projector/modeling_ccam_projector.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
================================================
@author: Jaron
@time: 2024/02/20 16:21:56
@email: fjjth98@163.com
@description: QFormer projector, convert image and video into fixed-length tokens
================================================
"""

import math
import torch
import torch.nn as nn
from torch.nn.functional import interpolate
from transformers.models.blip_2.modeling_blip_2 import Blip2QFormerModel, Blip2QFormerEncoder

from .configuration_ccam_projector import CCAMConfig


class SimpleQFormerOutput(nn.Module):
    # replace last residual MLP with normal MLP
    def __init__(self, config):
        super().__init__()
        self.dense = nn.Linear(config.intermediate_size, config.output_size)

    def forward(self, hidden_states: torch.Tensor, input_tensor: torch.Tensor = None) -> torch.Tensor:
        return self.dense(hidden_states)


class SimpleQFormerIdentity(nn.Module):
    # just to replace the first attention module with identity, since it is useless
 
    def forward(self, hidden_states: torch.Tensor, *args, **kwargs) -> torch.Tensor:
        return hidden_states,


class CCAMModel(Blip2QFormerModel):
    _auto_class = 'AutoModel'
    config_class = CCAMConfig
    base_model_prefix = 'model'
    supports_gradient_checkpointing = True
 
    def __init__(self, config: CCAMConfig):
        super(Blip2QFormerModel, self).__init__(config)
        self.gradient_checkpointing = False
        self.config = config
        self.num_query_tokens = config.num_query_tokens
        self.visual_attn_mask_type = config.visual_attn_mask_type

        self.layernorm = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps)
        self.dropout = nn.Dropout(config.hidden_dropout_prob)
        self.encoder = Blip2QFormerEncoder(config)
        self.encoder.layer[0].attention = SimpleQFormerIdentity()   # replace the 1st attention module with identity
        self.encoder.layer[-1].output_query = SimpleQFormerOutput(config)

        # initialize query tokens
        self.query_tokens = nn.Parameter(torch.zeros(1, config.num_query_tokens, config.hidden_size))

        # initialize pos embed
        self.spatial_pos_embed = self._create_pos_embed(*config.spatial_resolution, type=config.spatial_pos_embed_type)     # (H, W, C)
        self.temporal_pos_embed = self._create_pos_embed(config.temporal_resolution, type=config.temporal_pos_embed_type)   # (T, C)

        # initialize query attn mask
        if config.query_attn_mask_type == 'full':
            self.query_attn_mask = None
        elif config.query_attn_mask_type == 'causal':
            query_attn_mask = torch.ones(self.num_query_tokens, self.num_query_tokens)
            q = torch.arange(self.num_query_tokens)
            query_attn_mask.masked_fill_(q > q[:, None], 0)
            self.query_attn_mask = query_attn_mask[None]
        else:
            raise NotImplementedError(f'Do not support {self.query_attn_mask} query_attn_mask')

        self.post_init()

    def _create_pos_embed(self, *size: int, type: str = 'none') -> torch.Tensor:
        C = self.config.encoder_hidden_size
        if type == 'none':
            pos_embed = None
        elif type == 'learnable':
            pos_embed = nn.Parameter(.02 * torch.randn(*size, C))
        elif type == 'cosine':
            total_len = 1
            for i in size:
                total_len *= i
            raw = torch.outer(torch.arange(total_len), torch.exp(torch.arange(0, C, 2) * (-math.log(10000.) / C)))
            pos_embed = nn.Parameter(torch.stack((raw.sin(), raw.cos()), dim=-1).view(*size, C), requires_grad=False)
        else:
            raise NotImplementedError(f'Do not support {type} position embeddings')
        return pos_embed

    def get_attn_mask(self, embeddings: torch.Tensor) -> tuple[torch.Tensor, torch.Tensor]:
        """Get visual_attn_mask and query_attn_mask if needed 
            embeddings (torch.Tensor): (B, T, L, C)
        """
        B, T, L, _ = embeddings.size()
        device = embeddings.device

        # visual attn mask only work for videos
        if T > 1:
            if self.visual_attn_mask_type == 'ccam':
                base_attn_mask = torch.ones(T, T, device=device)
                t = torch.arange(T, device=device)
                base_attn_mask.masked_fill_(t > t[:, None], 0)
                visual_attn_mask = torch.cat((
                    torch.kron(
                        base_attn_mask,
                        torch.ones(self.num_query_tokens // T, L, device=device)
                    ),
                    torch.ones(self.num_query_tokens % T, T * L, device=device)
                ), dim=0)[None].expand(B, -1, -1)
            elif self.visual_attn_mask_type == 'full':
                visual_attn_mask = None
            else:
                raise NotImplementedError(f'Do not support {self.visual_attn_mask_type} attn_mask')
        else:
            visual_attn_mask = None

        if self.query_attn_mask is None:
            query_attn_mask = None
        else:
            query_attn_mask = self.query_attn_mask.expand(B, -1, -1)

        return visual_attn_mask, query_attn_mask

    def batch_forward_no_spatial(self, visual_embeds: torch.Tensor) -> torch.Tensor:
        """Batch forward without spatial mask position embeddings

        Args:
            visual_embeds (torch.Tensor): (B, T, L, C)

        Returns:
            torch.Tensor: (B, Q, C)
        """
        B, T, _, C = visual_embeds.size()
        query_embeds = self.query_tokens.expand(B, -1, -1)
        visual_attn_mask, query_attn_mask = self.get_attn_mask(visual_embeds)

        # add temporal position embeddings
        if self.temporal_pos_embed is not None:
            if T == self.temporal_pos_embed.size(0):
                pos_embed = self.temporal_pos_embed
            elif T == 1:
                pos_embed = 0. * self.temporal_pos_embed[:1]     # for deepspeed 
            else:
                pos_embed = interpolate(
                    self.temporal_pos_embed.T[None],    # (1, C, t)
                    size=(T,),
                    mode='linear',
                    align_corners=False
                )[0].T      # (T, C)
            visual_embeds = visual_embeds + pos_embed.view(1, T, 1, C)
        visual_embeds = visual_embeds.flatten(1, 2)

        return super().forward(
            query_embeds=query_embeds,
            attention_mask=query_attn_mask,
            encoder_hidden_states=visual_embeds,
            encoder_attention_mask=visual_attn_mask
        )[0]

    def forward(self, visual_embeds: torch.Tensor, split_sizes: list[int], unmasked_ids: torch.LongTensor = None):
        """
            visual_embeds (torch.Tensor): (T, L, C)
            split_sizes (list[int]): [t0, t1, ...] sum_i ti=T
            unmasked_ids (torch.LongTensor): If provided, should be in the shape of (T, L) whose value v 0<=v<=HW-1
            output_attentions (_type_, optional): _description_. Defaults to None.
            output_hidden_states (_type_, optional): _description_. Defaults to None.
            return_dict (_type_, optional): _description_. Defaults to None.
        """
        _, L, C = visual_embeds.size()

        # add spatial position embeddings
        if self.spatial_pos_embed is not None:
            pos_embed = self.spatial_pos_embed.view(-1, C)  # (H*W, C)
            if unmasked_ids is None:
                pos_embed = pos_embed.view(1, L, C)     # if not provided, L must equals to H*W
            else:
                pos_embed = pos_embed[unmasked_ids]     # (T, L, C)
            visual_embeds = visual_embeds + pos_embed

        # all inputs in this batch has the same t
        if len(set(split_sizes)) == 1:
            visual_embeds = visual_embeds.view(len(split_sizes), split_sizes[0], L, C)
            output = self.batch_forward_no_spatial(visual_embeds)
        else:
            visual_embeds = visual_embeds.split(split_sizes, dim=0)
            # group visual_embeds accoding to the number of frames
            output, group_visual_embeds = [None] * len(split_sizes), {}
            for idx, (embed, t) in enumerate(zip(visual_embeds, split_sizes)):
                if t in group_visual_embeds:
                    group_visual_embeds[t][0].append(idx)
                    group_visual_embeds[t][1].append(embed)
                else:
                    group_visual_embeds[t] = [[idx], [embed]]
            for idx, embeds in group_visual_embeds.values():
                cur_output = self.batch_forward_no_spatial(torch.stack(embeds, dim=0))
                for i, j in enumerate(idx):
                    output[j] = cur_output[i]
            output = torch.stack(output, dim=0)

        return output