Add track-specific conversion options, fix esbuild race condition

dev/convert.html

@@ -24,7 +24,7 @@
 			chunked: true,
 			chunkSize: 2**20
 		});
-		const outputFormat = new Mediabunny.Mp3OutputFormat({});
+		const outputFormat = new Mediabunny.Mp4OutputFormat({});
 
 		const button = document.createElement('button');
 		button.textContent = 'Cancel';
@@ -41,6 +41,7 @@
 				target
 			}),
 			audio: {
+				discard: true,
 				//codec: 'opus',
 				//bitrate: 128000,
 				//numberOfChannels: 1,
@@ -72,7 +73,7 @@
 				bitrate: 320000
 			},
 			*/
-			video: {
+			video: () => ({
 				//frameRate: 27.123,
 				//width: 320,
 				//forceTranscode: true,
@@ -91,7 +92,7 @@
 				//height: 512,
 				//width: 200,
 				//height: 100,
-			},
+			}),
 			trim: {
 				start: 0,
 				end: 20