| | import logging |
| | import math |
| | from abc import abstractmethod |
| | from typing import Iterable, List, Optional, Tuple, Union |
| |
|
| | import torch as th |
| | import torch.nn as nn |
| | import torch.nn.functional as F |
| | from einops import rearrange |
| | from torch.utils.checkpoint import checkpoint |
| |
|
| | from ...modules.attention import SpatialTransformer |
| | from ...modules.diffusionmodules.util import (avg_pool_nd, conv_nd, linear, |
| | normalization, |
| | timestep_embedding, zero_module) |
| | from ...modules.video_attention import SpatialVideoTransformer |
| | from ...util import exists |
| |
|
| | logpy = logging.getLogger(__name__) |
| |
|
| |
|
| | class AttentionPool2d(nn.Module): |
| | """ |
| | Adapted from CLIP: https://github.com/openai/CLIP/blob/main/clip/model.py |
| | """ |
| |
|
| | def __init__( |
| | self, |
| | spacial_dim: int, |
| | embed_dim: int, |
| | num_heads_channels: int, |
| | output_dim: Optional[int] = None, |
| | ): |
| | super().__init__() |
| | self.positional_embedding = nn.Parameter( |
| | th.randn(embed_dim, spacial_dim**2 + 1) / embed_dim**0.5 |
| | ) |
| | self.qkv_proj = conv_nd(1, embed_dim, 3 * embed_dim, 1) |
| | self.c_proj = conv_nd(1, embed_dim, output_dim or embed_dim, 1) |
| | self.num_heads = embed_dim // num_heads_channels |
| | self.attention = QKVAttention(self.num_heads) |
| |
|
| | def forward(self, x: th.Tensor) -> th.Tensor: |
| | b, c, _ = x.shape |
| | x = x.reshape(b, c, -1) |
| | x = th.cat([x.mean(dim=-1, keepdim=True), x], dim=-1) |
| | x = x + self.positional_embedding[None, :, :].to(x.dtype) |
| | x = self.qkv_proj(x) |
| | x = self.attention(x) |
| | x = self.c_proj(x) |
| | return x[:, :, 0] |
| |
|
| |
|
| | class TimestepBlock(nn.Module): |
| | """ |
| | Any module where forward() takes timestep embeddings as a second argument. |
| | """ |
| |
|
| | @abstractmethod |
| | def forward(self, x: th.Tensor, emb: th.Tensor): |
| | """ |
| | Apply the module to `x` given `emb` timestep embeddings. |
| | """ |
| |
|
| |
|
| | class TimestepEmbedSequential(nn.Sequential, TimestepBlock): |
| | """ |
| | A sequential module that passes timestep embeddings to the children that |
| | support it as an extra input. |
| | """ |
| |
|
| | def forward( |
| | self, |
| | x: th.Tensor, |
| | emb: th.Tensor, |
| | context: Optional[th.Tensor] = None, |
| | image_only_indicator: Optional[th.Tensor] = None, |
| | time_context: Optional[int] = None, |
| | num_video_frames: Optional[int] = None, |
| | ): |
| | from ...modules.diffusionmodules.video_model import VideoResBlock |
| |
|
| | for layer in self: |
| | module = layer |
| |
|
| | if isinstance(module, TimestepBlock) and not isinstance( |
| | module, VideoResBlock |
| | ): |
| | x = layer(x, emb) |
| | elif isinstance(module, VideoResBlock): |
| | x = layer(x, emb, num_video_frames, image_only_indicator) |
| | elif isinstance(module, SpatialVideoTransformer): |
| | x = layer( |
| | x, |
| | context, |
| | time_context, |
| | num_video_frames, |
| | image_only_indicator, |
| | ) |
| | elif isinstance(module, SpatialTransformer): |
| | x = layer(x, context) |
| | else: |
| | x = layer(x) |
| | return x |
| |
|
| |
|
| | class Upsample(nn.Module): |
| | """ |
| | An upsampling layer with an optional convolution. |
| | :param channels: channels in the inputs and outputs. |
| | :param use_conv: a bool determining if a convolution is applied. |
| | :param dims: determines if the signal is 1D, 2D, or 3D. If 3D, then |
| | upsampling occurs in the inner-two dimensions. |
| | """ |
| |
|
| | def __init__( |
| | self, |
| | channels: int, |
| | use_conv: bool, |
| | dims: int = 2, |
| | out_channels: Optional[int] = None, |
| | padding: int = 1, |
| | third_up: bool = False, |
| | kernel_size: int = 3, |
| | scale_factor: int = 2, |
| | ): |
| | super().__init__() |
| | self.channels = channels |
| | self.out_channels = out_channels or channels |
| | self.use_conv = use_conv |
| | self.dims = dims |
| | self.third_up = third_up |
| | self.scale_factor = scale_factor |
| | if use_conv: |
| | self.conv = conv_nd( |
| | dims, self.channels, self.out_channels, kernel_size, padding=padding |
| | ) |
| |
|
| | def forward(self, x: th.Tensor) -> th.Tensor: |
| | assert x.shape[1] == self.channels |
| |
|
| | if self.dims == 3: |
| | t_factor = 1 if not self.third_up else self.scale_factor |
| | x = F.interpolate( |
| | x, |
| | ( |
| | t_factor * x.shape[2], |
| | x.shape[3] * self.scale_factor, |
| | x.shape[4] * self.scale_factor, |
| | ), |
| | mode="nearest", |
| | ) |
| | else: |
| | x = F.interpolate(x, scale_factor=self.scale_factor, mode="nearest") |
| | if self.use_conv: |
| | x = self.conv(x) |
| | return x |
| |
|
| |
|
| | class Downsample(nn.Module): |
| | """ |
| | A downsampling layer with an optional convolution. |
| | :param channels: channels in the inputs and outputs. |
| | :param use_conv: a bool determining if a convolution is applied. |
| | :param dims: determines if the signal is 1D, 2D, or 3D. If 3D, then |
| | downsampling occurs in the inner-two dimensions. |
| | """ |
| |
|
| | def __init__( |
| | self, |
| | channels: int, |
| | use_conv: bool, |
| | dims: int = 2, |
| | out_channels: Optional[int] = None, |
| | padding: int = 1, |
| | third_down: bool = False, |
| | ): |
| | super().__init__() |
| | self.channels = channels |
| | self.out_channels = out_channels or channels |
| | self.use_conv = use_conv |
| | self.dims = dims |
| | stride = 2 if dims != 3 else ((1, 2, 2) if not third_down else (2, 2, 2)) |
| | if use_conv: |
| | logpy.info(f"Building a Downsample layer with {dims} dims.") |
| | logpy.info( |
| | f" --> settings are: \n in-chn: {self.channels}, out-chn: {self.out_channels}, " |
| | f"kernel-size: 3, stride: {stride}, padding: {padding}" |
| | ) |
| | if dims == 3: |
| | logpy.info(f" --> Downsampling third axis (time): {third_down}") |
| | self.op = conv_nd( |
| | dims, |
| | self.channels, |
| | self.out_channels, |
| | 3, |
| | stride=stride, |
| | padding=padding, |
| | ) |
| | else: |
| | assert self.channels == self.out_channels |
| | self.op = avg_pool_nd(dims, kernel_size=stride, stride=stride) |
| |
|
| | def forward(self, x: th.Tensor) -> th.Tensor: |
| | assert x.shape[1] == self.channels |
| |
|
| | return self.op(x) |
| |
|
| |
|
| | class ResBlock(TimestepBlock): |
| | """ |
| | A residual block that can optionally change the number of channels. |
| | :param channels: the number of input channels. |
| | :param emb_channels: the number of timestep embedding channels. |
| | :param dropout: the rate of dropout. |
| | :param out_channels: if specified, the number of out channels. |
| | :param use_conv: if True and out_channels is specified, use a spatial |
| | convolution instead of a smaller 1x1 convolution to change the |
| | channels in the skip connection. |
| | :param dims: determines if the signal is 1D, 2D, or 3D. |
| | :param use_checkpoint: if True, use gradient checkpointing on this module. |
| | :param up: if True, use this block for upsampling. |
| | :param down: if True, use this block for downsampling. |
| | """ |
| |
|
| | def __init__( |
| | self, |
| | channels: int, |
| | emb_channels: int, |
| | dropout: float, |
| | out_channels: Optional[int] = None, |
| | use_conv: bool = False, |
| | use_scale_shift_norm: bool = False, |
| | dims: int = 2, |
| | use_checkpoint: bool = False, |
| | up: bool = False, |
| | down: bool = False, |
| | kernel_size: int = 3, |
| | exchange_temb_dims: bool = False, |
| | skip_t_emb: bool = False, |
| | ): |
| | super().__init__() |
| | self.channels = channels |
| | self.emb_channels = emb_channels |
| | self.dropout = dropout |
| | self.out_channels = out_channels or channels |
| | self.use_conv = use_conv |
| | self.use_checkpoint = use_checkpoint |
| | self.use_scale_shift_norm = use_scale_shift_norm |
| | self.exchange_temb_dims = exchange_temb_dims |
| |
|
| | if isinstance(kernel_size, Iterable): |
| | padding = [k // 2 for k in kernel_size] |
| | else: |
| | padding = kernel_size // 2 |
| |
|
| | self.in_layers = nn.Sequential( |
| | normalization(channels), |
| | nn.SiLU(), |
| | conv_nd(dims, channels, self.out_channels, kernel_size, padding=padding), |
| | ) |
| |
|
| | self.updown = up or down |
| |
|
| | if up: |
| | self.h_upd = Upsample(channels, False, dims) |
| | self.x_upd = Upsample(channels, False, dims) |
| | elif down: |
| | self.h_upd = Downsample(channels, False, dims) |
| | self.x_upd = Downsample(channels, False, dims) |
| | else: |
| | self.h_upd = self.x_upd = nn.Identity() |
| |
|
| | self.skip_t_emb = skip_t_emb |
| | self.emb_out_channels = ( |
| | 2 * self.out_channels if use_scale_shift_norm else self.out_channels |
| | ) |
| | if self.skip_t_emb: |
| | logpy.info(f"Skipping timestep embedding in {self.__class__.__name__}") |
| | assert not self.use_scale_shift_norm |
| | self.emb_layers = None |
| | self.exchange_temb_dims = False |
| | else: |
| | self.emb_layers = nn.Sequential( |
| | nn.SiLU(), |
| | linear( |
| | emb_channels, |
| | self.emb_out_channels, |
| | ), |
| | ) |
| |
|
| | self.out_layers = nn.Sequential( |
| | normalization(self.out_channels), |
| | nn.SiLU(), |
| | nn.Dropout(p=dropout), |
| | zero_module( |
| | conv_nd( |
| | dims, |
| | self.out_channels, |
| | self.out_channels, |
| | kernel_size, |
| | padding=padding, |
| | ) |
| | ), |
| | ) |
| |
|
| | if self.out_channels == channels: |
| | self.skip_connection = nn.Identity() |
| | elif use_conv: |
| | self.skip_connection = conv_nd( |
| | dims, channels, self.out_channels, kernel_size, padding=padding |
| | ) |
| | else: |
| | self.skip_connection = conv_nd(dims, channels, self.out_channels, 1) |
| |
|
| | def forward(self, x: th.Tensor, emb: th.Tensor) -> th.Tensor: |
| | """ |
| | Apply the block to a Tensor, conditioned on a timestep embedding. |
| | :param x: an [N x C x ...] Tensor of features. |
| | :param emb: an [N x emb_channels] Tensor of timestep embeddings. |
| | :return: an [N x C x ...] Tensor of outputs. |
| | """ |
| | if self.use_checkpoint: |
| | return checkpoint(self._forward, x, emb) |
| | else: |
| | return self._forward(x, emb) |
| |
|
| | def _forward(self, x: th.Tensor, emb: th.Tensor) -> th.Tensor: |
| | if self.updown: |
| | in_rest, in_conv = self.in_layers[:-1], self.in_layers[-1] |
| | h = in_rest(x) |
| | h = self.h_upd(h) |
| | x = self.x_upd(x) |
| | h = in_conv(h) |
| | else: |
| | h = self.in_layers(x) |
| |
|
| | if self.skip_t_emb: |
| | emb_out = th.zeros_like(h) |
| | else: |
| | emb_out = self.emb_layers(emb).type(h.dtype) |
| | while len(emb_out.shape) < len(h.shape): |
| | emb_out = emb_out[..., None] |
| | if self.use_scale_shift_norm: |
| | out_norm, out_rest = self.out_layers[0], self.out_layers[1:] |
| | scale, shift = th.chunk(emb_out, 2, dim=1) |
| | h = out_norm(h) * (1 + scale) + shift |
| | h = out_rest(h) |
| | else: |
| | if self.exchange_temb_dims: |
| | emb_out = rearrange(emb_out, "b t c ... -> b c t ...") |
| | h = h + emb_out |
| | h = self.out_layers(h) |
| | return self.skip_connection(x) + h |
| |
|
| |
|
| | class AttentionBlock(nn.Module): |
| | """ |
| | An attention block that allows spatial positions to attend to each other. |
| | Originally ported from here, but adapted to the N-d case. |
| | https://github.com/hojonathanho/diffusion/blob/1e0dceb3b3495bbe19116a5e1b3596cd0706c543/diffusion_tf/models/unet.py#L66. |
| | """ |
| |
|
| | def __init__( |
| | self, |
| | channels: int, |
| | num_heads: int = 1, |
| | num_head_channels: int = -1, |
| | use_checkpoint: bool = False, |
| | use_new_attention_order: bool = False, |
| | ): |
| | super().__init__() |
| | self.channels = channels |
| | if num_head_channels == -1: |
| | self.num_heads = num_heads |
| | else: |
| | assert ( |
| | channels % num_head_channels == 0 |
| | ), f"q,k,v channels {channels} is not divisible by num_head_channels {num_head_channels}" |
| | self.num_heads = channels // num_head_channels |
| | self.use_checkpoint = use_checkpoint |
| | self.norm = normalization(channels) |
| | self.qkv = conv_nd(1, channels, channels * 3, 1) |
| | if use_new_attention_order: |
| | |
| | self.attention = QKVAttention(self.num_heads) |
| | else: |
| | |
| | self.attention = QKVAttentionLegacy(self.num_heads) |
| |
|
| | self.proj_out = zero_module(conv_nd(1, channels, channels, 1)) |
| |
|
| | def forward(self, x: th.Tensor, **kwargs) -> th.Tensor: |
| | return checkpoint(self._forward, x) |
| |
|
| | def _forward(self, x: th.Tensor) -> th.Tensor: |
| | b, c, *spatial = x.shape |
| | x = x.reshape(b, c, -1) |
| | qkv = self.qkv(self.norm(x)) |
| | h = self.attention(qkv) |
| | h = self.proj_out(h) |
| | return (x + h).reshape(b, c, *spatial) |
| |
|
| |
|
| | class QKVAttentionLegacy(nn.Module): |
| | """ |
| | A module which performs QKV attention. Matches legacy QKVAttention + input/ouput heads shaping |
| | """ |
| |
|
| | def __init__(self, n_heads: int): |
| | super().__init__() |
| | self.n_heads = n_heads |
| |
|
| | def forward(self, qkv: th.Tensor) -> th.Tensor: |
| | """ |
| | Apply QKV attention. |
| | :param qkv: an [N x (H * 3 * C) x T] tensor of Qs, Ks, and Vs. |
| | :return: an [N x (H * C) x T] tensor after attention. |
| | """ |
| | bs, width, length = qkv.shape |
| | assert width % (3 * self.n_heads) == 0 |
| | ch = width // (3 * self.n_heads) |
| | q, k, v = qkv.reshape(bs * self.n_heads, ch * 3, length).split(ch, dim=1) |
| | scale = 1 / math.sqrt(math.sqrt(ch)) |
| | weight = th.einsum( |
| | "bct,bcs->bts", q * scale, k * scale |
| | ) |
| | weight = th.softmax(weight.float(), dim=-1).type(weight.dtype) |
| | a = th.einsum("bts,bcs->bct", weight, v) |
| | return a.reshape(bs, -1, length) |
| |
|
| |
|
| | class QKVAttention(nn.Module): |
| | """ |
| | A module which performs QKV attention and splits in a different order. |
| | """ |
| |
|
| | def __init__(self, n_heads: int): |
| | super().__init__() |
| | self.n_heads = n_heads |
| |
|
| | def forward(self, qkv: th.Tensor) -> th.Tensor: |
| | """ |
| | Apply QKV attention. |
| | :param qkv: an [N x (3 * H * C) x T] tensor of Qs, Ks, and Vs. |
| | :return: an [N x (H * C) x T] tensor after attention. |
| | """ |
| | bs, width, length = qkv.shape |
| | assert width % (3 * self.n_heads) == 0 |
| | ch = width // (3 * self.n_heads) |
| | q, k, v = qkv.chunk(3, dim=1) |
| | scale = 1 / math.sqrt(math.sqrt(ch)) |
| | weight = th.einsum( |
| | "bct,bcs->bts", |
| | (q * scale).view(bs * self.n_heads, ch, length), |
| | (k * scale).view(bs * self.n_heads, ch, length), |
| | ) |
| | weight = th.softmax(weight.float(), dim=-1).type(weight.dtype) |
| | a = th.einsum("bts,bcs->bct", weight, v.reshape(bs * self.n_heads, ch, length)) |
| | return a.reshape(bs, -1, length) |
| |
|
| |
|
| | class Timestep(nn.Module): |
| | def __init__(self, dim: int): |
| | super().__init__() |
| | self.dim = dim |
| |
|
| | def forward(self, t: th.Tensor) -> th.Tensor: |
| | return timestep_embedding(t, self.dim) |
| |
|
| |
|
| | class UNetModel(nn.Module): |
| | """ |
| | The full UNet model with attention and timestep embedding. |
| | :param in_channels: channels in the input Tensor. |
| | :param model_channels: base channel count for the model. |
| | :param out_channels: channels in the output Tensor. |
| | :param num_res_blocks: number of residual blocks per downsample. |
| | :param attention_resolutions: a collection of downsample rates at which |
| | attention will take place. May be a set, list, or tuple. |
| | For example, if this contains 4, then at 4x downsampling, attention |
| | will be used. |
| | :param dropout: the dropout probability. |
| | :param channel_mult: channel multiplier for each level of the UNet. |
| | :param conv_resample: if True, use learned convolutions for upsampling and |
| | downsampling. |
| | :param dims: determines if the signal is 1D, 2D, or 3D. |
| | :param num_classes: if specified (as an int), then this model will be |
| | class-conditional with `num_classes` classes. |
| | :param use_checkpoint: use gradient checkpointing to reduce memory usage. |
| | :param num_heads: the number of attention heads in each attention layer. |
| | :param num_heads_channels: if specified, ignore num_heads and instead use |
| | a fixed channel width per attention head. |
| | :param num_heads_upsample: works with num_heads to set a different number |
| | of heads for upsampling. Deprecated. |
| | :param use_scale_shift_norm: use a FiLM-like conditioning mechanism. |
| | :param resblock_updown: use residual blocks for up/downsampling. |
| | :param use_new_attention_order: use a different attention pattern for potentially |
| | increased efficiency. |
| | """ |
| |
|
| | def __init__( |
| | self, |
| | in_channels: int, |
| | model_channels: int, |
| | out_channels: int, |
| | num_res_blocks: int, |
| | attention_resolutions: int, |
| | dropout: float = 0.0, |
| | channel_mult: Union[List, Tuple] = (1, 2, 4, 8), |
| | conv_resample: bool = True, |
| | dims: int = 2, |
| | num_classes: Optional[Union[int, str]] = None, |
| | use_checkpoint: bool = False, |
| | num_heads: int = -1, |
| | num_head_channels: int = -1, |
| | num_heads_upsample: int = -1, |
| | use_scale_shift_norm: bool = False, |
| | resblock_updown: bool = False, |
| | transformer_depth: int = 1, |
| | context_dim: Optional[int] = None, |
| | disable_self_attentions: Optional[List[bool]] = None, |
| | num_attention_blocks: Optional[List[int]] = None, |
| | disable_middle_self_attn: bool = False, |
| | disable_middle_transformer: bool = False, |
| | use_linear_in_transformer: bool = False, |
| | spatial_transformer_attn_type: str = "softmax", |
| | adm_in_channels: Optional[int] = None, |
| | ): |
| | super().__init__() |
| |
|
| | if num_heads_upsample == -1: |
| | num_heads_upsample = num_heads |
| |
|
| | if num_heads == -1: |
| | assert ( |
| | num_head_channels != -1 |
| | ), "Either num_heads or num_head_channels has to be set" |
| |
|
| | if num_head_channels == -1: |
| | assert ( |
| | num_heads != -1 |
| | ), "Either num_heads or num_head_channels has to be set" |
| |
|
| | self.in_channels = in_channels |
| | self.model_channels = model_channels |
| | self.out_channels = out_channels |
| | if isinstance(transformer_depth, int): |
| | transformer_depth = len(channel_mult) * [transformer_depth] |
| | transformer_depth_middle = transformer_depth[-1] |
| |
|
| | if isinstance(num_res_blocks, int): |
| | self.num_res_blocks = len(channel_mult) * [num_res_blocks] |
| | else: |
| | if len(num_res_blocks) != len(channel_mult): |
| | raise ValueError( |
| | "provide num_res_blocks either as an int (globally constant) or " |
| | "as a list/tuple (per-level) with the same length as channel_mult" |
| | ) |
| | self.num_res_blocks = num_res_blocks |
| |
|
| | if disable_self_attentions is not None: |
| | assert len(disable_self_attentions) == len(channel_mult) |
| | if num_attention_blocks is not None: |
| | assert len(num_attention_blocks) == len(self.num_res_blocks) |
| | assert all( |
| | map( |
| | lambda i: self.num_res_blocks[i] >= num_attention_blocks[i], |
| | range(len(num_attention_blocks)), |
| | ) |
| | ) |
| | logpy.info( |
| | f"Constructor of UNetModel received num_attention_blocks={num_attention_blocks}. " |
| | f"This option has LESS priority than attention_resolutions {attention_resolutions}, " |
| | f"i.e., in cases where num_attention_blocks[i] > 0 but 2**i not in attention_resolutions, " |
| | f"attention will still not be set." |
| | ) |
| |
|
| | self.attention_resolutions = attention_resolutions |
| | self.dropout = dropout |
| | self.channel_mult = channel_mult |
| | self.conv_resample = conv_resample |
| | self.num_classes = num_classes |
| | self.use_checkpoint = use_checkpoint |
| | self.num_heads = num_heads |
| | self.num_head_channels = num_head_channels |
| | self.num_heads_upsample = num_heads_upsample |
| |
|
| | time_embed_dim = model_channels * 4 |
| | self.time_embed = nn.Sequential( |
| | linear(model_channels, time_embed_dim), |
| | nn.SiLU(), |
| | linear(time_embed_dim, time_embed_dim), |
| | ) |
| |
|
| | if self.num_classes is not None: |
| | if isinstance(self.num_classes, int): |
| | self.label_emb = nn.Embedding(num_classes, time_embed_dim) |
| | elif self.num_classes == "continuous": |
| | logpy.info("setting up linear c_adm embedding layer") |
| | self.label_emb = nn.Linear(1, time_embed_dim) |
| | elif self.num_classes == "timestep": |
| | self.label_emb = nn.Sequential( |
| | Timestep(model_channels), |
| | nn.Sequential( |
| | linear(model_channels, time_embed_dim), |
| | nn.SiLU(), |
| | linear(time_embed_dim, time_embed_dim), |
| | ), |
| | ) |
| | elif self.num_classes == "sequential": |
| | assert adm_in_channels is not None |
| | self.label_emb = nn.Sequential( |
| | nn.Sequential( |
| | linear(adm_in_channels, time_embed_dim), |
| | nn.SiLU(), |
| | linear(time_embed_dim, time_embed_dim), |
| | ) |
| | ) |
| | else: |
| | raise ValueError |
| |
|
| | self.input_blocks = nn.ModuleList( |
| | [ |
| | TimestepEmbedSequential( |
| | conv_nd(dims, in_channels, model_channels, 3, padding=1) |
| | ) |
| | ] |
| | ) |
| | self._feature_size = model_channels |
| | input_block_chans = [model_channels] |
| | ch = model_channels |
| | ds = 1 |
| | for level, mult in enumerate(channel_mult): |
| | for nr in range(self.num_res_blocks[level]): |
| | layers = [ |
| | ResBlock( |
| | ch, |
| | time_embed_dim, |
| | dropout, |
| | out_channels=mult * model_channels, |
| | dims=dims, |
| | use_checkpoint=use_checkpoint, |
| | use_scale_shift_norm=use_scale_shift_norm, |
| | ) |
| | ] |
| | ch = mult * model_channels |
| | if ds in attention_resolutions: |
| | if num_head_channels == -1: |
| | dim_head = ch // num_heads |
| | else: |
| | num_heads = ch // num_head_channels |
| | dim_head = num_head_channels |
| |
|
| | if context_dim is not None and exists(disable_self_attentions): |
| | disabled_sa = disable_self_attentions[level] |
| | else: |
| | disabled_sa = False |
| |
|
| | if ( |
| | not exists(num_attention_blocks) |
| | or nr < num_attention_blocks[level] |
| | ): |
| | layers.append( |
| | SpatialTransformer( |
| | ch, |
| | num_heads, |
| | dim_head, |
| | depth=transformer_depth[level], |
| | context_dim=context_dim, |
| | disable_self_attn=disabled_sa, |
| | use_linear=use_linear_in_transformer, |
| | attn_type=spatial_transformer_attn_type, |
| | use_checkpoint=use_checkpoint, |
| | ) |
| | ) |
| | self.input_blocks.append(TimestepEmbedSequential(*layers)) |
| | self._feature_size += ch |
| | input_block_chans.append(ch) |
| | if level != len(channel_mult) - 1: |
| | out_ch = ch |
| | self.input_blocks.append( |
| | TimestepEmbedSequential( |
| | ResBlock( |
| | ch, |
| | time_embed_dim, |
| | dropout, |
| | out_channels=out_ch, |
| | dims=dims, |
| | use_checkpoint=use_checkpoint, |
| | use_scale_shift_norm=use_scale_shift_norm, |
| | down=True, |
| | ) |
| | if resblock_updown |
| | else Downsample( |
| | ch, conv_resample, dims=dims, out_channels=out_ch |
| | ) |
| | ) |
| | ) |
| | ch = out_ch |
| | input_block_chans.append(ch) |
| | ds *= 2 |
| | self._feature_size += ch |
| |
|
| | if num_head_channels == -1: |
| | dim_head = ch // num_heads |
| | else: |
| | num_heads = ch // num_head_channels |
| | dim_head = num_head_channels |
| |
|
| | self.middle_block = TimestepEmbedSequential( |
| | ResBlock( |
| | ch, |
| | time_embed_dim, |
| | dropout, |
| | out_channels=ch, |
| | dims=dims, |
| | use_checkpoint=use_checkpoint, |
| | use_scale_shift_norm=use_scale_shift_norm, |
| | ), |
| | SpatialTransformer( |
| | ch, |
| | num_heads, |
| | dim_head, |
| | depth=transformer_depth_middle, |
| | context_dim=context_dim, |
| | disable_self_attn=disable_middle_self_attn, |
| | use_linear=use_linear_in_transformer, |
| | attn_type=spatial_transformer_attn_type, |
| | use_checkpoint=use_checkpoint, |
| | ) |
| | if not disable_middle_transformer |
| | else th.nn.Identity(), |
| | ResBlock( |
| | ch, |
| | time_embed_dim, |
| | dropout, |
| | dims=dims, |
| | use_checkpoint=use_checkpoint, |
| | use_scale_shift_norm=use_scale_shift_norm, |
| | ), |
| | ) |
| | self._feature_size += ch |
| |
|
| | self.output_blocks = nn.ModuleList([]) |
| | for level, mult in list(enumerate(channel_mult))[::-1]: |
| | for i in range(self.num_res_blocks[level] + 1): |
| | ich = input_block_chans.pop() |
| | layers = [ |
| | ResBlock( |
| | ch + ich, |
| | time_embed_dim, |
| | dropout, |
| | out_channels=model_channels * mult, |
| | dims=dims, |
| | use_checkpoint=use_checkpoint, |
| | use_scale_shift_norm=use_scale_shift_norm, |
| | ) |
| | ] |
| | ch = model_channels * mult |
| | if ds in attention_resolutions: |
| | if num_head_channels == -1: |
| | dim_head = ch // num_heads |
| | else: |
| | num_heads = ch // num_head_channels |
| | dim_head = num_head_channels |
| |
|
| | if exists(disable_self_attentions): |
| | disabled_sa = disable_self_attentions[level] |
| | else: |
| | disabled_sa = False |
| |
|
| | if ( |
| | not exists(num_attention_blocks) |
| | or i < num_attention_blocks[level] |
| | ): |
| | layers.append( |
| | SpatialTransformer( |
| | ch, |
| | num_heads, |
| | dim_head, |
| | depth=transformer_depth[level], |
| | context_dim=context_dim, |
| | disable_self_attn=disabled_sa, |
| | use_linear=use_linear_in_transformer, |
| | attn_type=spatial_transformer_attn_type, |
| | use_checkpoint=use_checkpoint, |
| | ) |
| | ) |
| | if level and i == self.num_res_blocks[level]: |
| | out_ch = ch |
| | layers.append( |
| | ResBlock( |
| | ch, |
| | time_embed_dim, |
| | dropout, |
| | out_channels=out_ch, |
| | dims=dims, |
| | use_checkpoint=use_checkpoint, |
| | use_scale_shift_norm=use_scale_shift_norm, |
| | up=True, |
| | ) |
| | if resblock_updown |
| | else Upsample(ch, conv_resample, dims=dims, out_channels=out_ch) |
| | ) |
| | ds //= 2 |
| | self.output_blocks.append(TimestepEmbedSequential(*layers)) |
| | self._feature_size += ch |
| |
|
| | self.out = nn.Sequential( |
| | normalization(ch), |
| | nn.SiLU(), |
| | zero_module(conv_nd(dims, model_channels, out_channels, 3, padding=1)), |
| | ) |
| |
|
| | def forward( |
| | self, |
| | x: th.Tensor, |
| | timesteps: Optional[th.Tensor] = None, |
| | context: Optional[th.Tensor] = None, |
| | y: Optional[th.Tensor] = None, |
| | **kwargs, |
| | ) -> th.Tensor: |
| | """ |
| | Apply the model to an input batch. |
| | :param x: an [N x C x ...] Tensor of inputs. |
| | :param timesteps: a 1-D batch of timesteps. |
| | :param context: conditioning plugged in via crossattn |
| | :param y: an [N] Tensor of labels, if class-conditional. |
| | :return: an [N x C x ...] Tensor of outputs. |
| | """ |
| | assert (y is not None) == ( |
| | self.num_classes is not None |
| | ), "must specify y if and only if the model is class-conditional" |
| | hs = [] |
| | t_emb = timestep_embedding(timesteps, self.model_channels, repeat_only=False) |
| | emb = self.time_embed(t_emb) |
| |
|
| | if self.num_classes is not None: |
| | assert y.shape[0] == x.shape[0] |
| | emb = emb + self.label_emb(y) |
| |
|
| | h = x |
| | for module in self.input_blocks: |
| | h = module(h, emb, context) |
| | hs.append(h) |
| | h = self.middle_block(h, emb, context) |
| | for module in self.output_blocks: |
| | h = th.cat([h, hs.pop()], dim=1) |
| | h = module(h, emb, context) |
| | h = h.type(x.dtype) |
| |
|
| | return self.out(h) |
| |
|
