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Bugfix: Handle single sample MPEG2-TS video segments #4794

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merged 1 commit into from
Jul 20, 2022
Merged

Bugfix: Handle single sample MPEG2-TS video segments #4794

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26 changes: 19 additions & 7 deletions src/remux/mp4-remuxer.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,7 @@ export default class MP4Remuxer implements Remuxer {
private _initDTS!: number;
private nextAvcDts: number | null = null;
private nextAudioPts: number | null = null;
private videoSampleDuration: number | null = null;
private isAudioContiguous: boolean = false;
private isVideoContiguous: boolean = false;

Expand Down Expand Up @@ -139,7 +140,7 @@ export default class MP4Remuxer implements Remuxer {
const hasVideo = videoTrack.pid > -1;
const length = videoTrack.samples.length;
const enoughAudioSamples = audioTrack.samples.length > 0;
const enoughVideoSamples = length > 1;
const enoughVideoSamples = (flush && length > 0) || length > 1;
const canRemuxAvc =
((!hasAudio || enoughAudioSamples) &&
(!hasVideo || enoughVideoSamples)) ||
Expand Down Expand Up @@ -383,7 +384,7 @@ export default class MP4Remuxer implements Remuxer {
const initPTS: number = this._initPTS;
let nextAvcDts = this.nextAvcDts;
let offset = 8;
let mp4SampleDuration!: number;
let mp4SampleDuration = this.videoSampleDuration;
let firstDTS;
let lastDTS;
let minPTS: number = Number.POSITIVE_INFINITY;
Expand Down Expand Up @@ -435,9 +436,10 @@ export default class MP4Remuxer implements Remuxer {
// on Safari let's signal the same sample duration for all samples
// sample duration (as expected by trun MP4 boxes), should be the delta between sample DTS
// set this constant duration as being the avg delta between consecutive DTS.
const averageSampleDuration = Math.round(
(lastDTS - firstDTS) / (nbSamples - 1)
);
const inputDuration = lastDTS - firstDTS;
const averageSampleDuration = inputDuration
? Math.round(inputDuration / (nbSamples - 1))
: mp4SampleDuration || track.inputTimeScale / 30;

// handle broken streams with PTS < DTS, tolerance up 0.2 seconds
if (ptsDtsShift < 0) {
Expand Down Expand Up @@ -561,6 +563,7 @@ export default class MP4Remuxer implements Remuxer {
view.setUint32(0, mdatSize);
mdat.set(MP4.types.mdat, 4);

let stretchedLastFrame = false;
for (let i = 0; i < nbSamples; i++) {
const avcSample = inputSamples[i];
const avcSampleUnits = avcSample.units;
Expand All @@ -583,7 +586,9 @@ export default class MP4Remuxer implements Remuxer {
} else {
const config = this.config;
const lastFrameDuration =
avcSample.dts - inputSamples[i > 0 ? i - 1 : i].dts;
i > 0
? avcSample.dts - inputSamples[i - 1].dts
: averageSampleDuration;
if (config.stretchShortVideoTrack && this.nextAudioPts !== null) {
// In some cases, a segment's audio track duration may exceed the video track duration.
// Since we've already remuxed audio, and we know how long the audio track is, we look to
Expand All @@ -601,6 +606,8 @@ export default class MP4Remuxer implements Remuxer {
mp4SampleDuration = deltaToFrameEnd - lastFrameDuration;
if (mp4SampleDuration < 0) {
mp4SampleDuration = lastFrameDuration;
} else {
stretchedLastFrame = true;
}
logger.log(
`[mp4-remuxer]: It is approximately ${
Expand Down Expand Up @@ -637,11 +644,16 @@ export default class MP4Remuxer implements Remuxer {
}

console.assert(
mp4SampleDuration !== undefined,
mp4SampleDuration !== null,
'mp4SampleDuration must be computed'
);
// next AVC sample DTS should be equal to last sample DTS + last sample duration (in PES timescale)
mp4SampleDuration =
stretchedLastFrame || !mp4SampleDuration
? averageSampleDuration
: mp4SampleDuration;
this.nextAvcDts = nextAvcDts = lastDTS + mp4SampleDuration;
this.videoSampleDuration = mp4SampleDuration;
this.isVideoContiguous = true;
const moof = MP4.moof(
track.sequenceNumber++,
Expand Down