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# *************************************************************************
# This file may have been modified by Bytedance Inc. (“Bytedance Inc.'s Mo-
# difications”). All Bytedance Inc.'s Modifications are Copyright (2023) B-
# ytedance Inc..
# *************************************************************************
# Adapted from https://github.com/guoyww/AnimateDiff
import os
import imageio
import numpy as np
import torch
import torchvision
from PIL import Image
from typing import Union
from tqdm import tqdm
from einops import rearrange
def save_videos_grid(videos: torch.Tensor, path: str, rescale=False, n_rows=6, fps=25):
videos = rearrange(videos, "b c t h w -> t b c h w")
outputs = []
for x in videos:
x = torchvision.utils.make_grid(x, nrow=n_rows)
x = x.transpose(0, 1).transpose(1, 2).squeeze(-1)
if rescale:
x = (x + 1.0) / 2.0 # -1,1 -> 0,1
x = (x * 255).numpy().astype(np.uint8)
outputs.append(x)
os.makedirs(os.path.dirname(path), exist_ok=True)
imageio.mimsave(path, outputs, fps=fps)
def save_images_grid(images: torch.Tensor, path: str):
assert images.shape[2] == 1 # no time dimension
images = images.squeeze(2)
grid = torchvision.utils.make_grid(images)
grid = (grid * 255).numpy().transpose(1, 2, 0).astype(np.uint8)
os.makedirs(os.path.dirname(path), exist_ok=True)
Image.fromarray(grid).save(path)
# DDIM Inversion
@torch.no_grad()
def init_prompt(prompt, pipeline):
uncond_input = pipeline.tokenizer(
[""], padding="max_length", max_length=pipeline.tokenizer.model_max_length,
return_tensors="pt"
)
uncond_embeddings = pipeline.text_encoder(uncond_input.input_ids.to(pipeline.device))[0]
text_input = pipeline.tokenizer(
[prompt],
padding="max_length",
max_length=pipeline.tokenizer.model_max_length,
truncation=True,
return_tensors="pt",
)
text_embeddings = pipeline.text_encoder(text_input.input_ids.to(pipeline.device))[0]
context = torch.cat([uncond_embeddings, text_embeddings])
return context
def next_step(model_output: Union[torch.FloatTensor, np.ndarray], timestep: int,
sample: Union[torch.FloatTensor, np.ndarray], ddim_scheduler):
timestep, next_timestep = min(
timestep - ddim_scheduler.config.num_train_timesteps // ddim_scheduler.num_inference_steps, 999), timestep
alpha_prod_t = ddim_scheduler.alphas_cumprod[timestep] if timestep >= 0 else ddim_scheduler.final_alpha_cumprod
alpha_prod_t_next = ddim_scheduler.alphas_cumprod[next_timestep]
beta_prod_t = 1 - alpha_prod_t
next_original_sample = (sample - beta_prod_t ** 0.5 * model_output) / alpha_prod_t ** 0.5
next_sample_direction = (1 - alpha_prod_t_next) ** 0.5 * model_output
next_sample = alpha_prod_t_next ** 0.5 * next_original_sample + next_sample_direction
return next_sample
def get_noise_pred_single(latents, t, context, unet):
noise_pred = unet(latents, t, encoder_hidden_states=context)["sample"]
return noise_pred
@torch.no_grad()
def ddim_loop(pipeline, ddim_scheduler, latent, num_inv_steps, prompt):
context = init_prompt(prompt, pipeline)
uncond_embeddings, cond_embeddings = context.chunk(2)
all_latent = [latent]
latent = latent.clone().detach()
for i in tqdm(range(num_inv_steps)):
t = ddim_scheduler.timesteps[len(ddim_scheduler.timesteps) - i - 1]
noise_pred = get_noise_pred_single(latent, t, cond_embeddings, pipeline.unet)
latent = next_step(noise_pred, t, latent, ddim_scheduler)
all_latent.append(latent)
return all_latent
@torch.no_grad()
def ddim_inversion(pipeline, ddim_scheduler, video_latent, num_inv_steps, prompt=""):
ddim_latents = ddim_loop(pipeline, ddim_scheduler, video_latent, num_inv_steps, prompt)
return ddim_latents
def video2images(path, step=4, length=16, start=0):
reader = imageio.get_reader(path)
frames = []
for frame in reader:
frames.append(np.array(frame))
frames = frames[start::step][:length]
return frames
def images2video(video, path, fps=8):
imageio.mimsave(path, video, fps=fps)
return
tensor_interpolation = None
def get_tensor_interpolation_method():
return tensor_interpolation
def set_tensor_interpolation_method(is_slerp):
global tensor_interpolation
tensor_interpolation = slerp if is_slerp else linear
def linear(v1, v2, t):
return (1.0 - t) * v1 + t * v2
def slerp(
v0: torch.Tensor, v1: torch.Tensor, t: float, DOT_THRESHOLD: float = 0.9995
) -> torch.Tensor:
u0 = v0 / v0.norm()
u1 = v1 / v1.norm()
dot = (u0 * u1).sum()
if dot.abs() > DOT_THRESHOLD:
#logger.info(f'warning: v0 and v1 close to parallel, using linear interpolation instead.')
return (1.0 - t) * v0 + t * v1
omega = dot.acos()
return (((1.0 - t) * omega).sin() * v0 + (t * omega).sin() * v1) / omega.sin() |