Update app.py

app.py

@@ -250,22 +250,24 @@ def run_pipeline(prompt_text, steps, image_paths, audio_file_path, max_duration
     if audio_path:
 
         def add_silence_to_audio_ffmpeg(audio_path, tmp_audio_path, silence_duration_s=0.5):
-    
             command = [
-                'ffmpeg', 
-                '-i', audio_path,  
-                '-f', 'lavfi',  
-                '-t', str(silence_duration_s),  
-                '-i', 'anullsrc=r=16000:cl=stereo',  
-                '-filter_complex', '[1][0]concat=n=2:v=0:a=1[out]',  
-                '-map', '[out]', 
+                'ffmpeg',
+                '-i', audio_path,
+                '-f', 'lavfi',
+                '-t', str(silence_duration_s),
+                '-i', 'anullsrc=r=16000:cl=mono',  # generate 16 kHz mono
+                '-filter_complex',
+                (
+                    '[0:a]aresample=16000,pan=mono|c0=c0[a0];'
+                    '[1:a]aresample=16000,pan=mono|c0=c0[a1];'
+                    '[a1][a0]concat=n=2:v=0:a=1[out]'
+                ),
+                '-map', '[out]',
                 '-y', tmp_audio_path,
-                '-loglevel', 'quiet'
+                '-loglevel', 'error'
             ]
-            
             subprocess.run(command, check=True)
     
-        
         tmp_audio_path = os.path.join(output_dir, "tmp_audio.wav")
     
         add_silence_to_audio_ffmpeg(audio_path, tmp_audio_path)