Update app.py

app.py

@@ -58,7 +58,10 @@ def inference(audio_file, model_name, vocals, drums, bass, other, mp3, mp3_bitra
         os.rename(selected_stems[0], output_file)
     else:
         # Otherwise, use ffmpeg to mix the stems
-        ffmpeg_cmd = ["ffmpeg", "-y", "-i"] + selected_stems + ["-filter_complex", "amix=inputs=" + str(len(selected_stems)) + ":duration=longest", output_file]
+        ffmpeg_cmd = ["ffmpeg", "-y"]
+        for stem in selected_stems:
+            ffmpeg_cmd.extend(["-i", f"\"{stem}\""])  # Quote file paths
+        ffmpeg_cmd.extend(["-filter_complex", f"amix=inputs={len(selected_stems)}:duration=longest", f"\"{output_file}\""])  # Quote file paths
         subprocess.run(ffmpeg_cmd, check=True)
 
     return output_file