Make mfra box lookup more resilient

dev/convert.html

@@ -24,9 +24,7 @@
 			chunked: true,
 			chunkSize: 2**20
 		});
-		const outputFormat = new Mediabunny.AdtsOutputFormat({
-			onFrame: console.log
-		});
+		const outputFormat = new Mediabunny.Mp4OutputFormat({});
 
 		const button = document.createElement('button');
 		button.textContent = 'Cancel';

dev/demux.html

@@ -21,6 +21,8 @@
 
 		for await (const packet of sink.packets()) {
 			console.log(packet);
+
+			if (packet.timestamp > 135) break;
 		}
 
 		/*