Fix video export to match original repo implementation

Use the correct output format: pipe()[0] then video[0]
Remove unnecessary tensor conversion logic

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app.py

@@ -61,7 +61,7 @@ def generate_interpolation(
         # Generate video
         generator = torch.Generator(device="cuda").manual_seed(seed)
 
-        output = pipe(
+        video = pipe(
             prompt=prompt,
             first_image=first_image,
             last_image=last_image,
@@ -70,36 +70,14 @@ def generate_interpolation(
             num_frames=num_frames,
             guidance_scale=guidance_scale,
             generator=generator,
-        )
-
-        # Extract video frames - handle different output formats
-        if hasattr(output, 'frames'):
-            video_frames = output.frames[0]
-        elif isinstance(output, (list, tuple)):
-            video_frames = output[0]
-        else:
-            video_frames = output
-
-        # Convert tensor to numpy if needed
-        if torch.is_tensor(video_frames):
-            video_frames = video_frames.cpu().numpy()
-
-        # Ensure correct format: list of numpy arrays in [0, 255] range
-        if isinstance(video_frames, np.ndarray):
-            # If shape is (frames, height, width, channels)
-            if video_frames.ndim == 4:
-                # Convert from float [0, 1] to uint8 [0, 255] if needed
-                if video_frames.dtype == np.float32 or video_frames.dtype == np.float64:
-                    video_frames = (video_frames * 255).astype(np.uint8)
-                # Convert to list of frames
-                video_frames = [video_frames[i] for i in range(video_frames.shape[0])]
+        )[0]
 
         # Export to temporary file
         temp_file = tempfile.NamedTemporaryFile(delete=False, suffix=".mp4")
         output_path = temp_file.name
         temp_file.close()
 
-        export_to_video(video_frames, output_path, fps=fps)
+        export_to_video(video[0], output_path, fps=fps)
 
         status = f"✓ Video generated successfully! ({num_frames} frames at {fps} fps)"
         print(status)