Update app.py

app.py

@@ -157,8 +157,9 @@ async def convert_stream(
         # Step1: encode audio
         yield None, None, None, "Encoding audio track..."
         if use_mp3:
-            ffmpeg_audio_cmd = ["ffmpeg", "-y", "-i", str(input_path), "-ac", "1", "-ar", "24000",
-                                "-b:a", "8k", str(out_audio)]
+            out_audio = CONVERTED_FOLDER / f"{uuid.uuid4().hex}.mp3"
+            ffmpeg_audio_cmd = ["ffmpeg", "-y", "-i", str(input_path), "-ac", "1", "-ar", "24k",
+                                "-b:a", "8k", "-vn", str(out_audio)]
             await run_command_capture(ffmpeg_audio_cmd)
         else:
             # fdkaac branch