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import torch
from comfy.ldm.modules.diffusionmodules.util import make_beta_schedule
import math
def rescale_zero_terminal_snr_sigmas(sigmas):
alphas_cumprod = 1 / ((sigmas * sigmas) + 1)
alphas_bar_sqrt = alphas_cumprod.sqrt()
# Store old values.
alphas_bar_sqrt_0 = alphas_bar_sqrt[0].clone()
alphas_bar_sqrt_T = alphas_bar_sqrt[-1].clone()
# Shift so the last timestep is zero.
alphas_bar_sqrt -= (alphas_bar_sqrt_T)
# Scale so the first timestep is back to the old value.
alphas_bar_sqrt *= alphas_bar_sqrt_0 / (alphas_bar_sqrt_0 - alphas_bar_sqrt_T)
# Convert alphas_bar_sqrt to betas
alphas_bar = alphas_bar_sqrt**2 # Revert sqrt
alphas_bar[-1] = 4.8973451890853435e-08
return ((1 - alphas_bar) / alphas_bar) ** 0.5
def reshape_sigma(sigma, noise_dim):
if sigma.nelement() == 1:
return sigma.view(())
else:
return sigma.view(sigma.shape[:1] + (1,) * (noise_dim - 1))
class EPS:
def calculate_input(self, sigma, noise):
sigma = reshape_sigma(sigma, noise.ndim)
return noise / (sigma ** 2 + self.sigma_data ** 2) ** 0.5
def calculate_denoised(self, sigma, model_output, model_input):
sigma = reshape_sigma(sigma, model_output.ndim)
return model_input - model_output * sigma
def noise_scaling(self, sigma, noise, latent_image, max_denoise=False):
sigma = reshape_sigma(sigma, noise.ndim)
if max_denoise:
noise = noise * torch.sqrt(1.0 + sigma ** 2.0)
else:
noise = noise * sigma
noise += latent_image
return noise
def inverse_noise_scaling(self, sigma, latent):
return latent
class V_PREDICTION(EPS):
def calculate_denoised(self, sigma, model_output, model_input):
sigma = reshape_sigma(sigma, model_output.ndim)
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
class V_PREDICTION_DDPM:
"""CogVideoX v-prediction: model receives raw x_t (unscaled), predicts velocity v.
x_0 = sqrt(alpha) * x_t - sqrt(1-alpha) * v
= x_t / sqrt(sigma^2 + 1) - v * sigma / sqrt(sigma^2 + 1)
"""
def calculate_input(self, sigma, noise):
return noise
def calculate_denoised(self, sigma, model_output, model_input):
sigma = reshape_sigma(sigma, model_output.ndim)
return model_input / (sigma ** 2 + 1.0) ** 0.5 - model_output * sigma / (sigma ** 2 + 1.0) ** 0.5
def noise_scaling(self, sigma, noise, latent_image, max_denoise=False):
sigma = reshape_sigma(sigma, noise.ndim)
if max_denoise:
noise = noise * torch.sqrt(1.0 + sigma ** 2.0)
else:
noise = noise * sigma
noise += latent_image
return noise
def inverse_noise_scaling(self, sigma, latent):
return latent
class EDM(V_PREDICTION):
def calculate_denoised(self, sigma, model_output, model_input):
sigma = reshape_sigma(sigma, model_output.ndim)
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
class CONST:
def calculate_input(self, sigma, noise):
return noise
def calculate_denoised(self, sigma, model_output, model_input):
sigma = reshape_sigma(sigma, model_output.ndim)
return model_input - model_output * sigma
def noise_scaling(self, sigma, noise, latent_image, max_denoise=False):
sigma = reshape_sigma(sigma, noise.ndim)
s = getattr(self, "noise_scale", 1.0)
return sigma * (s * noise) + (1.0 - sigma) * latent_image
def inverse_noise_scaling(self, sigma, latent):
sigma = reshape_sigma(sigma, latent.ndim)
return latent / (1.0 - sigma)
class X0(EPS):
def calculate_denoised(self, sigma, model_output, model_input):
return model_output
class IMG_TO_IMG(X0):
def calculate_input(self, sigma, noise):
return noise
class IMG_TO_IMG_FLOW(CONST):
def calculate_denoised(self, sigma, model_output, model_input):
return model_output
def noise_scaling(self, sigma, noise, latent_image, max_denoise=False):
return latent_image
def inverse_noise_scaling(self, sigma, latent):
return 1.0 - latent
class IMG_TO_IMG_VELOCITY(CONST):
def calculate_denoised(self, sigma, model_output, model_input):
return model_input - model_output
def noise_scaling(self, sigma, noise, latent_image, max_denoise=False):
return latent_image
def inverse_noise_scaling(self, sigma, latent):
return latent
class COSMOS_RFLOW:
def calculate_input(self, sigma, noise):
sigma = (sigma / (sigma + 1))
sigma = reshape_sigma(sigma, noise.ndim)
return noise * (1.0 - sigma)
def calculate_denoised(self, sigma, model_output, model_input):
sigma = (sigma / (sigma + 1))
sigma = reshape_sigma(sigma, model_output.ndim)
return model_input * (1.0 - sigma) - model_output * sigma
def noise_scaling(self, sigma, noise, latent_image, max_denoise=False):
sigma = reshape_sigma(sigma, noise.ndim)
noise = noise * sigma
noise += latent_image
return noise
def inverse_noise_scaling(self, sigma, latent):
return latent
class ModelSamplingDiscrete(torch.nn.Module):
def __init__(self, model_config=None, zsnr=None):
super().__init__()
if model_config is not None:
sampling_settings = model_config.sampling_settings
else:
sampling_settings = {}
beta_schedule = sampling_settings.get("beta_schedule", "linear")
linear_start = sampling_settings.get("linear_start", 0.00085)
linear_end = sampling_settings.get("linear_end", 0.012)
timesteps = sampling_settings.get("timesteps", 1000)
if zsnr is None:
zsnr = sampling_settings.get("zsnr", False)
self._register_schedule(given_betas=None, beta_schedule=beta_schedule, timesteps=timesteps, linear_start=linear_start, linear_end=linear_end, cosine_s=8e-3, zsnr=zsnr)
self.sigma_data = 1.0
def _register_schedule(self, given_betas=None, beta_schedule="linear", timesteps=1000,
linear_start=1e-4, linear_end=2e-2, cosine_s=8e-3, zsnr=False):
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.cumprod(alphas, dim=0)
timesteps, = betas.shape
self.num_timesteps = int(timesteps)
self.linear_start = linear_start
self.linear_end = linear_end
self.zsnr = zsnr
# 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))
sigmas = ((1 - alphas_cumprod) / alphas_cumprod) ** 0.5
if self.zsnr:
sigmas = rescale_zero_terminal_snr_sigmas(sigmas)
self.set_sigmas(sigmas)
def set_sigmas(self, sigmas):
self.register_buffer('sigmas', sigmas.float())
self.register_buffer('log_sigmas', sigmas.log().float())
@property
def sigma_min(self):
return self.sigmas[0]
@property
def sigma_max(self):
return self.sigmas[-1]
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).to(sigma.device)
def sigma(self, timestep):
t = torch.clamp(timestep.float().to(self.log_sigmas.device), 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().to(timestep.device)
def percent_to_sigma(self, percent):
if percent <= 0.0:
return 999999999.9
if percent >= 1.0:
return 0.0
percent = 1.0 - percent
return self.sigma(torch.tensor(percent * 999.0)).item()
class ModelSamplingDiscreteEDM(ModelSamplingDiscrete):
def timestep(self, sigma):
return 0.25 * sigma.log()
def sigma(self, timestep):
return (timestep / 0.25).exp()
class ModelSamplingContinuousEDM(torch.nn.Module):
def __init__(self, model_config=None):
super().__init__()
if model_config is not None:
sampling_settings = model_config.sampling_settings
else:
sampling_settings = {}
sigma_min = sampling_settings.get("sigma_min", 0.002)
sigma_max = sampling_settings.get("sigma_max", 120.0)
sigma_data = sampling_settings.get("sigma_data", 1.0)
self.set_parameters(sigma_min, sigma_max, sigma_data)
def set_parameters(self, sigma_min, sigma_max, sigma_data):
self.sigma_data = sigma_data
sigmas = torch.linspace(math.log(sigma_min), math.log(sigma_max), 1000).exp()
self.register_buffer('sigmas', sigmas) #for compatibility with some schedulers
self.register_buffer('log_sigmas', sigmas.log())
@property
def sigma_min(self):
return self.sigmas[0]
@property
def sigma_max(self):
return self.sigmas[-1]
def timestep(self, sigma):
return 0.25 * sigma.log()
def sigma(self, timestep):
return (timestep / 0.25).exp()
def percent_to_sigma(self, percent):
if percent <= 0.0:
return 999999999.9
if percent >= 1.0:
return 0.0
percent = 1.0 - percent
log_sigma_min = math.log(self.sigma_min)
return math.exp((math.log(self.sigma_max) - log_sigma_min) * percent + log_sigma_min)
class ModelSamplingContinuousV(ModelSamplingContinuousEDM):
def timestep(self, sigma):
return sigma.atan() / math.pi * 2
def sigma(self, timestep):
return (timestep * math.pi / 2).tan()
def time_snr_shift(alpha, t):
if alpha == 1.0:
return t
return alpha * t / (1 + (alpha - 1) * t)
class ModelSamplingDiscreteFlow(torch.nn.Module):
def __init__(self, model_config=None):
super().__init__()
if model_config is not None:
sampling_settings = model_config.sampling_settings
else:
sampling_settings = {}
self.set_noise_scale(sampling_settings.get("noise_scale", 1.0))
self.set_parameters(
shift=sampling_settings.get("shift", 1.0),
multiplier=sampling_settings.get("multiplier", 1000),
)
def set_parameters(self, shift=1.0, timesteps=1000, multiplier=1000):
self.shift = shift
self.multiplier = multiplier
ts = self.sigma((torch.arange(1, timesteps + 1, 1) / timesteps) * multiplier)
self.register_buffer('sigmas', ts)
def set_noise_scale(self, noise_scale):
self.noise_scale = float(noise_scale)
@property
def sigma_min(self):
return self.sigmas[0]
@property
def sigma_max(self):
return self.sigmas[-1]
def timestep(self, sigma):
return sigma * self.multiplier
def sigma(self, timestep):
return time_snr_shift(self.shift, timestep / self.multiplier)
def percent_to_sigma(self, percent):
if percent <= 0.0:
return 1.0
if percent >= 1.0:
return 0.0
return time_snr_shift(self.shift, 1.0 - percent)
class ModelSamplingAV(ModelSamplingDiscreteFlow):
"""Flow sampling for packed audio-video latents whose audio stream has its own flow shift.
Carrying the audio latent scaled onto the video schedule makes the pack an ordinary
single-schedule flow latent whose audio target is scaled by audio_scale.
"""
def __init__(self, model_config=None):
super().__init__(model_config)
sampling_settings = model_config.sampling_settings if model_config is not None else {}
self.audio_shift = sampling_settings.get("audio_shift", None)
def set_parameters(self, shift=1.0, audio_shift=None, timesteps=1000, multiplier=1000):
self.audio_shift = audio_shift
super().set_parameters(shift=shift, timesteps=timesteps, multiplier=multiplier)
@property
def audio_scale(self):
if self.audio_shift is None:
return 1.0
return self.shift / self.audio_shift
class StableCascadeSampling(ModelSamplingDiscrete):
def __init__(self, model_config=None):
super().__init__()
if model_config is not None:
sampling_settings = model_config.sampling_settings
else:
sampling_settings = {}
self.set_parameters(sampling_settings.get("shift", 1.0))
def set_parameters(self, shift=1.0, cosine_s=8e-3):
self.shift = shift
self.cosine_s = torch.tensor(cosine_s)
self._init_alpha_cumprod = torch.cos(self.cosine_s / (1 + self.cosine_s) * torch.pi * 0.5) ** 2
#This part is just for compatibility with some schedulers in the codebase
self.num_timesteps = 10000
sigmas = torch.empty((self.num_timesteps), dtype=torch.float32)
for x in range(self.num_timesteps):
t = (x + 1) / self.num_timesteps
sigmas[x] = self.sigma(t)
self.set_sigmas(sigmas)
def sigma(self, timestep):
alpha_cumprod = (torch.cos((timestep + self.cosine_s) / (1 + self.cosine_s) * torch.pi * 0.5) ** 2 / self._init_alpha_cumprod)
if self.shift != 1.0:
var = alpha_cumprod
logSNR = (var/(1-var)).log()
logSNR += 2 * torch.log(1.0 / torch.tensor(self.shift))
alpha_cumprod = logSNR.sigmoid()
alpha_cumprod = alpha_cumprod.clamp(0.0001, 0.9999)
return ((1 - alpha_cumprod) / alpha_cumprod) ** 0.5
def timestep(self, sigma):
var = 1 / ((sigma * sigma) + 1)
var = var.clamp(0, 1.0)
s, min_var = self.cosine_s.to(var.device), self._init_alpha_cumprod.to(var.device)
t = (((var * min_var) ** 0.5).acos() / (torch.pi * 0.5)) * (1 + s) - s
return t
def percent_to_sigma(self, percent):
if percent <= 0.0:
return 999999999.9
if percent >= 1.0:
return 0.0
percent = 1.0 - percent
return self.sigma(torch.tensor(percent))
def flux_time_shift(mu: float, sigma: float, t):
return math.exp(mu) / (math.exp(mu) + (1 / t - 1) ** sigma)
class ModelSamplingFlux(torch.nn.Module):
def __init__(self, model_config=None):
super().__init__()
if model_config is not None:
sampling_settings = model_config.sampling_settings
else:
sampling_settings = {}
self.set_parameters(shift=sampling_settings.get("shift", 1.15))
def set_parameters(self, shift=1.15, timesteps=10000):
self.shift = shift
ts = self.sigma((torch.arange(1, timesteps + 1, 1) / timesteps))
self.register_buffer('sigmas', ts)
@property
def sigma_min(self):
return self.sigmas[0]
@property
def sigma_max(self):
return self.sigmas[-1]
def timestep(self, sigma):
return sigma
def sigma(self, timestep):
return flux_time_shift(self.shift, 1.0, timestep)
def percent_to_sigma(self, percent):
if percent <= 0.0:
return 1.0
if percent >= 1.0:
return 0.0
return flux_time_shift(self.shift, 1.0, 1.0 - percent)
class ModelSamplingCosmosRFlow(ModelSamplingContinuousEDM):
def timestep(self, sigma):
return sigma / (sigma + 1)
def sigma(self, timestep):
sigma_max = self.sigma_max
if timestep >= (sigma_max / (sigma_max + 1)):
return sigma_max
return timestep / (1 - timestep)
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