fix: resolve issue causing corrupted MP3 files during export

app.py

@@ -189,13 +189,13 @@ def move_stems_to_parent(input_dir):
                 new_instrumental_path = os.path.join(parent_dir, "instrumental.wav")
                 shutil.move(instrumental_path, new_instrumental_path)
 
-def combine_stems_for_all(input_dir, output_format):
+def combine_stems_for_all(input_dir, output_format="mp3"):
     """
-    Combine all stems for each song in the input directory.
+    Combine all stems for each song in the input directory and export as MP3.
     
     Args:
         input_dir (str): Input directory containing song folders
-        output_format (str): Output audio format (e.g., 'm4a')
+        output_format (str): Output audio format (default is 'mp3')
     
     Returns:
         str: Path to the combined audio file
@@ -226,19 +226,16 @@ def combine_stems_for_all(input_dir, output_format):
         # Trim silence at the end
         trimmed_combined = trim_silence_at_end(combined)
 
-        # Use .m4a extension for AAC audio
-        output_file = os.path.join(subdir, song_name)
+        # Set MP3 as the output format
+        output_file = os.path.join(subdir, f"{song_name}.{output_format}")
 
         try:
-            # Export combined audio
-            trimmed_combined.export(output_file, format="ipod", codec="aac")
-            print(f"Exported combined stems to {output_file}")
-        except CouldntEncodeError as e:
-            print(f"Encoding failed: {e}")
-            # Fallback to MP3 if M4A fails
-            output_file = os.path.join(subdir, f"{song_name}.mp3")
+            # Export combined audio to MP3
             trimmed_combined.export(output_file, format="mp3", codec="libmp3lame", bitrate="320k")
             print(f"Exported combined stems to MP3 format: {output_file}")
+        except CouldntEncodeError as e:
+            print(f"MP3 Encoding failed: {e}")
+            return None
 
         return output_file