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Add MP3 support to MPEG-TS demuxer

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This commit is contained in:
Vanilagy
2026-01-16 10:28:00 +01:00
parent c0f2693cb3
commit e3ee9d91a9
3 changed files with 136 additions and 29 deletions
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src/mpeg-ts/mpeg-ts-demuxer.ts
+98 -28
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@@ -50,13 +50,22 @@ import {
TRANSFER_CHARACTERISTICS_MAP_INVERSE,
UNDETERMINED_LANGUAGE,
} from '../misc';
import { FRAME_HEADER_SIZE as MP3_FRAME_HEADER_SIZE, readMp3FrameHeader } from '../../shared/mp3-misc';
import { EncodedPacket, PacketType, PLACEHOLDER_DATA } from '../packet';
import { FileSlice, readBytes, Reader, readU16Be, readU8 } from '../reader';
import { FileSlice, readBytes, Reader, readU16Be, readU32Be, readU8 } from '../reader';
const TIMESCALE = 90_000; // MPEG-TS timestamps run on a 90 kHz clock
const TS_PACKET_SIZE = 188;
const MISSING_PES_PACKET_ERROR = 'No PES packet found where one was expected.';
const enum MpegTsStreamType {
MP3_MPEG1 = 0x03,
MP3_MPEG2 = 0x04,
AAC = 0x0f,
AVC = 0x1b,
HEVC = 0x24,
}
type ElementaryStream = {
demuxer: MpegTsDemuxer;
pid: number;
@@ -218,7 +227,18 @@ export class MpegTsDemuxer extends Demuxer {
let info: ElementaryStream['info'] | null = null;
switch (streamType) {
case 0xf: {
case MpegTsStreamType.MP3_MPEG1:
case MpegTsStreamType.MP3_MPEG2: {
info = {
type: 'audio',
codec: 'mp3',
aacCodecInfo: null,
numberOfChannels: -1,
sampleRate: -1,
};
}; break;
case MpegTsStreamType.AAC: {
info = {
type: 'audio',
codec: 'aac',
@@ -228,9 +248,9 @@ export class MpegTsDemuxer extends Demuxer {
};
}; break;
case 0x1b:
case 0x24: {
const codec = streamType === 0x1b ? 'avc' : 'hevc';
case MpegTsStreamType.AVC:
case MpegTsStreamType.HEVC: {
const codec = streamType === MpegTsStreamType.AVC ? 'avc' : 'hevc';
info = {
type: 'video',
@@ -359,6 +379,19 @@ export class MpegTsDemuxer extends Demuxer {
elementaryStream.info.sampleRate
= aacFrequencyTable[header.samplingFrequencyIndex]!;
elementaryStream.initialized = true;
} else if (elementaryStream.info.codec === 'mp3') {
const word = readU32Be(FileSlice.tempFromBytes(pesPacket.data));
const result = readMp3FrameHeader(word, pesPacket.data.byteLength);
if (!result.header) {
throw new Error(
'Invalid MP3 audio stream; could not read frame header from first packet.',
);
}
elementaryStream.info.numberOfChannels = result.header.channel === 3 ? 1 : 2;
elementaryStream.info.sampleRate = result.header.sampleRate;
elementaryStream.initialized = true;
} else {
throw new Error('Unhandled.');
@@ -1438,6 +1471,7 @@ class MpegTsAudioTrackBacking extends MpegTsTrackBacking implements InputAudioTr
override async markNextPacket(context: PacketReadingContext): Promise<void> {
assert(!context.suppliedPacket);
const codec = this.elementaryStream.info.codec;
const CHUNK_SIZE = 128;
while (true) {
@@ -1448,35 +1482,71 @@ class MpegTsAudioTrackBacking extends MpegTsTrackBacking implements InputAudioTr
while (context.currentPos - startPos < remaining) {
const byte = context.readU8();
if (byte !== 0xff) {
continue;
}
context.skip(-1);
const possibleHeaderStartPos = context.currentPos;
if (codec === 'aac') {
if (byte !== 0xff) {
continue;
}
let remaining = context.ensureBuffered(MAX_FRAME_HEADER_SIZE);
if (remaining instanceof Promise) remaining = await remaining;
context.skip(-1);
const possibleHeaderStartPos = context.currentPos;
if (remaining < MAX_FRAME_HEADER_SIZE) {
return;
}
const headerBytes = context.readBytes(MAX_FRAME_HEADER_SIZE);
const header = readAdtsFrameHeader(FileSlice.tempFromBytes(headerBytes));
if (header) {
context.seekTo(possibleHeaderStartPos);
let remaining = context.ensureBuffered(header.frameLength);
let remaining = context.ensureBuffered(MAX_FRAME_HEADER_SIZE);
if (remaining instanceof Promise) remaining = await remaining;
return context.supplyPacket(
remaining,
Math.round(SAMPLES_PER_AAC_FRAME * TIMESCALE / this.elementaryStream.info.sampleRate),
);
if (remaining < MAX_FRAME_HEADER_SIZE) {
return;
}
const headerBytes = context.readBytes(MAX_FRAME_HEADER_SIZE);
const header = readAdtsFrameHeader(FileSlice.tempFromBytes(headerBytes));
if (header) {
context.seekTo(possibleHeaderStartPos);
let remaining = context.ensureBuffered(header.frameLength);
if (remaining instanceof Promise) remaining = await remaining;
return context.supplyPacket(
remaining,
Math.round(SAMPLES_PER_AAC_FRAME * TIMESCALE / this.elementaryStream.info.sampleRate),
);
} else {
context.seekTo(possibleHeaderStartPos + 1);
}
} else if (codec === 'mp3') {
if (byte !== 0xff) {
continue;
}
context.skip(-1);
const possibleHeaderStartPos = context.currentPos;
let remaining = context.ensureBuffered(MP3_FRAME_HEADER_SIZE);
if (remaining instanceof Promise) remaining = await remaining;
if (remaining < MP3_FRAME_HEADER_SIZE) {
return;
}
const headerBytes = context.readBytes(MP3_FRAME_HEADER_SIZE);
const word = readU32Be(FileSlice.tempFromBytes(headerBytes));
const result = readMp3FrameHeader(word, null);
if (result.header) {
context.seekTo(possibleHeaderStartPos);
let remaining = context.ensureBuffered(result.header.totalSize);
if (remaining instanceof Promise) remaining = await remaining;
const duration = result.header.audioSamplesInFrame * TIMESCALE
/ this.elementaryStream.info.sampleRate;
return context.supplyPacket(remaining, Math.round(duration));
} else {
context.seekTo(possibleHeaderStartPos + 1);
}
} else {
context.seekTo(possibleHeaderStartPos + 1);
throw new Error('Unreachable');
}
}