feat: set default disposition flag for English audio streams and disable for others

src/commandBuilder.ts

@@ -97,8 +97,19 @@ export function encodingCommandBuilder(videoInfo: parsedVideoInfo): string {
     }
     args.push(
       `-metadata:s:a:${index}`,
-      `language=${audioStream.language} \\\n`,
+      `language=${audioStream.language}`,
     );
+    if (audioStream.language === "eng") {
+      args.push(
+        `-disposition:a:${index}`,
+        `default \\\n`,
+      );
+    } else {
+      args.push(
+        `-disposition:a:${index}`,
+        `-1 \\\n`,
+      );
+    }
   }
 
   for (