Adjust timestamp logic for media sinks for more accurate audio timing

src/matroska/matroska-demuxer.ts

@@ -1,4 +1,5 @@
 import {
+	AacCodecInfo,
 	AudioCodec,
 	extractAudioCodecString,
 	extractAv1CodecInfoFromFrame,
@@ -122,6 +123,7 @@ type InternalTrack = {
 			sampleRate: number;
 			bitDepth: number;
 			codec: AudioCodec | null;
+			aacCodecInfo: AacCodecInfo | null;
 		};
 };
 type InternalVideoTrack = InternalTrack & { info: { type: 'video' } };
@@ -625,6 +627,9 @@ export class MatroskaDemuxer extends Demuxer {
 					) {
 						if (codecIdWithoutSuffix === CODEC_STRING_MAP.aac) {
 							this.currentTrack.info.codec = 'aac';
+							this.currentTrack.info.aacCodecInfo = {
+								isMpeg2: this.currentTrack.codecId.includes('MPEG2'),
+							};
 						} else if (this.currentTrack.codecId === CODEC_STRING_MAP.mp3) {
 							this.currentTrack.info.codec = 'mp3';
 						} else if (codecIdWithoutSuffix === CODEC_STRING_MAP.opus) {
@@ -695,6 +700,7 @@ export class MatroskaDemuxer extends Demuxer {
 						sampleRate: -1,
 						bitDepth: -1,
 						codec: null,
+						aacCodecInfo: null,
 					};
 				}
 			}; break;
@@ -1476,7 +1482,7 @@ class MatroskaAudioTrackBacking extends MatroskaTrackBacking<EncodedAudioSample>
 				codec: extractAudioCodecString({
 					codec: this.internalTrack.info.codec,
 					codecDescription: this.internalTrack.codecPrivate,
-					aacCodecInfo: null,
+					aacCodecInfo: this.internalTrack.info.aacCodecInfo,
 				}),
 				numberOfChannels: this.internalTrack.info.numberOfChannels,
 				sampleRate: this.internalTrack.info.sampleRate,

src/matroska/matroska-muxer.ts

@@ -487,7 +487,7 @@ export class MatroskaMuxer extends Muxer {
 			const timestamp = this.validateAndNormalizeTimestamp(trackData.track, cue.timestamp, true);
 
 			let bodyText = cue.text;
-			const timestampMs = Math.floor(timestamp * 1000);
+			const timestampMs = Math.round(timestamp * 1000);
 
 			// Replace in-body timestamps so that they're relative to the cue start time
 			inlineTimestampRegex.lastIndex = 0;
@@ -622,7 +622,7 @@ export class MatroskaMuxer extends Muxer {
 			this.createSegment();
 		}
 
-		const msTimestamp = Math.floor(1000 * chunk.timestamp);
+		const msTimestamp = Math.round(1000 * chunk.timestamp);
 		// We can only finalize this cluster (and begin a new one) if we know that each track will be able to
 		// start the new one with a key frame.
 		const keyFrameQueuedEverywhere = this.trackDatas.every((otherTrackData) => {
@@ -673,7 +673,7 @@ export class MatroskaMuxer extends Muxer {
 		view.setUint8(0, 0x80 | trackData.track.id);
 		view.setInt16(1, relativeTimestamp, false);
 
-		const msDuration = Math.floor(1000 * chunk.duration);
+		const msDuration = Math.round(1000 * chunk.duration);
 
 		if (msDuration === 0 && !chunk.additions) {
 			// No duration or additions, we can write out a SimpleBlock