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from dataclasses import dataclass
from typing import Optional, Tuple, Union
import torch
import torch.nn as nn
from ..configuration_utils import ConfigMixin, register_to_config
from ..modeling_utils import ModelMixin
from ..utils import BaseOutput
from .embeddings import GaussianFourierProjection, TimestepEmbedding, Timesteps
from .unet_1d_blocks import get_down_block, get_mid_block, get_up_block
@dataclass
class UNet1DOutput(BaseOutput):
"""
Args:
sample (`torch.FloatTensor` of shape `(batch_size, num_channels, sample_size)`):
Hidden states output. Output of last layer of model.
"""
sample: torch.FloatTensor
class UNet1DModel(ModelMixin, ConfigMixin):
r"""
UNet1DModel is a 1D UNet model that takes in a noisy sample and a timestep and returns sample shaped output.
This model inherits from [`ModelMixin`]. Check the superclass documentation for the generic methods the library
implements for all the model (such as downloading or saving, etc.)
Parameters:
sample_size (`int`, *optionl*): Default length of sample. Should be adaptable at runtime.
in_channels (`int`, *optional*, defaults to 2): Number of channels in the input sample.
out_channels (`int`, *optional*, defaults to 2): Number of channels in the output.
time_embedding_type (`str`, *optional*, defaults to `"fourier"`): Type of time embedding to use.
freq_shift (`int`, *optional*, defaults to 0): Frequency shift for fourier time embedding.
flip_sin_to_cos (`bool`, *optional*, defaults to :
obj:`False`): Whether to flip sin to cos for fourier time embedding.
down_block_types (`Tuple[str]`, *optional*, defaults to :
obj:`("DownBlock1D", "DownBlock1DNoSkip", "AttnDownBlock1D")`): Tuple of downsample block types.
up_block_types (`Tuple[str]`, *optional*, defaults to :
obj:`("UpBlock1D", "UpBlock1DNoSkip", "AttnUpBlock1D")`): Tuple of upsample block types.
block_out_channels (`Tuple[int]`, *optional*, defaults to :
obj:`(32, 32, 64)`): Tuple of block output channels.
"""
@register_to_config
def __init__(
self,
sample_size: int = 65536,
sample_rate: Optional[int] = None,
in_channels: int = 2,
out_channels: int = 2,
extra_in_channels: int = 0,
time_embedding_type: str = "fourier",
freq_shift: int = 0,
flip_sin_to_cos: bool = True,
use_timestep_embedding: bool = False,
down_block_types: Tuple[str] = ("DownBlock1DNoSkip", "DownBlock1D", "AttnDownBlock1D"),
mid_block_type: str = "UNetMidBlock1D",
up_block_types: Tuple[str] = ("AttnUpBlock1D", "UpBlock1D", "UpBlock1DNoSkip"),
block_out_channels: Tuple[int] = (32, 32, 64),
):
super().__init__()
self.sample_size = sample_size
# time
if time_embedding_type == "fourier":
self.time_proj = GaussianFourierProjection(
embedding_size=8, set_W_to_weight=False, log=False, flip_sin_to_cos=flip_sin_to_cos
)
timestep_input_dim = 2 * block_out_channels[0]
elif time_embedding_type == "positional":
self.time_proj = Timesteps(block_out_channels[0], flip_sin_to_cos, freq_shift)
timestep_input_dim = block_out_channels[0]
if use_timestep_embedding:
time_embed_dim = block_out_channels[0] * 4
self.time_embedding = TimestepEmbedding(timestep_input_dim, time_embed_dim)
self.down_blocks = nn.ModuleList([])
self.mid_block = None
self.up_blocks = nn.ModuleList([])
self.out_block = None
# down
output_channel = in_channels
for i, down_block_type in enumerate(down_block_types):
input_channel = output_channel
output_channel = block_out_channels[i]
if i == 0:
input_channel += extra_in_channels
down_block = get_down_block(
down_block_type,
in_channels=input_channel,
out_channels=output_channel,
)
self.down_blocks.append(down_block)
# mid
self.mid_block = get_mid_block(
mid_block_type=mid_block_type,
mid_channels=block_out_channels[-1],
in_channels=block_out_channels[-1],
out_channels=None,
)
# up
reversed_block_out_channels = list(reversed(block_out_channels))
output_channel = reversed_block_out_channels[0]
for i, up_block_type in enumerate(up_block_types):
prev_output_channel = output_channel
output_channel = reversed_block_out_channels[i + 1] if i < len(up_block_types) - 1 else out_channels
up_block = get_up_block(
up_block_type,
in_channels=prev_output_channel,
out_channels=output_channel,
)
self.up_blocks.append(up_block)
prev_output_channel = output_channel
# TODO(PVP, Nathan) placeholder for RL application to be merged shortly
# Totally fine to add another layer with a if statement - no need for nn.Identity here
def forward(
self,
sample: torch.FloatTensor,
timestep: Union[torch.Tensor, float, int],
return_dict: bool = True,
) -> Union[UNet1DOutput, Tuple]:
r"""
Args:
sample (`torch.FloatTensor`): `(batch_size, sample_size, num_channels)` noisy inputs tensor
timestep (`torch.FloatTensor` or `float` or `int): (batch) timesteps
return_dict (`bool`, *optional*, defaults to `True`):
Whether or not to return a [`~models.unet_1d.UNet1DOutput`] instead of a plain tuple.
Returns:
[`~models.unet_1d.UNet1DOutput`] or `tuple`: [`~models.unet_1d.UNet1DOutput`] if `return_dict` is True,
otherwise a `tuple`. When returning a tuple, the first element is the sample tensor.
"""
# 1. time
if len(timestep.shape) == 0:
timestep = timestep[None]
timestep_embed = self.time_proj(timestep)[..., None]
timestep_embed = timestep_embed.repeat([1, 1, sample.shape[2]]).to(sample.dtype)
# 2. down
down_block_res_samples = ()
for downsample_block in self.down_blocks:
sample, res_samples = downsample_block(hidden_states=sample, temb=timestep_embed)
down_block_res_samples += res_samples
# 3. mid
sample = self.mid_block(sample)
# 4. up
for i, upsample_block in enumerate(self.up_blocks):
res_samples = down_block_res_samples[-1:]
down_block_res_samples = down_block_res_samples[:-1]
sample = upsample_block(sample, res_samples)
if not return_dict:
return (sample,)
return UNet1DOutput(sample=sample)