diff --git a/dev/mux.html b/dev/mux.html
index ad0eeaf..3df9586 100644
--- a/dev/mux.html
+++ b/dev/mux.html
@@ -116,9 +116,10 @@
 	*/
 
 	let videoSource = new Mediabunny.CanvasSource(canvas, {
-		codec: 'avc',
+		codec: 'vp9',
 		//fullCodecString: 'avc1.42001f',
-		bitrate: 1e6
+		bitrate: 1e6,
+		onEncoderConfig: console.log,
 	});
 	let audioSource = new Mediabunny.AudioBufferSource({
 		codec: 'opus',
@@ -207,5 +208,5 @@ Testing... <00:17.350>One... <00:18.125>Two...
 	await output.finalize();
 
 	console.log(target);
-	download(new Blob([target.buffer]), 'test' + format.fileExtension);
+	//download(new Blob([target.buffer]), 'test' + format.fileExtension);
 </script>
\ No newline at end of file
diff --git a/src/sample.ts b/src/sample.ts
index 285fea2..1f2e074 100644
--- a/src/sample.ts
+++ b/src/sample.ts
@@ -201,7 +201,8 @@ export class VideoSample {
 				return new VideoSample(
 					new VideoFrame(data, {
 						timestamp: Math.trunc(init.timestamp! * SECOND_TO_MICROSECOND_FACTOR),
-						duration: Math.trunc((init.duration ?? 0) * SECOND_TO_MICROSECOND_FACTOR),
+						// Drag 0 to undefined
+						duration: Math.trunc((init.duration ?? 0) * SECOND_TO_MICROSECOND_FACTOR) || undefined,
 					}),
 					init,
 				);
@@ -373,13 +374,13 @@ export class VideoSample {
 				codedWidth: this.codedWidth,
 				codedHeight: this.codedHeight,
 				timestamp: this.microsecondTimestamp,
-				duration: this.microsecondDuration,
+				duration: this.microsecondDuration || undefined,
 				colorSpace: this.colorSpace,
 			});
 		} else {
 			return new VideoFrame(this._data, {
 				timestamp: this.microsecondTimestamp,
-				duration: this.microsecondDuration,
+				duration: this.microsecondDuration || undefined,
 			});
 		}
 	}