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"""SAMPLING ONLY.""" | |
import torch | |
from .dpm_solver import NoiseScheduleVP, model_wrapper, DPM_Solver | |
class DPMSolverSampler(object): | |
def __init__(self, model, **kwargs): | |
super().__init__() | |
self.model = model | |
to_torch = lambda x: x.clone().detach().to(torch.float32).to(model.device) | |
self.register_buffer('alphas_cumprod', to_torch(model.alphas_cumprod)) | |
def register_buffer(self, name, attr): | |
if type(attr) == torch.Tensor: | |
if attr.device != torch.device("cuda"): | |
attr = attr.to(torch.device("cuda")) | |
setattr(self, name, attr) | |
def sample(self, | |
S, | |
batch_size, | |
shape, | |
conditioning=None, | |
callback=None, | |
normals_sequence=None, | |
img_callback=None, | |
quantize_x0=False, | |
eta=0., | |
mask=None, | |
x0=None, | |
temperature=1., | |
noise_dropout=0., | |
score_corrector=None, | |
corrector_kwargs=None, | |
verbose=True, | |
x_T=None, | |
log_every_t=100, | |
unconditional_guidance_scale=1., | |
unconditional_conditioning=None, | |
# this has to come in the same format as the conditioning, # e.g. as encoded tokens, ... | |
**kwargs | |
): | |
if conditioning is not None: | |
if isinstance(conditioning, dict): | |
cbs = conditioning[list(conditioning.keys())[0]].shape[0] | |
if cbs != batch_size: | |
print(f"Warning: Got {cbs} conditionings but batch-size is {batch_size}") | |
else: | |
if conditioning.shape[0] != batch_size: | |
print(f"Warning: Got {conditioning.shape[0]} conditionings but batch-size is {batch_size}") | |
# sampling | |
C, H, W = shape | |
size = (batch_size, C, H, W) | |
# print(f'Data shape for DPM-Solver sampling is {size}, sampling steps {S}') | |
device = self.model.betas.device | |
if x_T is None: | |
img = torch.randn(size, device=device) | |
else: | |
img = x_T | |
ns = NoiseScheduleVP('discrete', alphas_cumprod=self.alphas_cumprod) | |
model_fn = model_wrapper( | |
lambda x, t, c: self.model.apply_model(x, t, c), | |
ns, | |
model_type="noise", | |
guidance_type="classifier-free", | |
condition=conditioning, | |
unconditional_condition=unconditional_conditioning, | |
guidance_scale=unconditional_guidance_scale, | |
) | |
dpm_solver = DPM_Solver(model_fn, ns, predict_x0=True, thresholding=False) | |
x = dpm_solver.sample(img, steps=S, skip_type="time_uniform", method="multistep", order=2, lower_order_final=True) | |
return x.to(device), None | |