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102 lines
3.9 KiB
Python
102 lines
3.9 KiB
Python
# Copyright 2024 HPC-AI Technology Inc.
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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# http://www.apache.org/licenses/LICENSE-2.0
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# SPDX-FileCopyrightText: Copyright (c) 2022-2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
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# SPDX-License-Identifier: Apache-2.0
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# reference: https://github.com/hpcaitech/Open-Sora/blob/main/opensora/schedulers/rf/rectified_flow.py
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import torch
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from torch.distributions import LogisticNormal
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def timestep_transform(
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t,
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model_kwargs,
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base_resolution=512 * 512,
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base_num_frames=1,
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scale=1.0,
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num_timesteps=1,
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):
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# Force fp16 input to fp32 to avoid nan output
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for key in ["height", "width", "num_frames"]:
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if model_kwargs[key].dtype == torch.float16:
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model_kwargs[key] = model_kwargs[key].float()
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t = t / num_timesteps
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resolution = model_kwargs["height"] * model_kwargs["width"]
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ratio_space = (resolution / base_resolution).sqrt()
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# NOTE: currently, we do not take fps into account
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# NOTE: temporal_reduction is hardcoded, this should be equal to the temporal reduction factor of the vae
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if model_kwargs["num_frames"][0] == 1:
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num_frames = torch.ones_like(model_kwargs["num_frames"])
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else:
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num_frames = model_kwargs["num_frames"] // 17 * 5
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ratio_time = (num_frames / base_num_frames).sqrt()
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ratio = ratio_space * ratio_time * scale
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new_t = ratio * t / (1 + (ratio - 1) * t)
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new_t = new_t * num_timesteps
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return new_t
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class RFlowScheduler:
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def __init__(
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self,
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num_timesteps=1000,
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num_sampling_steps=10,
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sample_method="uniform",
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loc=0.0,
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scale=1.0,
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use_timestep_transform=False,
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):
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self.num_timesteps = num_timesteps
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self.num_sampling_steps = num_sampling_steps
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assert sample_method in ["uniform", "logit-normal"]
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self.sample_method = sample_method
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if sample_method == "logit-normal":
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self.distribution = LogisticNormal(torch.tensor([loc]),
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torch.tensor([scale]))
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self.sample_t = lambda x: self.distribution.sample(
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(x.shape[0], ))[:, 0].to(x.device)
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self.use_timestep_transform = use_timestep_transform
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def add_noise(
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self,
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original_samples: torch.FloatTensor,
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noise: torch.FloatTensor,
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timesteps: torch.IntTensor,
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) -> torch.FloatTensor:
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timepoints = timesteps.float() / self.num_timesteps
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timepoints = 1 - timepoints # [1,1/1000]
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# timepoint (bsz) noise: (bsz, 4, frame, w ,h)
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# expand timepoint to noise shape
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timepoints = timepoints.unsqueeze(1).unsqueeze(1).unsqueeze(
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1).unsqueeze(1)
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timepoints = timepoints.repeat(1, noise.shape[1], noise.shape[2],
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noise.shape[3], noise.shape[4])
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return timepoints * original_samples + (1 - timepoints) * noise
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