Update app.py

app.py

@@ -375,10 +375,9 @@ def create_video(script_text: str, generate_script: bool, music_path: str | None
         final_video.write_videofile(
             output_path,
             fps=15,
-            codec="mpeg4",
+            codec="libx264",
             audio_codec="mp3",
-            threads=1,
-            preset="ultrafast",
+            threads=2,
             logger=None,
             verbose=False
         )