Fix SourceRef race conditions, fix "source" and "target" getter returning unused instances, add missing validation, make "getDurationFromMetadata" only exist on tracks, fix examples, expand media player to support live playback, change the signatures of some Input APIs

src/hls/hls-demuxer.ts

@@ -593,12 +593,6 @@ export class HlsDemuxer extends Demuxer {
 		return segmentedInput;
 	}
 
-	async getDurationFromMetadata(options: DurationMetadataRequestOptions): Promise<number | null> {
-		return this.hasMasterPlaylist
-			? null
-			: this.segmentedInputs[0]!.getDurationFromMetadata(options);
-	}
-
 	async getMetadataTags(): Promise<MetadataTags> {
 		return {};
 	}

src/hls/hls-muxer.ts

@@ -99,6 +99,7 @@ export class HlsMuxer extends Muxer {
 	maxLiveSegmentCount: number;
 	isRelativeToUnixEpoch = false;
 	globalTargetDuration: number;
+	numWrittenMasterPlaylists = 0;
 
 	playlists: Playlist[] = [];
 	playlistDeclarations: PlaylistDeclaration[] = [];
@@ -909,11 +910,11 @@ export class HlsMuxer extends Muxer {
 						return slice;
 					} else {
 						const playlistInfo = toPlaylistInfo(playlist);
-						const path = await this.getInitPath(playlistInfo);
-						validateInitPath(path);
+						const initPath = await this.getInitPath(playlistInfo);
+						validateInitPath(initPath);
 
 						playlist.initSegment = {
-							path,
+							path: initPath,
 							duration: 0,
 							timestamp: 0,
 							byteSize: 0,
@@ -921,7 +922,7 @@ export class HlsMuxer extends Muxer {
 						};
 
 						const target = await this.output._getTarget({
-							path,
+							path: initPath,
 							isRoot: false,
 						});
 						target.on('write', ({ end }) => {
@@ -1371,14 +1372,25 @@ export class HlsMuxer extends Muxer {
 
 		this.format._options.onMaster?.(masterPlaylistText);
 
-		const target = await this.output._getTarget({ path: pathedTarget.rootPath, isRoot: true });
-		const writer = new Writer(target);
+		let writer: Writer;
+		if (this.numWrittenMasterPlaylists === 0) {
+			// For the first master playlist write, we use the normal root writer getter, so that the target returned by
+			// Output.target emits valid write events.
+			writer = await this.output._getRootWriter();
+		} else {
+			// For subsequent master playlist writes, we *must* obtain a different target in order to overwrite
+			// the file.
+			const target = await this.output._getTarget({ path: pathedTarget.rootPath, isRoot: true });
+			writer = new Writer(target);
+			writer.start();
+		}
 
-		writer.start();
 		writer.write(textEncoder.encode(masterPlaylistText));
 
 		await writer.flush();
 		await writer.finalize();
+
+		this.numWrittenMasterPlaylists++;
 	}
 
 	private async tryWriteMasterPlaylist() {