Fix frame export for WanImageToVideoPipeline

- Add proper tensor/numpy conversion before export_to_video
- Handle multiple channel formats (NCHW to NHWC)
- Ensure RGB format and uint8 range for video export

videogen.py

@@ -10144,6 +10144,54 @@ def main(args):
                     print("Unknown output format.")
                     return
 
+                # Process frames for export - ensure correct format
+                # WanImageToVideoPipeline returns tensor with shape (batch, channels, frames, height, width)
+                # or (frames, channels, height, width) - need to convert to (frames, height, width, channels)
+                if isinstance(frames, torch.Tensor):
+                    # Convert tensor to numpy
+                    frames = frames.cpu().numpy()
+                
+                # Handle different frame array shapes
+                if isinstance(frames, np.ndarray):
+                    # If frames is 5D (batch, channels, frames, height, width), extract first batch
+                    if frames.ndim == 5:
+                        frames = frames[0]  # Now (channels, frames, height, width)
+                    
+                    # If frames is 4D (channels, frames, height, width), transpose to (frames, height, width, channels)
+                    if frames.ndim == 4:
+                        if frames.shape[0] in [1, 3, 4]:  # channels first
+                            frames = np.transpose(frames, (1, 2, 3, 0))  # (frames, height, width, channels)
+                        elif frames.shape[-1] in [1, 3, 4]:  # channels last, already correct
+                            pass  # Already in correct format
+                    
+                    # If frames is 3D (height, width, channels) or (frames, height, width), add dimension
+                    if frames.ndim == 3:
+                        if frames.shape[-1] not in [1, 3, 4] and frames.shape[0] in [1, 3, 4]:
+                            # channels first, need to transpose
+                            frames = np.transpose(frames, (1, 2, 0))
+                        # If single frame (height, width, channels), add batch dimension
+                        if frames.ndim == 3 and frames.shape[-1] in [1, 3, 4]:
+                            frames = np.expand_dims(frames, axis=0)
+                    
+                    # Ensure we have 3 channels (RGB) for export
+                    if frames.ndim == 4 and frames.shape[-1] == 1:
+                        # Grayscale, convert to RGB
+                        frames = np.repeat(frames, 3, axis=-1)
+                    elif frames.ndim == 4 and frames.shape[-1] > 4:
+                        # Too many channels, take first 3
+                        frames = frames[..., :3]
+                
+                # Ensure frames are in 0-255 uint8 range for video export
+                if isinstance(frames, np.ndarray):
+                    if frames.dtype == np.float32 or frames.dtype == np.float64:
+                        # Assume 0-1 range, convert to 0-255
+                        if frames.max() <= 1.0:
+                            frames = (frames * 255).astype(np.uint8)
+                        else:
+                            frames = frames.astype(np.uint8)
+                    elif frames.dtype != np.uint8:
+                        frames = frames.astype(np.uint8)
+
                 export_to_video(frames, f"{args.output}.mp4", fps=args.fps)
                 timing.end_step()  # video_generation