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Load community pipelines and components

##
Community pipelines

Community pipelines are any DiffusionPipeline class that are different from the original implementation as specified in their paper (for example, the StableDiffusionControlNetPipeline corresponds to the Text-to-Image Generation with ControlNet Conditioning paper). They provide additional functionality or extend the original implementation of a pipeline.

There are many cool community pipelines like Speech to Image or Composable Stable Diffusion, and you can find all the official community pipelines here.

To load any community pipeline on the Hub, pass the repository id of the community pipeline to the `custom_pipeline` argument and the model repository where you’d like to load the pipeline weights and components from. For example, the example below loads a dummy pipeline from `hf-internal-testing/diffusers-dummy-pipeline` and the pipeline weights and components from `google/ddpm-cifar10-32`:

🔒 By loading a community pipeline from the Hugging Face Hub, you are trusting that the code you are loading is safe. Make sure to inspect the code online before loading and running it automatically!

    from diffusers import DiffusionPipeline

    pipeline = DiffusionPipeline.from_pretrained(
        "google/ddpm-cifar10-32", custom_pipeline="hf-internal-testing/diffusers-dummy-pipeline", use_safetensors=True
    )

Loading an official community pipeline is similar, but you can mix loading weights from an official repository id and pass pipeline components directly. The example below loads the community CLIP Guided Stable Diffusion pipeline, and you can pass the CLIP model components directly to it:

    from diffusers import DiffusionPipeline
    from transformers import CLIPImageProcessor, CLIPModel

    clip_model_id = "laion/CLIP-ViT-B-32-laion2B-s34B-b79K"

    feature_extractor = CLIPImageProcessor.from_pretrained(clip_model_id)
    clip_model = CLIPModel.from_pretrained(clip_model_id)

    pipeline = DiffusionPipeline.from_pretrained(
        "runwayml/stable-diffusion-v1-5",
        custom_pipeline="clip_guided_stable_diffusion",
        clip_model=clip_model,
        feature_extractor=feature_extractor,
        use_safetensors=True,
    )

For more information about community pipelines, take a look at the Community pipelines guide for how to use them and if you’re interested in adding a community pipeline check out the How to contribute a community pipeline guide!

##
Community components

Community components allow users to build pipelines that may have customized components that are not a part of Diffusers. If your pipeline has custom components that Diffusers doesn’t already support, you need to provide their implementations as Python modules. These customized components could be a VAE, UNet, and scheduler. In most cases, the text encoder is imported from the Transformers library. The pipeline code itself can also be customized.

This section shows how users should use community components to build a community pipeline.

You’ll use the showlab/show-1-base pipeline checkpoint as an example. So, let’s start loading the components:

1. Import and load the text encoder from Transformers:

    from transformers import T5Tokenizer, T5EncoderModel

    pipe_id = "showlab/show-1-base"
    tokenizer = T5Tokenizer.from_pretrained(pipe_id, subfolder="tokenizer")
    text_encoder = T5EncoderModel.from_pretrained(pipe_id, subfolder="text_encoder")

2. Load a scheduler:

    from diffusers import DPMSolverMultistepScheduler

    scheduler = DPMSolverMultistepScheduler.from_pretrained(pipe_id, subfolder="scheduler")

3. Load an image processor:

    from transformers import CLIPFeatureExtractor

    feature_extractor = CLIPFeatureExtractor.from_pretrained(pipe_id, subfolder="feature_extractor")

In steps 4 and 5, the custom UNet and pipeline implementation must match the format shown in their files for this example to work.

4. Now you’ll load a custom UNet, which in this example, has already been implemented in the `showone_unet_3d_condition.py` script for your convenience. You’ll notice the `UNet3DConditionModel` class name is changed to `ShowOneUNet3DConditionModel` because UNet3DConditionModel already exists in Diffusers. Any components needed for the `ShowOneUNet3DConditionModel` class should be placed in the `showone_unet_3d_condition.py` script.

Once this is done, you can initialize the UNet:

    from showone_unet_3d_condition import ShowOneUNet3DConditionModel

    unet = ShowOneUNet3DConditionModel.from_pretrained(pipe_id, subfolder="unet")

5. Finally, you’ll load the custom pipeline code. For this example, it has already been created for you in the `pipeline_t2v_base_pixel.py` script. This script contains a custom `TextToVideoIFPipeline` class for generating videos from text. Just like the custom UNet, any code needed for the custom pipeline to work should go in the `pipeline_t2v_base_pixel.py` script.

Once everything is in place, you can initialize the `TextToVideoIFPipeline` with the `ShowOneUNet3DConditionModel`:

    from pipeline_t2v_base_pixel import TextToVideoIFPipeline
    import torch

    pipeline = TextToVideoIFPipeline(
        unet=unet,
        text_encoder=text_encoder,
        tokenizer=tokenizer,
        scheduler=scheduler,
        feature_extractor=feature_extractor
    )
    pipeline = pipeline.to(device="cuda")
    pipeline.torch_dtype = torch.float16

Push the pipeline to the Hub to share with the community!

    pipeline.push_to_hub("custom-t2v-pipeline")

After the pipeline is successfully pushed, you need a couple of changes:

1. Change the `_class_name` attribute in `model_index.json` to `"pipeline_t2v_base_pixel"` and `"TextToVideoIFPipeline"`.
2. Upload `showone_unet_3d_condition.py` to the `unet` directory.
3. Upload `pipeline_t2v_base_pixel.py` to the pipeline base directory.

To run inference, simply add the `trust_remote_code` argument while initializing the pipeline to handle all the “magic” behind the scenes.

    from diffusers import DiffusionPipeline
    import torch

    pipeline = DiffusionPipeline.from_pretrained(
        "<change-username>/<change-id>", trust_remote_code=True, torch_dtype=torch.float16
    ).to("cuda")

    prompt = "hello"

    # Text embeds
    prompt_embeds, negative_embeds = pipeline.encode_prompt(prompt)

    # Keyframes generation (8x64x40, 2fps)
    video_frames = pipeline(
        prompt_embeds=prompt_embeds,
        negative_prompt_embeds=negative_embeds,
        num_frames=8,
        height=40,
        width=64,
        num_inference_steps=2,
        guidance_scale=9.0,
        output_type="pt"
    ).frames