import torch import torch.nn as nn from torch.utils.checkpoint import checkpoint from transformers import T5Tokenizer, T5EncoderModel, CLIPTokenizer, CLIPTextModel import open_clip from ldm.util import default, count_params default_device = torch.device("cpu" if not torch.cuda.is_available() else "cuda") class AbstractEncoder(nn.Module): def __init__(self): super().__init__() def encode(self, *args, **kwargs): raise NotImplementedError class IdentityEncoder(AbstractEncoder): def encode(self, x): return x class ClassEmbedder(nn.Module): def __init__(self, embed_dim, n_classes=1000, key='class', ucg_rate=0.1): super().__init__() self.key = key self.embedding = nn.Embedding(n_classes, embed_dim) self.n_classes = n_classes self.ucg_rate = ucg_rate def forward(self, batch, key=None, disable_dropout=False): if key is None: key = self.key # this is for use in crossattn c = batch[key][:, None] if self.ucg_rate > 0. and not disable_dropout: mask = 1. - torch.bernoulli(torch.ones_like(c) * self.ucg_rate) c = mask * c + (1-mask) * torch.ones_like(c)*(self.n_classes-1) c = c.long() c = self.embedding(c) return c def get_unconditional_conditioning(self, bs, device=None): if device is None: device = default_device uc_class = self.n_classes - 1 # 1000 classes --> 0 ... 999, one extra class for ucg (class 1000) uc = torch.ones((bs,), device=device) * uc_class uc = {self.key: uc} return uc def disabled_train(self, mode=True): """Overwrite model.train with this function to make sure train/eval mode does not change anymore.""" return self class FrozenT5Embedder(AbstractEncoder): """Uses the T5 transformer encoder for text""" def __init__(self, version="google/t5-v1_1-large", device=None, max_length=77, freeze=True): # others are google/t5-v1_1-xl and google/t5-v1_1-xxl super().__init__() if device is None: device = default_device self.tokenizer = T5Tokenizer.from_pretrained(version) self.transformer = T5EncoderModel.from_pretrained(version) self.device = device self.max_length = max_length # TODO: typical value? if freeze: self.freeze() def freeze(self): self.transformer = self.transformer.eval() #self.train = disabled_train for param in self.parameters(): param.requires_grad = False def forward(self, text): batch_encoding = self.tokenizer(text, truncation=True, max_length=self.max_length, return_length=True, return_overflowing_tokens=False, padding="max_length", return_tensors="pt") tokens = batch_encoding["input_ids"].to(self.device) outputs = self.transformer(input_ids=tokens) z = outputs.last_hidden_state return z def encode(self, text): return self(text) class FrozenCLIPEmbedder(AbstractEncoder): """Uses the CLIP transformer encoder for text (from huggingface)""" LAYERS = [ "last", "pooled", "hidden" ] def __init__(self, version="openai/clip-vit-large-patch14", device=None, max_length=77, freeze=True, layer="last", layer_idx=None): # clip-vit-base-patch32 super().__init__() if device is None: device = default_device assert layer in self.LAYERS self.tokenizer = CLIPTokenizer.from_pretrained(version) self.transformer = CLIPTextModel.from_pretrained(version) self.device = device self.max_length = max_length if freeze: self.freeze() self.layer = layer self.layer_idx = layer_idx if layer == "hidden": assert layer_idx is not None assert 0 <= abs(layer_idx) <= 12 def freeze(self): self.transformer = self.transformer.eval() #self.train = disabled_train for param in self.parameters(): param.requires_grad = False def forward(self, text): batch_encoding = self.tokenizer(text, truncation=True, max_length=self.max_length, return_length=True, return_overflowing_tokens=False, padding="max_length", return_tensors="pt") tokens = batch_encoding["input_ids"].to(self.device) outputs = self.transformer(input_ids=tokens, output_hidden_states=self.layer=="hidden") if self.layer == "last": z = outputs.last_hidden_state elif self.layer == "pooled": z = outputs.pooler_output[:, None, :] else: z = outputs.hidden_states[self.layer_idx] return z def encode(self, text): return self(text) class FrozenOpenCLIPEmbedder(AbstractEncoder): """ Uses the OpenCLIP transformer encoder for text """ LAYERS = [ #"pooled", "last", "penultimate" ] def __init__(self, arch="ViT-H-14", version="laion2b_s32b_b79k", device=None, max_length=77, freeze=True, layer="last"): super().__init__() if device is None: device = default_device assert layer in self.LAYERS model, _, _ = open_clip.create_model_and_transforms(arch, device=torch.device('cpu'), pretrained=version) del model.visual self.model = model self.device = device self.max_length = max_length if freeze: self.freeze() self.layer = layer if self.layer == "last": self.layer_idx = 0 elif self.layer == "penultimate": self.layer_idx = 1 else: raise NotImplementedError() def freeze(self): self.model = self.model.eval() for param in self.parameters(): param.requires_grad = False def forward(self, text): tokens = open_clip.tokenize(text) z = self.encode_with_transformer(tokens.to(self.device)) return z def encode_with_transformer(self, text): x = self.model.token_embedding(text) # [batch_size, n_ctx, d_model] x = x + self.model.positional_embedding x = x.permute(1, 0, 2) # NLD -> LND x = self.text_transformer_forward(x, attn_mask=self.model.attn_mask) x = x.permute(1, 0, 2) # LND -> NLD x = self.model.ln_final(x) return x def text_transformer_forward(self, x: torch.Tensor, attn_mask = None): for i, r in enumerate(self.model.transformer.resblocks): if i == len(self.model.transformer.resblocks) - self.layer_idx: break if self.model.transformer.grad_checkpointing and not torch.jit.is_scripting(): x = checkpoint(r, x, attn_mask) else: x = r(x, attn_mask=attn_mask) return x def encode(self, text): return self(text) class FrozenCLIPT5Encoder(AbstractEncoder): def __init__(self, clip_version="openai/clip-vit-large-patch14", t5_version="google/t5-v1_1-xl", device=None, clip_max_length=77, t5_max_length=77): super().__init__() if device is None: device = default_device self.clip_encoder = FrozenCLIPEmbedder(clip_version, device, max_length=clip_max_length) self.t5_encoder = FrozenT5Embedder(t5_version, device, max_length=t5_max_length) print(f"{self.clip_encoder.__class__.__name__} has {count_params(self.clip_encoder)*1.e-6:.2f} M parameters, " f"{self.t5_encoder.__class__.__name__} comes with {count_params(self.t5_encoder)*1.e-6:.2f} M params.") def encode(self, text): return self(text) def forward(self, text): clip_z = self.clip_encoder.encode(text) t5_z = self.t5_encoder.encode(text) return [clip_z, t5_z]