fix cogvideox autoencoder decode

[Xiang-cd]

What does this PR do?

fix bug of #9568

Fixes # (issue)
it is a simple fix with a line code change.
cogvideox train with mixsure of image and video, so the vae must support reconstruction of image, I fix the image case.

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Who can review?

any one who familiar with vae.
@sayakpaul @DN6 @yiyixuxu

Core library:

• Schedulers: @yiyixuxu
• Pipelines and pipeline callbacks: @yiyixuxu and @asomoza
• Training examples: @sayakpaul
• Docs: @stevhliu and @sayakpaul
• JAX and MPS: @pcuenca
• Audio: @sanchit-gandhi
• General functionalities: @sayakpaul @yiyixuxu @DN6

Integrations:

• deepspeed: HF Trainer/Accelerate: @SunMarc
• PEFT: @sayakpaul @BenjaminBossan

HF projects:

• accelerate: different repo
• datasets: different repo
• transformers: different repo
• safetensors: different repo

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[a-r-r-o-w]

thank you, this looks correct!

[a-r-r-o-w]

The commit was to resolve the merge conflict with the following conv_cache line

[HuggingFaceDocBuilderDev]

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[sayakpaul]

@a-r-r-o-w could we have caught it with some tests? Or not really? In the former case, let's also add a test?

[a-r-r-o-w]

could we have caught it with some tests? Or not really? In the former case, let's also add a test?

Previously, we did not need to decode 1-frame video so this was not required, so testing for this case was not necessary. For Image-to-Video training, however, we need to be able to encode single frames (which is already supported). I think having decode work for a single frame is good to have too, since it could help with debugging.

[sayakpaul]

Cool. If you want to feel free to support a test.

[Xiang-cd]

thank you, the support of image decode is useful for image-video mix tasks and further research, and this was my first pr to huggingface, hope it could merge. :)

[yiyixuxu]

thanks for your PR!! @Xiang-cd