Finetuning issue with V-JEPA 2
Author: MattLiutt
Pull request: no
Labels: name: bug

### System Info

OS: Linux (GCP)
Python: 3.12
torch: 2.6.0+cuda12.4
CUDA: 12.4
GPU: A100 40GB
transformers: tested on main and v4.57.1

### Who can help?

@SunMarc @CyrilVallez @ArthurZucker @McPatate Might be related to VideoProcessor?

### Information

- [x] The official example scripts
- [ ] My own modified scripts

### Tasks

- [ ] An officially supported task in the `examples` folder (such as GLUE/SQuAD, ...)
- [x] My own task or dataset (give details below)

### Reproduction

I'm attempting to fine-tune a video classification model using the [facebook/vjepa2-vitl-fpc16-256-ssv2 notebook](https://huggingface.co/facebook/vjepa2-vitl-fpc16-256-ssv2/blob/main/notebook_finetuning.ipynb) and a nearly identical script ([gist here](https://gist.github.com/ariG23498/28bccc737c11d1692f6d0ad2a0d7cddb)) on a GCP A100 40GB instance.

My dataset loader uses torchcodec for video decoding and batch collation as in the gist above. `vids` is the video batch tensor with dimensions [batch_size, num_frames, channels, height, width]. When this tensor is fed to VJEPA2VideoProcessor, the error occurs. The training and preprocessing steps closely follow the official notebook. but got the report as:

```python
Traceback (most recent call last):
  File "/home/vjepa2/vjepa2.py", line 436, in <module>
    main()
  File "/home/vjepa2/vjepa2.py", line 399, in main
    training_history = run_training_loop(config, model, processor, train_loader, val_loader, device)
  File "/home/vjepa2/vjepa2.py", line 231, in run_training_loop
    inputs = processor(vids, return_tensors="pt").to(device)
  File "/home/vj2_env/lib/python3.12/site-packages/transformers/video_processing_utils.py", line 209, in __call__
    return self.preprocess(videos, **kwargs)
  File "/home/vj2_env/lib/python3.12/site-packages/transformers/video_processing_utils.py", line 391, in preprocess
    videos = self._prepare_input_videos(videos=videos, input_data_format=input_data_format, device=device)
  File "/home/vj2_env/lib/python3.12/site-packages/transformers/video_processing_utils.py", line 347, in _prepare_input_videos
    input_data_format = infer_channel_dimension_format(video)
  File "/home/vj2_env/lib/python3.12/site-packages/transformers/image_utils.py", line 312, in infer_channel_dimension_format
    raise ValueError(f"Unsupported number of image dimensions: {image.ndim}")

ValueError: Unsupported number of image dimensions: 6
```

### Expected behavior

The processor should handle the batch as per notebook expectations, or if batched input shape is unsupported, the documentation/code should clarify accepted input shapes for video batches.

### Additional Notes
I have verified vids.shape before the call and it's typically (batch, frames, ch, h, w), i.e., five dimensions.

The error hints at a tensor with six dimensions being passed, but my code (and the notebook) only creates 5D tensors for video batches.

Am I perhaps missing a step regarding batch collation or stacking, or should the processor support this format out of the box?

Comments:
Hey @MattLiutt, thanks for the report. It will be better if you can give us a minimal reproducer showing an issue with the processor if you think the issue lies there. For now, I think you can try to debug why the `image` passed in `infer_channel_dimension_format` is of dimension 6 instead of 5 and try to find the source of this mismatch between your original input and the one that was passed ! 

cc @zucchini-nlp if there is something i missed 

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