diff --git a/dev/demux.html b/dev/demux.html
index c86d370..091f7dd 100644
--- a/dev/demux.html
+++ b/dev/demux.html
@@ -46,10 +46,12 @@
 
 		const target = new Metamuxer.BufferTarget();
 		const output = new Metamuxer.Output({
-			format: new Metamuxer.MovOutputFormat({ fastStart: undefined }),
+			format: new Metamuxer.MkvOutputFormat(),
 			target
 		});
 
+		console.log(await input.getFormat());
+
 		const audioTrack = await input.getPrimaryAudioTrack();
 		const videoTrack = await input.getPrimaryVideoTrack();
 			
@@ -57,9 +59,9 @@
 
 		const decoderConfig = await audioTrack.getDecoderConfig();
 		const sampleSource = new Metamuxer.EncodedAudioSampleSource(await audioTrack.getCodec());
-		const audioDataSource = new Metamuxer.AudioDataSource({ codec: 'alaw', bitrate: 128e3 });
+		const audioDataSource = new Metamuxer.AudioDataSource({ codec: 'pcm-s16', bitrate: 128e3 });
 		const videoSampleSource = new Metamuxer.EncodedVideoSampleSource(await videoTrack.getCodec());
-		output.addAudioTrack(audioDataSource ?? sampleSource);
+		output.addAudioTrack(sampleSource);
 		output.addVideoTrack(videoSampleSource);
 
 		output.start();
@@ -67,18 +69,22 @@
 		const videoDecoderConfig = await videoTrack.getDecoderConfig();
 
 		
-		/*
+		
+		
 		for await (const sample of drain.samples()) {
+			//console.log(sample.timestamp);	
 			//sample.timestamp *= 2;
 			//console.log(sample);
 			//console.log(sample)
 			await sampleSource.digest(sample, { decoderConfig });
 		}
-		*/
-		for await (const { data } of new Metamuxer.AudioDataDrain(audioTrack).data()) {
+		/*
+		for await (const { data, timestamp } of new Metamuxer.AudioDataDrain(audioTrack).data()) {
+			//console.log("wow", data.timestamp);
 			//console.log(sample)
 			await audioDataSource.digest(data);
 		}
+			*/
 		for await (const sample of new Metamuxer.EncodedVideoSampleDrain(videoTrack).samples()) {
 			//console.log(sample)
 			await videoSampleSource.digest(sample, { decoderConfig: videoDecoderConfig });
@@ -96,7 +102,7 @@
 			a.click();
 			URL.revokeObjectURL(url);
 		}
-		download(new Blob([target.buffer]), 'converted.mov');
+		download(new Blob([target.buffer]), 'converted.mkv');
 
 		document.body.textContent = performance.now() - start;
 
diff --git a/src/input-format.ts b/src/input-format.ts
index c673d7c..9f4a44f 100644
--- a/src/input-format.ts
+++ b/src/input-format.ts
@@ -45,7 +45,7 @@ export class Mp4InputFormat extends IsobmffInputFormat {
 	/** @internal */
 	override async _canReadInput(input: Input) {
 		const majorBrand = await this._getMajorBrand(input);
-		return majorBrand !== 'qt  ';
+		return !!majorBrand && majorBrand !== 'qt  ';
 	}
 
 	getName() {
diff --git a/src/matroska/matroska-muxer.ts b/src/matroska/matroska-muxer.ts
index 549ac6b..1c111fb 100644
--- a/src/matroska/matroska-muxer.ts
+++ b/src/matroska/matroska-muxer.ts
@@ -32,8 +32,11 @@ import {
 } from '../subtitles';
 import {
 	AudioCodec,
+	PCM_CODECS,
+	PcmAudioCodec,
 	SubtitleCodec,
 	VideoCodec,
+	parsePcmCodec,
 	validateAudioChunkMetadata,
 	validateSubtitleMetadata,
 	validateVideoChunkMetadata,
@@ -103,15 +106,27 @@ type MatroskaAudioTrackData = MatroskaTrackData & { type: 'audio' };
 type MatroskaSubtitleTrackData = MatroskaTrackData & { type: 'subtitle' };
 
 const CODEC_STRING_MAP: Partial<Record<VideoCodec | AudioCodec | SubtitleCodec, string>> = {
-	avc: 'V_MPEG4/ISO/AVC',
-	hevc: 'V_MPEGH/ISO/HEVC',
-	vp8: 'V_VP8',
-	vp9: 'V_VP9',
-	av1: 'V_AV1',
-	aac: 'A_AAC', // TODO is this even correct
-	opus: 'A_OPUS',
-	vorbis: 'A_VORBIS',
-	webvtt: 'S_TEXT/WEBVTT',
+	'avc': 'V_MPEG4/ISO/AVC',
+	'hevc': 'V_MPEGH/ISO/HEVC',
+	'vp8': 'V_VP8',
+	'vp9': 'V_VP9',
+	'av1': 'V_AV1',
+
+	'aac': 'A_AAC',
+	'mp3': 'A_MPEG/L3',
+	'opus': 'A_OPUS',
+	'vorbis': 'A_VORBIS',
+	'flac': 'A_FLAC',
+	'pcm-u8': 'A_PCM/INT/LIT',
+	'pcm-s16': 'A_PCM/INT/LIT',
+	'pcm-s16be': 'A_PCM/INT/BIG',
+	'pcm-s24': 'A_PCM/INT/LIT',
+	'pcm-s24be': 'A_PCM/INT/BIG',
+	'pcm-s32': 'A_PCM/INT/LIT',
+	'pcm-s32be': 'A_PCM/INT/BIG',
+	'pcm-f32': 'A_PCM/FLOAT/IEEE',
+
+	'webvtt': 'S_TEXT/WEBVTT',
 };
 
 const TRACK_TYPE_MAP: Record<OutputTrack['type'], number> = {
@@ -470,6 +485,10 @@ export class MatroskaMuxer extends Muxer {
 	}
 
 	private audioSpecificTrackInfo(trackData: MatroskaAudioTrackData) {
+		const pcmInfo = (PCM_CODECS as readonly string[]).includes(trackData.track.source._codec)
+			? parsePcmCodec(trackData.track.source._codec as PcmAudioCodec)
+			: null;
+
 		return [
 			(trackData.info.decoderConfig.description
 				? {
@@ -480,7 +499,7 @@ export class MatroskaMuxer extends Muxer {
 			{ id: EBMLId.Audio, data: [
 				{ id: EBMLId.SamplingFrequency, data: new EBMLFloat32(trackData.info.sampleRate) },
 				{ id: EBMLId.Channels, data: trackData.info.numberOfChannels },
-				// TODO Bit depth for when PCM is a thing
+				pcmInfo ? { id: EBMLId.BitDepth, data: 8 * pcmInfo.sampleSize } : null,
 			] },
 		];
 	}
diff --git a/src/media-drain.ts b/src/media-drain.ts
index 7d2c4ce..42242c1 100644
--- a/src/media-drain.ts
+++ b/src/media-drain.ts
@@ -995,7 +995,7 @@ class PcmAudioDecoderWrapper extends DecoderWrapper<EncodedAudioSample, AudioDat
 			numberOfChannels: this.decoderConfig.numberOfChannels,
 			sampleRate: this.decoderConfig.sampleRate,
 			numberOfFrames,
-			timestamp: sample.timestamp,
+			timestamp: sample.microsecondTimestamp,
 		});
 
 		// Since all other decoders are async, we'll make this one behave async as well
diff --git a/src/media-source.ts b/src/media-source.ts
index 6ed857a..4867b34 100644
--- a/src/media-source.ts
+++ b/src/media-source.ts
@@ -499,39 +499,68 @@ class AudioEncoderWrapper {
 		assert(this.outputSampleSize);
 		assert(this.writeOutputValue);
 
+		// Need to extract data from the audio data before it's closed
+		const { numberOfChannels, numberOfFrames, sampleRate, timestamp } = audioData;
+
+		const CHUNK_SIZE = 2048;
+		const outputs: {
+			frameCount: number;
+			view: DataView;
+		}[] = [];
+
+		// Prepare all of the output buffers, each being bounded by CHUNK_SIZE so we don't generate huge samples
+		for (let frame = 0; frame < numberOfFrames; frame += CHUNK_SIZE) {
+			const frameCount = Math.min(CHUNK_SIZE, audioData.numberOfFrames - frame);
+			const outputSize = frameCount * numberOfChannels * this.outputSampleSize;
+			const outputBuffer = new ArrayBuffer(outputSize);
+			const outputView = new DataView(outputBuffer);
+
+			outputs.push({ frameCount, view: outputView });
+		}
+
 		// All user agents are required to support conversion to f32-planar
 		const allocationSize = audioData.allocationSize(({ planeIndex: 0, format: 'f32-planar' }));
 		const floats = new Float32Array(allocationSize / Float32Array.BYTES_PER_ELEMENT);
 
-		const channelCount = audioData.numberOfChannels;
-		const outputSize = audioData.numberOfFrames * channelCount * this.outputSampleSize;
-		const outputBuffer = new ArrayBuffer(outputSize);
-		const outputView = new DataView(outputBuffer);
-
-		for (let i = 0; i < channelCount; i++) {
+		for (let i = 0; i < numberOfChannels; i++) {
 			audioData.copyTo(floats, { planeIndex: i, format: 'f32-planar' });
-			for (let j = 0; j < floats.length; j++) {
-				// Write it interleaved... interleavedly?
-				this.writeOutputValue(outputView, (j * channelCount + i) * this.outputSampleSize, floats[j]!);
+
+			for (let j = 0; j < outputs.length; j++) {
+				const { frameCount, view } = outputs[j]!;
+
+				for (let k = 0; k < frameCount; k++) {
+					this.writeOutputValue(
+						view,
+						(k * numberOfChannels + i) * this.outputSampleSize,
+						floats[j * CHUNK_SIZE + k]!,
+					);
+				}
 			}
 		}
 
-		const sample = new EncodedAudioSample(
-			new Uint8Array(outputBuffer),
-			'key',
-			audioData.timestamp / 1e6,
-			audioData.duration / 1e6,
-		);
 		const meta: EncodedAudioChunkMetadata = {
 			decoderConfig: {
 				codec: this.encodingConfig.codec,
-				numberOfChannels: audioData.numberOfChannels,
-				sampleRate: audioData.sampleRate,
+				numberOfChannels,
+				sampleRate,
 			},
 		};
 
-		this.encodingConfig.onEncodedSample?.(sample, meta);
-		await this.muxer!.addEncodedAudioSample(this.source._connectedTrack!, sample, meta); // With backpressure
+		for (let i = 0; i < outputs.length; i++) {
+			const { frameCount, view } = outputs[i]!;
+			const outputBuffer = view.buffer;
+			const startFrame = i * CHUNK_SIZE;
+
+			const sample = new EncodedAudioSample(
+				new Uint8Array(outputBuffer),
+				'key',
+				timestamp / 1e6 + startFrame / sampleRate,
+				frameCount / sampleRate,
+			);
+
+			this.encodingConfig.onEncodedSample?.(sample, meta);
+			await this.muxer!.addEncodedAudioSample(this.source._connectedTrack!, sample, meta); // With backpressure
+		}
 	}
 
 	private ensureEncoder(audioData: AudioData) {
diff --git a/src/output-format.ts b/src/output-format.ts
index e8434d6..c75177e 100644
--- a/src/output-format.ts
+++ b/src/output-format.ts
@@ -158,7 +158,9 @@ export class MkvOutputFormat extends OutputFormat {
 	static getSupportedCodecs(): MediaCodec[] {
 		return [
 			'avc', 'hevc', 'vp8', 'vp9', 'av1',
-			'aac', 'opus', 'vorbis',
+			'aac', 'mp3', 'opus', 'vorbis', 'flac',
+			// pcm-s8, pcm-f32be, ulaw and alaw are not supported
+			'pcm-u8', 'pcm-s16', 'pcm-s16be', 'pcm-s24', 'pcm-s24be', 'pcm-s32', 'pcm-s32be', 'pcm-f32',
 			'webvtt',
 		];
 	}