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import torch
from k_diffusion import utils, sampling
from k_diffusion.external import DiscreteEpsDDPMDenoiser
from k_diffusion.sampling import default_noise_sampler, trange
from modules import shared, sd_samplers_cfg_denoiser, sd_samplers_kdiffusion, sd_samplers_common
class LCMCompVisDenoiser(DiscreteEpsDDPMDenoiser):
def __init__(self, model):
timesteps = 1000
original_timesteps = 50 # LCM Original Timesteps (default=50, for current version of LCM)
self.skip_steps = timesteps // original_timesteps
alphas_cumprod_valid = torch.zeros((original_timesteps), dtype=torch.float32, device=model.device)
for x in range(original_timesteps):
alphas_cumprod_valid[original_timesteps - 1 - x] = model.alphas_cumprod[timesteps - 1 - x * self.skip_steps]
super().__init__(model, alphas_cumprod_valid, quantize=None)
def get_sigmas(self, n=None,):
if n is None:
return sampling.append_zero(self.sigmas.flip(0))
start = self.sigma_to_t(self.sigma_max)
end = self.sigma_to_t(self.sigma_min)
t = torch.linspace(start, end, n, device=shared.sd_model.device)
return sampling.append_zero(self.t_to_sigma(t))
def sigma_to_t(self, sigma, quantize=None):
log_sigma = sigma.log()
dists = log_sigma - self.log_sigmas[:, None]
return dists.abs().argmin(dim=0).view(sigma.shape) * self.skip_steps + (self.skip_steps - 1)
def t_to_sigma(self, timestep):
t = torch.clamp(((timestep - (self.skip_steps - 1)) / self.skip_steps).float(), min=0, max=(len(self.sigmas) - 1))
return super().t_to_sigma(t)
def get_eps(self, *args, **kwargs):
return self.inner_model.apply_model(*args, **kwargs)
def get_scaled_out(self, sigma, output, input):
sigma_data = 0.5
scaled_timestep = utils.append_dims(self.sigma_to_t(sigma), output.ndim) * 10.0
c_skip = sigma_data**2 / (scaled_timestep**2 + sigma_data**2)
c_out = scaled_timestep / (scaled_timestep**2 + sigma_data**2) ** 0.5
return c_out * output + c_skip * input
def forward(self, input, sigma, **kwargs):
c_out, c_in = [utils.append_dims(x, input.ndim) for x in self.get_scalings(sigma)]
eps = self.get_eps(input * c_in, self.sigma_to_t(sigma), **kwargs)
return self.get_scaled_out(sigma, input + eps * c_out, input)
def sample_lcm(model, x, sigmas, extra_args=None, callback=None, disable=None, noise_sampler=None):
extra_args = {} if extra_args is None else extra_args
noise_sampler = default_noise_sampler(x) if noise_sampler is None else noise_sampler
s_in = x.new_ones([x.shape[0]])
for i in trange(len(sigmas) - 1, disable=disable):
denoised = model(x, sigmas[i] * s_in, **extra_args)
if callback is not None:
callback({'x': x, 'i': i, 'sigma': sigmas[i], 'sigma_hat': sigmas[i], 'denoised': denoised})
x = denoised
if sigmas[i + 1] > 0:
x += sigmas[i + 1] * noise_sampler(sigmas[i], sigmas[i + 1])
return x
class CFGDenoiserLCM(sd_samplers_cfg_denoiser.CFGDenoiser):
@property
def inner_model(self):
if self.model_wrap is None:
denoiser = LCMCompVisDenoiser
self.model_wrap = denoiser(shared.sd_model)
return self.model_wrap
class LCMSampler(sd_samplers_kdiffusion.KDiffusionSampler):
def __init__(self, funcname, sd_model, options=None):
super().__init__(funcname, sd_model, options)
self.model_wrap_cfg = CFGDenoiserLCM(self)
self.model_wrap = self.model_wrap_cfg.inner_model
samplers_lcm = [('LCM', sample_lcm, ['k_lcm'], {})]
samplers_data_lcm = [
sd_samplers_common.SamplerData(label, lambda model, funcname=funcname: LCMSampler(funcname, model), aliases, options)
for label, funcname, aliases, options in samplers_lcm
]
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