v0.25.1/latent_consistency_interpolate.py

import inspect
from typing import Any, Callable, Dict, List, Optional, Union

import numpy as np
import torch
from transformers import CLIPImageProcessor, CLIPTextModel, CLIPTokenizer

from diffusers.image_processor import VaeImageProcessor
from diffusers.loaders import FromSingleFileMixin, LoraLoaderMixin, TextualInversionLoaderMixin
from diffusers.models import AutoencoderKL, UNet2DConditionModel
from diffusers.models.lora import adjust_lora_scale_text_encoder
from diffusers.pipelines.pipeline_utils import DiffusionPipeline
from diffusers.pipelines.stable_diffusion import StableDiffusionPipelineOutput, StableDiffusionSafetyChecker
from diffusers.schedulers import LCMScheduler
from diffusers.utils import (
    USE_PEFT_BACKEND,
    deprecate,
    logging,
    replace_example_docstring,
    scale_lora_layers,
    unscale_lora_layers,
)
from diffusers.utils.torch_utils import randn_tensor


logger = logging.get_logger(__name__)  # pylint: disable=invalid-name

EXAMPLE_DOC_STRING = """
    Examples:
        ```py
        >>> import torch
        >>> import numpy as np

        >>> from diffusers import DiffusionPipeline

        >>> pipe = DiffusionPipeline.from_pretrained("SimianLuo/LCM_Dreamshaper_v7", custom_pipeline="latent_consistency_interpolate")
        >>> # To save GPU memory, torch.float16 can be used, but it may compromise image quality.
        >>> pipe.to(torch_device="cuda", torch_dtype=torch.float32)

        >>> prompts = ["A cat", "A dog", "A horse"]
        >>> num_inference_steps = 4
        >>> num_interpolation_steps = 24
        >>> seed = 1337

        >>> torch.manual_seed(seed)
        >>> np.random.seed(seed)

        >>> images = pipe(
                prompt=prompts,
                height=512,
                width=512,
                num_inference_steps=num_inference_steps,
                num_interpolation_steps=num_interpolation_steps,
                guidance_scale=8.0,
                embedding_interpolation_type="lerp",
                latent_interpolation_type="slerp",
                process_batch_size=4, # Make it higher or lower based on your GPU memory
                generator=torch.Generator(seed),
            )

        >>> # Save the images as a video
        >>> import imageio
        >>> from PIL import Image

        >>> def pil_to_video(images: List[Image.Image], filename: str, fps: int = 60) -> None:
                frames = [np.array(image) for image in images]
                with imageio.get_writer(filename, fps=fps) as video_writer:
                    for frame in frames:
                        video_writer.append_data(frame)

        >>> pil_to_video(images, "lcm_interpolate.mp4", fps=24)
        ```
"""


def lerp(
    v0: Union[torch.Tensor, np.ndarray],
    v1: Union[torch.Tensor, np.ndarray],
    t: Union[float, torch.Tensor, np.ndarray],
) -> Union[torch.Tensor, np.ndarray]:
    """
    Linearly interpolate between two vectors/tensors.

    Args:
        v0 (`torch.Tensor` or `np.ndarray`): First vector/tensor.
        v1 (`torch.Tensor` or `np.ndarray`): Second vector/tensor.
        t: (`float`, `torch.Tensor`, or `np.ndarray`):
            Interpolation factor. If float, must be between 0 and 1. If np.ndarray or
            torch.Tensor, must be one dimensional with values between 0 and 1.

    Returns:
        Union[torch.Tensor, np.ndarray]
            Interpolated vector/tensor between v0 and v1.
    """
    inputs_are_torch = False
    t_is_float = False

    if isinstance(v0, torch.Tensor):
        inputs_are_torch = True
        input_device = v0.device
        v0 = v0.cpu().numpy()
        v1 = v1.cpu().numpy()

    if isinstance(t, torch.Tensor):
        inputs_are_torch = True
        input_device = t.device
        t = t.cpu().numpy()
    elif isinstance(t, float):
        t_is_float = True
        t = np.array([t])

    t = t[..., None]
    v0 = v0[None, ...]
    v1 = v1[None, ...]
    v2 = (1 - t) * v0 + t * v1

    if t_is_float and v0.ndim > 1:
        assert v2.shape[0] == 1
        v2 = np.squeeze(v2, axis=0)
    if inputs_are_torch:
        v2 = torch.from_numpy(v2).to(input_device)

    return v2


def slerp(
    v0: Union[torch.Tensor, np.ndarray],
    v1: Union[torch.Tensor, np.ndarray],
    t: Union[float, torch.Tensor, np.ndarray],
    DOT_THRESHOLD=0.9995,
) -> Union[torch.Tensor, np.ndarray]:
    """
    Spherical linear interpolation between two vectors/tensors.

    Args:
        v0 (`torch.Tensor` or `np.ndarray`): First vector/tensor.
        v1 (`torch.Tensor` or `np.ndarray`): Second vector/tensor.
        t: (`float`, `torch.Tensor`, or `np.ndarray`):
            Interpolation factor. If float, must be between 0 and 1. If np.ndarray or
            torch.Tensor, must be one dimensional with values between 0 and 1.
        DOT_THRESHOLD (`float`, *optional*, default=0.9995):
            Threshold for when to use linear interpolation instead of spherical interpolation.

    Returns:
        `torch.Tensor` or `np.ndarray`:
            Interpolated vector/tensor between v0 and v1.
    """
    inputs_are_torch = False
    t_is_float = False

    if isinstance(v0, torch.Tensor):
        inputs_are_torch = True
        input_device = v0.device
        v0 = v0.cpu().numpy()
        v1 = v1.cpu().numpy()

    if isinstance(t, torch.Tensor):
        inputs_are_torch = True
        input_device = t.device
        t = t.cpu().numpy()
    elif isinstance(t, float):
        t_is_float = True
        t = np.array([t], dtype=v0.dtype)

    dot = np.sum(v0 * v1 / (np.linalg.norm(v0) * np.linalg.norm(v1)))
    if np.abs(dot) > DOT_THRESHOLD:
        # v1 and v2 are close to parallel
        # Use linear interpolation instead
        v2 = lerp(v0, v1, t)
    else:
        theta_0 = np.arccos(dot)
        sin_theta_0 = np.sin(theta_0)
        theta_t = theta_0 * t
        sin_theta_t = np.sin(theta_t)
        s0 = np.sin(theta_0 - theta_t) / sin_theta_0
        s1 = sin_theta_t / sin_theta_0
        s0 = s0[..., None]
        s1 = s1[..., None]
        v0 = v0[None, ...]
        v1 = v1[None, ...]
        v2 = s0 * v0 + s1 * v1

    if t_is_float and v0.ndim > 1:
        assert v2.shape[0] == 1
        v2 = np.squeeze(v2, axis=0)
    if inputs_are_torch:
        v2 = torch.from_numpy(v2).to(input_device)

    return v2


class LatentConsistencyModelWalkPipeline(
    DiffusionPipeline, TextualInversionLoaderMixin, LoraLoaderMixin, FromSingleFileMixin
):
    r"""
    Pipeline for text-to-image generation using a latent consistency model.

    This model inherits from [`DiffusionPipeline`]. Check the superclass documentation for the generic methods
    implemented for all pipelines (downloading, saving, running on a particular device, etc.).

    The pipeline also inherits the following loading methods:
        - [`~loaders.TextualInversionLoaderMixin.load_textual_inversion`] for loading textual inversion embeddings
        - [`~loaders.LoraLoaderMixin.load_lora_weights`] for loading LoRA weights
        - [`~loaders.LoraLoaderMixin.save_lora_weights`] for saving LoRA weights
        - [`~loaders.FromSingleFileMixin.from_single_file`] for loading `.ckpt` files

    Args:
        vae ([`AutoencoderKL`]):
            Variational Auto-Encoder (VAE) model to encode and decode images to and from latent representations.
        text_encoder ([`~transformers.CLIPTextModel`]):
            Frozen text-encoder ([clip-vit-large-patch14](https://huggingface.co/openai/clip-vit-large-patch14)).
        tokenizer ([`~transformers.CLIPTokenizer`]):
            A `CLIPTokenizer` to tokenize text.
        unet ([`UNet2DConditionModel`]):
            A `UNet2DConditionModel` to denoise the encoded image latents.
        scheduler ([`SchedulerMixin`]):
            A scheduler to be used in combination with `unet` to denoise the encoded image latents. Currently only
            supports [`LCMScheduler`].
        safety_checker ([`StableDiffusionSafetyChecker`]):
            Classification module that estimates whether generated images could be considered offensive or harmful.
            Please refer to the [model card](https://huggingface.co/runwayml/stable-diffusion-v1-5) for more details
            about a model's potential harms.
        feature_extractor ([`~transformers.CLIPImageProcessor`]):
            A `CLIPImageProcessor` to extract features from generated images; used as inputs to the `safety_checker`.
        requires_safety_checker (`bool`, *optional*, defaults to `True`):
            Whether the pipeline requires a safety checker component.
    """

    model_cpu_offload_seq = "text_encoder->unet->vae"
    _optional_components = ["safety_checker", "feature_extractor"]
    _exclude_from_cpu_offload = ["safety_checker"]
    _callback_tensor_inputs = ["latents", "denoised", "prompt_embeds", "w_embedding"]

    def __init__(
        self,
        vae: AutoencoderKL,
        text_encoder: CLIPTextModel,
        tokenizer: CLIPTokenizer,
        unet: UNet2DConditionModel,
        scheduler: LCMScheduler,
        safety_checker: StableDiffusionSafetyChecker,
        feature_extractor: CLIPImageProcessor,
        requires_safety_checker: bool = True,
    ):
        super().__init__()

        if safety_checker is None and requires_safety_checker:
            logger.warning(
                f"You have disabled the safety checker for {self.__class__} by passing `safety_checker=None`. Ensure"
                " that you abide to the conditions of the Stable Diffusion license and do not expose unfiltered"
                " results in services or applications open to the public. Both the diffusers team and Hugging Face"
                " strongly recommend to keep the safety filter enabled in all public facing circumstances, disabling"
                " it only for use-cases that involve analyzing network behavior or auditing its results. For more"
                " information, please have a look at https://github.com/huggingface/diffusers/pull/254 ."
            )

        if safety_checker is not None and feature_extractor is None:
            raise ValueError(
                "Make sure to define a feature extractor when loading {self.__class__} if you want to use the safety"
                " checker. If you do not want to use the safety checker, you can pass `'safety_checker=None'` instead."
            )

        self.register_modules(
            vae=vae,
            text_encoder=text_encoder,
            tokenizer=tokenizer,
            unet=unet,
            scheduler=scheduler,
            safety_checker=safety_checker,
            feature_extractor=feature_extractor,
        )
        self.vae_scale_factor = 2 ** (len(self.vae.config.block_out_channels) - 1)
        self.image_processor = VaeImageProcessor(vae_scale_factor=self.vae_scale_factor)
        self.register_to_config(requires_safety_checker=requires_safety_checker)

    # Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.StableDiffusionPipeline.enable_vae_slicing
    def enable_vae_slicing(self):
        r"""
        Enable sliced VAE decoding. When this option is enabled, the VAE will split the input tensor in slices to
        compute decoding in several steps. This is useful to save some memory and allow larger batch sizes.
        """
        self.vae.enable_slicing()

    # Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.StableDiffusionPipeline.disable_vae_slicing
    def disable_vae_slicing(self):
        r"""
        Disable sliced VAE decoding. If `enable_vae_slicing` was previously enabled, this method will go back to
        computing decoding in one step.
        """
        self.vae.disable_slicing()

    # Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.StableDiffusionPipeline.enable_vae_tiling
    def enable_vae_tiling(self):
        r"""
        Enable tiled VAE decoding. When this option is enabled, the VAE will split the input tensor into tiles to
        compute decoding and encoding in several steps. This is useful for saving a large amount of memory and to allow
        processing larger images.
        """
        self.vae.enable_tiling()

    # Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.StableDiffusionPipeline.disable_vae_tiling
    def disable_vae_tiling(self):
        r"""
        Disable tiled VAE decoding. If `enable_vae_tiling` was previously enabled, this method will go back to
        computing decoding in one step.
        """
        self.vae.disable_tiling()

    # Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.StableDiffusionPipeline.enable_freeu
    def enable_freeu(self, s1: float, s2: float, b1: float, b2: float):
        r"""Enables the FreeU mechanism as in https://arxiv.org/abs/2309.11497.

        The suffixes after the scaling factors represent the stages where they are being applied.

        Please refer to the [official repository](https://github.com/ChenyangSi/FreeU) for combinations of the values
        that are known to work well for different pipelines such as Stable Diffusion v1, v2, and Stable Diffusion XL.

        Args:
            s1 (`float`):
                Scaling factor for stage 1 to attenuate the contributions of the skip features. This is done to
                mitigate "oversmoothing effect" in the enhanced denoising process.
            s2 (`float`):
                Scaling factor for stage 2 to attenuate the contributions of the skip features. This is done to
                mitigate "oversmoothing effect" in the enhanced denoising process.
            b1 (`float`): Scaling factor for stage 1 to amplify the contributions of backbone features.
            b2 (`float`): Scaling factor for stage 2 to amplify the contributions of backbone features.
        """
        if not hasattr(self, "unet"):
            raise ValueError("The pipeline must have `unet` for using FreeU.")
        self.unet.enable_freeu(s1=s1, s2=s2, b1=b1, b2=b2)

    # Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.StableDiffusionPipeline.disable_freeu
    def disable_freeu(self):
        """Disables the FreeU mechanism if enabled."""
        self.unet.disable_freeu()

    # Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.StableDiffusionPipeline.encode_prompt
    def encode_prompt(
        self,
        prompt,
        device,
        num_images_per_prompt,
        do_classifier_free_guidance,
        negative_prompt=None,
        prompt_embeds: Optional[torch.FloatTensor] = None,
        negative_prompt_embeds: Optional[torch.FloatTensor] = None,
        lora_scale: Optional[float] = None,
        clip_skip: Optional[int] = None,
    ):
        r"""
        Encodes the prompt into text encoder hidden states.

        Args:
            prompt (`str` or `List[str]`, *optional*):
                prompt to be encoded
            device: (`torch.device`):
                torch device
            num_images_per_prompt (`int`):
                number of images that should be generated per prompt
            do_classifier_free_guidance (`bool`):
                whether to use classifier free guidance or not
            negative_prompt (`str` or `List[str]`, *optional*):
                The prompt or prompts not to guide the image generation. If not defined, one has to pass
                `negative_prompt_embeds` instead. Ignored when not using guidance (i.e., ignored if `guidance_scale` is
                less than `1`).
            prompt_embeds (`torch.FloatTensor`, *optional*):
                Pre-generated text embeddings. Can be used to easily tweak text inputs, *e.g.* prompt weighting. If not
                provided, text embeddings will be generated from `prompt` input argument.
            negative_prompt_embeds (`torch.FloatTensor`, *optional*):
                Pre-generated negative text embeddings. Can be used to easily tweak text inputs, *e.g.* prompt
                weighting. If not provided, negative_prompt_embeds will be generated from `negative_prompt` input
                argument.
            lora_scale (`float`, *optional*):
                A LoRA scale that will be applied to all LoRA layers of the text encoder if LoRA layers are loaded.
            clip_skip (`int`, *optional*):
                Number of layers to be skipped from CLIP while computing the prompt embeddings. A value of 1 means that
                the output of the pre-final layer will be used for computing the prompt embeddings.
        """
        # set lora scale so that monkey patched LoRA
        # function of text encoder can correctly access it
        if lora_scale is not None and isinstance(self, LoraLoaderMixin):
            self._lora_scale = lora_scale

            # dynamically adjust the LoRA scale
            if not USE_PEFT_BACKEND:
                adjust_lora_scale_text_encoder(self.text_encoder, lora_scale)
            else:
                scale_lora_layers(self.text_encoder, lora_scale)

        if prompt is not None and isinstance(prompt, str):
            batch_size = 1
        elif prompt is not None and isinstance(prompt, list):
            batch_size = len(prompt)
        else:
            batch_size = prompt_embeds.shape[0]

        if prompt_embeds is None:
            # textual inversion: procecss multi-vector tokens if necessary
            if isinstance(self, TextualInversionLoaderMixin):
                prompt = self.maybe_convert_prompt(prompt, self.tokenizer)

            text_inputs = self.tokenizer(
                prompt,
                padding="max_length",
                max_length=self.tokenizer.model_max_length,
                truncation=True,
                return_tensors="pt",
            )
            text_input_ids = text_inputs.input_ids
            untruncated_ids = self.tokenizer(prompt, padding="longest", return_tensors="pt").input_ids

            if untruncated_ids.shape[-1] >= text_input_ids.shape[-1] and not torch.equal(
                text_input_ids, untruncated_ids
            ):
                removed_text = self.tokenizer.batch_decode(
                    untruncated_ids[:, self.tokenizer.model_max_length - 1 : -1]
                )
                logger.warning(
                    "The following part of your input was truncated because CLIP can only handle sequences up to"
                    f" {self.tokenizer.model_max_length} tokens: {removed_text}"
                )

            if hasattr(self.text_encoder.config, "use_attention_mask") and self.text_encoder.config.use_attention_mask:
                attention_mask = text_inputs.attention_mask.to(device)
            else:
                attention_mask = None

            if clip_skip is None:
                prompt_embeds = self.text_encoder(text_input_ids.to(device), attention_mask=attention_mask)
                prompt_embeds = prompt_embeds[0]
            else:
                prompt_embeds = self.text_encoder(
                    text_input_ids.to(device), attention_mask=attention_mask, output_hidden_states=True
                )
                # Access the `hidden_states` first, that contains a tuple of
                # all the hidden states from the encoder layers. Then index into
                # the tuple to access the hidden states from the desired layer.
                prompt_embeds = prompt_embeds[-1][-(clip_skip + 1)]
                # We also need to apply the final LayerNorm here to not mess with the
                # representations. The `last_hidden_states` that we typically use for
                # obtaining the final prompt representations passes through the LayerNorm
                # layer.
                prompt_embeds = self.text_encoder.text_model.final_layer_norm(prompt_embeds)

        if self.text_encoder is not None:
            prompt_embeds_dtype = self.text_encoder.dtype
        elif self.unet is not None:
            prompt_embeds_dtype = self.unet.dtype
        else:
            prompt_embeds_dtype = prompt_embeds.dtype

        prompt_embeds = prompt_embeds.to(dtype=prompt_embeds_dtype, device=device)

        bs_embed, seq_len, _ = prompt_embeds.shape
        # duplicate text embeddings for each generation per prompt, using mps friendly method
        prompt_embeds = prompt_embeds.repeat(1, num_images_per_prompt, 1)
        prompt_embeds = prompt_embeds.view(bs_embed * num_images_per_prompt, seq_len, -1)

        # get unconditional embeddings for classifier free guidance
        if do_classifier_free_guidance and negative_prompt_embeds is None:
            uncond_tokens: List[str]
            if negative_prompt is None:
                uncond_tokens = [""] * batch_size
            elif prompt is not None and type(prompt) is not type(negative_prompt):
                raise TypeError(
                    f"`negative_prompt` should be the same type to `prompt`, but got {type(negative_prompt)} !="
                    f" {type(prompt)}."
                )
            elif isinstance(negative_prompt, str):
                uncond_tokens = [negative_prompt]
            elif batch_size != len(negative_prompt):
                raise ValueError(
                    f"`negative_prompt`: {negative_prompt} has batch size {len(negative_prompt)}, but `prompt`:"
                    f" {prompt} has batch size {batch_size}. Please make sure that passed `negative_prompt` matches"
                    " the batch size of `prompt`."
                )
            else:
                uncond_tokens = negative_prompt

            # textual inversion: procecss multi-vector tokens if necessary
            if isinstance(self, TextualInversionLoaderMixin):
                uncond_tokens = self.maybe_convert_prompt(uncond_tokens, self.tokenizer)

            max_length = prompt_embeds.shape[1]
            uncond_input = self.tokenizer(
                uncond_tokens,
                padding="max_length",
                max_length=max_length,
                truncation=True,
                return_tensors="pt",
            )

            if hasattr(self.text_encoder.config, "use_attention_mask") and self.text_encoder.config.use_attention_mask:
                attention_mask = uncond_input.attention_mask.to(device)
            else:
                attention_mask = None

            negative_prompt_embeds = self.text_encoder(
                uncond_input.input_ids.to(device),
                attention_mask=attention_mask,
            )
            negative_prompt_embeds = negative_prompt_embeds[0]

        if do_classifier_free_guidance:
            # duplicate unconditional embeddings for each generation per prompt, using mps friendly method
            seq_len = negative_prompt_embeds.shape[1]

            negative_prompt_embeds = negative_prompt_embeds.to(dtype=prompt_embeds_dtype, device=device)

            negative_prompt_embeds = negative_prompt_embeds.repeat(1, num_images_per_prompt, 1)
            negative_prompt_embeds = negative_prompt_embeds.view(batch_size * num_images_per_prompt, seq_len, -1)

        if isinstance(self, LoraLoaderMixin) and USE_PEFT_BACKEND:
            # Retrieve the original scale by scaling back the LoRA layers
            unscale_lora_layers(self.text_encoder, lora_scale)

        return prompt_embeds, negative_prompt_embeds

    # Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.StableDiffusionPipeline.run_safety_checker
    def run_safety_checker(self, image, device, dtype):
        if self.safety_checker is None:
            has_nsfw_concept = None
        else:
            if torch.is_tensor(image):
                feature_extractor_input = self.image_processor.postprocess(image, output_type="pil")
            else:
                feature_extractor_input = self.image_processor.numpy_to_pil(image)
            safety_checker_input = self.feature_extractor(feature_extractor_input, return_tensors="pt").to(device)
            image, has_nsfw_concept = self.safety_checker(
                images=image, clip_input=safety_checker_input.pixel_values.to(dtype)
            )
        return image, has_nsfw_concept

    # Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.StableDiffusionPipeline.prepare_latents
    def prepare_latents(self, batch_size, num_channels_latents, height, width, dtype, device, generator, latents=None):
        shape = (batch_size, num_channels_latents, height // self.vae_scale_factor, width // self.vae_scale_factor)
        if isinstance(generator, list) and len(generator) != batch_size:
            raise ValueError(
                f"You have passed a list of generators of length {len(generator)}, but requested an effective batch"
                f" size of {batch_size}. Make sure the batch size matches the length of the generators."
            )

        if latents is None:
            latents = randn_tensor(shape, generator=generator, device=device, dtype=dtype)
        else:
            latents = latents.to(device)

        # scale the initial noise by the standard deviation required by the scheduler
        latents = latents * self.scheduler.init_noise_sigma
        return latents

    def get_guidance_scale_embedding(self, w, embedding_dim=512, dtype=torch.float32):
        """
        See https://github.com/google-research/vdm/blob/dc27b98a554f65cdc654b800da5aa1846545d41b/model_vdm.py#L298

        Args:
            timesteps (`torch.Tensor`):
                generate embedding vectors at these timesteps
            embedding_dim (`int`, *optional*, defaults to 512):
                dimension of the embeddings to generate
            dtype:
                data type of the generated embeddings

        Returns:
            `torch.FloatTensor`: Embedding vectors with shape `(len(timesteps), embedding_dim)`
        """
        assert len(w.shape) == 1
        w = w * 1000.0

        half_dim = embedding_dim // 2
        emb = torch.log(torch.tensor(10000.0)) / (half_dim - 1)
        emb = torch.exp(torch.arange(half_dim, dtype=dtype) * -emb)
        emb = w.to(dtype)[:, None] * emb[None, :]
        emb = torch.cat([torch.sin(emb), torch.cos(emb)], dim=1)
        if embedding_dim % 2 == 1:  # zero pad
            emb = torch.nn.functional.pad(emb, (0, 1))
        assert emb.shape == (w.shape[0], embedding_dim)
        return emb

    # Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.StableDiffusionPipeline.prepare_extra_step_kwargs
    def prepare_extra_step_kwargs(self, generator, eta):
        # prepare extra kwargs for the scheduler step, since not all schedulers have the same signature
        # eta (η) is only used with the DDIMScheduler, it will be ignored for other schedulers.
        # eta corresponds to η in DDIM paper: https://arxiv.org/abs/2010.02502
        # and should be between [0, 1]

        accepts_eta = "eta" in set(inspect.signature(self.scheduler.step).parameters.keys())
        extra_step_kwargs = {}
        if accepts_eta:
            extra_step_kwargs["eta"] = eta

        # check if the scheduler accepts generator
        accepts_generator = "generator" in set(inspect.signature(self.scheduler.step).parameters.keys())
        if accepts_generator:
            extra_step_kwargs["generator"] = generator
        return extra_step_kwargs

    # Currently StableDiffusionPipeline.check_inputs with negative prompt stuff removed
    def check_inputs(
        self,
        prompt: Union[str, List[str]],
        height: int,
        width: int,
        callback_steps: int,
        prompt_embeds: Optional[torch.FloatTensor] = None,
        callback_on_step_end_tensor_inputs=None,
    ):
        if height % 8 != 0 or width % 8 != 0:
            raise ValueError(f"`height` and `width` have to be divisible by 8 but are {height} and {width}.")

        if callback_steps is not None and (not isinstance(callback_steps, int) or callback_steps <= 0):
            raise ValueError(
                f"`callback_steps` has to be a positive integer but is {callback_steps} of type"
                f" {type(callback_steps)}."
            )

        if callback_on_step_end_tensor_inputs is not None and not all(
            k in self._callback_tensor_inputs for k in callback_on_step_end_tensor_inputs
        ):
            raise ValueError(
                f"`callback_on_step_end_tensor_inputs` has to be in {self._callback_tensor_inputs}, but found {[k for k in callback_on_step_end_tensor_inputs if k not in self._callback_tensor_inputs]}"
            )

        if prompt is not None and prompt_embeds is not None:
            raise ValueError(
                f"Cannot forward both `prompt`: {prompt} and `prompt_embeds`: {prompt_embeds}. Please make sure to"
                " only forward one of the two."
            )
        elif prompt is None and prompt_embeds is None:
            raise ValueError(
                "Provide either `prompt` or `prompt_embeds`. Cannot leave both `prompt` and `prompt_embeds` undefined."
            )
        elif prompt is not None and (not isinstance(prompt, str) and not isinstance(prompt, list)):
            raise ValueError(f"`prompt` has to be of type `str` or `list` but is {type(prompt)}")

    @torch.no_grad()
    def interpolate_embedding(
        self,
        start_embedding: torch.FloatTensor,
        end_embedding: torch.FloatTensor,
        num_interpolation_steps: Union[int, List[int]],
        interpolation_type: str,
    ) -> torch.FloatTensor:
        if interpolation_type == "lerp":
            interpolation_fn = lerp
        elif interpolation_type == "slerp":
            interpolation_fn = slerp
        else:
            raise ValueError(
                f"embedding_interpolation_type must be one of ['lerp', 'slerp'], got {interpolation_type}."
            )

        embedding = torch.cat([start_embedding, end_embedding])
        steps = torch.linspace(0, 1, num_interpolation_steps, dtype=embedding.dtype).cpu().numpy()
        steps = np.expand_dims(steps, axis=tuple(range(1, embedding.ndim)))
        interpolations = []

        # Interpolate between text embeddings
        # TODO(aryan): Think of a better way of doing this
        # See if it can be done parallelly instead
        for i in range(embedding.shape[0] - 1):
            interpolations.append(interpolation_fn(embedding[i], embedding[i + 1], steps).squeeze(dim=1))

        interpolations = torch.cat(interpolations)
        return interpolations

    @torch.no_grad()
    def interpolate_latent(
        self,
        start_latent: torch.FloatTensor,
        end_latent: torch.FloatTensor,
        num_interpolation_steps: Union[int, List[int]],
        interpolation_type: str,
    ) -> torch.FloatTensor:
        if interpolation_type == "lerp":
            interpolation_fn = lerp
        elif interpolation_type == "slerp":
            interpolation_fn = slerp

        latent = torch.cat([start_latent, end_latent])
        steps = torch.linspace(0, 1, num_interpolation_steps, dtype=latent.dtype).cpu().numpy()
        steps = np.expand_dims(steps, axis=tuple(range(1, latent.ndim)))
        interpolations = []

        # Interpolate between latents
        # TODO: Think of a better way of doing this
        # See if it can be done parallelly instead
        for i in range(latent.shape[0] - 1):
            interpolations.append(interpolation_fn(latent[i], latent[i + 1], steps).squeeze(dim=1))

        return torch.cat(interpolations)

    @property
    def guidance_scale(self):
        return self._guidance_scale

    @property
    def cross_attention_kwargs(self):
        return self._cross_attention_kwargs

    @property
    def clip_skip(self):
        return self._clip_skip

    @property
    def num_timesteps(self):
        return self._num_timesteps

    @torch.no_grad()
    @replace_example_docstring(EXAMPLE_DOC_STRING)
    def __call__(
        self,
        prompt: Union[str, List[str]] = None,
        height: Optional[int] = None,
        width: Optional[int] = None,
        num_inference_steps: int = 4,
        num_interpolation_steps: int = 8,
        original_inference_steps: int = None,
        guidance_scale: float = 8.5,
        num_images_per_prompt: Optional[int] = 1,
        generator: Optional[Union[torch.Generator, List[torch.Generator]]] = None,
        latents: Optional[torch.FloatTensor] = None,
        prompt_embeds: Optional[torch.FloatTensor] = None,
        output_type: Optional[str] = "pil",
        return_dict: bool = True,
        cross_attention_kwargs: Optional[Dict[str, Any]] = None,
        clip_skip: Optional[int] = None,
        callback_on_step_end: Optional[Callable[[int, int, Dict], None]] = None,
        callback_on_step_end_tensor_inputs: List[str] = ["latents"],
        embedding_interpolation_type: str = "lerp",
        latent_interpolation_type: str = "slerp",
        process_batch_size: int = 4,
        **kwargs,
    ):
        r"""
        The call function to the pipeline for generation.

        Args:
            prompt (`str` or `List[str]`, *optional*):
                The prompt or prompts to guide image generation. If not defined, you need to pass `prompt_embeds`.
            height (`int`, *optional*, defaults to `self.unet.config.sample_size * self.vae_scale_factor`):
                The height in pixels of the generated image.
            width (`int`, *optional*, defaults to `self.unet.config.sample_size * self.vae_scale_factor`):
                The width in pixels of the generated image.
            num_inference_steps (`int`, *optional*, defaults to 50):
                The number of denoising steps. More denoising steps usually lead to a higher quality image at the
                expense of slower inference.
            original_inference_steps (`int`, *optional*):
                The original number of inference steps use to generate a linearly-spaced timestep schedule, from which
                we will draw `num_inference_steps` evenly spaced timesteps from as our final timestep schedule,
                following the Skipping-Step method in the paper (see Section 4.3). If not set this will default to the
                scheduler's `original_inference_steps` attribute.
            guidance_scale (`float`, *optional*, defaults to 7.5):
                A higher guidance scale value encourages the model to generate images closely linked to the text
                `prompt` at the expense of lower image quality. Guidance scale is enabled when `guidance_scale > 1`.
                Note that the original latent consistency models paper uses a different CFG formulation where the
                guidance scales are decreased by 1 (so in the paper formulation CFG is enabled when `guidance_scale >
                0`).
            num_images_per_prompt (`int`, *optional*, defaults to 1):
                The number of images to generate per prompt.
            generator (`torch.Generator` or `List[torch.Generator]`, *optional*):
                A [`torch.Generator`](https://pytorch.org/docs/stable/generated/torch.Generator.html) to make
                generation deterministic.
            latents (`torch.FloatTensor`, *optional*):
                Pre-generated noisy latents sampled from a Gaussian distribution, to be used as inputs for image
                generation. Can be used to tweak the same generation with different prompts. If not provided, a latents
                tensor is generated by sampling using the supplied random `generator`.
            prompt_embeds (`torch.FloatTensor`, *optional*):
                Pre-generated text embeddings. Can be used to easily tweak text inputs (prompt weighting). If not
                provided, text embeddings are generated from the `prompt` input argument.
            output_type (`str`, *optional*, defaults to `"pil"`):
                The output format of the generated image. Choose between `PIL.Image` or `np.array`.
            return_dict (`bool`, *optional*, defaults to `True`):
                Whether or not to return a [`~pipelines.stable_diffusion.StableDiffusionPipelineOutput`] instead of a
                plain tuple.
            cross_attention_kwargs (`dict`, *optional*):
                A kwargs dictionary that if specified is passed along to the [`AttentionProcessor`] as defined in
                [`self.processor`](https://github.com/huggingface/diffusers/blob/main/src/diffusers/models/attention_processor.py).
            clip_skip (`int`, *optional*):
                Number of layers to be skipped from CLIP while computing the prompt embeddings. A value of 1 means that
                the output of the pre-final layer will be used for computing the prompt embeddings.
            callback_on_step_end (`Callable`, *optional*):
                A function that calls at the end of each denoising steps during the inference. The function is called
                with the following arguments: `callback_on_step_end(self: DiffusionPipeline, step: int, timestep: int,
                callback_kwargs: Dict)`. `callback_kwargs` will include a list of all tensors as specified by
                `callback_on_step_end_tensor_inputs`.
            callback_on_step_end_tensor_inputs (`List`, *optional*):
                The list of tensor inputs for the `callback_on_step_end` function. The tensors specified in the list
                will be passed as `callback_kwargs` argument. You will only be able to include variables listed in the
                `._callback_tensor_inputs` attribute of your pipeine class.
            embedding_interpolation_type (`str`, *optional*, defaults to `"lerp"`):
                The type of interpolation to use for interpolating between text embeddings. Choose between `"lerp"` and `"slerp"`.
            latent_interpolation_type (`str`, *optional*, defaults to `"slerp"`):
                The type of interpolation to use for interpolating between latents. Choose between `"lerp"` and `"slerp"`.
            process_batch_size (`int`, *optional*, defaults to 4):
                The batch size to use for processing the images. This is useful when generating a large number of images
                and you want to avoid running out of memory.

        Examples:

        Returns:
            [`~pipelines.stable_diffusion.StableDiffusionPipelineOutput`] or `tuple`:
                If `return_dict` is `True`, [`~pipelines.stable_diffusion.StableDiffusionPipelineOutput`] is returned,
                otherwise a `tuple` is returned where the first element is a list with the generated images and the
                second element is a list of `bool`s indicating whether the corresponding generated image contains
                "not-safe-for-work" (nsfw) content.
        """

        callback = kwargs.pop("callback", None)
        callback_steps = kwargs.pop("callback_steps", None)

        if callback is not None:
            deprecate(
                "callback",
                "1.0.0",
                "Passing `callback` as an input argument to `__call__` is deprecated, consider use `callback_on_step_end`",
            )
        if callback_steps is not None:
            deprecate(
                "callback_steps",
                "1.0.0",
                "Passing `callback_steps` as an input argument to `__call__` is deprecated, consider use `callback_on_step_end`",
            )

        # 0. Default height and width to unet
        height = height or self.unet.config.sample_size * self.vae_scale_factor
        width = width or self.unet.config.sample_size * self.vae_scale_factor

        # 1. Check inputs. Raise error if not correct
        self.check_inputs(prompt, height, width, callback_steps, prompt_embeds, callback_on_step_end_tensor_inputs)
        self._guidance_scale = guidance_scale
        self._clip_skip = clip_skip
        self._cross_attention_kwargs = cross_attention_kwargs

        # 2. Define call parameters
        if prompt is not None and isinstance(prompt, str):
            batch_size = 1
        elif prompt is not None and isinstance(prompt, list):
            batch_size = len(prompt)
        else:
            batch_size = prompt_embeds.shape[0]
        if batch_size < 2:
            raise ValueError(f"`prompt` must have length of atleast 2 but found {batch_size}")
        if num_images_per_prompt != 1:
            raise ValueError("`num_images_per_prompt` must be `1` as no other value is supported yet")
        if prompt_embeds is not None:
            raise ValueError("`prompt_embeds` must be None since it is not supported yet")
        if latents is not None:
            raise ValueError("`latents` must be None since it is not supported yet")

        device = self._execution_device
        # do_classifier_free_guidance = guidance_scale > 1.0

        lora_scale = (
            self.cross_attention_kwargs.get("scale", None) if self.cross_attention_kwargs is not None else None
        )

        self.scheduler.set_timesteps(num_inference_steps, device, original_inference_steps=original_inference_steps)
        timesteps = self.scheduler.timesteps
        num_channels_latents = self.unet.config.in_channels
        # bs = batch_size * num_images_per_prompt

        # 3. Encode initial input prompt
        prompt_embeds_1, _ = self.encode_prompt(
            prompt[:1],
            device,
            num_images_per_prompt=num_images_per_prompt,
            do_classifier_free_guidance=False,
            negative_prompt=None,
            prompt_embeds=prompt_embeds,
            negative_prompt_embeds=None,
            lora_scale=lora_scale,
            clip_skip=self.clip_skip,
        )

        # 4. Prepare initial latent variables
        latents_1 = self.prepare_latents(
            1,
            num_channels_latents,
            height,
            width,
            prompt_embeds_1.dtype,
            device,
            generator,
            latents,
        )

        extra_step_kwargs = self.prepare_extra_step_kwargs(generator, None)
        num_warmup_steps = len(timesteps) - num_inference_steps * self.scheduler.order
        self._num_timesteps = len(timesteps)
        images = []

        # 5. Iterate over prompts and perform latent walk. Note that we do this two prompts at a time
        #    otherwise the memory usage ends up being too high.
        with self.progress_bar(total=batch_size - 1) as prompt_progress_bar:
            for i in range(1, batch_size):
                # 6. Encode current prompt
                prompt_embeds_2, _ = self.encode_prompt(
                    prompt[i : i + 1],
                    device,
                    num_images_per_prompt=num_images_per_prompt,
                    do_classifier_free_guidance=False,
                    negative_prompt=None,
                    prompt_embeds=prompt_embeds,
                    negative_prompt_embeds=None,
                    lora_scale=lora_scale,
                    clip_skip=self.clip_skip,
                )

                # 7. Prepare current latent variables
                latents_2 = self.prepare_latents(
                    1,
                    num_channels_latents,
                    height,
                    width,
                    prompt_embeds_2.dtype,
                    device,
                    generator,
                    latents,
                )

                # 8. Interpolate between previous and current prompt embeddings and latents
                inference_embeddings = self.interpolate_embedding(
                    start_embedding=prompt_embeds_1,
                    end_embedding=prompt_embeds_2,
                    num_interpolation_steps=num_interpolation_steps,
                    interpolation_type=embedding_interpolation_type,
                )
                inference_latents = self.interpolate_latent(
                    start_latent=latents_1,
                    end_latent=latents_2,
                    num_interpolation_steps=num_interpolation_steps,
                    interpolation_type=latent_interpolation_type,
                )
                next_prompt_embeds = inference_embeddings[-1:].detach().clone()
                next_latents = inference_latents[-1:].detach().clone()
                bs = num_interpolation_steps

                # 9. Perform inference in batches. Note the use of `process_batch_size` to control the batch size
                #    of the inference. This is useful for reducing memory usage and can be configured based on the
                #    available GPU memory.
                with self.progress_bar(
                    total=(bs + process_batch_size - 1) // process_batch_size
                ) as batch_progress_bar:
                    for batch_index in range(0, bs, process_batch_size):
                        batch_inference_latents = inference_latents[batch_index : batch_index + process_batch_size]
                        batch_inference_embedddings = inference_embeddings[
                            batch_index : batch_index + process_batch_size
                        ]

                        self.scheduler.set_timesteps(
                            num_inference_steps, device, original_inference_steps=original_inference_steps
                        )
                        timesteps = self.scheduler.timesteps

                        current_bs = batch_inference_embedddings.shape[0]
                        w = torch.tensor(self.guidance_scale - 1).repeat(current_bs)
                        w_embedding = self.get_guidance_scale_embedding(
                            w, embedding_dim=self.unet.config.time_cond_proj_dim
                        ).to(device=device, dtype=latents_1.dtype)

                        # 10. Perform inference for current batch
                        with self.progress_bar(total=num_inference_steps) as progress_bar:
                            for index, t in enumerate(timesteps):
                                batch_inference_latents = batch_inference_latents.to(batch_inference_embedddings.dtype)

                                # model prediction (v-prediction, eps, x)
                                model_pred = self.unet(
                                    batch_inference_latents,
                                    t,
                                    timestep_cond=w_embedding,
                                    encoder_hidden_states=batch_inference_embedddings,
                                    cross_attention_kwargs=self.cross_attention_kwargs,
                                    return_dict=False,
                                )[0]

                                # compute the previous noisy sample x_t -> x_t-1
                                batch_inference_latents, denoised = self.scheduler.step(
                                    model_pred, t, batch_inference_latents, **extra_step_kwargs, return_dict=False
                                )
                                if callback_on_step_end is not None:
                                    callback_kwargs = {}
                                    for k in callback_on_step_end_tensor_inputs:
                                        callback_kwargs[k] = locals()[k]
                                    callback_outputs = callback_on_step_end(self, index, t, callback_kwargs)

                                    batch_inference_latents = callback_outputs.pop("latents", batch_inference_latents)
                                    batch_inference_embedddings = callback_outputs.pop(
                                        "prompt_embeds", batch_inference_embedddings
                                    )
                                    w_embedding = callback_outputs.pop("w_embedding", w_embedding)
                                    denoised = callback_outputs.pop("denoised", denoised)

                                # call the callback, if provided
                                if index == len(timesteps) - 1 or (
                                    (index + 1) > num_warmup_steps and (index + 1) % self.scheduler.order == 0
                                ):
                                    progress_bar.update()
                                    if callback is not None and index % callback_steps == 0:
                                        step_idx = index // getattr(self.scheduler, "order", 1)
                                        callback(step_idx, t, batch_inference_latents)

                        denoised = denoised.to(batch_inference_embedddings.dtype)

                        # Note: This is not supported because you would get black images in your latent walk if
                        #       NSFW concept is detected
                        # if not output_type == "latent":
                        #     image = self.vae.decode(denoised / self.vae.config.scaling_factor, return_dict=False)[0]
                        #     image, has_nsfw_concept = self.run_safety_checker(image, device, inference_embeddings.dtype)
                        # else:
                        #     image = denoised
                        #     has_nsfw_concept = None

                        # if has_nsfw_concept is None:
                        #     do_denormalize = [True] * image.shape[0]
                        # else:
                        #     do_denormalize = [not has_nsfw for has_nsfw in has_nsfw_concept]

                        image = self.vae.decode(denoised / self.vae.config.scaling_factor, return_dict=False)[0]
                        do_denormalize = [True] * image.shape[0]
                        has_nsfw_concept = None

                        image = self.image_processor.postprocess(
                            image, output_type=output_type, do_denormalize=do_denormalize
                        )
                        images.append(image)

                        batch_progress_bar.update()

                prompt_embeds_1 = next_prompt_embeds
                latents_1 = next_latents

                prompt_progress_bar.update()

        # 11. Determine what should be returned
        if output_type == "pil":
            images = [image for image_list in images for image in image_list]
        elif output_type == "np":
            images = np.concatenate(images)
        elif output_type == "pt":
            images = torch.cat(images)
        else:
            raise ValueError("`output_type` must be one of 'pil', 'np' or 'pt'.")

        # Offload all models
        self.maybe_free_model_hooks()

        if not return_dict:
            return (images, has_nsfw_concept)

        return StableDiffusionPipelineOutput(images=images, nsfw_content_detected=has_nsfw_concept)