Bump patch

* feature(isobmff): read disabled tracks

* Put enabled ISOBMFF tracks first

---------

Co-authored-by: Vanilagy <[email protected]>

README.md

@@ -39,6 +39,10 @@ Mediabunny is a JavaScript library for reading, writing, and converting media fi
   <a href="https://pqina.nl/pintura/" target="_blank" rel="sponsored">
     <img src="./docs/public/sponsors/pintura-labs.png" width="50" height="50" alt="Pintura Labs">
   </a>
+  &nbsp;&nbsp;&nbsp;&nbsp;
+  <a href="https://ponder.ai/" target="_blank" rel="sponsored">
+    <img src="./docs/public/sponsors/ponder.png" width="50" height="50" alt="Ponder">
+  </a>
 </div>
 
 ### Bronze sponsors

dev/convert.html

@@ -57,7 +57,7 @@
 			output,
 			audio: (_, n) => ({
 				discard: n > 1,
-				codec: 'aac',
+				//codec: 'opus',
 				//codec: 'opus',
 				/*
 				process: (sample) => {
@@ -73,7 +73,7 @@
 				//numberOfChannels: 1,
 				//sampleRate: 4000
 				//discard: true
-				forceTranscode: true,
+				//forceTranscode: true,
 			}),
 			/*
 			video: {
@@ -100,6 +100,9 @@
 			},
 			*/
 			video: () => ({
+				width: 720,
+				frameRate: 30,
+				bitrate: Mediabunny.QUALITY_VERY_LOW,
 				//discard: true,
 				/*
 				process: (sample) => {
@@ -176,8 +179,8 @@
 				}
 			},
 			trim: {
-				//start: 0,
-				//end: 10
+				start: 0,
+				end: 20
 			},
 		});
 		console.log(conversion);

dev/demux.html

@@ -14,6 +14,20 @@
 			source: new Mediabunny.BlobSource(file),
 		});
 
+		console.log(await input.getTracks());
+
+		/*
+		return;
+
+		const audioTrack = await input.getPrimaryAudioTrack();
+		const sink = new Mediabunny.EncodedPacketSink(audioTrack);
+
+		for await (const packet of sink.packets()) {
+			console.log(packet.timestamp, packet.duration, packet.type)
+		}
+		*/
+
+		/*
 		const audioTrack = await input.getPrimaryAudioTrack();
 		const sink = new Mediabunny.AudioSampleSink(audioTrack);
 
@@ -27,6 +41,7 @@
 			lastEnd = sample.timestamp + sample.duration;
 			sample.close();
 		}
+		*/
 		
 		/*
 		const sink = new Mediabunny.EncodedPacketSink(videoTrack);

docs/guide/reading-media-files.md

@@ -106,6 +106,10 @@ track.languageCode; // => string
 
 // A user-defined name for this track.
 track.name; // => string
+
+// Information about the intended usage of the track
+// (default, commentary, hearing-impaired, visually-impaired, etc.)
+track.disposition; // TrackDisposition
 ```
 
 #### Codec information

docs/guide/writing-media-files.md

@@ -56,6 +56,7 @@ output.addVideoTrack(videoSource, {
 output.addAudioTrack(audioSourceEng, {
 	language: 'eng', // ISO 639-2/T language code
 	name: 'Developer Commentary', // Sets a user-defined track name
+	disposition: { commentary: true }, // Sets additional flags in the file
 });
 output.addAudioTrack(audioSourceGer, {
 	language: 'ger',

docs/index.md

@@ -98,6 +98,7 @@ const sponsors = {
 	],
 	silver: [
 		{ image: '/sponsors/pintura-labs.png', name: 'Pintura Labs', url: 'https://pqina.nl/pintura/' },
+		{ image: '/sponsors/ponder.png', name: 'Ponder', url: 'https://ponder.ai/' },
 	],
 	bronze: [
 		{ image: '/sponsors/rve.png', name: 'React Video Editor', url: 'https://www.reactvideoeditor.com/' },

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "mediabunny",
-  "version": "1.24.6",
+  "version": "1.25.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "mediabunny",
-      "version": "1.24.6",
+      "version": "1.25.1",
       "license": "MPL-2.0",
       "workspaces": [
         "packages/*"
@@ -7749,9 +7749,9 @@
       }
     },
     "node_modules/mediabunny": {
-      "version": "1.24.5",
-      "resolved": "https://registry.npmjs.org/mediabunny/-/mediabunny-1.24.5.tgz",
-      "integrity": "sha512-4Sd5x8WXQiuDKZcJDAiQjyD0Lg/cg9p+dBShCM02F1pMvKdB9R6+WHZ9NFCFSqViVPX2fYSu95ZIpBUg9+TwTQ==",
+      "version": "1.25.0",
+      "resolved": "https://registry.npmjs.org/mediabunny/-/mediabunny-1.25.0.tgz",
+      "integrity": "sha512-ozaqk6zS2Vbf3+3+OoxKfnCVeZRcv5PO8DgQtBrM5vpWIbpEK+kMVV6pgfo4mC3XtMwvQEMbhj3zEf0LNklh9w==",
       "license": "MPL-2.0",
       "peer": true,
       "workspaces": [
@@ -12242,7 +12242,7 @@
     },
     "packages/mp3-encoder": {
       "name": "@mediabunny/mp3-encoder",
-      "version": "1.24.6",
+      "version": "1.25.1",
       "license": "MPL-2.0",
       "devDependencies": {
         "@types/emscripten": "^1.40.1"

package.json

@@ -1,7 +1,7 @@
 {
   "name": "mediabunny",
   "author": "Vanilagy",
-  "version": "1.24.6",
+  "version": "1.25.1",
   "description": "Pure TypeScript media toolkit for reading, writing, and converting media files, directly in the browser.",
   "type": "module",
   "workspaces": [

packages/mp3-encoder/package.json

@@ -1,7 +1,7 @@
 {
   "name": "@mediabunny/mp3-encoder",
   "author": "Vanilagy",
-  "version": "1.24.6",
+  "version": "1.25.1",
   "description": "MP3 encoder extension for Mediabunny, based on LAME.",
   "main": "./dist/bundles/mediabunny-mp3-encoder.mjs",
   "module": "./dist/bundles/mediabunny-mp3-encoder.mjs",

src/adts/adts-demuxer.ts

@@ -21,6 +21,7 @@ import {
 } from '../misc';
 import { EncodedPacket, PLACEHOLDER_DATA } from '../packet';
 import { readBytes, Reader } from '../reader';
+import { DEFAULT_TRACK_DISPOSITION } from '../metadata';
 import { FrameHeader, MAX_FRAME_HEADER_SIZE, MIN_FRAME_HEADER_SIZE, readFrameHeader } from './adts-reader';
 
 const SAMPLES_PER_AAC_FRAME = 1024;
@@ -188,6 +189,12 @@ class AdtsAudioTrackBacking implements InputAudioTrackBacking {
 		return sampleRate;
 	}
 
+	getDisposition() {
+		return {
+			...DEFAULT_TRACK_DISPOSITION,
+		};
+	}
+
 	async getDecoderConfig(): Promise<AudioDecoderConfig> {
 		assert(this.demuxer.firstFrameHeader);
 

src/codec-data.ts

@@ -24,7 +24,7 @@ import {
 	toUint8Array,
 } from './misc';
 import { PacketType } from './packet';
-import { MetadataTags } from './tags';
+import { MetadataTags } from './metadata';
 
 // References for AVC/HEVC code:
 // ISO 14496-15
@@ -229,7 +229,7 @@ const extractNalUnitTypeForAvc = (data: Uint8Array) => {
 };
 
 /** Builds an AvcDecoderConfigurationRecord from an AVC packet in Annex B format. */
-export const extractAvcDecoderConfigurationRecord = (packetData: Uint8Array) => {
+export const extractAvcDecoderConfigurationRecord = (packetData: Uint8Array): AvcDecoderConfigurationRecord | null => {
 	try {
 		const nalUnits = findNalUnitsInAnnexB(packetData);
 
@@ -247,60 +247,27 @@ export const extractAvcDecoderConfigurationRecord = (packetData: Uint8Array) =>
 
 		// Let's get the first SPS for profile and level information
 		const spsData = spsUnits[0]!;
-		const bitstream = new Bitstream(removeEmulationPreventionBytes(spsData));
+		const spsInfo = parseAvcSps(spsData);
+		assert(spsInfo !== null);
 
-		bitstream.skipBits(1); // forbidden_zero_bit
-		bitstream.skipBits(2); // nal_ref_idc
-		const nal_unit_type = bitstream.readBits(5);
+		const hasExtendedData = spsInfo.profileIdc === 100
+			|| spsInfo.profileIdc === 110
+			|| spsInfo.profileIdc === 122
+			|| spsInfo.profileIdc === 144;
 
-		if (nal_unit_type !== 7) { // SPS NAL unit type is 7
-			console.error('Invalid SPS NAL unit type');
-			return null;
-		}
-
-		const profile_idc = bitstream.readAlignedByte();
-		const constraint_flags = bitstream.readAlignedByte();
-		const level_idc = bitstream.readAlignedByte();
-
-		const record: AvcDecoderConfigurationRecord = {
+		return {
 			configurationVersion: 1,
-			avcProfileIndication: profile_idc,
-			profileCompatibility: constraint_flags,
-			avcLevelIndication: level_idc,
+			avcProfileIndication: spsInfo.profileIdc,
+			profileCompatibility: spsInfo.constraintFlags,
+			avcLevelIndication: spsInfo.levelIdc,
 			lengthSizeMinusOne: 3, // Typically 4 bytes for length field
 			sequenceParameterSets: spsUnits,
 			pictureParameterSets: ppsUnits,
-			chromaFormat: null,
-			bitDepthLumaMinus8: null,
-			bitDepthChromaMinus8: null,
-			sequenceParameterSetExt: null,
+			chromaFormat: hasExtendedData ? spsInfo.chromaFormatIdc : null,
+			bitDepthLumaMinus8: hasExtendedData ? spsInfo.bitDepthLumaMinus8 : null,
+			bitDepthChromaMinus8: hasExtendedData ? spsInfo.bitDepthChromaMinus8 : null,
+			sequenceParameterSetExt: hasExtendedData ? spsExtUnits : null,
 		};
-
-		if (
-			profile_idc === 100
-			|| profile_idc === 110
-			|| profile_idc === 122
-			|| profile_idc === 144
-		) {
-			readExpGolomb(bitstream); // seq_parameter_set_id
-
-			const chroma_format_idc = readExpGolomb(bitstream);
-
-			if (chroma_format_idc === 3) {
-				bitstream.skipBits(1); // separate_colour_plane_flag
-			}
-
-			const bit_depth_luma_minus8 = readExpGolomb(bitstream);
-
-			const bit_depth_chroma_minus8 = readExpGolomb(bitstream);
-
-			record.chromaFormat = chroma_format_idc;
-			record.bitDepthLumaMinus8 = bit_depth_luma_minus8;
-			record.bitDepthChromaMinus8 = bit_depth_chroma_minus8;
-			record.sequenceParameterSetExt = spsExtUnits;
-		}
-
-		return record;
 	} catch (error) {
 		console.error('Error building AVC Decoder Configuration Record:', error);
 		return null;
@@ -377,6 +344,206 @@ export const serializeAvcDecoderConfigurationRecord = (record: AvcDecoderConfigu
 	return new Uint8Array(bytes);
 };
 
+/** Deserializes an AvcDecoderConfigurationRecord from the format specified in Section 5.3.3.1 of ISO 14496-15. */
+export const deserializeAvcDecoderConfigurationRecord = (data: Uint8Array): AvcDecoderConfigurationRecord | null => {
+	try {
+		const view = toDataView(data);
+		let offset = 0;
+
+		// Read header
+		const configurationVersion = view.getUint8(offset++);
+		const avcProfileIndication = view.getUint8(offset++);
+		const profileCompatibility = view.getUint8(offset++);
+		const avcLevelIndication = view.getUint8(offset++);
+		const lengthSizeMinusOne = view.getUint8(offset++) & 0x03;
+
+		const numOfSequenceParameterSets = view.getUint8(offset++) & 0x1F;
+
+		// Read SPS
+		const sequenceParameterSets: Uint8Array[] = [];
+		for (let i = 0; i < numOfSequenceParameterSets; i++) {
+			const length = view.getUint16(offset, false);
+			offset += 2;
+
+			sequenceParameterSets.push(data.subarray(offset, offset + length));
+			offset += length;
+		}
+
+		const numOfPictureParameterSets = view.getUint8(offset++);
+
+		// Read PPS
+		const pictureParameterSets: Uint8Array[] = [];
+		for (let i = 0; i < numOfPictureParameterSets; i++) {
+			const length = view.getUint16(offset, false);
+			offset += 2;
+
+			pictureParameterSets.push(data.subarray(offset, offset + length));
+			offset += length;
+		}
+
+		const record: AvcDecoderConfigurationRecord = {
+			configurationVersion,
+			avcProfileIndication,
+			profileCompatibility,
+			avcLevelIndication,
+			lengthSizeMinusOne,
+			sequenceParameterSets,
+			pictureParameterSets,
+			chromaFormat: null,
+			bitDepthLumaMinus8: null,
+			bitDepthChromaMinus8: null,
+			sequenceParameterSetExt: null,
+		};
+
+		// Check if there are extended profile fields
+		if (
+			(
+				avcProfileIndication === 100
+				|| avcProfileIndication === 110
+				|| avcProfileIndication === 122
+				|| avcProfileIndication === 144
+			)
+			&& offset + 4 <= data.length
+		) {
+			const chromaFormat = view.getUint8(offset++) & 0x03;
+			const bitDepthLumaMinus8 = view.getUint8(offset++) & 0x07;
+			const bitDepthChromaMinus8 = view.getUint8(offset++) & 0x07;
+			const numOfSequenceParameterSetExt = view.getUint8(offset++);
+
+			record.chromaFormat = chromaFormat;
+			record.bitDepthLumaMinus8 = bitDepthLumaMinus8;
+			record.bitDepthChromaMinus8 = bitDepthChromaMinus8;
+
+			// Read SPS Ext
+			const sequenceParameterSetExt: Uint8Array[] = [];
+			for (let i = 0; i < numOfSequenceParameterSetExt; i++) {
+				const length = view.getUint16(offset, false);
+				offset += 2;
+
+				sequenceParameterSetExt.push(data.subarray(offset, offset + length));
+				offset += length;
+			}
+
+			record.sequenceParameterSetExt = sequenceParameterSetExt;
+		}
+
+		return record;
+	} catch (error) {
+		console.error('Error deserializing AVC Decoder Configuration Record:', error);
+		return null;
+	}
+};
+
+export type AvcSpsInfo = {
+	profileIdc: number;
+	constraintFlags: number;
+	levelIdc: number;
+	frameMbsOnlyFlag: number;
+	chromaFormatIdc: number | null;
+	bitDepthLumaMinus8: number | null;
+	bitDepthChromaMinus8: number | null;
+};
+
+/** Parses an AVC SPS (Sequence Parameter Set) to extract basic information. */
+export const parseAvcSps = (sps: Uint8Array): AvcSpsInfo | null => {
+	try {
+		const bitstream = new Bitstream(removeEmulationPreventionBytes(sps));
+
+		bitstream.skipBits(1); // forbidden_zero_bit
+		bitstream.skipBits(2); // nal_ref_idc
+		const nalUnitType = bitstream.readBits(5);
+
+		if (nalUnitType !== 7) { // SPS NAL unit type is 7
+			return null;
+		}
+
+		const profileIdc = bitstream.readAlignedByte();
+		const constraintFlags = bitstream.readAlignedByte();
+		const levelIdc = bitstream.readAlignedByte();
+
+		readExpGolomb(bitstream); // seq_parameter_set_id
+
+		let chromaFormatIdc: number | null = null;
+		let bitDepthLumaMinus8: number | null = null;
+		let bitDepthChromaMinus8: number | null = null;
+
+		// Handle high profile chroma_format_idc
+		if (
+			profileIdc === 100
+			|| profileIdc === 110
+			|| profileIdc === 122
+			|| profileIdc === 244
+			|| profileIdc === 44
+			|| profileIdc === 83
+			|| profileIdc === 86
+			|| profileIdc === 118
+			|| profileIdc === 128
+		) {
+			chromaFormatIdc = readExpGolomb(bitstream);
+			if (chromaFormatIdc === 3) {
+				bitstream.skipBits(1); // separate_colour_plane_flag
+			}
+			bitDepthLumaMinus8 = readExpGolomb(bitstream);
+			bitDepthChromaMinus8 = readExpGolomb(bitstream);
+			bitstream.skipBits(1); // qpprime_y_zero_transform_bypass_flag
+			const seqScalingMatrixPresentFlag = bitstream.readBits(1);
+			if (seqScalingMatrixPresentFlag) {
+				for (let i = 0; i < (chromaFormatIdc !== 3 ? 8 : 12); i++) {
+					const seqScalingListPresentFlag = bitstream.readBits(1);
+					if (seqScalingListPresentFlag) {
+						const sizeOfScalingList = i < 6 ? 16 : 64;
+						let lastScale = 8;
+						let nextScale = 8;
+						for (let j = 0; j < sizeOfScalingList; j++) {
+							if (nextScale !== 0) {
+								const deltaScale = readSignedExpGolomb(bitstream);
+								nextScale = (lastScale + deltaScale + 256) % 256;
+							}
+							lastScale = nextScale === 0 ? lastScale : nextScale;
+						}
+					}
+				}
+			}
+		}
+
+		readExpGolomb(bitstream); // log2_max_frame_num_minus4
+
+		const picOrderCntType = readExpGolomb(bitstream);
+		if (picOrderCntType === 0) {
+			readExpGolomb(bitstream); // log2_max_pic_order_cnt_lsb_minus4
+		} else if (picOrderCntType === 1) {
+			bitstream.skipBits(1); // delta_pic_order_always_zero_flag
+			readSignedExpGolomb(bitstream); // offset_for_non_ref_pic
+			readSignedExpGolomb(bitstream); // offset_for_top_to_bottom_field
+			const numRefFramesInPicOrderCntCycle = readExpGolomb(bitstream);
+			for (let i = 0; i < numRefFramesInPicOrderCntCycle; i++) {
+				readSignedExpGolomb(bitstream); // offset_for_ref_frame[i]
+			}
+		}
+
+		readExpGolomb(bitstream); // max_num_ref_frames
+		bitstream.skipBits(1); // gaps_in_frame_num_value_allowed_flag
+
+		readExpGolomb(bitstream); // pic_width_in_mbs_minus1
+		readExpGolomb(bitstream); // pic_height_in_map_units_minus1
+
+		const frameMbsOnlyFlag = bitstream.readBits(1);
+
+		return {
+			profileIdc,
+			constraintFlags,
+			levelIdc,
+			frameMbsOnlyFlag,
+			chromaFormatIdc,
+			bitDepthLumaMinus8,
+			bitDepthChromaMinus8,
+		};
+	} catch (error) {
+		console.error('Error parsing AVC SPS:', error);
+		return null;
+	}
+};
+
 // Data specified in ISO 14496-15
 export type HevcDecoderConfigurationRecord = {
 	configurationVersion: number;

src/conversion.ts

@@ -48,7 +48,7 @@ import {
 import { Output, TrackType } from './output';
 import { Mp4OutputFormat } from './output-format';
 import { AudioSample, clampCropRectangle, validateCropRectangle, VideoSample } from './sample';
-import { MetadataTags, validateMetadataTags } from './tags';
+import { MetadataTags, validateMetadataTags } from './metadata';
 import { NullTarget } from './target';
 
 /**
@@ -1043,6 +1043,7 @@ export class Conversion {
 								duration: 1 / frameRate,
 							});
 							await this._registerVideoSample(track, trackOptions, source, sample);
+							sample.close();
 						}
 					};
 
@@ -1079,12 +1080,11 @@ export class Conversion {
 							duration: frameRate !== undefined ? 1 / frameRate : duration,
 						});
 						await this._registerVideoSample(track, trackOptions, source, sample);
+						sample.close();
 
 						if (frameRate !== undefined) {
 							lastCanvas = canvas;
 							lastCanvasTimestamp = adjustedSampleTimestamp;
-						} else {
-							sample.close();
 						}
 					}
 
@@ -1184,9 +1184,10 @@ export class Conversion {
 
 		this.output.addVideoTrack(videoSource, {
 			frameRate: trackOptions.frameRate,
-			// TEMP: This condition can be removed when all demuxers properly homogenize to BCP47 in v2
+			// TODO: This condition can be removed when all demuxers properly homogenize to BCP47 in v2
 			languageCode: isIso639Dash2LanguageCode(track.languageCode) ? track.languageCode : undefined,
 			name: track.name ?? undefined,
+			disposition: track.disposition,
 			rotation: needsRerender ? 0 : totalRotation, // Rerendering will bake the rotation into the output
 		});
 		this._addedCounts.video++;
@@ -1423,9 +1424,10 @@ export class Conversion {
 		}
 
 		this.output.addAudioTrack(audioSource, {
-			// TEMP: This condition can be removed when all demuxers properly homogenize to BCP47 in v2
+			// TODO: This condition can be removed when all demuxers properly homogenize to BCP47 in v2
 			languageCode: isIso639Dash2LanguageCode(track.languageCode) ? track.languageCode : undefined,
 			name: track.name ?? undefined,
+			disposition: track.disposition,
 		});
 		this._addedCounts.audio++;
 		this._totalTrackCount++;

src/demuxer.ts

@@ -8,7 +8,7 @@
 
 import { Input } from './input';
 import { InputTrack } from './input-track';
-import { MetadataTags } from './tags';
+import { MetadataTags } from './metadata';
 
 export abstract class Demuxer {
 	input: Input;

src/encode.ts

@@ -115,9 +115,15 @@ export type VideoEncodingAdditionalOptions = {
 	 * format that supports transparency (such as WebM or Matroska).
 	 */
 	alpha?: 'discard' | 'keep';
-	/** Configures the bitrate mode. */
+	/** Configures the bitrate mode; defaults to `'variable'`. */
 	bitrateMode?: 'constant' | 'variable';
-	/** The latency mode used by the encoder; controls the performance-quality tradeoff. */
+	/**
+	 * The latency mode used by the encoder; controls the performance-quality tradeoff.
+	 *
+	 * - `'quality'` (default): The encoder prioritizes quality over latency, and no frames can be dropped.
+	 * - `'realtime'`: The encoder prioritizes low latency over quality, and may drop frames if the encoder becomes
+	 * overloaded to keep up with real-time requirements.
+	 */
 	latencyMode?: 'quality' | 'realtime';
 	/**
 	 * The full codec string as specified in the WebCodecs Codec Registry. This string must match the codec
@@ -125,7 +131,8 @@ export type VideoEncodingAdditionalOptions = {
 	 */
 	fullCodecString?: string;
 	/**
-	 * A hint that configures the hardware acceleration method of this codec. This is best left on `'no-preference'`.
+	 * A hint that configures the hardware acceleration method of this codec. This is best left on `'no-preference'`,
+	 * the default.
 	 */
 	hardwareAcceleration?: 'no-preference' | 'prefer-hardware' | 'prefer-software';
 	/**
@@ -403,31 +410,31 @@ export class Quality {
  * @group Encoding
  * @public
  */
-export const QUALITY_VERY_LOW = new Quality(0.3);
+export const QUALITY_VERY_LOW = /* #__PURE__ */ new Quality(0.3);
 /**
  * Represents a low media quality.
  * @group Encoding
  * @public
  */
-export const QUALITY_LOW = new Quality(0.6);
+export const QUALITY_LOW = /* #__PURE__ */ new Quality(0.6);
 /**
  * Represents a medium media quality.
  * @group Encoding
  * @public
  */
-export const QUALITY_MEDIUM = new Quality(1);
+export const QUALITY_MEDIUM = /* #__PURE__ */ new Quality(1);
 /**
  * Represents a high media quality.
  * @group Encoding
  * @public
  */
-export const QUALITY_HIGH = new Quality(2);
+export const QUALITY_HIGH = /* #__PURE__ */ new Quality(2);
 /**
  * Represents a very high media quality.
  * @group Encoding
  * @public
  */
-export const QUALITY_VERY_HIGH = new Quality(4);
+export const QUALITY_VERY_HIGH = /* #__PURE__ */ new Quality(4);
 
 /**
  * Checks if the browser is able to encode the given codec.

src/flac/flac-demuxer.ts

@@ -28,7 +28,7 @@ import {
 	readU32Be,
 	readU8,
 } from '../reader';
-import { MetadataTags } from '../tags';
+import { DEFAULT_TRACK_DISPOSITION, MetadataTags } from '../metadata';
 import {
 	calculateCrc8,
 	readBlockSize,
@@ -565,6 +565,12 @@ class FlacAudioTrackBacking implements InputAudioTrackBacking {
 		return this.demuxer.audioInfo.sampleRate;
 	}
 
+	getDisposition() {
+		return {
+			...DEFAULT_TRACK_DISPOSITION,
+		};
+	}
+
 	async getFirstTimestamp() {
 		return 0;
 	}

src/flac/flac-muxer.ts

@@ -20,7 +20,7 @@ import { Output, OutputAudioTrack } from '../output';
 import { FlacOutputFormat } from '../output-format';
 import { EncodedPacket } from '../packet';
 import { FileSlice, readBytes } from '../reader';
-import { AttachedImage, metadataTagsAreEmpty } from '../tags';
+import { AttachedImage, metadataTagsAreEmpty } from '../metadata';
 import { Writer } from '../writer';
 import {
 	readBlockSize,
@@ -28,7 +28,7 @@ import {
 	readCodedNumber,
 } from './flac-misc';
 
-const FLAC_HEADER = new Uint8Array([0x66, 0x4c, 0x61, 0x43]); // 'fLaC'
+const FLAC_HEADER = /* #__PURE__ */ new Uint8Array([0x66, 0x4c, 0x61, 0x43]); // 'fLaC'
 const STREAMINFO_SIZE = 38;
 const STREAMINFO_BLOCK_SIZE = 34;
 

src/id3.ts

@@ -7,7 +7,7 @@
  */
 
 import { decodeSynchsafe, encodeSynchsafe } from '../shared/mp3-misc';
-import { MetadataTags } from './tags';
+import { MetadataTags } from './metadata';
 import {
 	coalesceIndex,
 	textDecoder,

src/index.ts

@@ -202,6 +202,7 @@ export {
 	AttachedImage,
 	RichImageData,
 	AttachedFile,
-} from './tags';
+	TrackDisposition,
+} from './metadata';
 
 // 🐡🦔

src/input-format.ts

@@ -481,56 +481,56 @@ export class AdtsInputFormat extends InputFormat {
  * @group Input formats
  * @public
  */
-export const MP4 = new Mp4InputFormat();
+export const MP4 = /* #__PURE__ */ new Mp4InputFormat();
 /**
  * QuickTime File Format input format singleton.
  * @group Input formats
  * @public
  */
-export const QTFF = new QuickTimeInputFormat();
+export const QTFF = /* #__PURE__ */ new QuickTimeInputFormat();
 /**
  * Matroska input format singleton.
  * @group Input formats
  * @public
  */
-export const MATROSKA = new MatroskaInputFormat();
+export const MATROSKA = /* #__PURE__ */ new MatroskaInputFormat();
 /**
  * WebM input format singleton.
  * @group Input formats
  * @public
  */
-export const WEBM = new WebMInputFormat();
+export const WEBM = /* #__PURE__ */ new WebMInputFormat();
 /**
  * MP3 input format singleton.
  * @group Input formats
  * @public
  */
-export const MP3 = new Mp3InputFormat();
+export const MP3 = /* #__PURE__ */ new Mp3InputFormat();
 /**
  * WAVE input format singleton.
  * @group Input formats
  * @public
  */
-export const WAVE = new WaveInputFormat();
+export const WAVE = /* #__PURE__ */ new WaveInputFormat();
 /**
  * Ogg input format singleton.
  * @group Input formats
  * @public
  */
-export const OGG = new OggInputFormat();
+export const OGG = /* #__PURE__ */ new OggInputFormat();
 /**
  * ADTS input format singleton.
  * @group Input formats
  * @public
  */
-export const ADTS = new AdtsInputFormat();
+export const ADTS = /* #__PURE__ */ new AdtsInputFormat();
 
 /**
  * FLAC input format singleton.
  * @group Input formats
  * @public
  */
-export const FLAC = new FlacInputFormat();
+export const FLAC = /* #__PURE__ */ new FlacInputFormat();
 
 /**
  * List of all input format singletons. If you don't need to support all input formats, you should specify the

src/input-track.ts

@@ -14,6 +14,7 @@ import { EncodedPacketSink, PacketRetrievalOptions } from './media-sink';
 import { assert, Rotation } from './misc';
 import { TrackType } from './output';
 import { EncodedPacket, PacketType } from './packet';
+import { TrackDisposition } from './metadata';
 
 /**
  * Contains aggregate statistics about the encoded packets of a track.
@@ -36,6 +37,7 @@ export interface InputTrackBacking {
 	getName(): string | null;
 	getLanguageCode(): string;
 	getTimeResolution(): number;
+	getDisposition(): TrackDisposition;
 	getFirstTimestamp(): Promise<number>;
 	computeDuration(): Promise<number>;
 
@@ -128,6 +130,11 @@ export abstract class InputTrack {
 		return this._backing.getTimeResolution();
 	}
 
+	/** The track's disposition, i.e. information about its intended usage. */
+	get disposition() {
+		return this._backing.getDisposition();
+	}
+
 	/**
 	 * Returns the start timestamp of the first packet of this track, in seconds. While often near zero, this value
 	 * may be positive or even negative. A negative starting timestamp means the track's timing has been offset. Samples

src/isobmff/isobmff-boxes.ts

@@ -44,7 +44,7 @@ import {
 	Sample,
 } from './isobmff-muxer';
 import { parseOpusIdentificationHeader } from '../codec-data';
-import { MetadataTags, RichImageData } from '../tags';
+import { MetadataTags, RichImageData } from '../metadata';
 
 export class IsobmffBoxWriter {
 	private helper = new Uint8Array(8);
@@ -135,8 +135,8 @@ export class IsobmffBoxWriter {
 	}
 }
 
-const bytes = new Uint8Array(8);
-const view = new DataView(bytes.buffer);
+const bytes = /* #__PURE__ */ new Uint8Array(8);
+const view = /* #__PURE__ */ new DataView(bytes.buffer);
 
 const u8 = (value: number) => {
 	return [(value % 0x100 + 0x100) % 0x100];
@@ -243,7 +243,7 @@ const rotationMatrix = (rotationInDegrees: number): TransformationMatrix => {
 		0, 0, 1,
 	];
 };
-const IDENTITY_MATRIX = rotationMatrix(0);
+const IDENTITY_MATRIX = /* #__PURE__ */ rotationMatrix(0);
 
 const matrixToBytes = (matrix: TransformationMatrix) => {
 	return [
@@ -421,7 +421,12 @@ export const tkhd = (
 		matrix = IDENTITY_MATRIX;
 	}
 
-	return fullBox('tkhd', +needsU64, 3, [
+	let flags = 0x2; // Track in movie
+	if (trackData.track.metadata.disposition?.default !== false) {
+		flags |= 0x1; // Track enabled
+	}
+
+	return fullBox('tkhd', +needsU64, flags, [
 		u32OrU64(creationTime), // Creation time
 		u32OrU64(creationTime), // Modification time
 		u32(trackData.track.id), // Track ID

src/isobmff/isobmff-demuxer.ts

@@ -51,13 +51,13 @@ import {
 	MATRIX_COEFFICIENTS_MAP_INVERSE,
 	normalizeRotation,
 	roundToMultiple,
-	roundToPrecision,
 	Rotation,
 	textDecoder,
 	TransformationMatrix,
 	TRANSFER_CHARACTERISTICS_MAP_INVERSE,
 	UNDETERMINED_LANGUAGE,
 	toDataView,
+	roundIfAlmostInteger,
 } from '../misc';
 import { EncodedPacket, PLACEHOLDER_DATA } from '../packet';
 import { buildIsobmffMimeType } from './isobmff-misc';
@@ -86,12 +86,13 @@ import {
 	readU8,
 	readAscii,
 } from '../reader';
-import { MetadataTags, RichImageData } from '../tags';
+import { DEFAULT_TRACK_DISPOSITION, MetadataTags, RichImageData, TrackDisposition } from '../metadata';
 
 type InternalTrack = {
 	id: number;
 	demuxer: IsobmffDemuxer;
 	inputTrack: InputTrack | null;
+	disposition: TrackDisposition;
 	timescale: number;
 	durationInMovieTimescale: number;
 	durationInMediaTimescale: number;
@@ -315,6 +316,9 @@ export class IsobmffDemuxer extends Demuxer {
 					this.moovSlice = moovSlice;
 					this.readContiguousBoxes(this.moovSlice);
 
+					// Put default tracks first
+					this.tracks.sort((a, b) => Number(b.disposition.default) - Number(a.disposition.default));
+
 					for (const track of this.tracks) {
 						// Modify the edit list offset based on the previous segment durations. They are in different
 						// timescales, so we first convert to seconds and then into the track timescale.
@@ -651,6 +655,9 @@ export class IsobmffDemuxer extends Demuxer {
 					id: -1,
 					demuxer: this,
 					inputTrack: null,
+					disposition: {
+						...DEFAULT_TRACK_DISPOSITION,
+					},
 					info: null,
 					timescale: -1,
 					durationInMovieTimescale: -1,
@@ -695,10 +702,10 @@ export class IsobmffDemuxer extends Demuxer {
 				const version = readU8(slice);
 				const flags = readU24Be(slice);
 
-				const trackEnabled = (flags & 0x1) !== 0;
-				if (!trackEnabled) {
-					break;
-				}
+				// Spec says disabled tracks are to be treated like they don't exist, but in practice, they are treated
+				// more like non-default tracks.
+				const trackEnabled = !!(flags & 0x1);
+				track.disposition.default = trackEnabled;
 
 				// Skip over creation & modification time to reach the track ID
 				if (version === 0) {
@@ -2345,6 +2352,10 @@ abstract class IsobmffTrackBacking implements InputTrackBacking {
 		return this.internalTrack.timescale;
 	}
 
+	getDisposition() {
+		return this.internalTrack.disposition;
+	}
+
 	async computeDuration() {
 		const lastPacket = await this.getPacket(Infinity, { metadataOnly: true });
 		return (lastPacket?.timestamp ?? 0) + (lastPacket?.duration ?? 0);
@@ -2388,7 +2399,7 @@ abstract class IsobmffTrackBacking implements InputTrackBacking {
 		// Do a little rounding to catch cases where the result is very close to an integer. If it is, it's likely
 		// that the number was originally an integer divided by the timescale. For stability, it's best
 		// to return the integer in this case.
-		return roundToPrecision(timestamp * this.internalTrack.timescale, 14) + this.internalTrack.editListOffset;
+		return roundIfAlmostInteger(timestamp * this.internalTrack.timescale) + this.internalTrack.editListOffset;
 	}
 
 	async getPacket(timestamp: number, options: PacketRetrievalOptions) {

src/isobmff/isobmff-reader.ts

@@ -6,7 +6,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-import { RichImageData } from '../tags';
+import { RichImageData } from '../metadata';
 import { textDecoder } from '../misc';
 import { FileSlice, readAscii, readBytes, readI32Be, readU16Be, readU32Be, readU64Be, readU8 } from '../reader';
 

src/matroska/ebml.ts

@@ -88,6 +88,10 @@ export enum EBMLId {
 	FlagEnabled = 0xb9,
 	FlagDefault = 0x88,
 	FlagForced = 0x55aa,
+	FlagOriginal = 0x55ae,
+	FlagHearingImpaired = 0x55ab,
+	FlagVisualImpaired = 0x55ac,
+	FlagCommentary = 0x55af,
 	FlagLacing = 0x9c,
 	Name = 0x536e,
 	Language = 0x22b59c,

src/matroska/matroska-demuxer.ts

@@ -31,7 +31,7 @@ import {
 	InputVideoTrack,
 	InputVideoTrackBacking,
 } from '../input-track';
-import { AttachedFile, MetadataTags } from '../tags';
+import { AttachedFile, DEFAULT_TRACK_DISPOSITION, MetadataTags, TrackDisposition } from '../metadata';
 import { PacketRetrievalOptions } from '../media-sink';
 import {
 	assert,
@@ -43,7 +43,7 @@ import {
 	MATRIX_COEFFICIENTS_MAP_INVERSE,
 	normalizeRotation,
 	Rotation,
-	roundToPrecision,
+	roundIfAlmostInteger,
 	TRANSFER_CHARACTERISTICS_MAP_INVERSE,
 	UNDETERMINED_LANGUAGE,
 } from '../misc';
@@ -61,7 +61,6 @@ import {
 	readElementHeader,
 	readElementId,
 	readFloat,
-	readSignedInt,
 	readUnsignedInt,
 	readVarInt,
 	resync,
@@ -137,7 +136,6 @@ type ClusterBlock = {
 	timestamp: number;
 	duration: number;
 	isKeyFrame: boolean;
-	referencedTimestamps: number[];
 	data: Uint8Array;
 	lacing: BlockLacing;
 	decoded: boolean;
@@ -190,7 +188,7 @@ type InternalTrack = {
 	}[];
 	cuePoints: CuePoint[];
 
-	isDefault: boolean;
+	disposition: TrackDisposition;
 	inputTrack: InputTrack | null;
 	codecId: string | null;
 	codecPrivate: Uint8Array | null;
@@ -539,7 +537,7 @@ export class MatroskaDemuxer extends Demuxer {
 		}
 
 		// Put default tracks first
-		this.currentSegment.tracks.sort((a, b) => Number(b.isDefault) - Number(a.isDefault));
+		this.currentSegment.tracks.sort((a, b) => Number(b.disposition.default) - Number(a.disposition.default));
 
 		// Now, let's distribute the cue points to the tracks
 		const idToTrack = new Map(this.currentSegment.tracks.map(x => [x.id, x]));
@@ -649,21 +647,15 @@ export class MatroskaDemuxer extends Demuxer {
 			// This must hold, as track datas only get created if a block for that track is encountered
 			assert(trackData.blocks.length > 0);
 
-			let blockReferencesExist = false;
 			let hasLacedBlocks = false;
 
 			for (let i = 0; i < trackData.blocks.length; i++) {
 				const block = trackData.blocks[i]!;
 				block.timestamp += cluster.timestamp;
 
-				blockReferencesExist ||= block.referencedTimestamps.length > 0;
 				hasLacedBlocks ||= block.lacing !== BlockLacing.None;
 			}
 
-			if (blockReferencesExist) {
-				trackData.blocks = sortBlocksByReferences(trackData.blocks);
-			}
-
 			trackData.presentationTimestamps = trackData.blocks
 				.map((block, i) => ({ timestamp: block.timestamp, blockIndex: i }))
 				.sort((a, b) => a.timestamp - b.timestamp);
@@ -859,7 +851,6 @@ export class MatroskaDemuxer extends Demuxer {
 					timestamp: frameTimestamp,
 					duration: frameDuration,
 					isKeyFrame: originalBlock.isKeyFrame,
-					referencedTimestamps: originalBlock.referencedTimestamps,
 					data: frameData,
 					lacing: BlockLacing.None,
 					decoded: true,
@@ -998,7 +989,9 @@ export class MatroskaDemuxer extends Demuxer {
 					clusterPositionCache: [],
 					cuePoints: [],
 
-					isDefault: false,
+					disposition: {
+						...DEFAULT_TRACK_DISPOSITION,
+					},
 					inputTrack: null,
 					codecId: null,
 					codecPrivate: null,
@@ -1163,7 +1156,37 @@ export class MatroskaDemuxer extends Demuxer {
 			case EBMLId.FlagDefault: {
 				if (!this.currentTrack) break;
 
-				this.currentTrack.isDefault = !!readUnsignedInt(slice, size);
+				this.currentTrack.disposition.default = !!readUnsignedInt(slice, size);
+			}; break;
+
+			case EBMLId.FlagForced: {
+				if (!this.currentTrack) break;
+
+				this.currentTrack.disposition.forced = !!readUnsignedInt(slice, size);
+			}; break;
+
+			case EBMLId.FlagOriginal: {
+				if (!this.currentTrack) break;
+
+				this.currentTrack.disposition.original = !!readUnsignedInt(slice, size);
+			}; break;
+
+			case EBMLId.FlagHearingImpaired: {
+				if (!this.currentTrack) break;
+
+				this.currentTrack.disposition.hearingImpaired = !!readUnsignedInt(slice, size);
+			}; break;
+
+			case EBMLId.FlagVisualImpaired: {
+				if (!this.currentTrack) break;
+
+				this.currentTrack.disposition.visuallyImpaired = !!readUnsignedInt(slice, size);
+			}; break;
+
+			case EBMLId.FlagCommentary: {
+				if (!this.currentTrack) break;
+
+				this.currentTrack.disposition.commentary = !!readUnsignedInt(slice, size);
 			}; break;
 
 			case EBMLId.CodecID: {
@@ -1383,9 +1406,17 @@ export class MatroskaDemuxer extends Demuxer {
 				const relativeTimestamp = readI16Be(slice);
 
 				const flags = readU8(slice);
-				const isKeyFrame = !!(flags & 0x80);
 				const lacing = (flags >> 1) & 0x3 as BlockLacing; // If the block is laced, we'll expand it later
 
+				let isKeyFrame = !!(flags & 0x80);
+				if (trackData.track.info?.type === 'audio' && trackData.track.info.codec) {
+					// Some files don't mark their audio packets as key packets (I'm looking at you, Firefox). But, we
+					// can fix this in most cases: if we recognize the codec of the track, then we know every packet is
+					// necessarily a key packet, no matter what the container says.
+					// https://github.com/Vanilagy/mediabunny/issues/192
+					isKeyFrame = true;
+				}
+
 				const blockData = readBytes(slice, size - (slice.filePos - dataStartPos));
 				const hasDecodingInstructions = trackData.track.decodingInstructions.length > 0;
 
@@ -1393,7 +1424,6 @@ export class MatroskaDemuxer extends Demuxer {
 					timestamp: relativeTimestamp, // We'll add the cluster's timestamp to this later
 					duration: 0, // Will set later
 					isKeyFrame,
-					referencedTimestamps: [],
 					data: blockData,
 					lacing,
 					decoded: !hasDecodingInstructions,
@@ -1406,13 +1436,7 @@ export class MatroskaDemuxer extends Demuxer {
 
 				this.readContiguousElements(slice.slice(dataStartPos, size));
 
-				if (this.currentBlock) {
-					for (let i = 0; i < this.currentBlock.referencedTimestamps.length; i++) {
-						this.currentBlock.referencedTimestamps[i]! += this.currentBlock.timestamp;
-					}
-
-					this.currentBlock = null;
-				}
+				this.currentBlock = null;
 			}; break;
 
 			case EBMLId.Block: {
@@ -1436,7 +1460,6 @@ export class MatroskaDemuxer extends Demuxer {
 					timestamp: relativeTimestamp, // We'll add the cluster's timestamp to this later
 					duration: 0, // Will set later
 					isKeyFrame: true,
-					referencedTimestamps: [],
 					data: blockData,
 					lacing,
 					decoded: !hasDecodingInstructions,
@@ -1487,11 +1510,8 @@ export class MatroskaDemuxer extends Demuxer {
 				if (!this.currentBlock) break;
 
 				this.currentBlock.isKeyFrame = false;
-
-				const relativeTimestamp = readSignedInt(slice, size);
-
-				// We'll offset this by the block's timestamp later
-				this.currentBlock.referencedTimestamps.push(relativeTimestamp);
+				// We ignore the actual value here, we just use the reference as an indicator for "not a key frame".
+				// This is in line with FFmpeg's behavior.
 			}; break;
 
 			case EBMLId.Tag: {
@@ -1859,6 +1879,10 @@ abstract class MatroskaTrackBacking implements InputTrackBacking {
 		return this.internalTrack.segment.timestampFactor;
 	}
 
+	getDisposition() {
+		return this.internalTrack.disposition;
+	}
+
 	async getFirstPacket(options: PacketRetrievalOptions) {
 		return this.performClusterLookup(
 			null,
@@ -1886,7 +1910,7 @@ abstract class MatroskaTrackBacking implements InputTrackBacking {
 		// Do a little rounding to catch cases where the result is very close to an integer. If it is, it's likely
 		// that the number was originally an integer divided by the timescale. For stability, it's best
 		// to return the integer in this case.
-		return roundToPrecision(timestamp * this.internalTrack.segment.timestampFactor, 14);
+		return roundIfAlmostInteger(timestamp * this.internalTrack.segment.timestampFactor);
 	}
 
 	async getPacket(timestamp: number, options: PacketRetrievalOptions) {
@@ -2380,43 +2404,3 @@ class MatroskaAudioTrackBacking extends MatroskaTrackBacking implements InputAud
 		};
 	}
 }
-
-/** Sorts blocks such that referenced blocks come before the blocks that reference them. */
-const sortBlocksByReferences = (blocks: ClusterBlock[]) => {
-	const timestampToBlock = new Map<number, ClusterBlock>();
-
-	for (let i = 0; i < blocks.length; i++) {
-		const block = blocks[i]!;
-		timestampToBlock.set(block.timestamp, block);
-	}
-
-	const processedBlocks = new Set<ClusterBlock>();
-	const result: ClusterBlock[] = [];
-
-	const processBlock = (block: ClusterBlock) => {
-		if (processedBlocks.has(block)) {
-			return;
-		}
-
-		// Marking the block as processed here already; prevents this algorithm from dying on cycles
-		processedBlocks.add(block);
-
-		for (let j = 0; j < block.referencedTimestamps.length; j++) {
-			const timestamp = block.referencedTimestamps[j]!;
-			const otherBlock = timestampToBlock.get(timestamp);
-			if (!otherBlock) {
-				continue;
-			}
-
-			processBlock(otherBlock);
-		}
-
-		result.push(block);
-	};
-
-	for (let i = 0; i < blocks.length; i++) {
-		processBlock(blocks[i]!);
-	}
-
-	return result;
-};

src/matroska/matroska-muxer.ts

@@ -63,7 +63,7 @@ import { Muxer } from '../muxer';
 import { Writer } from '../writer';
 import { EncodedPacket } from '../packet';
 import { parseOpusIdentificationHeader } from '../codec-data';
-import { AttachedFile } from '../tags';
+import { AttachedFile } from '../metadata';
 
 const MIN_CLUSTER_TIMESTAMP_MS = -(2 ** 15);
 const MAX_CLUSTER_TIMESTAMP_MS = 2 ** 15 - 1;
@@ -304,6 +304,24 @@ export class MatroskaMuxer extends Muxer {
 				{ id: EBMLId.TrackNumber, data: trackData.track.id },
 				{ id: EBMLId.TrackUID, data: trackData.track.id },
 				{ id: EBMLId.TrackType, data: TRACK_TYPE_MAP[trackData.type] },
+				trackData.track.metadata.disposition?.default === false
+					? { id: EBMLId.FlagDefault, data: 0 }
+					: null,
+				trackData.track.metadata.disposition?.forced
+					? { id: EBMLId.FlagForced, data: 1 }
+					: null,
+				trackData.track.metadata.disposition?.hearingImpaired
+					? { id: EBMLId.FlagHearingImpaired, data: 1 }
+					: null,
+				trackData.track.metadata.disposition?.visuallyImpaired
+					? { id: EBMLId.FlagVisualImpaired, data: 1 }
+					: null,
+				trackData.track.metadata.disposition?.original
+					? { id: EBMLId.FlagOriginal, data: 1 }
+					: null,
+				trackData.track.metadata.disposition?.commentary
+					? { id: EBMLId.FlagCommentary, data: 1 }
+					: null,
 				{ id: EBMLId.FlagLacing, data: 0 },
 				{ id: EBMLId.Language, data: trackData.track.metadata.languageCode ?? UNDETERMINED_LANGUAGE },
 				{ id: EBMLId.CodecID, data: codecId },

src/media-sink.ts

@@ -8,10 +8,12 @@
 
 import { parsePcmCodec, PCM_AUDIO_CODECS, PcmAudioCodec, VideoCodec, AudioCodec } from './codec';
 import {
+	deserializeAvcDecoderConfigurationRecord,
 	determineVideoPacketType,
 	extractHevcNalUnits,
 	extractNalUnitTypeForHevc,
 	HevcNalUnitType,
+	parseAvcSps,
 } from './codec-data';
 import { CustomVideoDecoder, customVideoDecoders, CustomAudioDecoder, customAudioDecoders } from './custom-coder';
 import { InputDisposedError } from './input';
@@ -24,6 +26,7 @@ import {
 	getInt24,
 	getUint24,
 	insertSorted,
+	isChromium,
 	isFirefox,
 	isNumber,
 	isWebKit,
@@ -33,6 +36,7 @@ import {
 	Rotation,
 	toAsyncIterator,
 	toDataView,
+	toUint8Array,
 	validateAnyIterable,
 } from './misc';
 import { EncodedPacket } from './packet';
@@ -872,6 +876,22 @@ class VideoDecoderWrapper extends DecoderWrapper<VideoSample> {
 				}
 			};
 
+			if (codec === 'avc' && this.decoderConfig.description && isChromium()) {
+				// Chromium has/had a bug with playing interlaced AVC (https://issues.chromium.org/issues/456919096)
+				// which can be worked around by requesting that software decoding be used. So, here we peek into the
+				// AVC description, if present, and switch to software decoding if we find interlaced content.
+				const record = deserializeAvcDecoderConfigurationRecord(toUint8Array(this.decoderConfig.description));
+				if (record && record.sequenceParameterSets.length > 0) {
+					const sps = parseAvcSps(record.sequenceParameterSets[0]!);
+					if (sps && sps.frameMbsOnlyFlag === 0) {
+						this.decoderConfig = {
+							...this.decoderConfig,
+							hardwareAcceleration: 'prefer-software',
+						};
+					}
+				}
+			}
+
 			this.decoder = new VideoDecoder({
 				output: (frame) => {
 					try {
@@ -882,7 +902,7 @@ class VideoDecoderWrapper extends DecoderWrapper<VideoSample> {
 				},
 				error: onError,
 			});
-			this.decoder.configure(decoderConfig);
+			this.decoder.configure(this.decoderConfig);
 		}
 	}
 

src/metadata.ts

@@ -259,3 +259,62 @@ export const metadataTagsAreEmpty = (tags: MetadataTags) => {
 		&& tags.comment === undefined
 		&& (tags.raw === undefined || Object.keys(tags.raw).length === 0);
 };
+
+/**
+ * Specifies a track's disposition, i.e. information about its intended usage.
+ * @public
+ * @group Miscellaneous
+ */
+export type TrackDisposition = {
+	/**
+	 * Indicates that this track is eligible for automatic selection by a player; that it is the main track among other,
+	 * non-default tracks of the same type.
+	 */
+	default: boolean;
+	/**
+	 * Indicates that players should always display this track by default, even if it goes against the user's default
+	 * preferences. For example, a subtitle track only containing translations of foreign-language audio.
+	 */
+	forced: boolean;
+	/** Indicates that this track is in the content's original language. */
+	original: boolean;
+	/** Indicates that this track contains commentary. */
+	commentary: boolean;
+	/** Indicates that this track is intended for hearing-impaired users. */
+	hearingImpaired: boolean;
+	/** Indicates that this track is intended for visually-impaired users. */
+	visuallyImpaired: boolean;
+};
+
+export const DEFAULT_TRACK_DISPOSITION: TrackDisposition = {
+	default: true,
+	forced: false,
+	original: false,
+	commentary: false,
+	hearingImpaired: false,
+	visuallyImpaired: false,
+};
+
+export const validateTrackDisposition = (disposition: Partial<TrackDisposition>) => {
+	if (!disposition || typeof disposition !== 'object') {
+		throw new TypeError('disposition must be an object.');
+	}
+	if (disposition.default !== undefined && typeof disposition.default !== 'boolean') {
+		throw new TypeError('disposition.default must be a boolean.');
+	}
+	if (disposition.forced !== undefined && typeof disposition.forced !== 'boolean') {
+		throw new TypeError('disposition.forced must be a boolean.');
+	}
+	if (disposition.original !== undefined && typeof disposition.original !== 'boolean') {
+		throw new TypeError('disposition.original must be a boolean.');
+	}
+	if (disposition.commentary !== undefined && typeof disposition.commentary !== 'boolean') {
+		throw new TypeError('disposition.commentary must be a boolean.');
+	}
+	if (disposition.hearingImpaired !== undefined && typeof disposition.hearingImpaired !== 'boolean') {
+		throw new TypeError('disposition.hearingImpaired must be a boolean.');
+	}
+	if (disposition.visuallyImpaired !== undefined && typeof disposition.visuallyImpaired !== 'boolean') {
+		throw new TypeError('disposition.visuallyImpaired must be a boolean.');
+	}
+};

src/misc.ts

@@ -174,8 +174,8 @@ export const toDataView = (source: AllowSharedBufferSource) => {
 	}
 };
 
-export const textDecoder = new TextDecoder();
-export const textEncoder = new TextEncoder();
+export const textDecoder = /* #__PURE__ */ new TextDecoder();
+export const textEncoder = /* #__PURE__ */ new TextEncoder();
 
 export const isIso88591Compatible = (text: string) => {
 	for (let i = 0; i < text.length; i++) {
@@ -201,7 +201,7 @@ export const COLOR_PRIMARIES_MAP = {
 	bt2020: 9, // ITU-R BT.202
 	smpte432: 12, // SMPTE EG 432-1
 };
-export const COLOR_PRIMARIES_MAP_INVERSE = invertObject(COLOR_PRIMARIES_MAP);
+export const COLOR_PRIMARIES_MAP_INVERSE = /* #__PURE__ */ invertObject(COLOR_PRIMARIES_MAP);
 
 export const TRANSFER_CHARACTERISTICS_MAP = {
 	'bt709': 1, // ITU-R BT.709
@@ -211,7 +211,7 @@ export const TRANSFER_CHARACTERISTICS_MAP = {
 	'pq': 16, // Rec. ITU-R BT.2100-2 perceptual quantization (PQ) system
 	'hlg': 18, // Rec. ITU-R BT.2100-2 hybrid loggamma (HLG) system
 };
-export const TRANSFER_CHARACTERISTICS_MAP_INVERSE = invertObject(TRANSFER_CHARACTERISTICS_MAP);
+export const TRANSFER_CHARACTERISTICS_MAP_INVERSE = /* #__PURE__ */ invertObject(TRANSFER_CHARACTERISTICS_MAP);
 
 export const MATRIX_COEFFICIENTS_MAP = {
 	'rgb': 0, // Identity
@@ -220,7 +220,7 @@ export const MATRIX_COEFFICIENTS_MAP = {
 	'smpte170m': 6, // SMPTE 170M
 	'bt2020-ncl': 9, // ITU-R BT.2020-2 (non-constant luminance)
 };
-export const MATRIX_COEFFICIENTS_MAP_INVERSE = invertObject(MATRIX_COEFFICIENTS_MAP);
+export const MATRIX_COEFFICIENTS_MAP_INVERSE = /* #__PURE__ */ invertObject(MATRIX_COEFFICIENTS_MAP);
 
 export type RequiredNonNull<T> = {
 	[K in keyof T]-?: NonNullable<T[K]>;
@@ -486,9 +486,14 @@ export const clamp = (value: number, min: number, max: number) => {
 
 export const UNDETERMINED_LANGUAGE = 'und';
 
-export const roundToPrecision = (value: number, digits: number) => {
-	const factor = 10 ** digits;
-	return Math.round(value * factor) / factor;
+export const roundIfAlmostInteger = (value: number) => {
+	const rounded = Math.round(value);
+
+	if (Math.abs(value / rounded - 1) < 10 * Number.EPSILON) {
+		return rounded;
+	} else {
+		return value;
+	}
 };
 
 export const roundToMultiple = (value: number, multiple: number) => {
@@ -665,10 +670,7 @@ export const isWebKit = () => {
 	}
 
 	// This even returns true for WebKit-wrapping browsers such as Chrome on iOS
-	const result = !!(typeof navigator !== 'undefined' && navigator.vendor?.match(/apple/i));
-
-	isWebKitCache = result;
-	return result;
+	return isWebKitCache = !!(typeof navigator !== 'undefined' && navigator.vendor?.match(/apple/i));
 };
 
 let isFirefoxCache: boolean | null = null;
@@ -680,6 +682,15 @@ export const isFirefox = () => {
 	return isFirefoxCache = typeof navigator !== 'undefined' && navigator.userAgent?.includes('Firefox');
 };
 
+let isChromiumCache: boolean | null = null;
+export const isChromium = () => {
+	if (isChromiumCache !== null) {
+		return isChromiumCache;
+	}
+
+	return isChromiumCache = !!(typeof navigator !== 'undefined' && navigator.vendor?.includes('Google Inc'));
+};
+
 /**
  * T or a promise that resolves to T.
  * @group Miscellaneous

src/mp3/mp3-demuxer.ts

@@ -10,7 +10,7 @@ import { AudioCodec } from '../codec';
 import { Demuxer } from '../demuxer';
 import { Input } from '../input';
 import { InputAudioTrack, InputAudioTrackBacking } from '../input-track';
-import { MetadataTags } from '../tags';
+import { DEFAULT_TRACK_DISPOSITION, MetadataTags } from '../metadata';
 import { PacketRetrievalOptions } from '../media-sink';
 import { assert, AsyncMutex, binarySearchExact, binarySearchLessOrEqual, UNDETERMINED_LANGUAGE } from '../misc';
 import { EncodedPacket, PLACEHOLDER_DATA } from '../packet';
@@ -257,6 +257,12 @@ class Mp3AudioTrackBacking implements InputAudioTrackBacking {
 		return this.demuxer.firstFrameHeader.sampleRate;
 	}
 
+	getDisposition() {
+		return {
+			...DEFAULT_TRACK_DISPOSITION,
+		};
+	}
+
 	async getDecoderConfig(): Promise<AudioDecoderConfig> {
 		assert(this.demuxer.firstFrameHeader);
 

src/mp3/mp3-muxer.ts

@@ -7,7 +7,7 @@
  */
 
 import { assert, toDataView } from '../misc';
-import { metadataTagsAreEmpty } from '../tags';
+import { metadataTagsAreEmpty } from '../metadata';
 import { Muxer } from '../muxer';
 import { Output, OutputAudioTrack } from '../output';
 import { Mp3OutputFormat } from '../output-format';

src/muxer.ts

@@ -46,21 +46,21 @@ export abstract class Muxer {
 
 	private trackTimestampInfo = new WeakMap<OutputTrack, {
 		maxTimestamp: number;
-		maxTimestampBeforeLastKeyFrame: number;
+		maxTimestampBeforeLastKeyPacket: number;
 	}>();
 
-	protected validateAndNormalizeTimestamp(track: OutputTrack, timestampInSeconds: number, isKeyFrame: boolean) {
+	protected validateAndNormalizeTimestamp(track: OutputTrack, timestampInSeconds: number, isKeyPacket: boolean) {
 		timestampInSeconds += track.source._timestampOffset;
 
 		let timestampInfo = this.trackTimestampInfo.get(track);
 		if (!timestampInfo) {
-			if (!isKeyFrame) {
-				throw new Error('First frame must be a key frame.');
+			if (!isKeyPacket) {
+				throw new Error('First packet must be a key packet.');
 			}
 
 			timestampInfo = {
 				maxTimestamp: timestampInSeconds,
-				maxTimestampBeforeLastKeyFrame: timestampInSeconds,
+				maxTimestampBeforeLastKeyPacket: timestampInSeconds,
 			};
 			this.trackTimestampInfo.set(track, timestampInfo);
 		}
@@ -69,15 +69,15 @@ export abstract class Muxer {
 			throw new Error(`Timestamps must be non-negative (got ${timestampInSeconds}s).`);
 		}
 
-		if (isKeyFrame) {
-			timestampInfo.maxTimestampBeforeLastKeyFrame = timestampInfo.maxTimestamp;
+		if (isKeyPacket) {
+			timestampInfo.maxTimestampBeforeLastKeyPacket = timestampInfo.maxTimestamp;
 		}
 
-		if (timestampInSeconds < timestampInfo.maxTimestampBeforeLastKeyFrame) {
+		if (timestampInSeconds < timestampInfo.maxTimestampBeforeLastKeyPacket) {
 			throw new Error(
-				`Timestamps cannot be smaller than the highest timestamp of the previous GOP (a GOP begins with a key`
-				+ ` frame and ends right before the next key frame). Got ${timestampInSeconds}s, but highest timestamp`
-				+ ` is ${timestampInfo.maxTimestampBeforeLastKeyFrame}s.`,
+				`Timestamps cannot be smaller than the largest timestamp of the previous GOP (a GOP begins with a key`
+				+ ` packet and ends right before the next key packet). Got ${timestampInSeconds}s, but largest`
+				+ ` timestamp is ${timestampInfo.maxTimestampBeforeLastKeyPacket}s.`,
 			);
 		}
 

src/ogg/ogg-demuxer.ts

@@ -12,14 +12,14 @@ import { Demuxer } from '../demuxer';
 import { Input } from '../input';
 import { InputAudioTrack, InputAudioTrackBacking } from '../input-track';
 import { PacketRetrievalOptions } from '../media-sink';
-import { MetadataTags } from '../tags';
+import { DEFAULT_TRACK_DISPOSITION, MetadataTags } from '../metadata';
 import {
 	assert,
 	AsyncMutex,
 	binarySearchLessOrEqual,
 	findLast,
 	last,
-	roundToPrecision,
+	roundIfAlmostInteger,
 	toDataView,
 	UNDETERMINED_LANGUAGE,
 } from '../misc';
@@ -463,6 +463,12 @@ class OggAudioTrackBacking implements InputAudioTrackBacking {
 		return UNDETERMINED_LANGUAGE;
 	}
 
+	getDisposition() {
+		return {
+			...DEFAULT_TRACK_DISPOSITION,
+		};
+	}
+
 	async getFirstTimestamp() {
 		return 0;
 	}
@@ -577,7 +583,7 @@ class OggAudioTrackBacking implements InputAudioTrackBacking {
 			return this.getPacketSequential(timestamp, options);
 		}
 
-		const timestampInSamples = roundToPrecision(timestamp * this.internalSampleRate, 14);
+		const timestampInSamples = roundIfAlmostInteger(timestamp * this.internalSampleRate);
 		if (timestampInSamples === 0) {
 			// Fast path for timestamp 0 - avoids binary search when playing back from the start
 			return this.getFirstPacket(options);
@@ -910,7 +916,7 @@ class OggAudioTrackBacking implements InputAudioTrackBacking {
 		const release = await this.sequentialScanMutex.acquire(); // Requires exclusivity because we write to a cache
 
 		try {
-			const timestampInSamples = roundToPrecision(timestamp * this.internalSampleRate, 14);
+			const timestampInSamples = roundIfAlmostInteger(timestamp * this.internalSampleRate);
 			timestamp = timestampInSamples / this.internalSampleRate;
 
 			const index = binarySearchLessOrEqual(

src/output.ts

@@ -7,7 +7,7 @@
  */
 
 import { AsyncMutex, isIso639Dash2LanguageCode, Rotation } from './misc';
-import { MetadataTags, validateMetadataTags } from './tags';
+import { MetadataTags, TrackDisposition, validateMetadataTags, validateTrackDisposition } from './metadata';
 import { Muxer } from './muxer';
 import { OutputFormat } from './output-format';
 import { AudioSource, MediaSource, SubtitleSource, VideoSource } from './media-source';
@@ -74,6 +74,8 @@ export type BaseTrackMetadata = {
 	languageCode?: string;
 	/** A user-defined name for this track, like "English" or "Director Commentary". */
 	name?: string;
+	/** The track's disposition, i.e. information about its intended usage. */
+	disposition?: Partial<TrackDisposition>;
 	/**
 	 * The maximum amount of encoded packets that will be added to this track. Setting this field provides the muxer
 	 * with an additional signal that it can use to preallocate space in the file.
@@ -129,6 +131,9 @@ const validateBaseTrackMetadata = (metadata: BaseTrackMetadata) => {
 	if (metadata.name !== undefined && typeof metadata.name !== 'string') {
 		throw new TypeError('metadata.name, when provided, must be a string.');
 	}
+	if (metadata.disposition !== undefined) {
+		validateTrackDisposition(metadata.disposition);
+	}
 	if (
 		metadata.maximumPacketCount !== undefined
 		&& (!Number.isInteger(metadata.maximumPacketCount) || metadata.maximumPacketCount < 0)

src/packet.ts

@@ -8,7 +8,7 @@
 
 import { SECOND_TO_MICROSECOND_FACTOR } from './misc';
 
-export const PLACEHOLDER_DATA = new Uint8Array(0);
+export const PLACEHOLDER_DATA = /* #__PURE__ */ new Uint8Array(0);
 
 /**
  * The type of a packet. Key packets can be decoded without previous packets, while delta packets depend on previous

src/wave/wave-demuxer.ts

@@ -11,7 +11,7 @@ import { Demuxer } from '../demuxer';
 import { Input } from '../input';
 import { InputAudioTrack, InputAudioTrackBacking } from '../input-track';
 import { PacketRetrievalOptions } from '../media-sink';
-import { MetadataTags } from '../tags';
+import { DEFAULT_TRACK_DISPOSITION, MetadataTags } from '../metadata';
 import { assert, UNDETERMINED_LANGUAGE } from '../misc';
 import { EncodedPacket, PLACEHOLDER_DATA } from '../packet';
 import { readAscii, readBytes, Reader, readU16, readU32, readU64 } from '../reader';
@@ -407,6 +407,12 @@ class WaveAudioTrackBacking implements InputAudioTrackBacking {
 		return UNDETERMINED_LANGUAGE;
 	}
 
+	getDisposition() {
+		return {
+			...DEFAULT_TRACK_DISPOSITION,
+		};
+	}
+
 	async getFirstTimestamp() {
 		return 0;
 	}

src/wave/wave-muxer.ts

@@ -15,7 +15,7 @@ import { Writer } from '../writer';
 import { EncodedPacket } from '../packet';
 import { WavOutputFormat } from '../output-format';
 import { assert, assertNever, isIso88591Compatible, keyValueIterator } from '../misc';
-import { MetadataTags, metadataTagsAreEmpty } from '../tags';
+import { MetadataTags, metadataTagsAreEmpty } from '../metadata';
 import { Id3V2Writer } from '../id3';
 
 export class WaveMuxer extends Muxer {

test/node/disposition.test.ts

@@ -0,0 +1,92 @@
+import { expect, test } from 'vitest';
+import { Output } from '../../src/output.js';
+import { MkvOutputFormat } from '../../src/output-format.js';
+import { BufferTarget } from '../../src/target.js';
+import { EncodedVideoPacketSource } from '../../src/media-source.js';
+import { EncodedPacket } from '../../src/packet.js';
+import { Input } from '../../src/input.js';
+import { BufferSource } from '../../src/source.js';
+import { ALL_FORMATS } from '../../src/input-format.js';
+
+test('Default track disposition', async () => {
+	const output = new Output({
+		format: new MkvOutputFormat(),
+		target: new BufferTarget(),
+	});
+
+	const source = new EncodedVideoPacketSource('avc');
+	output.addVideoTrack(source);
+
+	await output.start();
+	await source.add(new EncodedPacket(new Uint8Array(1024), 'key', 0, 1), {
+		decoderConfig: {
+			codec: 'avc1.123456',
+			codedWidth: 1920,
+			codedHeight: 1080,
+		},
+	});
+
+	await output.finalize();
+
+	using input = new Input({
+		source: new BufferSource(output.target.buffer!),
+		formats: ALL_FORMATS,
+	});
+
+	const track = (await input.getPrimaryVideoTrack())!;
+
+	expect(track.disposition).toEqual({
+		default: true,
+		forced: false,
+		original: false,
+		hearingImpaired: false,
+		visuallyImpaired: false,
+		commentary: false,
+	});
+});
+
+test('Customized track disposition', async () => {
+	const output = new Output({
+		format: new MkvOutputFormat(),
+		target: new BufferTarget(),
+	});
+
+	const source = new EncodedVideoPacketSource('avc');
+	output.addVideoTrack(source, {
+		disposition: {
+			default: false,
+			forced: true,
+			original: true,
+			hearingImpaired: true,
+			visuallyImpaired: true,
+			commentary: true,
+		},
+	});
+
+	await output.start();
+	await source.add(new EncodedPacket(new Uint8Array(1024), 'key', 0, 1), {
+		decoderConfig: {
+			codec: 'avc1.123456',
+			codedWidth: 1920,
+			codedHeight: 1080,
+		},
+	});
+
+	await output.finalize();
+
+	using input = new Input({
+		source: new BufferSource(output.target.buffer!),
+		formats: ALL_FORMATS,
+	});
+
+	const track = (await input.getPrimaryVideoTrack())!;
+
+	expect(track.disposition).toEqual({
+		default: false,
+		forced: true,
+		original: true,
+		hearingImpaired: true,
+		visuallyImpaired: true,
+		commentary: true,
+	});
+});

test/node/metadata-tags.test.ts

@@ -15,7 +15,7 @@ import { EncodedPacket } from '../../src/packet.js';
 import { Input } from '../../src/input.js';
 import { BufferSource, FilePathSource } from '../../src/source.js';
 import { ALL_FORMATS } from '../../src/input-format.js';
-import { AttachedFile, MetadataTags } from '../../src/tags.js';
+import { AttachedFile, MetadataTags } from '../../src/metadata.js';
 import path from 'node:path';
 import { AudioCodec, buildAudioCodecString } from '../../src/codec.js';
 import { Conversion } from '../../src/conversion.js';