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Preserve playback position on watchdog recovery

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This commit is contained in:
James Magahern
2026-06-12 19:47:02 -07:00
parent c4fb23d971
commit 53487087a2
2 changed files with 201 additions and 29 deletions
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125
public/app.js
View File

@@ -53,10 +53,13 @@ const MIN_PENDING_FRAME_QUEUE = 12;
const MIN_DECODED_FRAME_QUEUE = 24;
const IMAGE_DECODE_TIMEOUT_MS = 3000;
const FRAME_STALL_CHECK_MS = 1000;
const FRAME_STARTUP_STALL_RESET_MS = 10000;
const FRAME_STALL_RESET_MS = 6000;
const PLAYBACK_RESTART_COOLDOWN_MS = 8000;
const FRAME_STARTUP_STALL_RESET_MS = 15000;
const FRAME_STALL_RESET_MS = 12000;
const FRAME_PACKET_ACTIVITY_GRACE_MS = 5000;
const FRAME_UNPAINTED_PACKET_RESET_MS = 20000;
const PLAYBACK_RESTART_COOLDOWN_MS = 15000;
const PLAYBACK_RESTART_DELAY_MS = 750;
const MIN_RECOVERY_RESUME_SECONDS = 2;
const METADATA_REFRESH_ATTEMPTS = 20;
const METADATA_REFRESH_INTERVAL_MS = 650;
@@ -82,6 +85,7 @@ const state = {
seekable: false,
isSeeking: false,
seekPointerId: null,
isRestartingPlayback: false,
seekPreviewTime: 0,
lastSeekCommitTime: null,
lastSeekCommitAt: 0,
@@ -385,7 +389,7 @@ window.addEventListener('online', () => {
const stallReason = getFrameStallReason();
if (state.session && !elements.audio.paused && stallReason) {
restartPlaybackStreams(`network_recovered_${stallReason}`);
void restartPlaybackStreams(`network_recovered_${stallReason}`);
}
});
@@ -393,7 +397,7 @@ document.addEventListener('visibilitychange', () => {
const stallReason = getFrameStallReason();
if (!document.hidden && state.session && !elements.audio.paused && stallReason) {
restartPlaybackStreams(`visible_${stallReason}`);
void restartPlaybackStreams(`visible_${stallReason}`);
}
});
@@ -505,7 +509,7 @@ function clearFrameWatchdog() {
}
function checkFrameWatchdog() {
if (!state.session || state.isSeeking || document.hidden || elements.audio.paused || elements.audio.ended || elements.audio.readyState === 0) {
if (!state.session || state.isSeeking || state.isRestartingPlayback || document.hidden || elements.audio.paused || elements.audio.ended || elements.audio.readyState === 0) {
return;
}
@@ -515,13 +519,13 @@ function checkFrameWatchdog() {
return;
}
restartPlaybackStreams(stallReason);
void restartPlaybackStreams(stallReason);
}
function getFrameStallReason() {
const now = Date.now();
if (!state.session || state.isSeeking || elements.audio.paused || elements.audio.ended || elements.audio.readyState === 0) {
if (!state.session || state.isSeeking || state.isRestartingPlayback || elements.audio.paused || elements.audio.ended || elements.audio.readyState === 0) {
return '';
}
@@ -529,6 +533,21 @@ function getFrameStallReason() {
return '';
}
const hasRecentPackets = state.lastFramePacketAt > state.lastFramePaintedAt
&& now - state.lastFramePacketAt < FRAME_PACKET_ACTIVITY_GRACE_MS;
if (hasRecentPackets) {
const unpaintedSince = state.lastFramePaintedAt > state.lastPlaybackRestartAt
? state.lastFramePaintedAt
: state.lastPlaybackRestartAt;
if (now - unpaintedSince < FRAME_UNPAINTED_PACKET_RESET_MS) {
return '';
}
return 'frame_packets_unpainted';
}
if (state.lastFramePaintedAt < state.lastPlaybackRestartAt) {
return now - state.lastPlaybackRestartAt >= FRAME_STARTUP_STALL_RESET_MS ? 'frame_startup_stalled' : '';
}
@@ -536,8 +555,8 @@ function getFrameStallReason() {
return now - state.lastFramePaintedAt >= FRAME_STALL_RESET_MS ? 'frame_paint_stalled' : '';
}
function restartPlaybackStreams(reason = 'frame_stalled') {
if (!state.session) {
async function restartPlaybackStreams(reason = 'frame_stalled') {
if (!state.session || state.isRestartingPlayback) {
return;
}
@@ -545,9 +564,27 @@ function restartPlaybackStreams(reason = 'frame_stalled') {
noteClientTelemetry('playbackRestarts');
sendClientTelemetry({ force: true, reason });
if (state.seekable && Number.isFinite(state.duration) && state.duration > 0) {
state.lastPlaybackRestartAt = Date.now();
void seekTo(getVisiblePlaybackTime());
state.isRestartingPlayback = true;
try {
const resumeTime = getVisiblePlaybackTime();
if (resumeTime >= MIN_RECOVERY_RESUME_SECONDS) {
const resumed = await resumePlaybackAt(resumeTime, reason);
if (resumed) {
return;
}
}
restartPlaybackFromCurrentSource(reason);
} finally {
state.isRestartingPlayback = false;
}
}
function restartPlaybackFromCurrentSource(reason) {
if (!state.session) {
return;
}
@@ -578,6 +615,67 @@ function restartPlaybackStreams(reason = 'frame_stalled') {
}, PLAYBACK_RESTART_DELAY_MS);
}
async function resumePlaybackAt(value, reason) {
const sessionId = state.session?.id;
if (!sessionId) {
return false;
}
const duration = state.duration;
const targetTime = clampNumber(value, 0, Number.isFinite(duration) ? duration : Number.MAX_SAFE_INTEGER);
try {
const response = await fetch(`/api/session/${encodeURIComponent(sessionId)}/seek`, {
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({ time: targetTime, allowBestEffort: true, reason }),
});
const payload = await response.json();
if (response.status === 409) {
return false;
}
if (!response.ok) {
throw new Error(payload.error ?? 'Recovery seek failed.');
}
if (state.session?.id !== sessionId) {
return true;
}
state.generation += 1;
state.streamGeneration += 1;
state.session = payload;
updateSessionMetadata(payload);
state.playbackOffset = Number.isFinite(payload.seekSeconds) ? payload.seekSeconds : targetTime;
state.seekPreviewTime = state.playbackOffset;
state.isSeeking = false;
state.frameCount = 0;
state.lastFramePacketAt = 0;
state.lastFramePaintedAt = 0;
elements.loader.hidden = false;
clearPlayerMessage();
clearFrameQueue({ keepCurrent: true });
syncPlayhead();
if (state.websocket) {
state.websocket.close(1000, 'client recovery seek');
state.websocket = null;
}
elements.audio.pause();
elements.audio.removeAttribute('src');
elements.audio.load();
connectPlaybackStreams();
return true;
} catch (error) {
console.warn('Playback recovery seek failed', error);
return false;
}
}
function handleFramePacket(packet, streamGeneration) {
if (!(packet instanceof ArrayBuffer) || packet.byteLength <= 8) {
return;
@@ -990,6 +1088,7 @@ function stopSession({ showEntry: shouldShowEntry = true } = {}) {
state.seekable = false;
state.isSeeking = false;
state.seekPointerId = null;
state.isRestartingPlayback = false;
state.seekPreviewTime = 0;
state.lastSeekCommitTime = null;
state.lastSeekCommitAt = 0;

103
server/index.js
View File

@@ -46,6 +46,20 @@ const MAX_YT_DLP_OUTPUT_BYTES = 8 * 1024 * 1024;
const RELAY_BRANCH_PAUSE_BYTES = Math.floor(MAX_RELAY_BRANCH_QUEUE_BYTES / 2);
const JPEG_SOI = Buffer.from([0xff, 0xd8]);
const JPEG_EOI = Buffer.from([0xff, 0xd9]);
const BEST_EFFORT_RESUME_MAX_SECONDS = 30 * 24 * 60 * 60;
const RECORDED_MEDIA_EXTENSIONS = new Set([
'.avi',
'.flv',
'.m4v',
'.mkv',
'.mov',
'.mp4',
'.mpeg',
'.mpg',
'.ogv',
'.webm',
'.wmv',
]);
const defaults = {
fps: clampInteger(process.env.DEFAULT_FPS, 24, 1, 30),
@@ -169,8 +183,10 @@ app.post('/api/session', async (request, response) => {
options,
duration: null,
metadataStatus,
metadataProbePromise: null,
seekSeconds: 0,
seekGeneration: 0,
forceSplitPlayback: false,
createdAt: Date.now(),
lastUsedAt: Date.now(),
});
@@ -201,7 +217,7 @@ app.get('/api/session/:sessionId', (request, response) => {
response.json(formatSessionPayload(session));
});
app.post('/api/session/:sessionId/seek', (request, response) => {
app.post('/api/session/:sessionId/seek', async (request, response) => {
const session = getSession(request.params.sessionId);
if (!session) {
@@ -209,11 +225,6 @@ app.post('/api/session/:sessionId/seek', (request, response) => {
return;
}
if (!isSessionSeekable(session)) {
response.status(409).json({ error: 'This stream is not seekable.' });
return;
}
const requestedSeconds = Number(request.body?.time);
if (!Number.isFinite(requestedSeconds)) {
@@ -221,21 +232,42 @@ app.post('/api/session/:sessionId/seek', (request, response) => {
return;
}
const seekSeconds = clampNumber(requestedSeconds, 0, session.duration);
const allowBestEffort = request.body?.allowBestEffort === true;
if (!isSessionSeekable(session) && allowBestEffort && session.metadataStatus !== 'unavailable') {
await ensureSessionDuration(session);
}
const canSeekExactly = isSessionSeekable(session);
const canResumeBestEffort = allowBestEffort && canBestEffortResumeWithoutDuration(session);
if (!canSeekExactly && !canResumeBestEffort) {
response.status(409).json({ error: 'This stream is not seekable.' });
return;
}
const seekSeconds = canSeekExactly
? clampNumber(requestedSeconds, 0, session.duration)
: clampNumber(requestedSeconds, 0, BEST_EFFORT_RESUME_MAX_SECONDS);
const playback = playbacks.get(session.id);
const stopReason = allowBestEffort ? 'client_recovery_seek' : 'client_seek';
session.seekSeconds = seekSeconds;
session.seekGeneration += 1;
session.lastUsedAt = Date.now();
if (!canSeekExactly && canResumeBestEffort && PLAYBACK_CONNECTION_MODE === 'relay') {
session.forceSplitPlayback = true;
}
if (playback && !playback.closed) {
playback.stop('client_seek');
playback.stop(stopReason);
if (playbacks.get(session.id) === playback) {
playbacks.delete(session.id);
}
}
logInfo(`session seeked id=${shortId(session.id)} time=${seekSeconds.toFixed(3)} duration=${session.duration.toFixed(3)}`);
logInfo(`session seeked id=${shortId(session.id)} reason=${stopReason} time=${seekSeconds.toFixed(3)} duration=${Number.isFinite(session.duration) ? session.duration.toFixed(3) : 'unknown'} exact=${canSeekExactly}`);
response.json(formatSessionPayload(session));
});
@@ -701,7 +733,26 @@ function hasRecordedDuration(session) {
return Number.isFinite(session.duration) && session.duration > 0;
}
function canBestEffortResumeWithoutDuration(session) {
return session.sourceKind === 'youtube'
|| isLikelyRecordedMediaUrl(session.originalUrl)
|| isLikelyRecordedMediaUrl(session.url);
}
function isLikelyRecordedMediaUrl(value) {
try {
const parsed = new URL(value);
return RECORDED_MEDIA_EXTENSIONS.has(path.extname(parsed.pathname).toLowerCase());
} catch {
return false;
}
}
function getSessionPlaybackConnectionMode(session) {
if (session.forceSplitPlayback) {
return 'split';
}
if (PLAYBACK_CONNECTION_MODE === 'relay' && hasRecordedDuration(session)) {
return 'split';
}
@@ -710,26 +761,48 @@ function getSessionPlaybackConnectionMode(session) {
}
function startSessionMetadataProbe(session) {
void probeSessionDuration(session).then((duration) => {
void ensureSessionDuration(session);
}
function ensureSessionDuration(session) {
if (hasRecordedDuration(session)) {
return Promise.resolve(session.duration);
}
if (session.metadataProbePromise) {
return session.metadataProbePromise;
}
session.metadataStatus = 'pending';
const probePromise = probeSessionDuration(session).then((duration) => {
const current = sessions.get(session.id);
if (current !== session) {
return;
return duration;
}
session.duration = duration;
session.metadataStatus = Number.isFinite(duration) ? 'ready' : 'unavailable';
return duration;
}).catch((error) => {
const current = sessions.get(session.id);
if (current !== session) {
return;
}
if (current === session) {
session.duration = null;
session.metadataStatus = 'unavailable';
logWarn(`duration probe failed id=${shortId(session.id)} error=${oneLine(error.message)}`);
}
return null;
}).finally(() => {
if (session.metadataProbePromise === probePromise) {
session.metadataProbePromise = null;
}
});
session.metadataProbePromise = probePromise;
return probePromise;
}
async function probeSessionDuration(session) {