Add Streamed transform.

[gleize]

Motivation and Context

There are currently no easy way to handle the processing / transform of large video files without loading them fully in memory (which can blow-up rather quickly).
The proposed solution tackles that issue by making transforms iterable over clip of upper bounded duration.

Example :

iterable_transform = Streamed(
  clip_duration=2.,
  clip_transform=BlaBlaClipTransform(...),
  return_iterable=True,
)
for transformed_clip in iterable_transform(video):
  clip_result = model(transformed_clip)

How Has This Been Tested

Added unit test and ran python -m unittest discover -v -s ./tests -p test_transforms.py.
I'm also using this same code in my own training pipeline.

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have completed my CLA (see CONTRIBUTING)
• I have added tests to cover my changes.
• All new and existing tests passed.

[gleize]

Any update / feedback on this ? It's been there for a while.

[meta-cla]

Hi @gleize!

Thank you for your pull request.

We require contributors to sign our Contributor License Agreement, and yours needs attention.

You currently have a record in our system, but the CLA is no longer valid, and will need to be resubmitted.

Process

In order for us to review and merge your suggested changes, please sign at https://code.facebook.com/cla. If you are contributing on behalf of someone else (eg your employer), the individual CLA may not be sufficient and your employer may need to sign the corporate CLA.

Once the CLA is signed, our tooling will perform checks and validations. Afterwards, the pull request will be tagged with CLA signed. The tagging process may take up to 1 hour after signing. Please give it that time before contacting us about it.

If you have received this in error or have any questions, please contact us at cla@meta.com. Thanks!