Add video classification pipeline
# What does this PR do?

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Adds a video classification pipeline using VideoMAE.

Fixes # (issue)


## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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- [x] Did you write any new necessary tests?


## Who can review?

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Models:

- albert, bert, xlm: @LysandreJik
- blenderbot, bart, marian, pegasus, encoderdecoder,  t5: @patrickvonplaten, @patil-suraj
- longformer, reformer, transfoxl, xlnet: @patrickvonplaten
- fsmt: @stas00
- funnel: @sgugger
- gpt2: @patrickvonplaten, @LysandreJik
- rag: @patrickvonplaten, @lhoestq
- tensorflow: @LysandreJik

Library:

- benchmarks: @patrickvonplaten
- deepspeed: @stas00
- ray/raytune: @richardliaw, @amogkam
- text generation: @patrickvonplaten
- tokenizers: @n1t0, @LysandreJik
- trainer: @sgugger
- pipelines: @LysandreJik

Documentation: @sgugger

HF projects:

- datasets: [different repo](https://github.com/huggingface/datasets)
- rust tokenizers: [different repo](https://github.com/huggingface/tokenizers)

Examples:

- maintained examples (not research project or legacy): @sgugger, @patil-suraj
- research_projects/bert-loses-patience: @JetRunner
- research_projects/distillation: @VictorSanh

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_The documentation is not available anymore as the PR was closed or merged._<|||||>The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_20151). All of your documentation changes will be reflected on that endpoint.<|||||>The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_20151). All of your documentation changes will be reflected on that endpoint.<|||||>The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_20151). All of your documentation changes will be reflected on that endpoint.<|||||>The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_20151). All of your documentation changes will be reflected on that endpoint.<|||||>The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_20151). All of your documentation changes will be reflected on that endpoint.<|||||>The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_20151). All of your documentation changes will be reflected on that endpoint.<|||||>The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_20151). All of your documentation changes will be reflected on that endpoint.<|||||>The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_20151). All of your documentation changes will be reflected on that endpoint.<|||||>The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_20151). All of your documentation changes will be reflected on that endpoint.<|||||>Holding off on this PR as we discuss https://github.com/huggingface/datasets/issues/5225 - I think I will update the PR here to use `av` instead of `decord` because of it. Feel free to join the conversation there.

---

edit: wrong issue link<|||||>> Holding off on this PR as we discuss #5225 - I think I will update the PR here to use `av` instead of `decord` because of it. Feel free to join the conversation there.

Your link is wrong I think, you meant https://github.com/huggingface/datasets/issues/5225 (Tip: GH will shorten the URL on its own so you don't have to care, just copy&paste raw URLs :) )

Maybe a core maintainer could jump in, but I feel like "blocking" PRs like this is not desirable, we should merge whatever is ready first, and hardmonize later. if this PRs code isolate the dependency enough, it should be  a breeze to update.
And if it's not it could be an argument in favor/defavor of some library. Real code always trumps whatever feelings about library X.<|||||>I agree the PR should not be held off until a feature is merged in Datasets. We can adapt to it later on when Datasets has the features.<|||||>Ok thanks for the advice @Narsil and @sgugger - in that case I'll just resolve all PR comments here and finish this out this week.<|||||>@Narsil is it ok to leave decord for now? I think its fine for this use case, and is just constrained to this pipeline. Later, we'll probably want to add some `video_utils.py` file, just as we do with image utils, where we can keep some more permanent video utilities.

Based on the convo in the datasets repo, I think we'll end up using PyAV.

To try this feature:

```python
from transformers import pipeline

pipe = pipeline('video-classification')
pipe('https://huggingface.co/datasets/nateraw/video-demo/resolve/main/archery.mp4')

# Result
"""
[{'score': 0.6418354511260986, 'label': 'archery'}, {'score': 0.0026529659517109394, 'label': 'riding unicycle'}, {'score': 0.00258301617577672, 'label': 'golf driving'}, {'score': 0.002545431721955538, 'label': 'throwing ball'}, {'score': 0.0023797585163265467, 'label': 'tobogganing'}]
"""
```