init

primitive_anything/michelangelo/models/asl_diffusion/inference_utils.py

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+# -*- coding: utf-8 -*-
+
+import torch
+from tqdm import tqdm
+from typing import Tuple, List, Union, Optional
+from diffusers.schedulers import DDIMScheduler
+
+
+__all__ = ["ddim_sample"]
+
+
+def ddim_sample(ddim_scheduler: DDIMScheduler,
+                diffusion_model: torch.nn.Module,
+                shape: Union[List[int], Tuple[int]],
+                cond: torch.FloatTensor,
+                steps: int,
+                eta: float = 0.0,
+                guidance_scale: float = 3.0,
+                do_classifier_free_guidance: bool = True,
+                generator: Optional[torch.Generator] = None,
+                device: torch.device = "cuda:0",
+                disable_prog: bool = True):
+
+    assert steps > 0, f"{steps} must > 0."
+
+    # init latents
+    bsz = cond.shape[0]
+    if do_classifier_free_guidance:
+        bsz = bsz // 2
+
+    latents = torch.randn(
+        (bsz, *shape),
+        generator=generator,
+        device=cond.device,
+        dtype=cond.dtype,
+    )
+    # scale the initial noise by the standard deviation required by the scheduler
+    latents = latents * ddim_scheduler.init_noise_sigma
+    # set timesteps
+    ddim_scheduler.set_timesteps(steps)
+    timesteps = ddim_scheduler.timesteps.to(device)
+    # prepare extra kwargs for the scheduler step, since not all schedulers have the same signature
+    # eta (η) is only used with the DDIMScheduler, and between [0, 1]
+    extra_step_kwargs = {
+        "eta": eta,
+        "generator": generator
+    }
+
+    # reverse
+    for i, t in enumerate(tqdm(timesteps, disable=disable_prog, desc="DDIM Sampling:", leave=False)):
+        # expand the latents if we are doing classifier free guidance
+        latent_model_input = (
+            torch.cat([latents] * 2)
+            if do_classifier_free_guidance
+            else latents
+        )
+        # latent_model_input = scheduler.scale_model_input(latent_model_input, t)
+        # predict the noise residual
+        timestep_tensor = torch.tensor([t], dtype=torch.long, device=device)
+        timestep_tensor = timestep_tensor.expand(latent_model_input.shape[0])
+        noise_pred = diffusion_model.forward(latent_model_input, timestep_tensor, cond)
+
+        # perform guidance
+        if do_classifier_free_guidance:
+            noise_pred_uncond, noise_pred_text = noise_pred.chunk(2)
+            noise_pred = noise_pred_uncond + guidance_scale * (
+                    noise_pred_text - noise_pred_uncond
+            )
+            # text_embeddings_for_guidance = encoder_hidden_states.chunk(
+            #     2)[1] if do_classifier_free_guidance else encoder_hidden_states
+        # compute the previous noisy sample x_t -> x_t-1
+        latents = ddim_scheduler.step(
+            noise_pred, t, latents, **extra_step_kwargs
+        ).prev_sample
+
+        yield latents, t
+
+
+def karra_sample():
+    pass