diff --git a/dev/convert.html b/dev/convert.html
index a14d831..f85cc61 100644
--- a/dev/convert.html
+++ b/dev/convert.html
@@ -25,7 +25,7 @@
 			chunked: true,
 			chunkSize: 2**20
 		});
-		const outputFormat = new Mediabunny.FlacOutputFormat();
+		const outputFormat = new Mediabunny.Mp4OutputFormat();
 
 		const p = document.createElement('p');
 		p.textContent = 'Capturing...';
@@ -96,6 +96,7 @@
 			input,
 			output,
 			audio: {
+				discard: true,
 				//forceTranscode: true,
 				//sampleFormat: 's16',
 			},
@@ -124,7 +125,7 @@
 			},
 			*/
 			video: {
-				discard: true,
+				//discard: true,
 			},
 			tags: {} ?? {
 				title: 'Bigggy',
@@ -144,6 +145,7 @@
 				}
 			},
 			trim: {
+				end: 10,
 				//start: startTime,
 				//end: startTime + 2,
 			},
diff --git a/src/codec.ts b/src/codec.ts
index 0c868b1..e763a98 100644
--- a/src/codec.ts
+++ b/src/codec.ts
@@ -784,6 +784,37 @@ export const validateVideoChunkMetadata = (metadata: EncodedVideoChunkMetadata |
 			'Video chunk metadata decoder configuration must specify a valid codedHeight (positive integer).',
 		);
 	}
+	if (
+		metadata.decoderConfig.displayAspectWidth !== undefined
+		&& (
+			!Number.isInteger(metadata.decoderConfig.displayAspectWidth)
+			|| metadata.decoderConfig.displayAspectWidth <= 0
+		)
+	) {
+		throw new TypeError(
+			'Video chunk metadata decoder configuration displayAspectWidth, when defined, must be a positive integer.',
+		);
+	}
+	if (
+		metadata.decoderConfig.displayAspectHeight !== undefined
+		&& (
+			!Number.isInteger(metadata.decoderConfig.displayAspectHeight)
+			|| metadata.decoderConfig.displayAspectHeight <= 0
+		)
+	) {
+		throw new TypeError(
+			'Video chunk metadata decoder configuration displayAspectHeight, when defined, must be a positive integer.',
+		);
+	}
+	if (
+		(metadata.decoderConfig.displayAspectWidth !== undefined)
+		!== (metadata.decoderConfig.displayAspectHeight !== undefined)
+	) {
+		throw new TypeError(
+			'Video chunk metadata decoder configuration must specify both displayAspectWidth and displayAspectHeight,'
+			+ ' or neither.',
+		);
+	}
 	if (metadata.decoderConfig.description !== undefined) {
 		if (!isAllowSharedBufferSource(metadata.decoderConfig.description)) {
 			throw new TypeError(
diff --git a/src/isobmff/isobmff-demuxer.ts b/src/isobmff/isobmff-demuxer.ts
index 4d215a1..7e468f6 100644
--- a/src/isobmff/isobmff-demuxer.ts
+++ b/src/isobmff/isobmff-demuxer.ts
@@ -1475,10 +1475,13 @@ export class IsobmffDemuxer extends Demuxer {
 				const num = readU32Be(slice);
 				const den = readU32Be(slice);
 
-				if (num > den) {
-					track.info.squarePixelWidth = Math.round(track.info.width * num / den);
-				} else {
-					track.info.squarePixelHeight = Math.round(track.info.height * den / num);
+				// https://github.com/Vanilagy/mediabunny/issues/362
+				if (num > 0 && den > 0) {
+					if (num > den) {
+						track.info.squarePixelWidth = Math.round(track.info.width * num / den);
+					} else {
+						track.info.squarePixelHeight = Math.round(track.info.height * den / num);
+					}
 				}
 			}; break;
 
diff --git a/src/matroska/matroska-demuxer.ts b/src/matroska/matroska-demuxer.ts
index a88f077..87ebece 100644
--- a/src/matroska/matroska-demuxer.ts
+++ b/src/matroska/matroska-demuxer.ts
@@ -1051,14 +1051,16 @@ export class MatroskaDemuxer extends Demuxer {
 							const num = this.currentTrack.info.displayWidth * this.currentTrack.info.height;
 							const den = this.currentTrack.info.displayHeight * this.currentTrack.info.width;
 
-							if (num > den) {
-								this.currentTrack.info.squarePixelWidth = Math.round(
-									this.currentTrack.info.width * num / den,
-								);
-							} else {
-								this.currentTrack.info.squarePixelHeight = Math.round(
-									this.currentTrack.info.height * den / num,
-								);
+							if (num > 0 && den > 0) {
+								if (num > den) {
+									this.currentTrack.info.squarePixelWidth = Math.round(
+										this.currentTrack.info.width * num / den,
+									);
+								} else {
+									this.currentTrack.info.squarePixelHeight = Math.round(
+										this.currentTrack.info.height * den / num,
+									);
+								}
 							}
 						}
 
diff --git a/src/misc.ts b/src/misc.ts
index ee90e1c..129c58c 100644
--- a/src/misc.ts
+++ b/src/misc.ts
@@ -938,6 +938,8 @@ export type Rational = {
 };
 
 export const simplifyRational = (rational: Rational): Rational => {
+	assert(Number.isInteger(rational.num));
+	assert(Number.isInteger(rational.den));
 	assert(rational.den !== 0);
 
 	let a = Math.abs(rational.num);
diff --git a/src/mpeg-ts/mpeg-ts-demuxer.ts b/src/mpeg-ts/mpeg-ts-demuxer.ts
index 652c796..80b09e5 100644
--- a/src/mpeg-ts/mpeg-ts-demuxer.ts
+++ b/src/mpeg-ts/mpeg-ts-demuxer.ts
@@ -474,18 +474,22 @@ export class MpegTsDemuxer extends Demuxer {
 
 									elementaryStream.info.width = spsInfo.displayWidth;
 									elementaryStream.info.height = spsInfo.displayHeight;
-									if (spsInfo.pixelAspectRatio.num > spsInfo.pixelAspectRatio.den) {
-										elementaryStream.info.squarePixelWidth = Math.round(
-											elementaryStream.info.width
-											* spsInfo.pixelAspectRatio.num / spsInfo.pixelAspectRatio.den,
-										);
-										elementaryStream.info.squarePixelHeight = elementaryStream.info.height;
-									} else {
-										elementaryStream.info.squarePixelWidth = elementaryStream.info.width;
-										elementaryStream.info.squarePixelHeight = Math.round(
-											elementaryStream.info.height
-											* spsInfo.pixelAspectRatio.den / spsInfo.pixelAspectRatio.num,
-										);
+
+									const num = spsInfo.pixelAspectRatio.num;
+									const den = spsInfo.pixelAspectRatio.den;
+
+									if (num > 0 && den > 0) {
+										if (num > den) {
+											elementaryStream.info.squarePixelWidth = Math.round(
+												elementaryStream.info.width * num / den,
+											);
+											elementaryStream.info.squarePixelHeight = elementaryStream.info.height;
+										} else {
+											elementaryStream.info.squarePixelWidth = elementaryStream.info.width;
+											elementaryStream.info.squarePixelHeight = Math.round(
+												elementaryStream.info.height * den / num,
+											);
+										}
 									}
 
 									elementaryStream.info.colorSpace = {