Update app.py

app.py

@@ -38,15 +38,17 @@ if uploaded_file is not None:
                     "-filter_complex", f"[0:v]setpts={video_speed}*PTS[v];[0:a]atempo={audio_speed}[a]",
                     "-map", "[v]", "-map", "[a]",
                     "-vcodec", "libx264", "-crf", "28", "-preset", "fast",
+                    "-movflags", "+faststart",
                     "-y", output_path
                 ]
             else:
-                # Lossless mode (copy original codec without full re-encode)
+                # Lossless mode (copy video, re-encode only audio, make it browser-playable)
                 cmd = [
                     "ffmpeg", "-i", input_path,
                     "-filter_complex", f"[0:v]setpts={video_speed}*PTS[v];[0:a]atempo={audio_speed}[a]",
                     "-map", "[v]", "-map", "[a]",
-                    "-c:v", "copy", "-c:a", "aac", "-b:a", "192k",  # copy video, re-encode only audio for sync
+                    "-c:v", "copy", "-c:a", "aac", "-b:a", "192k",
+                    "-movflags", "+faststart",  # ensures browser playback
                     "-y", output_path
                 ]
 
@@ -54,8 +56,10 @@ if uploaded_file is not None:
 
             st.success("✅ Processing complete!")
 
+            # Show processed video
             st.video(output_path)
 
+            # Download button
             with open(output_path, "rb") as f:
                 st.download_button(
                     label="Download Processed Video",