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Handle invalid signed "tfdt" decode time values #5333

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merged 3 commits into from
Mar 24, 2023
Merged

Handle invalid signed "tfdt" decode time values #5333

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5135cf9
Handle invalid signed "tfdt" decode time values
robwalch Mar 24, 2023
2726f52
Return latest result (falls back to playlist time)
robwalch Mar 24, 2023
6c493ea
Safe check for value over 2^63
robwalch Mar 24, 2023
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7 changes: 4 additions & 3 deletions src/remux/passthrough-remuxer.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -168,11 +168,12 @@ class PassThroughRemuxer implements Remuxer {
}

const startDTS = getStartDTS(initData, data);
const decodeTime = startDTS === null ? timeOffset : startDTS;
if (
isInvalidInitPts(initPTS, startDTS, timeOffset) ||
isInvalidInitPts(initPTS, decodeTime, timeOffset) ||
(initSegment.timescale !== initPTS.timescale && accurateTimeOffset)
) {
initSegment.initPTS = startDTS - timeOffset;
initSegment.initPTS = decodeTime - timeOffset;
this.initPTS = initPTS = {
baseTime: initSegment.initPTS,
timescale: 1,
Expand All @@ -181,7 +182,7 @@ class PassThroughRemuxer implements Remuxer {

const duration = getDuration(data, initData);
const startTime = audioTrack
? startDTS - initPTS.baseTime / initPTS.timescale
? decodeTime - initPTS.baseTime / initPTS.timescale
: (lastEndTime as number);
const endTime = startTime + duration;
offsetStartDTS(initData, data, initPTS.baseTime / initPTS.timescale);
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23 changes: 18 additions & 5 deletions src/utils/mp4-tools.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -350,10 +350,13 @@ export function parseSinf(sinf: Uint8Array): Uint8Array | null {
* @returns the earliest base media decode start time for the
* fragment, in seconds
*/
export function getStartDTS(initData: InitData, fmp4: Uint8Array): number {
export function getStartDTS(
initData: InitData,
fmp4: Uint8Array
): number | null {
// we need info from two children of each track fragment box
return (
findBox(fmp4, ['moof', 'traf']).reduce((result: number | null, traf) => {
return findBox(fmp4, ['moof', 'traf']).reduce(
(result: number | null, traf) => {
const tfdt = findBox(traf, ['tfdt'])[0];
const version = tfdt[0];
const start = findBox(traf, ['tfhd']).reduce(
Expand All @@ -364,7 +367,16 @@ export function getStartDTS(initData: InitData, fmp4: Uint8Array): number {
if (track) {
let baseTime = readUint32(tfdt, 4);
if (version === 1) {
baseTime *= Math.pow(2, 32);
// If value is too large, assume signed 64-bit. Negative track fragment decode times are invalid, but they exist in the wild.
// This prevents large values from being used for initPTS, which can cause playlist sync issues.
// https://github.com/video-dev/hls.js/issues/5303
if (baseTime === UINT32_MAX) {
logger.warn(
`[mp4-demuxer]: Ignoring assumed invalid signed 64-bit track fragment decode time`
);
return result;
}
baseTime *= UINT32_MAX + 1;
baseTime += readUint32(tfdt, 8);
}
// assume a 90kHz clock if no timescale was specified
Expand All @@ -390,7 +402,8 @@ export function getStartDTS(initData: InitData, fmp4: Uint8Array): number {
return start;
}
return result;
}, null) || 0
},
null
);
}

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