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import torch | ||
import numpy as np | ||
from comfy.ldm.modules.diffusionmodules.util import make_beta_schedule | ||
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class EPS: | ||
def calculate_input(self, sigma, noise): | ||
sigma = sigma.view(sigma.shape[:1] + (1,) * (noise.ndim - 1)) | ||
return noise / (sigma ** 2 + self.sigma_data ** 2) ** 0.5 | ||
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def calculate_denoised(self, sigma, model_output, model_input): | ||
sigma = sigma.view(sigma.shape[:1] + (1,) * (model_output.ndim - 1)) | ||
return model_input - model_output * sigma | ||
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class V_PREDICTION(EPS): | ||
def calculate_denoised(self, sigma, model_output, model_input): | ||
sigma = sigma.view(sigma.shape[:1] + (1,) * (model_output.ndim - 1)) | ||
return model_input * self.sigma_data ** 2 / (sigma ** 2 + self.sigma_data ** 2) - model_output * sigma * self.sigma_data / (sigma ** 2 + self.sigma_data ** 2) ** 0.5 | ||
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class ModelSamplingDiscrete(torch.nn.Module): | ||
def __init__(self, model_config=None): | ||
super().__init__() | ||
beta_schedule = "linear" | ||
if model_config is not None: | ||
beta_schedule = model_config.beta_schedule | ||
self._register_schedule(given_betas=None, beta_schedule=beta_schedule, timesteps=1000, linear_start=0.00085, linear_end=0.012, cosine_s=8e-3) | ||
self.sigma_data = 1.0 | ||
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def _register_schedule(self, given_betas=None, beta_schedule="linear", timesteps=1000, | ||
linear_start=1e-4, linear_end=2e-2, cosine_s=8e-3): | ||
if given_betas is not None: | ||
betas = given_betas | ||
else: | ||
betas = make_beta_schedule(beta_schedule, timesteps, linear_start=linear_start, linear_end=linear_end, cosine_s=cosine_s) | ||
alphas = 1. - betas | ||
alphas_cumprod = torch.tensor(np.cumprod(alphas, axis=0), dtype=torch.float32) | ||
# alphas_cumprod_prev = np.append(1., alphas_cumprod[:-1]) | ||
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timesteps, = betas.shape | ||
self.num_timesteps = int(timesteps) | ||
self.linear_start = linear_start | ||
self.linear_end = linear_end | ||
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# self.register_buffer('betas', torch.tensor(betas, dtype=torch.float32)) | ||
# self.register_buffer('alphas_cumprod', torch.tensor(alphas_cumprod, dtype=torch.float32)) | ||
# self.register_buffer('alphas_cumprod_prev', torch.tensor(alphas_cumprod_prev, dtype=torch.float32)) | ||
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sigmas = ((1 - alphas_cumprod) / alphas_cumprod) ** 0.5 | ||
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self.register_buffer('sigmas', sigmas) | ||
self.register_buffer('log_sigmas', sigmas.log()) | ||
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@property | ||
def sigma_min(self): | ||
return self.sigmas[0] | ||
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@property | ||
def sigma_max(self): | ||
return self.sigmas[-1] | ||
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def timestep(self, sigma): | ||
log_sigma = sigma.log() | ||
dists = log_sigma.to(self.log_sigmas.device) - self.log_sigmas[:, None] | ||
return dists.abs().argmin(dim=0).view(sigma.shape) | ||
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def sigma(self, timestep): | ||
t = torch.clamp(timestep.float(), min=0, max=(len(self.sigmas) - 1)) | ||
low_idx = t.floor().long() | ||
high_idx = t.ceil().long() | ||
w = t.frac() | ||
log_sigma = (1 - w) * self.log_sigmas[low_idx] + w * self.log_sigmas[high_idx] | ||
return log_sigma.exp() | ||
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def percent_to_sigma(self, percent): | ||
return self.sigma(torch.tensor(percent * 999.0)) | ||
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