Add some HLS events, add configurable target duration, add public-API OutputTrack

src/hls/hls-muxer.ts

@@ -11,9 +11,10 @@ import {
 	OutputVideoTrack,
 	TrackType,
 } from '../output';
-import { HlsOutputFormat, HlsOutputFormatOptions, OutputFormat } from '../output-format';
+import { HlsOutputFormat, HlsOutputFormatOptions, HlsOutputSegmentInfo, OutputFormat } from '../output-format';
 import { EncodedPacket } from '../packet';
 import { SubtitleCue, SubtitleMetadata } from '../subtitles';
+import { Target } from '../target';
 
 type HlsTrackData = {
 	track: OutputTrack;
@@ -59,7 +60,7 @@ export class HlsMuxer extends Muxer {
 	getPlaylistPath: NonNullable<HlsOutputFormatOptions['getPlaylistPath']>;
 	getSegmentPath: NonNullable<HlsOutputFormatOptions['getSegmentPath']>;
 
-	targetSegmentDuration = 2;
+	targetSegmentDuration: number;
 	trackDatas: HlsTrackData[] = [];
 
 	playlists: Playlist[] = [];
@@ -73,6 +74,7 @@ export class HlsMuxer extends Muxer {
 		super(output);
 
 		this.format = format;
+		this.targetSegmentDuration = format._options.targetDuration ?? 5;
 
 		this.getPlaylistPath = format._options.getPlaylistPath
 			?? (({ n }) => `playlist-${n}.m3u8`);
@@ -303,10 +305,10 @@ export class HlsMuxer extends Muxer {
 			let candidateScore = -Infinity;
 
 			for (const track of tracks) {
-				if (track.type === 'video') {
+				if (track.isVideoTrack()) {
 					videoCount++;
 					requiresRotationMetadata ||= (track.metadata.rotation ?? 0) !== 0;
-				} else if (track.type === 'audio') {
+				} else if (track.isAudioTrack()) {
 					audioCount++;
 				}
 
@@ -715,14 +717,16 @@ export class HlsMuxer extends Muxer {
 			}
 
 			// We can finalize a new segment! Let's first get the path
-			const relativeSegmentPath = await this.getSegmentPath({
+			const segmentInfo: HlsOutputSegmentInfo = {
 				n: playlist.nextSegmentId,
 				format: playlist.segmentFormat,
 				playlist: {
 					n: playlist.id,
 					tracks: playlist.tracks,
 				},
-			});
+			};
+
+			const relativeSegmentPath = await this.getSegmentPath(segmentInfo);
 			if (typeof relativeSegmentPath !== 'string') {
 				throw new TypeError('options.getSegmentPath must return or resolve to a string');
 			}
@@ -737,6 +741,8 @@ export class HlsMuxer extends Muxer {
 			playlist.nextSegmentId++;
 
 			let segmentSize = 0;
+			let outputTarget: Target | null = null;
+
 			const output = new Output({
 				format: playlist.segmentFormat,
 				rootPath: fullSegmentPath,
@@ -744,6 +750,7 @@ export class HlsMuxer extends Muxer {
 					const target = await this.output._getTarget(request);
 
 					if (request.path === fullSegmentPath) {
+						outputTarget = target;
 						target.onwrite = (_, end) => segmentSize = Math.max(segmentSize, end);
 					}
 
@@ -803,6 +810,9 @@ export class HlsMuxer extends Muxer {
 				throw e;
 			}
 
+			assert(outputTarget);
+			this.format._options.onSegment?.(outputTarget, segmentInfo);
+
 			if (videoEndIndex > 0) {
 				assert(videoTrack);
 				videoTrack.packets.splice(0, videoEndIndex);
@@ -883,7 +893,12 @@ export class HlsMuxer extends Muxer {
 				+ '\n'
 				+ '#EXT-X-ENDLIST\n';
 
-			const target = await this.output._getTarget({ path: playlistPath });
+			this.format._options.onPlaylist?.(playlistText, {
+				n: playlist.id,
+				tracks: playlist.tracks,
+			});
+
+			const target = await this.output._getTarget({ path: playlistPath, isRoot: false });
 			const writer = target._createWriter();
 			writer.write(textEncoder.encode(playlistText));
 			await writer.finalize();
@@ -942,8 +957,8 @@ export class HlsMuxer extends Muxer {
 
 					masterPlaylistText += `,CODECS="${codecs.join(',')}"`;
 
-					const videoTrack = decl.playlist.tracks.find(x => x.type === 'video');
-					if (videoTrack) {
+					const videoTrack = decl.playlist.tracks.find(x => x.isVideoTrack());
+					if (videoTrack?.isVideoTrack()) {
 						const trackData = this.trackDatas.find(x => x.track === videoTrack) as
 							HlsVideoTrackData | undefined;
 						const decoderConfig = trackData?.info.decoderConfig;
@@ -1059,6 +1074,8 @@ export class HlsMuxer extends Muxer {
 				}
 			}
 
+			this.format._options.onMaster?.(masterPlaylistText);
+
 			const rootWriter = await this.output._getRootWriter();
 			rootWriter.write(textEncoder.encode(masterPlaylistText));
 		})();

src/index.ts

@@ -23,6 +23,11 @@ if ((globalThis as Record<symbol, unknown>)[MEDIABUNNY_LOADED_SYMBOL]) {
 export {
 	Output,
 	OutputOptions,
+	OutputTrack,
+	OutputVideoTrack,
+	OutputAudioTrack,
+	OutputSubtitleTrack,
+	OutputTrackGroup,
 	BaseTrackMetadata,
 	VideoTrackMetadata,
 	AudioTrackMetadata,
@@ -136,7 +141,6 @@ export {
 	prefer,
 } from './misc';
 export {
-	OutputTrackGroup,
 	TrackType,
 	ALL_TRACK_TYPES,
 } from './output';

src/isobmff/isobmff-muxer.ts

@@ -199,7 +199,7 @@ export class IsobmffMuxer extends Muxer {
 			this.writer.ensureMonotonicity = true;
 		}
 
-		const holdsAvc = this.output._tracks.some(x => x.type === 'video' && x.source._codec === 'avc');
+		const holdsAvc = this.output._tracks.some(x => x.isVideoTrack() && x.source._codec === 'avc');
 
 		// Write the header
 		{

src/media-source.ts

@@ -10,6 +10,7 @@ import { buildAacAudioSpecificConfig, parseAacAudioSpecificConfig } from '../sha
 import {
 	AUDIO_CODECS,
 	AudioCodec,
+	MediaCodec,
 	parsePcmCodec,
 	PCM_AUDIO_CODECS,
 	PcmAudioCodec,
@@ -62,6 +63,8 @@ import {
  * @public
  */
 export abstract class MediaSource {
+	/** @internal */
+	abstract readonly _codec: MediaCodec;
 	/** @internal */
 	_connectedTrack: OutputTrack | null = null;
 	/** @internal */
@@ -154,7 +157,7 @@ export abstract class VideoSource extends MediaSource {
 	/** @internal */
 	override _connectedTrack: OutputVideoTrack | null = null;
 	/** @internal */
-	_codec: VideoCodec;
+	override readonly _codec: VideoCodec;
 
 	/** Internal constructor. */
 	constructor(codec: VideoCodec) {
@@ -1475,7 +1478,7 @@ export abstract class AudioSource extends MediaSource {
 	/** @internal */
 	override _connectedTrack: OutputAudioTrack | null = null;
 	/** @internal */
-	_codec: AudioCodec;
+	override readonly _codec: AudioCodec;
 
 	/** Internal constructor. */
 	constructor(codec: AudioCodec) {
@@ -2459,7 +2462,7 @@ export abstract class SubtitleSource extends MediaSource {
 	/** @internal */
 	override _connectedTrack: OutputSubtitleTrack | null = null;
 	/** @internal */
-	_codec: SubtitleCodec;
+	override readonly _codec: SubtitleCodec;
 
 	/** Internal constructor. */
 	constructor(codec: SubtitleCodec) {

src/output-format.ts

@@ -30,6 +30,7 @@ import { MpegTsMuxer } from './mpeg-ts/mpeg-ts-muxer';
 import { WaveMuxer } from './wave/wave-muxer';
 import { HlsMuxer } from './hls/hls-muxer';
 import { MaybePromise } from './misc';
+import { Target } from './target';
 
 /**
  * Specifies an inclusive range of integers.
@@ -1099,7 +1100,7 @@ export type HlsOutputPlaylistInfo = {
 	tracks: OutputTrack[];
 };
 
-type HlsOutputSegmentInfo = {
+export type HlsOutputSegmentInfo = {
 	n: number;
 	format: OutputFormat;
 	playlist: HlsOutputPlaylistInfo;
@@ -1107,8 +1108,13 @@ type HlsOutputSegmentInfo = {
 
 export type HlsOutputFormatOptions = {
 	segmentFormats: OutputFormat[];
+	targetDuration?: number;
 	getPlaylistPath?: (info: HlsOutputPlaylistInfo) => MaybePromise<string>;
 	getSegmentPath?: (info: HlsOutputSegmentInfo) => MaybePromise<string>;
+
+	onMaster?: (content: string) => unknown;
+	onPlaylist?: (content: string, info: HlsOutputPlaylistInfo) => unknown;
+	onSegment?: (target: Target, info: HlsOutputSegmentInfo) => unknown;
 };
 
 export class HlsOutputFormat extends OutputFormat {
@@ -1127,12 +1133,27 @@ export class HlsOutputFormat extends OutputFormat {
 		) {
 			throw new TypeError('options.segmentFormats must be a non-empty array of OutputFormat instances.');
 		}
+		if (
+			options.targetDuration !== undefined
+			&& (typeof options.targetDuration !== 'number' || options.targetDuration <= 0)
+		) {
+			throw new TypeError('options.targetDuration, when provided, must be a positive number.');
+		}
 		if (options.getPlaylistPath !== undefined && typeof options.getPlaylistPath !== 'function') {
 			throw new TypeError('options.getPlaylistPath, when provided, must be a function.');
 		}
 		if (options.getSegmentPath !== undefined && typeof options.getSegmentPath !== 'function') {
 			throw new TypeError('options.getSegmentPath, when provided, must be a function.');
 		}
+		if (options.onMaster !== undefined && typeof options.onMaster !== 'function') {
+			throw new TypeError('options.onMaster, when provided, must be a function.');
+		}
+		if (options.onPlaylist !== undefined && typeof options.onPlaylist !== 'function') {
+			throw new TypeError('options.onPlaylist, when provided, must be a function.');
+		}
+		if (options.onSegment !== undefined && typeof options.onSegment !== 'function') {
+			throw new TypeError('options.onSegment, when provided, must be a function.');
+		}
 
 		super();
 

src/output.ts

@@ -16,6 +16,7 @@ import { Writer } from './writer';
 
 export type TargetRequest = {
 	path: string;
+	isRoot: boolean;
 };
 
 /**
@@ -47,27 +48,101 @@ export const ALL_TRACK_TYPES = ['video', 'audio', 'subtitle'] as const;
  */
 export type TrackType = typeof ALL_TRACK_TYPES[number];
 
-export type OutputTrack = {
-	id: number;
-	output: Output;
-	type: TrackType;
-} & ({
-	type: 'video';
-	source: VideoSource;
-	metadata: VideoTrackMetadata;
-} | {
-	type: 'audio';
-	source: AudioSource;
-	metadata: AudioTrackMetadata;
-} | {
-	type: 'subtitle';
-	source: SubtitleSource;
-	metadata: SubtitleTrackMetadata;
-});
+/**
+ * Represents a track added to an {@link Output}.
+ * @group Output files
+ * @public
+ */
+export abstract class OutputTrack {
+	/** @internal */
+	readonly id: number;
+	/** The {@link Output} this track belongs to. */
+	readonly output: Output;
+	/** The type of this track. */
+	readonly type: TrackType;
+	/** The media source providing data for this track. */
+	readonly source: MediaSource;
+	/** The metadata associated with this track. */
+	readonly metadata: BaseTrackMetadata;
 
-export type OutputVideoTrack = OutputTrack & { type: 'video' };
-export type OutputAudioTrack = OutputTrack & { type: 'audio' };
-export type OutputSubtitleTrack = OutputTrack & { type: 'subtitle' };
+	/** @internal */
+	protected constructor(
+		id: number,
+		output: Output,
+		type: TrackType,
+		source: MediaSource,
+		metadata: BaseTrackMetadata,
+	) {
+		this.id = id;
+		this.output = output;
+		this.type = type;
+		this.source = source;
+		this.metadata = metadata;
+	}
+
+	/** Returns true if and only if this track is a video track. */
+	isVideoTrack(): this is OutputVideoTrack {
+		return this.type === 'video';
+	}
+
+	/** Returns true if and only if this track is an audio track. */
+	isAudioTrack(): this is OutputAudioTrack {
+		return this.type === 'audio';
+	}
+
+	/** Returns true if and only if this track is a subtitle track. */
+	isSubtitleTrack(): this is OutputSubtitleTrack {
+		return this.type === 'subtitle';
+	}
+}
+
+/**
+ * An {@link OutputTrack} containing video data.
+ * @group Output files
+ * @public
+ */
+export class OutputVideoTrack extends OutputTrack {
+	declare readonly type: 'video';
+	declare readonly source: VideoSource;
+	declare readonly metadata: VideoTrackMetadata;
+
+	/** @internal */
+	constructor(id: number, output: Output, source: VideoSource, metadata: VideoTrackMetadata) {
+		super(id, output, 'video', source, metadata);
+	}
+}
+
+/**
+ * An {@link OutputTrack} containing audio data.
+ * @group Output files
+ * @public
+ */
+export class OutputAudioTrack extends OutputTrack {
+	declare readonly type: 'audio';
+	declare readonly source: AudioSource;
+	declare readonly metadata: AudioTrackMetadata;
+
+	/** @internal */
+	constructor(id: number, output: Output, source: AudioSource, metadata: AudioTrackMetadata) {
+		super(id, output, 'audio', source, metadata);
+	}
+}
+
+/**
+ * An {@link OutputTrack} containing subtitle data.
+ * @group Output files
+ * @public
+ */
+export class OutputSubtitleTrack extends OutputTrack {
+	declare readonly type: 'subtitle';
+	declare readonly source: SubtitleSource;
+	declare readonly metadata: SubtitleTrackMetadata;
+
+	/** @internal */
+	constructor(id: number, output: Output, source: SubtitleSource, metadata: SubtitleTrackMetadata) {
+		super(id, output, 'subtitle', source, metadata);
+	}
+}
 
 export class OutputTrackGroup {
 	/** @internal */
@@ -246,7 +321,7 @@ export class Output<
 		}
 
 		assert(this._rootPath !== null);
-		const returnValue = this._target({ path: this._rootPath });
+		const returnValue = this._target({ path: this._rootPath, isRoot: true });
 		if (returnValue instanceof Promise) {
 			throw new TypeError(
 				'Output.target cannot be used when the target function resolves asynchronously.',
@@ -310,7 +385,7 @@ export class Output<
 
 			if (typeof this._target === 'function') {
 				assert(this._rootPath !== null);
-				const rootTarget = await this._getTarget({ path: this._rootPath });
+				const rootTarget = await this._getTarget({ path: this._rootPath, isRoot: true });
 				writer = rootTarget._createWriter();
 			} else {
 				writer = this._target._createWriter();
@@ -346,7 +421,9 @@ export class Output<
 		const metadataCopy = { ...metadata };
 		metadataCopy.group ??= this._defaultTrackGroup;
 
-		this._addTrack('video', source, metadataCopy);
+		return this._addTrack(new OutputVideoTrack(
+			this._tracks.length + 1, this, source, metadataCopy,
+		));
 	}
 
 	/** Adds an audio track to the output with the given source. Can only be called before the output is started. */
@@ -359,7 +436,9 @@ export class Output<
 		const metadataCopy = { ...metadata };
 		metadataCopy.group ??= this._defaultTrackGroup;
 
-		this._addTrack('audio', source, metadataCopy);
+		return this._addTrack(new OutputAudioTrack(
+			this._tracks.length + 1, this, source, metadataCopy,
+		));
 	}
 
 	/** Adds a subtitle track to the output with the given source. Can only be called before the output is started. */
@@ -372,7 +451,9 @@ export class Output<
 		const metadataCopy = { ...metadata };
 		metadataCopy.group ??= this._defaultTrackGroup;
 
-		this._addTrack('subtitle', source, metadataCopy);
+		return this._addTrack(new OutputSubtitleTrack(
+			this._tracks.length + 1, this, source, metadataCopy,
+		));
 	}
 
 	/**
@@ -392,26 +473,26 @@ export class Output<
 	}
 
 	/** @internal */
-	private _addTrack(type: OutputTrack['type'], source: MediaSource, metadata: BaseTrackMetadata) {
+	private _addTrack<T extends OutputTrack>(track: T) {
 		if (this.state !== 'pending') {
 			throw new Error('Cannot add track after output has been started or canceled.');
 		}
-		if (source._connectedTrack) {
+		if (track.source._connectedTrack) {
 			throw new Error('Source is already used for a track.');
 		}
 
 		// Verify maximum track count constraints
 		const supportedTrackCounts = this.format.getSupportedTrackCounts();
 		const presentTracksOfThisType = this._tracks.reduce(
-			(count, track) => count + (track.type === type ? 1 : 0),
+			(count, t) => count + (t.type === track.type ? 1 : 0),
 			0,
 		);
-		const maxCount = supportedTrackCounts[type].max;
+		const maxCount = supportedTrackCounts[track.type].max;
 		if (presentTracksOfThisType === maxCount) {
 			throw new Error(
 				maxCount === 0
-					? `${this.format._name} does not support ${type} tracks.`
-					: (`${this.format._name} does not support more than ${maxCount} ${type} track`
+					? `${this.format._name} does not support ${track.type} tracks.`
+					: (`${this.format._name} does not support more than ${maxCount} ${track.type} track`
 						+ `${maxCount === 1 ? '' : 's'}.`),
 			);
 		}
@@ -423,15 +504,7 @@ export class Output<
 			);
 		}
 
-		const track = {
-			id: this._tracks.length + 1,
-			output: this,
-			type,
-			source: source as unknown,
-			metadata,
-		} as OutputTrack;
-
-		if (track.type === 'video') {
+		if (track.isVideoTrack()) {
 			const supportedVideoCodecs = this.format.getSupportedVideoCodecs();
 
 			if (supportedVideoCodecs.length === 0) {
@@ -446,7 +519,7 @@ export class Output<
 					+ this.format._codecUnsupportedHint(track.source._codec),
 				);
 			}
-		} else if (track.type === 'audio') {
+		} else if (track.isAudioTrack()) {
 			const supportedAudioCodecs = this.format.getSupportedAudioCodecs();
 
 			if (supportedAudioCodecs.length === 0) {
@@ -461,7 +534,7 @@ export class Output<
 					+ this.format._codecUnsupportedHint(track.source._codec),
 				);
 			}
-		} else if (track.type === 'subtitle') {
+		} else if (track.isSubtitleTrack()) {
 			const supportedSubtitleCodecs = this.format.getSupportedSubtitleCodecs();
 
 			if (supportedSubtitleCodecs.length === 0) {
@@ -479,7 +552,9 @@ export class Output<
 		}
 
 		this._tracks.push(track);
-		source._connectedTrack = track;
+		track.source._connectedTrack = track;
+
+		return track;
 	}
 
 	/**

test/node/hls-output.test.ts

@@ -831,6 +831,7 @@ const setUpSegmentationEnvironment = async (options: {
 	const output = new Output({
 		format: new HlsOutputFormat({
 			segmentFormats: [new MpegTsOutputFormat()], // No ADTS for simplicity
+			targetDuration: 2,
 		}),
 		target: (request) => {
 			const target = new BufferTarget();
@@ -1731,3 +1732,65 @@ segment-1-1.ts
 `,
 	);
 });
+
+test('onSegment, onPlaylist, onMaster events', async () => {
+	const onSegment = vi.fn();
+	const onPlaylist = vi.fn();
+	const onMaster = vi.fn();
+
+	const output = new Output({
+		format: new HlsOutputFormat({
+			segmentFormats: [new MpegTsOutputFormat()],
+			targetDuration: 2,
+			onSegment,
+			onPlaylist,
+			onMaster,
+		}),
+		target: () => new BufferTarget(),
+		rootPath: '',
+	});
+
+	const source = videoSource();
+	output.addVideoTrack(source);
+
+	await output.start();
+
+	// First segment
+	await source.add(new EncodedPacket(avcPacketData, 'key', 0, 0), avcMetadata);
+	await source.add(new EncodedPacket(avcPacketData, 'delta', 0.5, 0), avcMetadata);
+	await source.add(new EncodedPacket(avcPacketData, 'delta', 1, 0), avcMetadata);
+	await source.add(new EncodedPacket(avcPacketData, 'delta', 1.5, 0), avcMetadata);
+	expect(onSegment).toHaveBeenCalledTimes(0);
+
+	// Second segment starts, first one is finalized
+	await source.add(new EncodedPacket(avcPacketData, 'key', 2, 0), avcMetadata);
+	expect(onSegment).toHaveBeenCalledTimes(1);
+	expect(onSegment.mock.calls[0]![1]).toEqual(expect.objectContaining({ n: 1 }));
+
+	await source.add(new EncodedPacket(avcPacketData, 'delta', 2.5, 0), avcMetadata);
+	await source.add(new EncodedPacket(avcPacketData, 'delta', 3, 0), avcMetadata);
+	await source.add(new EncodedPacket(avcPacketData, 'delta', 3.5, 0), avcMetadata);
+
+	expect(onPlaylist).not.toHaveBeenCalled();
+	expect(onMaster).not.toHaveBeenCalled();
+
+	await output.finalize();
+
+	// Second segment finalized on close
+	expect(onSegment).toHaveBeenCalledTimes(2);
+	expect(onSegment.mock.calls[1]![1]).toEqual(expect.objectContaining({ n: 2 }));
+
+	// Both segment calls should have a Target as the first argument
+	expect(onSegment.mock.calls[0]![0]).toBeDefined();
+	expect(onSegment.mock.calls[1]![0]).toBeDefined();
+
+	// Playlist and master should have been called once each
+	expect(onPlaylist).toHaveBeenCalledTimes(1);
+	expect(typeof onPlaylist.mock.calls[0]![0]).toBe('string');
+	expect(onPlaylist.mock.calls[0]![0]).toContain('#EXTM3U');
+	expect(onPlaylist.mock.calls[0]![1]).toEqual(expect.objectContaining({ n: 1 }));
+
+	expect(onMaster).toHaveBeenCalledTimes(1);
+	expect(typeof onMaster.mock.calls[0]![0]).toBe('string');
+	expect(onMaster.mock.calls[0]![0]).toContain('#EXTM3U');
+});

todo.txt

@@ -6,10 +6,6 @@ Also, why not just have the packet metadata on the packet? I think that would ma
 
 - Add an HLS "live mode". Challenge, where does bitrate come from?
 
-events:
-- onPlaylist
-- onSegment
-- onMaster
-
 - hls muxer starting offset
-- hls demuxer offset by segment number * targetduration
+- hls demuxer offset by segment number * targetduration
+- fmp4 muxing (CMAF??)