File size: 7,620 Bytes
920fd91 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 | import torch, math
from typing_extensions import Literal
class FlowMatchScheduler():
def __init__(self, template: Literal["FLUX.1", "Wan", "Qwen-Image", "FLUX.2", "Z-Image"] = "FLUX.1"):
self.set_timesteps_fn = {
"FLUX.1": FlowMatchScheduler.set_timesteps_flux,
"Wan": FlowMatchScheduler.set_timesteps_wan,
"Qwen-Image": FlowMatchScheduler.set_timesteps_qwen_image,
"FLUX.2": FlowMatchScheduler.set_timesteps_flux2,
"Z-Image": FlowMatchScheduler.set_timesteps_z_image,
}.get(template, FlowMatchScheduler.set_timesteps_flux)
self.num_train_timesteps = 1000
@staticmethod
def set_timesteps_flux(num_inference_steps=100, denoising_strength=1.0, shift=None):
sigma_min = 0.003/1.002
sigma_max = 1.0
shift = 3 if shift is None else shift
num_train_timesteps = 1000
sigma_start = sigma_min + (sigma_max - sigma_min) * denoising_strength
sigmas = torch.linspace(sigma_start, sigma_min, num_inference_steps)
sigmas = shift * sigmas / (1 + (shift - 1) * sigmas)
timesteps = sigmas * num_train_timesteps
return sigmas, timesteps
@staticmethod
def set_timesteps_wan(num_inference_steps=100, denoising_strength=1.0, shift=None):
sigma_min = 0.0
sigma_max = 1.0
shift = 5 if shift is None else shift
num_train_timesteps = 1000
sigma_start = sigma_min + (sigma_max - sigma_min) * denoising_strength
sigmas = torch.linspace(sigma_start, sigma_min, num_inference_steps + 1)[:-1]
sigmas = shift * sigmas / (1 + (shift - 1) * sigmas)
timesteps = sigmas * num_train_timesteps
return sigmas, timesteps
@staticmethod
def _calculate_shift_qwen_image(image_seq_len, base_seq_len=256, max_seq_len=8192, base_shift=0.5, max_shift=0.9):
m = (max_shift - base_shift) / (max_seq_len - base_seq_len)
b = base_shift - m * base_seq_len
mu = image_seq_len * m + b
return mu
@staticmethod
def set_timesteps_qwen_image(num_inference_steps=100, denoising_strength=1.0, exponential_shift_mu=None, dynamic_shift_len=None):
sigma_min = 0.0
sigma_max = 1.0
num_train_timesteps = 1000
shift_terminal = 0.02
# Sigmas
sigma_start = sigma_min + (sigma_max - sigma_min) * denoising_strength
sigmas = torch.linspace(sigma_start, sigma_min, num_inference_steps + 1)[:-1]
# Mu
if exponential_shift_mu is not None:
mu = exponential_shift_mu
elif dynamic_shift_len is not None:
mu = FlowMatchScheduler._calculate_shift_qwen_image(dynamic_shift_len)
else:
mu = 0.8
sigmas = math.exp(mu) / (math.exp(mu) + (1 / sigmas - 1))
# Shift terminal
one_minus_z = 1 - sigmas
scale_factor = one_minus_z[-1] / (1 - shift_terminal)
sigmas = 1 - (one_minus_z / scale_factor)
# Timesteps
timesteps = sigmas * num_train_timesteps
return sigmas, timesteps
@staticmethod
def compute_empirical_mu(image_seq_len, num_steps):
a1, b1 = 8.73809524e-05, 1.89833333
a2, b2 = 0.00016927, 0.45666666
if image_seq_len > 4300:
mu = a2 * image_seq_len + b2
return float(mu)
m_200 = a2 * image_seq_len + b2
m_10 = a1 * image_seq_len + b1
a = (m_200 - m_10) / 190.0
b = m_200 - 200.0 * a
mu = a * num_steps + b
return float(mu)
@staticmethod
def set_timesteps_flux2(num_inference_steps=100, denoising_strength=1.0, dynamic_shift_len=1024//16*1024//16):
sigma_min = 1 / num_inference_steps
sigma_max = 1.0
num_train_timesteps = 1000
sigma_start = sigma_min + (sigma_max - sigma_min) * denoising_strength
sigmas = torch.linspace(sigma_start, sigma_min, num_inference_steps)
mu = FlowMatchScheduler.compute_empirical_mu(dynamic_shift_len, num_inference_steps)
sigmas = math.exp(mu) / (math.exp(mu) + (1 / sigmas - 1))
timesteps = sigmas * num_train_timesteps
return sigmas, timesteps
@staticmethod
def set_timesteps_z_image(num_inference_steps=100, denoising_strength=1.0, shift=None, target_timesteps=None):
sigma_min = 0.0
sigma_max = 1.0
shift = 3 if shift is None else shift
num_train_timesteps = 1000
sigma_start = sigma_min + (sigma_max - sigma_min) * denoising_strength
sigmas = torch.linspace(sigma_start, sigma_min, num_inference_steps + 1)[:-1]
sigmas = shift * sigmas / (1 + (shift - 1) * sigmas)
timesteps = sigmas * num_train_timesteps
if target_timesteps is not None:
target_timesteps = target_timesteps.to(dtype=timesteps.dtype, device=timesteps.device)
for timestep in target_timesteps:
timestep_id = torch.argmin((timesteps - timestep).abs())
timesteps[timestep_id] = timestep
return sigmas, timesteps
def set_training_weight(self):
steps = 1000
x = self.timesteps
y = torch.exp(-2 * ((x - steps / 2) / steps) ** 2)
y_shifted = y - y.min()
bsmntw_weighing = y_shifted * (steps / y_shifted.sum())
if len(self.timesteps) != 1000:
# This is an empirical formula.
bsmntw_weighing = bsmntw_weighing * (len(self.timesteps) / steps)
bsmntw_weighing = bsmntw_weighing + bsmntw_weighing[1]
self.linear_timesteps_weights = bsmntw_weighing
def set_timesteps(self, num_inference_steps=100, denoising_strength=1.0, training=False, **kwargs):
self.sigmas, self.timesteps = self.set_timesteps_fn(
num_inference_steps=num_inference_steps,
denoising_strength=denoising_strength,
**kwargs,
)
if training:
self.set_training_weight()
self.training = True
else:
self.training = False
def step(self, model_output, timestep, sample, to_final=False, **kwargs):
if isinstance(timestep, torch.Tensor):
timestep = timestep.cpu()
timestep_id = torch.argmin((self.timesteps - timestep).abs())
sigma = self.sigmas[timestep_id]
if to_final or timestep_id + 1 >= len(self.timesteps):
sigma_ = 0
else:
sigma_ = self.sigmas[timestep_id + 1]
prev_sample = sample + model_output * (sigma_ - sigma)
return prev_sample
def return_to_timestep(self, timestep, sample, sample_stablized):
if isinstance(timestep, torch.Tensor):
timestep = timestep.cpu()
timestep_id = torch.argmin((self.timesteps - timestep).abs())
sigma = self.sigmas[timestep_id]
model_output = (sample - sample_stablized) / sigma
return model_output
def add_noise(self, original_samples, noise, timestep):
if isinstance(timestep, torch.Tensor):
timestep = timestep.cpu()
timestep_id = torch.argmin((self.timesteps - timestep).abs())
sigma = self.sigmas[timestep_id]
sample = (1 - sigma) * original_samples + sigma * noise
return sample
def training_target(self, sample, noise, timestep):
target = noise - sample
return target
def training_weight(self, timestep):
timestep_id = torch.argmin((self.timesteps - timestep.to(self.timesteps.device)).abs())
weights = self.linear_timesteps_weights[timestep_id]
return weights
|