Refine av1C box data

dev/demux.html

@@ -29,7 +29,6 @@
 		output.start();
 
 		for await (const frame of drain.frames(0, 10)) {
-			console.log(frame.timestamp, frame.duration)
 			await mediaSource.digest(frame);
 			frame.close();
 		}

dev/player.html

@@ -38,6 +38,8 @@ const input = new Metamuxer.Input({
 	source
 });
 
+console.log(await input.getMimeType())
+
 const videoTrack = await input.getPrimaryVideoTrack(); 
 const audioTrack = await input.getPrimaryAudioTrack();