Add @mediabunny/aac-encoder extension package

src/adts/adts-demuxer.ts

@@ -6,7 +6,8 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-import { aacChannelMap, aacFrequencyTable, AudioCodec } from '../codec';
+import { aacChannelMap, aacFrequencyTable } from '../../shared/aac-misc';
+import { AudioCodec } from '../codec';
 import { Demuxer } from '../demuxer';
 import {
 	ID3_V2_HEADER_SIZE,

src/adts/adts-misc.ts

@@ -1,47 +0,0 @@
-/*!
- * Copyright (c) 2026-present, Vanilagy and contributors
- *
- * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at https://mozilla.org/MPL/2.0/.
- */
-
-import { AacAudioSpecificConfig } from '../codec';
-import { Bitstream } from '../misc';
-
-export type AdtsHeaderTemplate = {
-	header: Uint8Array;
-	bitstream: Bitstream;
-};
-
-export const buildAdtsHeaderTemplate = (config: AacAudioSpecificConfig): AdtsHeaderTemplate => {
-	const header = new Uint8Array(7);
-	const bitstream = new Bitstream(header);
-
-	const { objectType, frequencyIndex, channelConfiguration } = config;
-	const profile = objectType - 1;
-
-	bitstream.writeBits(12, 0b1111_11111111); // Syncword
-	bitstream.writeBits(1, 0); // MPEG Version
-	bitstream.writeBits(2, 0); // Layer
-	bitstream.writeBits(1, 1); // Protection absence
-	bitstream.writeBits(2, profile); // Profile
-	bitstream.writeBits(4, frequencyIndex); // MPEG-4 Sampling Frequency Index
-	bitstream.writeBits(1, 0); // Private bit
-	bitstream.writeBits(3, channelConfiguration); // MPEG-4 Channel Configuration
-	bitstream.writeBits(1, 0); // Originality
-	bitstream.writeBits(1, 0); // Home
-	bitstream.writeBits(1, 0); // Copyright ID bit
-	bitstream.writeBits(1, 0); // Copyright ID start
-	bitstream.skipBits(13); // Frame length (to be filled per packet)
-	bitstream.writeBits(11, 0x7ff); // Buffer fullness
-	bitstream.writeBits(2, 0); // Number of AAC frames minus 1
-	// Omit CRC check
-
-	return { header, bitstream };
-};
-
-export const writeAdtsFrameLength = (bitstream: Bitstream, frameLength: number) => {
-	bitstream.pos = 30;
-	bitstream.writeBits(13, frameLength);
-};

src/adts/adts-muxer.ts

@@ -6,16 +6,17 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-import { parseAacAudioSpecificConfig, validateAudioChunkMetadata } from '../codec';
+import { buildAdtsHeaderTemplate, parseAacAudioSpecificConfig, writeAdtsFrameLength } from '../../shared/aac-misc';
+import { Bitstream } from '../../shared/bitstream';
+import { validateAudioChunkMetadata } from '../codec';
 import { Id3V2Writer } from '../id3';
 import { metadataTagsAreEmpty } from '../metadata';
-import { assert, Bitstream, toUint8Array } from '../misc';
+import { assert, toUint8Array } from '../misc';
 import { Muxer } from '../muxer';
 import { Output, OutputAudioTrack } from '../output';
 import { AdtsOutputFormat } from '../output-format';
 import { EncodedPacket } from '../packet';
 import { Writer } from '../writer';
-import { buildAdtsHeaderTemplate, writeAdtsFrameLength } from './adts-misc';
 
 export class AdtsMuxer extends Muxer {
 	private format: AdtsOutputFormat;

src/adts/adts-reader.ts

@@ -6,7 +6,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-import { Bitstream } from '../misc';
+import { Bitstream } from '../../shared/bitstream';
 import { FileSlice, readBytes } from '../reader';
 
 export const MIN_ADTS_FRAME_HEADER_SIZE = 7;

src/codec-data.ts

@@ -11,7 +11,6 @@ import {
 	assert,
 	assertNever,
 	base64ToBytes,
-	Bitstream,
 	bytesToBase64,
 	keyValueIterator,
 	getUint24,
@@ -30,6 +29,7 @@ import {
 import { PacketType } from './packet';
 import { MetadataTags } from './metadata';
 import { AC3_SAMPLE_RATES, EAC3_REDUCED_SAMPLE_RATES } from '../shared/ac3-misc';
+import { Bitstream } from '../shared/bitstream';
 
 // References for AVC/HEVC code:
 // ISO 14496-15

src/codec.ts

@@ -6,6 +6,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
+import { parseAacAudioSpecificConfig } from '../shared/aac-misc';
 import {
 	Av1CodecInfo,
 	AvcDecoderConfigurationRecord,
@@ -13,7 +14,6 @@ import {
 	Vp9CodecInfo,
 } from './codec-data';
 import {
-	Bitstream,
 	COLOR_PRIMARIES_MAP,
 	MATRIX_COEFFICIENTS_MAP,
 	TRANSFER_CHARACTERISTICS_MAP,
@@ -590,106 +590,6 @@ export const extractAudioCodecString = (trackInfo: {
 	throw new TypeError(`Unhandled codec '${codec}'.`);
 };
 
-export type AacAudioSpecificConfig = {
-	objectType: number;
-	frequencyIndex: number;
-	sampleRate: number | null;
-	channelConfiguration: number;
-	numberOfChannels: number | null;
-};
-
-export const aacFrequencyTable = [
-	96000, 88200, 64000, 48000, 44100, 32000,
-	24000, 22050, 16000, 12000, 11025, 8000, 7350,
-];
-
-export const aacChannelMap = [-1, 1, 2, 3, 4, 5, 6, 8];
-
-export const parseAacAudioSpecificConfig = (bytes: Uint8Array | null): AacAudioSpecificConfig => {
-	if (!bytes || bytes.byteLength < 2) {
-		throw new TypeError('AAC description must be at least 2 bytes long.');
-	}
-
-	const bitstream = new Bitstream(bytes);
-
-	let objectType = bitstream.readBits(5);
-	if (objectType === 31) {
-		objectType = 32 + bitstream.readBits(6);
-	}
-
-	const frequencyIndex = bitstream.readBits(4);
-	let sampleRate: number | null = null;
-	if (frequencyIndex === 15) {
-		sampleRate = bitstream.readBits(24);
-	} else {
-		if (frequencyIndex < aacFrequencyTable.length) {
-			sampleRate = aacFrequencyTable[frequencyIndex]!;
-		}
-	}
-
-	const channelConfiguration = bitstream.readBits(4);
-	let numberOfChannels: number | null = null;
-	if (channelConfiguration >= 1 && channelConfiguration <= 7) {
-		numberOfChannels = aacChannelMap[channelConfiguration]!;
-	}
-
-	return {
-		objectType,
-		frequencyIndex,
-		sampleRate,
-		channelConfiguration,
-		numberOfChannels,
-	};
-};
-
-export const buildAacAudioSpecificConfig = (config: {
-	objectType: number;
-	sampleRate: number;
-	numberOfChannels: number;
-}) => {
-	let frequencyIndex = aacFrequencyTable.indexOf(config.sampleRate);
-	let customSampleRate: number | null = null;
-
-	if (frequencyIndex === -1) {
-		frequencyIndex = 15;
-		customSampleRate = config.sampleRate;
-	}
-
-	const channelConfiguration = aacChannelMap.indexOf(config.numberOfChannels);
-	if (channelConfiguration === -1) {
-		throw new TypeError(`Unsupported number of channels: ${config.numberOfChannels}`);
-	}
-
-	let bitCount = 5 + 4 + 4;
-	if (config.objectType >= 32) {
-		bitCount += 6;
-	}
-	if (frequencyIndex === 15) {
-		bitCount += 24;
-	}
-
-	const byteCount = Math.ceil(bitCount / 8);
-	const bytes = new Uint8Array(byteCount);
-	const bitstream = new Bitstream(bytes);
-
-	if (config.objectType < 32) {
-		bitstream.writeBits(5, config.objectType);
-	} else {
-		bitstream.writeBits(5, 31);
-		bitstream.writeBits(6, config.objectType - 32);
-	}
-
-	bitstream.writeBits(4, frequencyIndex);
-
-	if (frequencyIndex === 15) {
-		bitstream.writeBits(24, customSampleRate!);
-	}
-
-	bitstream.writeBits(4, channelConfiguration);
-
-	return bytes;
-};
-
 export const OPUS_SAMPLE_RATE = 48_000;
 
 const PCM_CODEC_REGEX = /^pcm-([usf])(\d+)+(be)?$/;

src/conversion.ts

@@ -774,6 +774,12 @@ export class Conversion {
 					);
 				}
 
+				if (codecs.includes('aac')) {
+					elements.push(
+						'\nThe @mediabunny/aac-encoder extension package provides support for encoding AAC.',
+					);
+				}
+
 				if (codecs.includes('ac3') || codecs.includes('eac3')) {
 					elements.push(
 						'\nThe @mediabunny/ac3 extension package provides support'

src/flac/flac-demuxer.ts

@@ -15,7 +15,6 @@ import {
 	assert,
 	AsyncMutex,
 	binarySearchLessOrEqual,
-	Bitstream,
 	textDecoder,
 	UNDETERMINED_LANGUAGE,
 } from '../misc';
@@ -37,6 +36,7 @@ import {
 	readSampleRate,
 	getSampleRateOrUncommon,
 } from './flac-misc';
+import { Bitstream } from '../../shared/bitstream';
 
 type FlacAudioInfo = {
 	numberOfChannels: number;

src/flac/flac-misc.ts

@@ -6,7 +6,8 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-import { assert, assertNever, Bitstream } from '../misc';
+import { Bitstream } from '../../shared/bitstream';
+import { assert, assertNever } from '../misc';
 import { FileSlice, readBytes, readU16Be, readU8 } from '../reader';
 
 type BlockSizeOrUncommon = number | 'uncommon-u16' | 'uncommon-u8';

src/flac/flac-muxer.ts

@@ -10,7 +10,6 @@ import { validateAudioChunkMetadata } from '../codec';
 import { createVorbisComments, FlacBlockType } from '../codec-data';
 import {
 	assert,
-	Bitstream,
 	textEncoder,
 	toDataView,
 	toUint8Array,
@@ -27,6 +26,7 @@ import {
 	getBlockSizeOrUncommon,
 	readCodedNumber,
 } from './flac-misc';
+import { Bitstream } from '../../shared/bitstream';
 
 const FLAC_HEADER = /* #__PURE__ */ new Uint8Array([0x66, 0x4c, 0x61, 0x43]); // 'fLaC'
 const STREAMINFO_SIZE = 38;

src/isobmff/isobmff-boxes.ts

@@ -20,7 +20,6 @@ import {
 	UNDETERMINED_LANGUAGE,
 	assertNever,
 	keyValueIterator,
-	Bitstream,
 } from '../misc';
 import {
 	AudioCodec,
@@ -46,6 +45,7 @@ import {
 } from './isobmff-muxer';
 import { parseAc3SyncFrame, parseEac3SyncFrame, parseOpusIdentificationHeader } from '../codec-data';
 import { MetadataTags, RichImageData } from '../metadata';
+import { Bitstream } from '../../shared/bitstream';
 
 export class IsobmffBoxWriter {
 	private helper = new Uint8Array(8);

src/isobmff/isobmff-demuxer.ts

@@ -6,6 +6,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
+import { parseAacAudioSpecificConfig } from '../../shared/aac-misc';
 import {
 	AacCodecInfo,
 	AudioCodec,
@@ -13,7 +14,6 @@ import {
 	extractVideoCodecString,
 	MediaCodec,
 	OPUS_SAMPLE_RATE,
-	parseAacAudioSpecificConfig,
 	parsePcmCodec,
 	PCM_AUDIO_CODECS,
 	PcmAudioCodec,
@@ -47,7 +47,6 @@ import {
 	assert,
 	binarySearchExact,
 	binarySearchLessOrEqual,
-	Bitstream,
 	COLOR_PRIMARIES_MAP_INVERSE,
 	findLastIndex,
 	isIso639Dash2LanguageCode,
@@ -92,6 +91,7 @@ import {
 } from '../reader';
 import { DEFAULT_TRACK_DISPOSITION, MetadataTags, RichImageData, TrackDisposition } from '../metadata';
 import { AC3_SAMPLE_RATES } from '../../shared/ac3-misc';
+import { Bitstream } from '../../shared/bitstream';
 
 type InternalTrack = {
 	id: number;

src/isobmff/isobmff-muxer.ts

@@ -13,10 +13,8 @@ import { BufferTargetWriter, Writer } from '../writer';
 import { assert, computeRationalApproximation, last, promiseWithResolvers, Rational, simplifyRational } from '../misc';
 import { IsobmffOutputFormatOptions, IsobmffOutputFormat, MovOutputFormat } from '../output-format';
 import { inlineTimestampRegex, SubtitleConfig, SubtitleCue, SubtitleMetadata } from '../subtitles';
+import { aacChannelMap, aacFrequencyTable, buildAacAudioSpecificConfig } from '../../shared/aac-misc';
 import {
-	aacChannelMap,
-	aacFrequencyTable,
-	buildAacAudioSpecificConfig,
 	parsePcmCodec,
 	PCM_AUDIO_CODECS,
 	PcmAudioCodec,

src/matroska/matroska-muxer.ts

@@ -6,8 +6,8 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
+import { Bitstream } from '../../shared/bitstream';
 import {
-	Bitstream,
 	COLOR_PRIMARIES_MAP,
 	MATRIX_COEFFICIENTS_MAP,
 	TRANSFER_CHARACTERISTICS_MAP,
@@ -49,10 +49,8 @@ import {
 	inlineTimestampRegex,
 	parseSubtitleTimestamp,
 } from '../subtitles';
+import { aacChannelMap, aacFrequencyTable, buildAacAudioSpecificConfig } from '../../shared/aac-misc';
 import {
-	aacChannelMap,
-	aacFrequencyTable,
-	buildAacAudioSpecificConfig,
 	OPUS_SAMPLE_RATE,
 	PCM_AUDIO_CODECS,
 	PcmAudioCodec,

src/media-source.ts

@@ -6,11 +6,10 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
+import { buildAacAudioSpecificConfig, parseAacAudioSpecificConfig } from '../shared/aac-misc';
 import {
 	AUDIO_CODECS,
 	AudioCodec,
-	buildAacAudioSpecificConfig,
-	parseAacAudioSpecificConfig,
 	parsePcmCodec,
 	PCM_AUDIO_CODECS,
 	PcmAudioCodec,

src/misc.ts

@@ -6,6 +6,8 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
+import { Bitstream } from '../shared/bitstream';
+
 export function assert(x: unknown): asserts x {
 	if (!x) {
 		throw new Error('Assertion failed.');
@@ -39,85 +41,6 @@ export const isU32 = (value: number) => {
 	return value >= 0 && value < 2 ** 32;
 };
 
-export class Bitstream {
-	/** Current offset in bits. */
-	pos = 0;
-
-	constructor(public bytes: Uint8Array) {}
-
-	seekToByte(byteOffset: number) {
-		this.pos = 8 * byteOffset;
-	}
-
-	private readBit() {
-		const byteIndex = Math.floor(this.pos / 8);
-		const byte = this.bytes[byteIndex] ?? 0;
-		const bitIndex = 0b111 - (this.pos & 0b111);
-		const bit = (byte & (1 << bitIndex)) >> bitIndex;
-
-		this.pos++;
-		return bit;
-	}
-
-	readBits(n: number) {
-		if (n === 1) {
-			return this.readBit();
-		}
-
-		let result = 0;
-
-		for (let i = 0; i < n; i++) {
-			result <<= 1;
-			result |= this.readBit();
-		}
-
-		return result;
-	}
-
-	writeBits(n: number, value: number) {
-		const end = this.pos + n;
-
-		for (let i = this.pos; i < end; i++) {
-			const byteIndex = Math.floor(i / 8);
-			let byte = this.bytes[byteIndex]!;
-			const bitIndex = 0b111 - (i & 0b111);
-
-			byte &= ~(1 << bitIndex);
-			byte |= ((value & (1 << (end - i - 1))) >> (end - i - 1)) << bitIndex;
-			this.bytes[byteIndex] = byte;
-		}
-
-		this.pos = end;
-	};
-
-	readAlignedByte() {
-		// Ensure we're byte-aligned
-		if (this.pos % 8 !== 0) {
-			throw new Error('Bitstream is not byte-aligned.');
-		}
-
-		const byteIndex = this.pos / 8;
-		const byte = this.bytes[byteIndex] ?? 0;
-
-		this.pos += 8;
-		return byte;
-	}
-
-	skipBits(n: number) {
-		this.pos += n;
-	}
-
-	getBitsLeft() {
-		return this.bytes.length * 8 - this.pos;
-	}
-
-	clone() {
-		const clone = new Bitstream(this.bytes);
-		clone.pos = this.pos;
-		return clone;
-	}
-}
-
 /** Reads an exponential-Golomb universal code from a Bitstream.  */
 export const readExpGolomb = (bitstream: Bitstream) => {
 	let leadingZeroBits = 0;

src/mpeg-ts/mpeg-ts-demuxer.ts

@@ -8,10 +8,9 @@
 
 import { SAMPLES_PER_AAC_FRAME } from '../adts/adts-demuxer';
 import { MAX_ADTS_FRAME_HEADER_SIZE, readAdtsFrameHeader } from '../adts/adts-reader';
+import { aacChannelMap, aacFrequencyTable } from '../../shared/aac-misc';
 import {
-	aacChannelMap,
 	AacCodecInfo,
-	aacFrequencyTable,
 	AudioCodec,
 	extractAudioCodecString,
 	extractVideoCodecString,
@@ -54,7 +53,6 @@ import {
 	assert,
 	binarySearchExact,
 	binarySearchLessOrEqual,
-	Bitstream,
 	COLOR_PRIMARIES_MAP_INVERSE,
 	findLastIndex,
 	floorToMultiple,
@@ -71,6 +69,7 @@ import { EncodedPacket, PacketType, PLACEHOLDER_DATA } from '../packet';
 import { FileSlice, readBytes, Reader, readU16Be, readU32Be, readU8 } from '../reader';
 import { buildMpegTsMimeType, MpegTsStreamType, TIMESCALE, TS_PACKET_SIZE } from './mpeg-ts-misc';
 import { AC3_SAMPLE_RATES } from '../../shared/ac3-misc';
+import { Bitstream } from '../../shared/bitstream';
 
 // Resources:
 // ISO/IEC 13818-1

src/mpeg-ts/mpeg-ts-muxer.ts

@@ -6,8 +6,8 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-import { parseAacAudioSpecificConfig, validateAudioChunkMetadata, validateVideoChunkMetadata } from '../codec';
-import { buildAdtsHeaderTemplate, writeAdtsFrameLength } from '../adts/adts-misc';
+import { buildAdtsHeaderTemplate, parseAacAudioSpecificConfig, writeAdtsFrameLength } from '../../shared/aac-misc';
+import { validateAudioChunkMetadata, validateVideoChunkMetadata } from '../codec';
 import {
 	AC3_REGISTRATION_DESCRIPTOR,
 	AvcDecoderConfigurationRecord,
@@ -23,7 +23,8 @@ import {
 	iterateNalUnitsInAnnexB,
 	iterateNalUnitsInLengthPrefixed,
 } from '../codec-data';
-import { assert, Bitstream, promiseWithResolvers, setUint24, toDataView, toUint8Array } from '../misc';
+import { Bitstream } from '../../shared/bitstream';
+import { assert, promiseWithResolvers, setUint24, toDataView, toUint8Array } from '../misc';
 import { Muxer } from '../muxer';
 import { Output, OutputAudioTrack, OutputTrack, OutputVideoTrack } from '../output';
 import { MpegTsOutputFormat } from '../output-format';