import math from typing import Optional, Union import torch from torch import nn from ...configuration_utils import ConfigMixin, register_to_config from ...models import ModelMixin from ...models.attention import FeedForward from ...models.attention_processor import Attention from ...models.embeddings import TimestepEmbedding, Timesteps, get_2d_sincos_pos_embed from ...models.modeling_outputs import Transformer2DModelOutput from ...models.normalization import AdaLayerNorm from ...utils import logging logger = logging.get_logger(__name__) # pylint: disable=invalid-name def _no_grad_trunc_normal_(tensor, mean, std, a, b): # Cut & paste from PyTorch official master until it's in a few official releases - RW # Method based on https://people.sc.fsu.edu/~jburkardt/presentations/truncated_normal.pdf def norm_cdf(x): # Computes standard normal cumulative distribution function return (1.0 + math.erf(x / math.sqrt(2.0))) / 2.0 if (mean < a - 2 * std) or (mean > b + 2 * std): logger.warning( "mean is more than 2 std from [a, b] in nn.init.trunc_normal_. " "The distribution of values may be incorrect." ) with torch.no_grad(): # Values are generated by using a truncated uniform distribution and # then using the inverse CDF for the normal distribution. # Get upper and lower cdf values l = norm_cdf((a - mean) / std) u = norm_cdf((b - mean) / std) # Uniformly fill tensor with values from [l, u], then translate to # [2l-1, 2u-1]. tensor.uniform_(2 * l - 1, 2 * u - 1) # Use inverse cdf transform for normal distribution to get truncated # standard normal tensor.erfinv_() # Transform to proper mean, std tensor.mul_(std * math.sqrt(2.0)) tensor.add_(mean) # Clamp to ensure it's in the proper range tensor.clamp_(min=a, max=b) return tensor def trunc_normal_(tensor, mean=0.0, std=1.0, a=-2.0, b=2.0): # type: (torch.Tensor, float, float, float, float) -> torch.Tensor r"""Fills the input Tensor with values drawn from a truncated normal distribution. The values are effectively drawn from the normal distribution :math:`\mathcal{N}(\text{mean}, \text{std}^2)` with values outside :math:`[a, b]` redrawn until they are within the bounds. The method used for generating the random values works best when :math:`a \leq \text{mean} \leq b`. Args: tensor: an n-dimensional `torch.Tensor` mean: the mean of the normal distribution std: the standard deviation of the normal distribution a: the minimum cutoff value b: the maximum cutoff value Examples: >>> w = torch.empty(3, 5) >>> nn.init.trunc_normal_(w) """ return _no_grad_trunc_normal_(tensor, mean, std, a, b) class PatchEmbed(nn.Module): """2D Image to Patch Embedding""" def __init__( self, height=224, width=224, patch_size=16, in_channels=3, embed_dim=768, layer_norm=False, flatten=True, bias=True, use_pos_embed=True, ): super().__init__() num_patches = (height // patch_size) * (width // patch_size) self.flatten = flatten self.layer_norm = layer_norm self.proj = nn.Conv2d( in_channels, embed_dim, kernel_size=(patch_size, patch_size), stride=patch_size, bias=bias ) if layer_norm: self.norm = nn.LayerNorm(embed_dim, elementwise_affine=False, eps=1e-6) else: self.norm = None self.use_pos_embed = use_pos_embed if self.use_pos_embed: pos_embed = get_2d_sincos_pos_embed(embed_dim, int(num_patches**0.5)) self.register_buffer("pos_embed", torch.from_numpy(pos_embed).float().unsqueeze(0), persistent=False) def forward(self, latent): latent = self.proj(latent) if self.flatten: latent = latent.flatten(2).transpose(1, 2) # BCHW -> BNC if self.layer_norm: latent = self.norm(latent) if self.use_pos_embed: return latent + self.pos_embed else: return latent class SkipBlock(nn.Module): def __init__(self, dim: int): super().__init__() self.skip_linear = nn.Linear(2 * dim, dim) # Use torch.nn.LayerNorm for now, following the original code self.norm = nn.LayerNorm(dim) def forward(self, x, skip): x = self.skip_linear(torch.cat([x, skip], dim=-1)) x = self.norm(x) return x # Modified to support both pre-LayerNorm and post-LayerNorm configurations # Don't support AdaLayerNormZero for now # Modified from diffusers.models.attention.BasicTransformerBlock class UTransformerBlock(nn.Module): r""" A modification of BasicTransformerBlock which supports pre-LayerNorm and post-LayerNorm configurations. Parameters: dim (`int`): The number of channels in the input and output. num_attention_heads (`int`): The number of heads to use for multi-head attention. attention_head_dim (`int`): The number of channels in each head. dropout (`float`, *optional*, defaults to 0.0): The dropout probability to use. cross_attention_dim (`int`, *optional*): The size of the encoder_hidden_states vector for cross attention. activation_fn (`str`, *optional*, defaults to `"geglu"`): Activation function to be used in feed-forward. num_embeds_ada_norm (:obj: `int`, *optional*): The number of diffusion steps used during training. See `Transformer2DModel`. attention_bias (:obj: `bool`, *optional*, defaults to `False`): Configure if the attentions should contain a bias parameter. only_cross_attention (`bool`, *optional*): Whether to use only cross-attention layers. In this case two cross attention layers are used. double_self_attention (`bool`, *optional*): Whether to use two self-attention layers. In this case no cross attention layers are used. upcast_attention (`bool`, *optional*): Whether to upcast the query and key to float32 when performing the attention calculation. norm_elementwise_affine (`bool`, *optional*): Whether to use learnable per-element affine parameters during layer normalization. norm_type (`str`, defaults to `"layer_norm"`): The layer norm implementation to use. pre_layer_norm (`bool`, *optional*): Whether to perform layer normalization before the attention and feedforward operations ("pre-LayerNorm"), as opposed to after ("post-LayerNorm"). Note that `BasicTransformerBlock` uses pre-LayerNorm, e.g. `pre_layer_norm = True`. final_dropout (`bool`, *optional*): Whether to use a final Dropout layer after the feedforward network. """ def __init__( self, dim: int, num_attention_heads: int, attention_head_dim: int, dropout=0.0, cross_attention_dim: Optional[int] = None, activation_fn: str = "geglu", num_embeds_ada_norm: Optional[int] = None, attention_bias: bool = False, only_cross_attention: bool = False, double_self_attention: bool = False, upcast_attention: bool = False, norm_elementwise_affine: bool = True, norm_type: str = "layer_norm", pre_layer_norm: bool = True, final_dropout: bool = False, ): super().__init__() self.only_cross_attention = only_cross_attention self.use_ada_layer_norm = (num_embeds_ada_norm is not None) and norm_type == "ada_norm" self.pre_layer_norm = pre_layer_norm if norm_type in ("ada_norm", "ada_norm_zero") and num_embeds_ada_norm is None: raise ValueError( f"`norm_type` is set to {norm_type}, but `num_embeds_ada_norm` is not defined. Please make sure to" f" define `num_embeds_ada_norm` if setting `norm_type` to {norm_type}." ) # 1. Self-Attn self.attn1 = Attention( query_dim=dim, heads=num_attention_heads, dim_head=attention_head_dim, dropout=dropout, bias=attention_bias, cross_attention_dim=cross_attention_dim if only_cross_attention else None, upcast_attention=upcast_attention, ) # 2. Cross-Attn if cross_attention_dim is not None or double_self_attention: self.attn2 = Attention( query_dim=dim, cross_attention_dim=cross_attention_dim if not double_self_attention else None, heads=num_attention_heads, dim_head=attention_head_dim, dropout=dropout, bias=attention_bias, upcast_attention=upcast_attention, ) # is self-attn if encoder_hidden_states is none else: self.attn2 = None if self.use_ada_layer_norm: self.norm1 = AdaLayerNorm(dim, num_embeds_ada_norm) else: self.norm1 = nn.LayerNorm(dim, elementwise_affine=norm_elementwise_affine) if cross_attention_dim is not None or double_self_attention: # We currently only use AdaLayerNormZero for self attention where there will only be one attention block. # I.e. the number of returned modulation chunks from AdaLayerZero would not make sense if returned during # the second cross attention block. self.norm2 = ( AdaLayerNorm(dim, num_embeds_ada_norm) if self.use_ada_layer_norm else nn.LayerNorm(dim, elementwise_affine=norm_elementwise_affine) ) else: self.norm2 = None # 3. Feed-forward self.norm3 = nn.LayerNorm(dim, elementwise_affine=norm_elementwise_affine) self.ff = FeedForward(dim, dropout=dropout, activation_fn=activation_fn, final_dropout=final_dropout) def forward( self, hidden_states, attention_mask=None, encoder_hidden_states=None, encoder_attention_mask=None, timestep=None, cross_attention_kwargs=None, class_labels=None, ): # Pre-LayerNorm if self.pre_layer_norm: if self.use_ada_layer_norm: norm_hidden_states = self.norm1(hidden_states, timestep) else: norm_hidden_states = self.norm1(hidden_states) else: norm_hidden_states = hidden_states # 1. Self-Attention cross_attention_kwargs = cross_attention_kwargs if cross_attention_kwargs is not None else {} attn_output = self.attn1( norm_hidden_states, encoder_hidden_states=encoder_hidden_states if self.only_cross_attention else None, attention_mask=attention_mask, **cross_attention_kwargs, ) # Post-LayerNorm if not self.pre_layer_norm: if self.use_ada_layer_norm: attn_output = self.norm1(attn_output, timestep) else: attn_output = self.norm1(attn_output) hidden_states = attn_output + hidden_states if self.attn2 is not None: # Pre-LayerNorm if self.pre_layer_norm: norm_hidden_states = ( self.norm2(hidden_states, timestep) if self.use_ada_layer_norm else self.norm2(hidden_states) ) else: norm_hidden_states = hidden_states # TODO (Birch-San): Here we should prepare the encoder_attention mask correctly # prepare attention mask here # 2. Cross-Attention attn_output = self.attn2( norm_hidden_states, encoder_hidden_states=encoder_hidden_states, attention_mask=encoder_attention_mask, **cross_attention_kwargs, ) # Post-LayerNorm if not self.pre_layer_norm: attn_output = self.norm2(attn_output, timestep) if self.use_ada_layer_norm else self.norm2(attn_output) hidden_states = attn_output + hidden_states # 3. Feed-forward # Pre-LayerNorm if self.pre_layer_norm: norm_hidden_states = self.norm3(hidden_states) else: norm_hidden_states = hidden_states ff_output = self.ff(norm_hidden_states) # Post-LayerNorm if not self.pre_layer_norm: ff_output = self.norm3(ff_output) hidden_states = ff_output + hidden_states return hidden_states # Like UTransformerBlock except with LayerNorms on the residual backbone of the block # Modified from diffusers.models.attention.BasicTransformerBlock class UniDiffuserBlock(nn.Module): r""" A modification of BasicTransformerBlock which supports pre-LayerNorm and post-LayerNorm configurations and puts the LayerNorms on the residual backbone of the block. This matches the transformer block in the [original UniDiffuser implementation](https://github.com/thu-ml/unidiffuser/blob/main/libs/uvit_multi_post_ln_v1.py#L104). Parameters: dim (`int`): The number of channels in the input and output. num_attention_heads (`int`): The number of heads to use for multi-head attention. attention_head_dim (`int`): The number of channels in each head. dropout (`float`, *optional*, defaults to 0.0): The dropout probability to use. cross_attention_dim (`int`, *optional*): The size of the encoder_hidden_states vector for cross attention. activation_fn (`str`, *optional*, defaults to `"geglu"`): Activation function to be used in feed-forward. num_embeds_ada_norm (:obj: `int`, *optional*): The number of diffusion steps used during training. See `Transformer2DModel`. attention_bias (:obj: `bool`, *optional*, defaults to `False`): Configure if the attentions should contain a bias parameter. only_cross_attention (`bool`, *optional*): Whether to use only cross-attention layers. In this case two cross attention layers are used. double_self_attention (`bool`, *optional*): Whether to use two self-attention layers. In this case no cross attention layers are used. upcast_attention (`bool`, *optional*): Whether to upcast the query and key to float() when performing the attention calculation. norm_elementwise_affine (`bool`, *optional*): Whether to use learnable per-element affine parameters during layer normalization. norm_type (`str`, defaults to `"layer_norm"`): The layer norm implementation to use. pre_layer_norm (`bool`, *optional*): Whether to perform layer normalization before the attention and feedforward operations ("pre-LayerNorm"), as opposed to after ("post-LayerNorm"). The original UniDiffuser implementation is post-LayerNorm (`pre_layer_norm = False`). final_dropout (`bool`, *optional*): Whether to use a final Dropout layer after the feedforward network. """ def __init__( self, dim: int, num_attention_heads: int, attention_head_dim: int, dropout=0.0, cross_attention_dim: Optional[int] = None, activation_fn: str = "geglu", num_embeds_ada_norm: Optional[int] = None, attention_bias: bool = False, only_cross_attention: bool = False, double_self_attention: bool = False, upcast_attention: bool = False, norm_elementwise_affine: bool = True, norm_type: str = "layer_norm", pre_layer_norm: bool = False, final_dropout: bool = True, ): super().__init__() self.only_cross_attention = only_cross_attention self.use_ada_layer_norm = (num_embeds_ada_norm is not None) and norm_type == "ada_norm" self.pre_layer_norm = pre_layer_norm if norm_type in ("ada_norm", "ada_norm_zero") and num_embeds_ada_norm is None: raise ValueError( f"`norm_type` is set to {norm_type}, but `num_embeds_ada_norm` is not defined. Please make sure to" f" define `num_embeds_ada_norm` if setting `norm_type` to {norm_type}." ) # 1. Self-Attn self.attn1 = Attention( query_dim=dim, heads=num_attention_heads, dim_head=attention_head_dim, dropout=dropout, bias=attention_bias, cross_attention_dim=cross_attention_dim if only_cross_attention else None, upcast_attention=upcast_attention, ) # 2. Cross-Attn if cross_attention_dim is not None or double_self_attention: self.attn2 = Attention( query_dim=dim, cross_attention_dim=cross_attention_dim if not double_self_attention else None, heads=num_attention_heads, dim_head=attention_head_dim, dropout=dropout, bias=attention_bias, upcast_attention=upcast_attention, ) # is self-attn if encoder_hidden_states is none else: self.attn2 = None if self.use_ada_layer_norm: self.norm1 = AdaLayerNorm(dim, num_embeds_ada_norm) else: self.norm1 = nn.LayerNorm(dim, elementwise_affine=norm_elementwise_affine) if cross_attention_dim is not None or double_self_attention: # We currently only use AdaLayerNormZero for self attention where there will only be one attention block. # I.e. the number of returned modulation chunks from AdaLayerZero would not make sense if returned during # the second cross attention block. self.norm2 = ( AdaLayerNorm(dim, num_embeds_ada_norm) if self.use_ada_layer_norm else nn.LayerNorm(dim, elementwise_affine=norm_elementwise_affine) ) else: self.norm2 = None # 3. Feed-forward self.norm3 = nn.LayerNorm(dim, elementwise_affine=norm_elementwise_affine) self.ff = FeedForward(dim, dropout=dropout, activation_fn=activation_fn, final_dropout=final_dropout) def forward( self, hidden_states, attention_mask=None, encoder_hidden_states=None, encoder_attention_mask=None, timestep=None, cross_attention_kwargs=None, class_labels=None, ): # Following the diffusers transformer block implementation, put the LayerNorm on the # residual backbone # Pre-LayerNorm if self.pre_layer_norm: if self.use_ada_layer_norm: hidden_states = self.norm1(hidden_states, timestep) else: hidden_states = self.norm1(hidden_states) # 1. Self-Attention cross_attention_kwargs = cross_attention_kwargs if cross_attention_kwargs is not None else {} attn_output = self.attn1( hidden_states, encoder_hidden_states=encoder_hidden_states if self.only_cross_attention else None, attention_mask=attention_mask, **cross_attention_kwargs, ) hidden_states = attn_output + hidden_states # Following the diffusers transformer block implementation, put the LayerNorm on the # residual backbone # Post-LayerNorm if not self.pre_layer_norm: if self.use_ada_layer_norm: hidden_states = self.norm1(hidden_states, timestep) else: hidden_states = self.norm1(hidden_states) if self.attn2 is not None: # Pre-LayerNorm if self.pre_layer_norm: hidden_states = ( self.norm2(hidden_states, timestep) if self.use_ada_layer_norm else self.norm2(hidden_states) ) # TODO (Birch-San): Here we should prepare the encoder_attention mask correctly # prepare attention mask here # 2. Cross-Attention attn_output = self.attn2( hidden_states, encoder_hidden_states=encoder_hidden_states, attention_mask=encoder_attention_mask, **cross_attention_kwargs, ) hidden_states = attn_output + hidden_states # Post-LayerNorm if not self.pre_layer_norm: hidden_states = ( self.norm2(hidden_states, timestep) if self.use_ada_layer_norm else self.norm2(hidden_states) ) # 3. Feed-forward # Pre-LayerNorm if self.pre_layer_norm: hidden_states = self.norm3(hidden_states) ff_output = self.ff(hidden_states) hidden_states = ff_output + hidden_states # Post-LayerNorm if not self.pre_layer_norm: hidden_states = self.norm3(hidden_states) return hidden_states # Modified from diffusers.models.transformer_2d.Transformer2DModel # Modify the transformer block structure to be U-Net like following U-ViT # Only supports patch-style input and torch.nn.LayerNorm currently # https://github.com/baofff/U-ViT class UTransformer2DModel(ModelMixin, ConfigMixin): """ Transformer model based on the [U-ViT](https://github.com/baofff/U-ViT) architecture for image-like data. Compared to [`Transformer2DModel`], this model has skip connections between transformer blocks in a "U"-shaped fashion, similar to a U-Net. Supports only continuous (actual embeddings) inputs, which are embedded via a [`PatchEmbed`] layer and then reshaped to (b, t, d). Parameters: num_attention_heads (`int`, *optional*, defaults to 16): The number of heads to use for multi-head attention. attention_head_dim (`int`, *optional*, defaults to 88): The number of channels in each head. in_channels (`int`, *optional*): Pass if the input is continuous. The number of channels in the input. out_channels (`int`, *optional*): The number of output channels; if `None`, defaults to `in_channels`. num_layers (`int`, *optional*, defaults to 1): The number of layers of Transformer blocks to use. dropout (`float`, *optional*, defaults to 0.0): The dropout probability to use. norm_num_groups (`int`, *optional*, defaults to `32`): The number of groups to use when performing Group Normalization. cross_attention_dim (`int`, *optional*): The number of encoder_hidden_states dimensions to use. attention_bias (`bool`, *optional*): Configure if the TransformerBlocks' attention should contain a bias parameter. sample_size (`int`, *optional*): Pass if the input is discrete. The width of the latent images. Note that this is fixed at training time as it is used for learning a number of position embeddings. See `ImagePositionalEmbeddings`. num_vector_embeds (`int`, *optional*): Pass if the input is discrete. The number of classes of the vector embeddings of the latent pixels. Includes the class for the masked latent pixel. patch_size (`int`, *optional*, defaults to 2): The patch size to use in the patch embedding. activation_fn (`str`, *optional*, defaults to `"geglu"`): Activation function to be used in feed-forward. num_embeds_ada_norm ( `int`, *optional*): Pass if at least one of the norm_layers is `AdaLayerNorm`. The number of diffusion steps used during training. Note that this is fixed at training time as it is used to learn a number of embeddings that are added to the hidden states. During inference, you can denoise for up to but not more than steps than `num_embeds_ada_norm`. use_linear_projection (int, *optional*): TODO: Not used only_cross_attention (`bool`, *optional*): Whether to use only cross-attention layers. In this case two cross attention layers are used in each transformer block. upcast_attention (`bool`, *optional*): Whether to upcast the query and key to float() when performing the attention calculation. norm_type (`str`, *optional*, defaults to `"layer_norm"`): The Layer Normalization implementation to use. Defaults to `torch.nn.LayerNorm`. block_type (`str`, *optional*, defaults to `"unidiffuser"`): The transformer block implementation to use. If `"unidiffuser"`, has the LayerNorms on the residual backbone of each transformer block; otherwise has them in the attention/feedforward branches (the standard behavior in `diffusers`.) pre_layer_norm (`bool`, *optional*): Whether to perform layer normalization before the attention and feedforward operations ("pre-LayerNorm"), as opposed to after ("post-LayerNorm"). The original UniDiffuser implementation is post-LayerNorm (`pre_layer_norm = False`). norm_elementwise_affine (`bool`, *optional*): Whether to use learnable per-element affine parameters during layer normalization. use_patch_pos_embed (`bool`, *optional*): Whether to use position embeddings inside the patch embedding layer (`PatchEmbed`). final_dropout (`bool`, *optional*): Whether to use a final Dropout layer after the feedforward network. """ @register_to_config def __init__( self, num_attention_heads: int = 16, attention_head_dim: int = 88, in_channels: Optional[int] = None, out_channels: Optional[int] = None, num_layers: int = 1, dropout: float = 0.0, norm_num_groups: int = 32, cross_attention_dim: Optional[int] = None, attention_bias: bool = False, sample_size: Optional[int] = None, num_vector_embeds: Optional[int] = None, patch_size: Optional[int] = 2, activation_fn: str = "geglu", num_embeds_ada_norm: Optional[int] = None, use_linear_projection: bool = False, only_cross_attention: bool = False, upcast_attention: bool = False, norm_type: str = "layer_norm", block_type: str = "unidiffuser", pre_layer_norm: bool = False, norm_elementwise_affine: bool = True, use_patch_pos_embed=False, ff_final_dropout: bool = False, ): super().__init__() self.use_linear_projection = use_linear_projection self.num_attention_heads = num_attention_heads self.attention_head_dim = attention_head_dim inner_dim = num_attention_heads * attention_head_dim # 1. Input # Only support patch input of shape (batch_size, num_channels, height, width) for now assert in_channels is not None and patch_size is not None, "Patch input requires in_channels and patch_size." assert sample_size is not None, "UTransformer2DModel over patched input must provide sample_size" # 2. Define input layers self.height = sample_size self.width = sample_size self.patch_size = patch_size self.pos_embed = PatchEmbed( height=sample_size, width=sample_size, patch_size=patch_size, in_channels=in_channels, embed_dim=inner_dim, use_pos_embed=use_patch_pos_embed, ) # 3. Define transformers blocks # Modify this to have in_blocks ("downsample" blocks, even though we don't actually downsample), a mid_block, # and out_blocks ("upsample" blocks). Like a U-Net, there are skip connections from in_blocks to out_blocks in # a "U"-shaped fashion (e.g. first in_block to last out_block, etc.). # Quick hack to make the transformer block type configurable if block_type == "unidiffuser": block_cls = UniDiffuserBlock else: block_cls = UTransformerBlock self.transformer_in_blocks = nn.ModuleList( [ block_cls( inner_dim, num_attention_heads, attention_head_dim, dropout=dropout, cross_attention_dim=cross_attention_dim, activation_fn=activation_fn, num_embeds_ada_norm=num_embeds_ada_norm, attention_bias=attention_bias, only_cross_attention=only_cross_attention, upcast_attention=upcast_attention, norm_type=norm_type, pre_layer_norm=pre_layer_norm, norm_elementwise_affine=norm_elementwise_affine, final_dropout=ff_final_dropout, ) for d in range(num_layers // 2) ] ) self.transformer_mid_block = block_cls( inner_dim, num_attention_heads, attention_head_dim, dropout=dropout, cross_attention_dim=cross_attention_dim, activation_fn=activation_fn, num_embeds_ada_norm=num_embeds_ada_norm, attention_bias=attention_bias, only_cross_attention=only_cross_attention, upcast_attention=upcast_attention, norm_type=norm_type, pre_layer_norm=pre_layer_norm, norm_elementwise_affine=norm_elementwise_affine, final_dropout=ff_final_dropout, ) # For each skip connection, we use a SkipBlock (concatenation + Linear + LayerNorm) to process the inputs # before each transformer out_block. self.transformer_out_blocks = nn.ModuleList( [ nn.ModuleDict( { "skip": SkipBlock( inner_dim, ), "block": block_cls( inner_dim, num_attention_heads, attention_head_dim, dropout=dropout, cross_attention_dim=cross_attention_dim, activation_fn=activation_fn, num_embeds_ada_norm=num_embeds_ada_norm, attention_bias=attention_bias, only_cross_attention=only_cross_attention, upcast_attention=upcast_attention, norm_type=norm_type, pre_layer_norm=pre_layer_norm, norm_elementwise_affine=norm_elementwise_affine, final_dropout=ff_final_dropout, ), } ) for d in range(num_layers // 2) ] ) # 4. Define output layers self.out_channels = in_channels if out_channels is None else out_channels # Following the UniDiffuser U-ViT implementation, we process the transformer output with # a LayerNorm layer with per-element affine params self.norm_out = nn.LayerNorm(inner_dim) def forward( self, hidden_states, encoder_hidden_states=None, timestep=None, class_labels=None, cross_attention_kwargs=None, return_dict: bool = True, hidden_states_is_embedding: bool = False, unpatchify: bool = True, ): """ Args: hidden_states ( When discrete, `torch.LongTensor` of shape `(batch size, num latent pixels)`. When continuous, `torch.Tensor` of shape `(batch size, channel, height, width)`): Input hidden_states encoder_hidden_states ( `torch.LongTensor` of shape `(batch size, encoder_hidden_states dim)`, *optional*): Conditional embeddings for cross attention layer. If not given, cross-attention defaults to self-attention. timestep ( `torch.long`, *optional*): Optional timestep to be applied as an embedding in AdaLayerNorm's. Used to indicate denoising step. class_labels ( `torch.LongTensor` of shape `(batch size, num classes)`, *optional*): Optional class labels to be applied as an embedding in AdaLayerZeroNorm. Used to indicate class labels conditioning. cross_attention_kwargs (*optional*): Keyword arguments to supply to the cross attention layers, if used. return_dict (`bool`, *optional*, defaults to `True`): Whether or not to return a [`models.unets.unet_2d_condition.UNet2DConditionOutput`] instead of a plain tuple. hidden_states_is_embedding (`bool`, *optional*, defaults to `False`): Whether or not hidden_states is an embedding directly usable by the transformer. In this case we will ignore input handling (e.g. continuous, vectorized, etc.) and directly feed hidden_states into the transformer blocks. unpatchify (`bool`, *optional*, defaults to `True`): Whether to unpatchify the transformer output. Returns: [`~models.transformer_2d.Transformer2DModelOutput`] or `tuple`: [`~models.transformer_2d.Transformer2DModelOutput`] if `return_dict` is True, otherwise a `tuple`. When returning a tuple, the first element is the sample tensor. """ # 0. Check inputs if not unpatchify and return_dict: raise ValueError( f"Cannot both define `unpatchify`: {unpatchify} and `return_dict`: {return_dict} since when" f" `unpatchify` is {unpatchify} the returned output is of shape (batch_size, seq_len, hidden_dim)" " rather than (batch_size, num_channels, height, width)." ) # 1. Input if not hidden_states_is_embedding: hidden_states = self.pos_embed(hidden_states) # 2. Blocks # In ("downsample") blocks skips = [] for in_block in self.transformer_in_blocks: hidden_states = in_block( hidden_states, encoder_hidden_states=encoder_hidden_states, timestep=timestep, cross_attention_kwargs=cross_attention_kwargs, class_labels=class_labels, ) skips.append(hidden_states) # Mid block hidden_states = self.transformer_mid_block(hidden_states) # Out ("upsample") blocks for out_block in self.transformer_out_blocks: hidden_states = out_block["skip"](hidden_states, skips.pop()) hidden_states = out_block["block"]( hidden_states, encoder_hidden_states=encoder_hidden_states, timestep=timestep, cross_attention_kwargs=cross_attention_kwargs, class_labels=class_labels, ) # 3. Output # Don't support AdaLayerNorm for now, so no conditioning/scale/shift logic hidden_states = self.norm_out(hidden_states) # hidden_states = self.proj_out(hidden_states) if unpatchify: # unpatchify height = width = int(hidden_states.shape[1] ** 0.5) hidden_states = hidden_states.reshape( shape=(-1, height, width, self.patch_size, self.patch_size, self.out_channels) ) hidden_states = torch.einsum("nhwpqc->nchpwq", hidden_states) output = hidden_states.reshape( shape=(-1, self.out_channels, height * self.patch_size, width * self.patch_size) ) else: output = hidden_states if not return_dict: return (output,) return Transformer2DModelOutput(sample=output) class UniDiffuserModel(ModelMixin, ConfigMixin): """ Transformer model for a image-text [UniDiffuser](https://arxiv.org/pdf/2303.06555.pdf) model. This is a modification of [`UTransformer2DModel`] with input and output heads for the VAE-embedded latent image, the CLIP-embedded image, and the CLIP-embedded prompt (see paper for more details). Parameters: text_dim (`int`): The hidden dimension of the CLIP text model used to embed images. clip_img_dim (`int`): The hidden dimension of the CLIP vision model used to embed prompts. num_attention_heads (`int`, *optional*, defaults to 16): The number of heads to use for multi-head attention. attention_head_dim (`int`, *optional*, defaults to 88): The number of channels in each head. in_channels (`int`, *optional*): Pass if the input is continuous. The number of channels in the input. out_channels (`int`, *optional*): The number of output channels; if `None`, defaults to `in_channels`. num_layers (`int`, *optional*, defaults to 1): The number of layers of Transformer blocks to use. dropout (`float`, *optional*, defaults to 0.0): The dropout probability to use. norm_num_groups (`int`, *optional*, defaults to `32`): The number of groups to use when performing Group Normalization. cross_attention_dim (`int`, *optional*): The number of encoder_hidden_states dimensions to use. attention_bias (`bool`, *optional*): Configure if the TransformerBlocks' attention should contain a bias parameter. sample_size (`int`, *optional*): Pass if the input is discrete. The width of the latent images. Note that this is fixed at training time as it is used for learning a number of position embeddings. See `ImagePositionalEmbeddings`. num_vector_embeds (`int`, *optional*): Pass if the input is discrete. The number of classes of the vector embeddings of the latent pixels. Includes the class for the masked latent pixel. patch_size (`int`, *optional*, defaults to 2): The patch size to use in the patch embedding. activation_fn (`str`, *optional*, defaults to `"geglu"`): Activation function to be used in feed-forward. num_embeds_ada_norm ( `int`, *optional*): Pass if at least one of the norm_layers is `AdaLayerNorm`. The number of diffusion steps used during training. Note that this is fixed at training time as it is used to learn a number of embeddings that are added to the hidden states. During inference, you can denoise for up to but not more than steps than `num_embeds_ada_norm`. use_linear_projection (int, *optional*): TODO: Not used only_cross_attention (`bool`, *optional*): Whether to use only cross-attention layers. In this case two cross attention layers are used in each transformer block. upcast_attention (`bool`, *optional*): Whether to upcast the query and key to float32 when performing the attention calculation. norm_type (`str`, *optional*, defaults to `"layer_norm"`): The Layer Normalization implementation to use. Defaults to `torch.nn.LayerNorm`. block_type (`str`, *optional*, defaults to `"unidiffuser"`): The transformer block implementation to use. If `"unidiffuser"`, has the LayerNorms on the residual backbone of each transformer block; otherwise has them in the attention/feedforward branches (the standard behavior in `diffusers`.) pre_layer_norm (`bool`, *optional*): Whether to perform layer normalization before the attention and feedforward operations ("pre-LayerNorm"), as opposed to after ("post-LayerNorm"). The original UniDiffuser implementation is post-LayerNorm (`pre_layer_norm = False`). norm_elementwise_affine (`bool`, *optional*): Whether to use learnable per-element affine parameters during layer normalization. use_patch_pos_embed (`bool`, *optional*): Whether to use position embeddings inside the patch embedding layer (`PatchEmbed`). ff_final_dropout (`bool`, *optional*): Whether to use a final Dropout layer after the feedforward network. use_data_type_embedding (`bool`, *optional*): Whether to use a data type embedding. This is only relevant for UniDiffuser-v1 style models; UniDiffuser-v1 is continue-trained from UniDiffuser-v0 on non-publically-available data and accepts a `data_type` argument, which can either be `1` to use the weights trained on non-publically-available data or `0` otherwise. This argument is subsequently embedded by the data type embedding, if used. """ @register_to_config def __init__( self, text_dim: int = 768, clip_img_dim: int = 512, num_text_tokens: int = 77, num_attention_heads: int = 16, attention_head_dim: int = 88, in_channels: Optional[int] = None, out_channels: Optional[int] = None, num_layers: int = 1, dropout: float = 0.0, norm_num_groups: int = 32, cross_attention_dim: Optional[int] = None, attention_bias: bool = False, sample_size: Optional[int] = None, num_vector_embeds: Optional[int] = None, patch_size: Optional[int] = None, activation_fn: str = "geglu", num_embeds_ada_norm: Optional[int] = None, use_linear_projection: bool = False, only_cross_attention: bool = False, upcast_attention: bool = False, norm_type: str = "layer_norm", block_type: str = "unidiffuser", pre_layer_norm: bool = False, use_timestep_embedding=False, norm_elementwise_affine: bool = True, use_patch_pos_embed=False, ff_final_dropout: bool = True, use_data_type_embedding: bool = False, ): super().__init__() # 0. Handle dimensions self.inner_dim = num_attention_heads * attention_head_dim assert sample_size is not None, "UniDiffuserModel over patched input must provide sample_size" self.sample_size = sample_size self.in_channels = in_channels self.out_channels = in_channels if out_channels is None else out_channels self.patch_size = patch_size # Assume image is square... self.num_patches = (self.sample_size // patch_size) * (self.sample_size // patch_size) # 1. Define input layers # 1.1 Input layers for text and image input # For now, only support patch input for VAE latent image input self.vae_img_in = PatchEmbed( height=sample_size, width=sample_size, patch_size=patch_size, in_channels=in_channels, embed_dim=self.inner_dim, use_pos_embed=use_patch_pos_embed, ) self.clip_img_in = nn.Linear(clip_img_dim, self.inner_dim) self.text_in = nn.Linear(text_dim, self.inner_dim) # 1.2. Timestep embeddings for t_img, t_text self.timestep_img_proj = Timesteps( self.inner_dim, flip_sin_to_cos=True, downscale_freq_shift=0, ) self.timestep_img_embed = ( TimestepEmbedding( self.inner_dim, 4 * self.inner_dim, out_dim=self.inner_dim, ) if use_timestep_embedding else nn.Identity() ) self.timestep_text_proj = Timesteps( self.inner_dim, flip_sin_to_cos=True, downscale_freq_shift=0, ) self.timestep_text_embed = ( TimestepEmbedding( self.inner_dim, 4 * self.inner_dim, out_dim=self.inner_dim, ) if use_timestep_embedding else nn.Identity() ) # 1.3. Positional embedding self.num_text_tokens = num_text_tokens self.num_tokens = 1 + 1 + num_text_tokens + 1 + self.num_patches self.pos_embed = nn.Parameter(torch.zeros(1, self.num_tokens, self.inner_dim)) self.pos_embed_drop = nn.Dropout(p=dropout) trunc_normal_(self.pos_embed, std=0.02) # 1.4. Handle data type token embeddings for UniDiffuser-V1, if necessary self.use_data_type_embedding = use_data_type_embedding if self.use_data_type_embedding: self.data_type_token_embedding = nn.Embedding(2, self.inner_dim) self.data_type_pos_embed_token = nn.Parameter(torch.zeros(1, 1, self.inner_dim)) # 2. Define transformer blocks self.transformer = UTransformer2DModel( num_attention_heads=num_attention_heads, attention_head_dim=attention_head_dim, in_channels=in_channels, out_channels=out_channels, num_layers=num_layers, dropout=dropout, norm_num_groups=norm_num_groups, cross_attention_dim=cross_attention_dim, attention_bias=attention_bias, sample_size=sample_size, num_vector_embeds=num_vector_embeds, patch_size=patch_size, activation_fn=activation_fn, num_embeds_ada_norm=num_embeds_ada_norm, use_linear_projection=use_linear_projection, only_cross_attention=only_cross_attention, upcast_attention=upcast_attention, norm_type=norm_type, block_type=block_type, pre_layer_norm=pre_layer_norm, norm_elementwise_affine=norm_elementwise_affine, use_patch_pos_embed=use_patch_pos_embed, ff_final_dropout=ff_final_dropout, ) # 3. Define output layers patch_dim = (patch_size**2) * out_channels self.vae_img_out = nn.Linear(self.inner_dim, patch_dim) self.clip_img_out = nn.Linear(self.inner_dim, clip_img_dim) self.text_out = nn.Linear(self.inner_dim, text_dim) @torch.jit.ignore def no_weight_decay(self): return {"pos_embed"} def forward( self, latent_image_embeds: torch.Tensor, image_embeds: torch.Tensor, prompt_embeds: torch.Tensor, timestep_img: Union[torch.Tensor, float, int], timestep_text: Union[torch.Tensor, float, int], data_type: Optional[Union[torch.Tensor, float, int]] = 1, encoder_hidden_states=None, cross_attention_kwargs=None, ): """ Args: latent_image_embeds (`torch.Tensor` of shape `(batch size, latent channels, height, width)`): Latent image representation from the VAE encoder. image_embeds (`torch.Tensor` of shape `(batch size, 1, clip_img_dim)`): CLIP-embedded image representation (unsqueezed in the first dimension). prompt_embeds (`torch.Tensor` of shape `(batch size, seq_len, text_dim)`): CLIP-embedded text representation. timestep_img (`torch.long` or `float` or `int`): Current denoising step for the image. timestep_text (`torch.long` or `float` or `int`): Current denoising step for the text. data_type: (`torch.int` or `float` or `int`, *optional*, defaults to `1`): Only used in UniDiffuser-v1-style models. Can be either `1`, to use weights trained on nonpublic data, or `0` otherwise. encoder_hidden_states ( `torch.LongTensor` of shape `(batch size, encoder_hidden_states dim)`, *optional*): Conditional embeddings for cross attention layer. If not given, cross-attention defaults to self-attention. cross_attention_kwargs (*optional*): Keyword arguments to supply to the cross attention layers, if used. Returns: `tuple`: Returns relevant parts of the model's noise prediction: the first element of the tuple is tbe VAE image embedding, the second element is the CLIP image embedding, and the third element is the CLIP text embedding. """ batch_size = latent_image_embeds.shape[0] # 1. Input # 1.1. Map inputs to shape (B, N, inner_dim) vae_hidden_states = self.vae_img_in(latent_image_embeds) clip_hidden_states = self.clip_img_in(image_embeds) text_hidden_states = self.text_in(prompt_embeds) num_text_tokens, num_img_tokens = text_hidden_states.size(1), vae_hidden_states.size(1) # 1.2. Encode image timesteps to single token (B, 1, inner_dim) if not torch.is_tensor(timestep_img): timestep_img = torch.tensor([timestep_img], dtype=torch.long, device=vae_hidden_states.device) # broadcast to batch dimension in a way that's compatible with ONNX/Core ML timestep_img = timestep_img * torch.ones(batch_size, dtype=timestep_img.dtype, device=timestep_img.device) timestep_img_token = self.timestep_img_proj(timestep_img) # t_img_token does not contain any weights and will always return f32 tensors # but time_embedding might be fp16, so we need to cast here. timestep_img_token = timestep_img_token.to(dtype=self.dtype) timestep_img_token = self.timestep_img_embed(timestep_img_token) timestep_img_token = timestep_img_token.unsqueeze(dim=1) # 1.3. Encode text timesteps to single token (B, 1, inner_dim) if not torch.is_tensor(timestep_text): timestep_text = torch.tensor([timestep_text], dtype=torch.long, device=vae_hidden_states.device) # broadcast to batch dimension in a way that's compatible with ONNX/Core ML timestep_text = timestep_text * torch.ones(batch_size, dtype=timestep_text.dtype, device=timestep_text.device) timestep_text_token = self.timestep_text_proj(timestep_text) # t_text_token does not contain any weights and will always return f32 tensors # but time_embedding might be fp16, so we need to cast here. timestep_text_token = timestep_text_token.to(dtype=self.dtype) timestep_text_token = self.timestep_text_embed(timestep_text_token) timestep_text_token = timestep_text_token.unsqueeze(dim=1) # 1.4. Concatenate all of the embeddings together. if self.use_data_type_embedding: assert data_type is not None, "data_type must be supplied if the model uses a data type embedding" if not torch.is_tensor(data_type): data_type = torch.tensor([data_type], dtype=torch.int, device=vae_hidden_states.device) # broadcast to batch dimension in a way that's compatible with ONNX/Core ML data_type = data_type * torch.ones(batch_size, dtype=data_type.dtype, device=data_type.device) data_type_token = self.data_type_token_embedding(data_type).unsqueeze(dim=1) hidden_states = torch.cat( [ timestep_img_token, timestep_text_token, data_type_token, text_hidden_states, clip_hidden_states, vae_hidden_states, ], dim=1, ) else: hidden_states = torch.cat( [timestep_img_token, timestep_text_token, text_hidden_states, clip_hidden_states, vae_hidden_states], dim=1, ) # 1.5. Prepare the positional embeddings and add to hidden states # Note: I think img_vae should always have the proper shape, so there's no need to interpolate # the position embeddings. if self.use_data_type_embedding: pos_embed = torch.cat( [self.pos_embed[:, : 1 + 1, :], self.data_type_pos_embed_token, self.pos_embed[:, 1 + 1 :, :]], dim=1 ) else: pos_embed = self.pos_embed hidden_states = hidden_states + pos_embed hidden_states = self.pos_embed_drop(hidden_states) # 2. Blocks hidden_states = self.transformer( hidden_states, encoder_hidden_states=encoder_hidden_states, timestep=None, class_labels=None, cross_attention_kwargs=cross_attention_kwargs, return_dict=False, hidden_states_is_embedding=True, unpatchify=False, )[0] # 3. Output # Split out the predicted noise representation. if self.use_data_type_embedding: ( t_img_token_out, t_text_token_out, data_type_token_out, text_out, img_clip_out, img_vae_out, ) = hidden_states.split((1, 1, 1, num_text_tokens, 1, num_img_tokens), dim=1) else: t_img_token_out, t_text_token_out, text_out, img_clip_out, img_vae_out = hidden_states.split( (1, 1, num_text_tokens, 1, num_img_tokens), dim=1 ) img_vae_out = self.vae_img_out(img_vae_out) # unpatchify height = width = int(img_vae_out.shape[1] ** 0.5) img_vae_out = img_vae_out.reshape( shape=(-1, height, width, self.patch_size, self.patch_size, self.out_channels) ) img_vae_out = torch.einsum("nhwpqc->nchpwq", img_vae_out) img_vae_out = img_vae_out.reshape( shape=(-1, self.out_channels, height * self.patch_size, width * self.patch_size) ) img_clip_out = self.clip_img_out(img_clip_out) text_out = self.text_out(text_out) return img_vae_out, img_clip_out, text_out