsModel,
);
if (audioCache.has(nextKey)) {
preloadFromOffset(offset + 1);
return;
}
const pending = preloadRequests.current.get(nextSentence);
if (pending) {
void pending
.finally(() => {
preloadFromOffset(offset + 1);
})
.catch(() => {
// Prevent unhandled rejections from the chained preload progression.
});
return;
}
void processSentence(nextSentence, true)
.catch((error) => {
const status = (() => {
if (typeof error === 'object' && error !== null && 'status' in error) {
const maybe = (error as { status?: unknown }).status;
return typeof maybe === 'number' ? maybe : undefined;
}
return undefined;
})();
const code = (() => {
if (typeof error === 'object' && error !== null && 'code' in error) {
const maybe = (error as { code?: unknown }).code;
return typeof maybe === 'string' ? maybe : undefined;
}
return undefined;
})();
// Ignore quota errors during preload.
if (!(status === 429 && code === 'USER_DAILY_QUOTA_EXCEEDED')) {
console.error(`Error preloading sentence at offset ${offset}:`, error);
}
})
.finally(() => {
preloadFromOffset(offset + 1);
});
};
try {
preloadFromOffset(1);
} catch (error) {
console.error('Error initiating preload:', error);
}
@ -1576,7 +1604,7 @@ export function TTSProvider({ children }: { children: ReactNode }): ReactElement
// Start playing current sentence
playAudio();
// Start preloading next sentence in parallel
// Start background lookahead preloading for upcoming sentences.
preloadNextAudio();
return () => {