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Fix HLS muxer spec violations

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Vanilagy
2026-03-30 18:03:10 +02:00
parent 3bcbcc13f0
commit 6b677291cd
1 changed files with 72 additions and 42 deletions
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src/hls/hls-muxer.ts
+72 -42
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@@ -270,6 +270,7 @@ export class HlsMuxer extends Muxer {
const uniqueMetadata = new Set(unpairedVideoTracks.map(({ metadata }) => {
let key = '';
key += `${metadata.languageCode ?? UNDETERMINED_LANGUAGE}-`;
key += `${metadata.name ?? ''}-`;
key += `${metadata.disposition?.default ?? true}-`;
key += `${metadata.disposition?.primary ?? false}-`;
key += `${metadata.disposition?.forced ?? false}-`;
@@ -308,6 +309,7 @@ export class HlsMuxer extends Muxer {
const uniqueMetadata = new Set(unpairedAudioTracks.map(({ metadata }) => {
let key = '';
key += `${metadata.languageCode ?? UNDETERMINED_LANGUAGE}-`;
key += `${metadata.name ?? ''}-`;
key += `${metadata.disposition?.default ?? true}-`;
key += `${metadata.disposition?.primary ?? false}-`;
key += `${metadata.disposition?.forced ?? false}-`;
@@ -992,6 +994,14 @@ export class HlsMuxer extends Muxer {
trackData.closed = true;
}
// Compute a single target duration across all playlists, as the spec mandates they match
let globalTargetDuration = this.targetSegmentDuration;
for (const playlist of this.playlists) {
for (const segment of playlist.writtenSegments) {
globalTargetDuration = Math.max(globalTargetDuration, segment.duration);
}
}
for (const playlist of this.playlists) {
if (playlist.currentSegmentStartTimestamp !== null) {
await this.advancePlaylist(playlist);
@@ -1001,17 +1011,45 @@ export class HlsMuxer extends Muxer {
let peakBitrate = 0;
let totalBits = 0;
let totalDuration = 0;
for (const segment of playlist.writtenSegments) {
peakBitrate = Math.max(peakBitrate, 8 * segment.byteSize / segment.duration);
// Per spec, peak bitrate is the largest bit rate of any contiguous set of segments whose total duration is
// between 0.5 and 1.5 times the target duration
const segments = playlist.writtenSegments;
for (let i = 0; i < segments.length; i++) {
totalDuration += segments[i]!.duration;
let windowBytes = 0;
let windowDuration = 0;
for (let j = i; j < segments.length; j++) {
windowBytes += segments[j]!.byteSize;
windowDuration += segments[j]!.duration;
if (windowDuration >= 0.5 * globalTargetDuration && windowDuration <= 1.5 * globalTargetDuration) {
peakBitrate = Math.max(peakBitrate, 8 * windowBytes / windowDuration);
}
if (windowDuration > 1.5 * globalTargetDuration) {
break;
}
}
}
// Fallback: if no contiguous set falls within the range, use per-segment max
if (peakBitrate === 0) {
for (const segment of segments) {
peakBitrate = Math.max(peakBitrate, 8 * segment.byteSize / segment.duration);
}
}
for (const segment of segments) {
totalBits += 8 * segment.byteSize;
}
playlist.peakBitrate = peakBitrate;
if (playlist.currentSegmentStartTimestamp !== null) {
playlist.averageBitrate = totalBits / playlist.currentSegmentStartTimestamp;
}
playlist.averageBitrate = totalBits / (totalDuration || 1);
}
// Write all playlists in parallel
@@ -1023,10 +1061,8 @@ export class HlsMuxer extends Muxer {
this.format._options.onSegment?.(playlist.singleFile.target, playlist.singleFile.info);
}
let targetDuration = this.targetSegmentDuration;
let hasByteOffsets = false;
for (const segment of playlist.writtenSegments) {
targetDuration = Math.max(targetDuration, segment.duration);
hasByteOffsets ||= segment.byteOffset !== null;
}
@@ -1049,7 +1085,7 @@ export class HlsMuxer extends Muxer {
const playlistText = '#EXTM3U\n'
+ `#EXT-X-VERSION:${version}\n`
+ '#EXT-X-PLAYLIST-TYPE:VOD\n'
+ `#EXT-X-TARGETDURATION:${Math.ceil(targetDuration)}\n` // Must be a "decimal-integer"
+ `#EXT-X-TARGETDURATION:${Math.ceil(globalTargetDuration)}\n` // Must be a "decimal-integer"
+ '#EXT-X-INDEPENDENT-SEGMENTS\n' // TODO not when live
+ (isKeyPacketsOnly ? '#EXT-X-I-FRAMES-ONLY\n' : '')
+ (playlist.initSegment
@@ -1085,9 +1121,12 @@ export class HlsMuxer extends Muxer {
const masterPlaylistPromise = (async () => {
let masterPlaylistText = '#EXTM3U\n';
let lastGroupId: string | null = null;
let firstVariantWritten = false;
let lastGroupId: string | null = null;
let groupIdTrackCount = 0;
let hasHadDefaultTrackInGroup = false;
for (const decl of this.playlistDeclarations) {
if (decl.groupId === null) {
const isKeyPacketsOnly = decl.playlist.tracks[0]!.isVideoTrack()
@@ -1101,7 +1140,7 @@ export class HlsMuxer extends Muxer {
}
let peakDeclBitrate = 0;
let totalDeclAverageBitrate = 0;
let maxRefAverageBitrate = 0;
if (decl.references.length > 0) {
const firstRef = decl.references[0]!;
@@ -1113,17 +1152,13 @@ export class HlsMuxer extends Muxer {
for (const ref of decl.references) {
assert(ref.playlist.peakBitrate !== null);
peakDeclBitrate = Math.max(peakDeclBitrate, ref.playlist.peakBitrate);
if (ref.playlist.averageBitrate !== null) {
totalDeclAverageBitrate += ref.playlist.averageBitrate;
}
maxRefAverageBitrate = Math.max(maxRefAverageBitrate, ref.playlist.averageBitrate ?? 0);
}
}
assert(decl.playlist.peakBitrate !== null);
const totalPeakBitrate = decl.playlist.peakBitrate + peakDeclBitrate;
const totalAverageBitrate = (decl.playlist.averageBitrate ?? 0)
+ totalDeclAverageBitrate / (decl.references.length || 1);
const totalAverageBitrate = (decl.playlist.averageBitrate ?? 0) + maxRefAverageBitrate;
if (!firstVariantWritten) {
masterPlaylistText += '\n';
@@ -1167,19 +1202,8 @@ export class HlsMuxer extends Muxer {
// FRAME-RATE is not defined for EXT-X-I-FRAME-STREAM-INF
if (!isKeyPacketsOnly && videoTrack.metadata.frameRate !== undefined) {
masterPlaylistText += `,FRAME-RATE=${+videoTrack.metadata.frameRate.toFixed(16)}`;
}
}
const name = decl.playlist.tracks.find(x => x.metadata.name !== undefined)?.metadata.name;
if (name !== undefined) {
if (/[\n\r"]/.test(name)) {
console.warn(
'Dropping track name since it includes a line feed, carriage return, or double quote'
+ ' character, which are not allowed in HLS playlist attributes.',
);
} else {
masterPlaylistText += `,NAME="${name}"`;
// Spec requires that frame rate be rounded to 3 decimal places
masterPlaylistText += `,FRAME-RATE=${+videoTrack.metadata.frameRate.toFixed(3)}`;
}
}
@@ -1209,28 +1233,33 @@ export class HlsMuxer extends Muxer {
const track = decl.playlist.tracks[0]!;
const type = track.type;
const name = track.metadata.name;
let name = track.metadata.name ?? null;
const languageCode = track.metadata.languageCode;
const disposition = track.metadata.disposition;
if (lastGroupId === null || decl.groupId !== lastGroupId) {
groupIdTrackCount = 0;
masterPlaylistText += '\n';
hasHadDefaultTrackInGroup = false;
}
lastGroupId = decl.groupId;
groupIdTrackCount++;
masterPlaylistText += `#EXT-X-MEDIA:TYPE=${type.toUpperCase()},GROUP-ID="${decl.groupId}"`;
if (name !== undefined) {
if (/[\n\r"]/.test(name)) {
console.warn(
'Dropping track name since it includes a line feed, carriage return, or double quote'
+ ' character, which are not allowed in HLS playlist attributes.',
);
} else {
masterPlaylistText += `,NAME="${name}"`;
}
if (name !== null && /[\n\r"]/.test(name)) {
console.warn(
'Dropping track name since it includes a line feed, carriage return, or double quote'
+ ' character, which are not allowed in HLS playlist attributes.',
);
name = null;
}
// Name is required, so we have to set it to SOMETHING
name ??= `${languageCode ?? decl.groupId}-${groupIdTrackCount}`;
masterPlaylistText += `,NAME="${name}"`;
if (languageCode !== undefined) {
masterPlaylistText += `,LANGUAGE="${languageCode}"`;
}
@@ -1239,9 +1268,10 @@ export class HlsMuxer extends Muxer {
const dispositionDefault = disposition?.default ?? true;
const dispositionForced = disposition?.forced ?? false;
if (dispositionPrimary) {
if (dispositionPrimary && !hasHadDefaultTrackInGroup) {
// HLS's "DEFAULT" behaves like our "primary"
masterPlaylistText += ',DEFAULT=YES';
hasHadDefaultTrackInGroup = true; // Only one DEFAULT label per group allowed
}
if (dispositionPrimary || dispositionDefault) {
@@ -1258,7 +1288,7 @@ export class HlsMuxer extends Muxer {
const decoderConfig = trackData?.info.decoderConfig;
if (decoderConfig) {
masterPlaylistText += `,CHANNELS=${decoderConfig.numberOfChannels}`;
masterPlaylistText += `,CHANNELS="${decoderConfig.numberOfChannels}"`;
}
}