# Copyright 2023 The HuggingFace Team. All rights reserved. # # 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. from typing import Optional from torch import nn from .transformer_2d import Transformer2DModel, Transformer2DModelOutput class DualTransformer2DModel(nn.Module): """ Dual transformer wrapper that combines two `Transformer2DModel`s for mixed inference. 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 and output. num_layers (`int`, *optional*, defaults to 1): The number of layers of Transformer blocks to use. dropout (`float`, *optional*, defaults to 0.1): The dropout probability to use. cross_attention_dim (`int`, *optional*): The number of encoder_hidden_states dimensions to use. 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. 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`. attention_bias (`bool`, *optional*): Configure if the TransformerBlocks' attention should contain a bias parameter. """ def __init__( self, num_attention_heads: int = 16, attention_head_dim: int = 88, in_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, activation_fn: str = "geglu", num_embeds_ada_norm: Optional[int] = None, ): super().__init__() self.transformers = nn.ModuleList( [ Transformer2DModel( num_attention_heads=num_attention_heads, attention_head_dim=attention_head_dim, in_channels=in_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, activation_fn=activation_fn, num_embeds_ada_norm=num_embeds_ada_norm, ) for _ in range(2) ] ) # Variables that can be set by a pipeline: # The ratio of transformer1 to transformer2's output states to be combined during inference self.mix_ratio = 0.5 # The shape of `encoder_hidden_states` is expected to be # `(batch_size, condition_lengths[0]+condition_lengths[1], num_features)` self.condition_lengths = [77, 257] # Which transformer to use to encode which condition. # E.g. `(1, 0)` means that we'll use `transformers[1](conditions[0])` and `transformers[0](conditions[1])` self.transformer_index_for_condition = [1, 0] def forward( self, hidden_states, encoder_hidden_states, timestep=None, attention_mask=None, cross_attention_kwargs=None, return_dict: bool = True, ): """ Args: hidden_states ( When discrete, `torch.LongTensor` of shape `(batch size, num latent pixels)`. When continuous, `torch.FloatTensor` 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. attention_mask (`torch.FloatTensor`, *optional*): Optional attention mask to be applied in Attention. cross_attention_kwargs (`dict`, *optional*): A kwargs dictionary that if specified is passed along to the `AttentionProcessor` as defined under `self.processor` in [diffusers.models.attention_processor](https://github.com/huggingface/diffusers/blob/main/src/diffusers/models/attention_processor.py). return_dict (`bool`, *optional*, defaults to `True`): Whether or not to return a [`models.unets.unet_2d_condition.UNet2DConditionOutput`] instead of a plain tuple. 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. """ input_states = hidden_states encoded_states = [] tokens_start = 0 # attention_mask is not used yet for i in range(2): # for each of the two transformers, pass the corresponding condition tokens condition_state = encoder_hidden_states[:, tokens_start : tokens_start + self.condition_lengths[i]] transformer_index = self.transformer_index_for_condition[i] encoded_state = self.transformers[transformer_index]( input_states, encoder_hidden_states=condition_state, timestep=timestep, cross_attention_kwargs=cross_attention_kwargs, return_dict=False, )[0] encoded_states.append(encoded_state - input_states) tokens_start += self.condition_lengths[i] output_states = encoded_states[0] * self.mix_ratio + encoded_states[1] * (1 - self.mix_ratio) output_states = output_states + input_states if not return_dict: return (output_states,) return Transformer2DModelOutput(sample=output_states)