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# Copyright 2024 NVIDIA CORPORATION & AFFILIATES | |
# | |
# Licensed under the Apache License, Version 2.0 (the "License"); | |
# you may not use this file except in compliance with the License. | |
# You may obtain a copy of the License at | |
# | |
# http://www.apache.org/licenses/LICENSE-2.0 | |
# | |
# Unless required by applicable law or agreed to in writing, software | |
# distributed under the License is distributed on an "AS IS" BASIS, | |
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
# See the License for the specific language governing permissions and | |
# limitations under the License. | |
# | |
# SPDX-License-Identifier: Apache-2.0 | |
"""SAMPLING ONLY.""" | |
import numpy as np | |
import torch | |
from diffusion.model.sa_solver import NoiseScheduleVP, SASolver, model_wrapper | |
from .model import gaussian_diffusion as gd | |
class SASolverSampler: | |
def __init__( | |
self, | |
model, | |
noise_schedule="linear", | |
diffusion_steps=1000, | |
device="cpu", | |
): | |
super().__init__() | |
self.model = model | |
self.device = device | |
to_torch = lambda x: x.clone().detach().to(torch.float32).to(device) | |
betas = torch.tensor(gd.get_named_beta_schedule(noise_schedule, diffusion_steps)) | |
alphas = 1.0 - betas | |
self.register_buffer("alphas_cumprod", to_torch(np.cumprod(alphas, axis=0))) | |
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=0.0, | |
mask=None, | |
x0=None, | |
temperature=1.0, | |
noise_dropout=0.0, | |
score_corrector=None, | |
corrector_kwargs=None, | |
verbose=True, | |
x_T=None, | |
log_every_t=100, | |
unconditional_guidance_scale=1.0, | |
unconditional_conditioning=None, | |
model_kwargs={}, | |
# 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) | |
device = self.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( | |
self.model, | |
ns, | |
model_type="noise", | |
guidance_type="classifier-free", | |
condition=conditioning, | |
unconditional_condition=unconditional_conditioning, | |
guidance_scale=unconditional_guidance_scale, | |
model_kwargs=model_kwargs, | |
) | |
sasolver = SASolver(model_fn, ns, algorithm_type="data_prediction") | |
tau_t = lambda t: eta if 0.2 <= t <= 0.8 else 0 | |
x = sasolver.sample( | |
mode="few_steps", | |
x=img, | |
tau=tau_t, | |
steps=S, | |
skip_type="time", | |
skip_order=1, | |
predictor_order=2, | |
corrector_order=2, | |
pc_mode="PEC", | |
return_intermediate=False, | |
) | |
return x.to(device), None | |