src/diffusers/models/autoencoders/autoencoder_kl_cogvideox.py

# Copyright 2024 The CogVideoX team, Tsinghua University & ZhipuAI and 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, Tuple, Union

import numpy as np
import torch
import torch.nn as nn
import torch.nn.functional as F

from ...configuration_utils import ConfigMixin, register_to_config
from ...loaders.single_file_model import FromOriginalModelMixin
from ...utils import logging
from ...utils.accelerate_utils import apply_forward_hook
from ..activations import get_activation
from ..downsampling import CogVideoXDownsample3D
from ..modeling_outputs import AutoencoderKLOutput
from ..modeling_utils import ModelMixin
from ..upsampling import CogVideoXUpsample3D
from .vae import DecoderOutput, DiagonalGaussianDistribution


logger = logging.get_logger(__name__)  # pylint: disable=invalid-name


class CogVideoXSafeConv3d(nn.Conv3d):
    """
    A 3D convolution layer that splits the input tensor into smaller parts to avoid OOM in CogVideoX Model.
    """

    def forward(self, input: torch.Tensor) -> torch.Tensor:
        memory_count = torch.prod(torch.tensor(input.shape)).item() * 2 / 1024**3

        # Set to 2GB, suitable for CuDNN
        if memory_count > 2:
            kernel_size = self.kernel_size[0]
            part_num = int(memory_count / 2) + 1
            input_chunks = torch.chunk(input, part_num, dim=2)

            if kernel_size > 1:
                input_chunks = [input_chunks[0]] + [
                    torch.cat((input_chunks[i - 1][:, :, -kernel_size + 1 :], input_chunks[i]), dim=2)
                    for i in range(1, len(input_chunks))
                ]

            output_chunks = []
            for input_chunk in input_chunks:
                output_chunks.append(super().forward(input_chunk))
            output = torch.cat(output_chunks, dim=2)
            return output
        else:
            return super().forward(input)


class CogVideoXCausalConv3d(nn.Module):
    r"""A 3D causal convolution layer that pads the input tensor to ensure causality in CogVideoX Model.

    Args:
        in_channels (int): Number of channels in the input tensor.
        out_channels (int): Number of output channels.
        kernel_size (Union[int, Tuple[int, int, int]]): Size of the convolutional kernel.
        stride (int, optional): Stride of the convolution. Default is 1.
        dilation (int, optional): Dilation rate of the convolution. Default is 1.
        pad_mode (str, optional): Padding mode. Default is "constant".
    """

    def __init__(
        self,
        in_channels: int,
        out_channels: int,
        kernel_size: Union[int, Tuple[int, int, int]],
        stride: int = 1,
        dilation: int = 1,
        pad_mode: str = "constant",
    ):
        super().__init__()

        if isinstance(kernel_size, int):
            kernel_size = (kernel_size,) * 3

        time_kernel_size, height_kernel_size, width_kernel_size = kernel_size

        self.pad_mode = pad_mode
        time_pad = dilation * (time_kernel_size - 1) + (1 - stride)
        height_pad = height_kernel_size // 2
        width_pad = width_kernel_size // 2

        self.height_pad = height_pad
        self.width_pad = width_pad
        self.time_pad = time_pad
        self.time_causal_padding = (width_pad, width_pad, height_pad, height_pad, time_pad, 0)

        self.temporal_dim = 2
        self.time_kernel_size = time_kernel_size

        stride = (stride, 1, 1)
        dilation = (dilation, 1, 1)
        self.conv = CogVideoXSafeConv3d(
            in_channels=in_channels,
            out_channels=out_channels,
            kernel_size=kernel_size,
            stride=stride,
            dilation=dilation,
        )

        self.conv_cache = None

    def fake_context_parallel_forward(self, inputs: torch.Tensor) -> torch.Tensor:
        dim = self.temporal_dim
        kernel_size = self.time_kernel_size
        if kernel_size == 1:
            return inputs

        inputs = inputs.transpose(0, dim)

        if self.conv_cache is not None:
            inputs = torch.cat([self.conv_cache.transpose(0, dim).to(inputs.device), inputs], dim=0)
        else:
            inputs = torch.cat([inputs[:1]] * (kernel_size - 1) + [inputs], dim=0)

        inputs = inputs.transpose(0, dim).contiguous()
        return inputs

    def _clear_fake_context_parallel_cache(self):
        del self.conv_cache
        self.conv_cache = None

    def forward(self, inputs: torch.Tensor) -> torch.Tensor:
        input_parallel = self.fake_context_parallel_forward(inputs)

        self._clear_fake_context_parallel_cache()
        self.conv_cache = input_parallel[:, :, -self.time_kernel_size + 1 :].contiguous().detach().clone().cpu()

        padding_2d = (self.width_pad, self.width_pad, self.height_pad, self.height_pad)
        input_parallel = F.pad(input_parallel, padding_2d, mode="constant", value=0)

        output_parallel = self.conv(input_parallel)
        output = output_parallel
        return output


class CogVideoXSpatialNorm3D(nn.Module):
    r"""
    Spatially conditioned normalization as defined in https://arxiv.org/abs/2209.09002. This implementation is specific
    to 3D-video like data.

    CogVideoXSafeConv3d is used instead of nn.Conv3d to avoid OOM in CogVideoX Model.

    Args:
        f_channels (`int`):
            The number of channels for input to group normalization layer, and output of the spatial norm layer.
        zq_channels (`int`):
            The number of channels for the quantized vector as described in the paper.
    """

    def __init__(
        self,
        f_channels: int,
        zq_channels: int,
        groups: int = 32,
    ):
        super().__init__()
        self.norm_layer = nn.GroupNorm(num_channels=f_channels, num_groups=groups, eps=1e-6, affine=True)
        self.conv_y = CogVideoXCausalConv3d(zq_channels, f_channels, kernel_size=1, stride=1)
        self.conv_b = CogVideoXCausalConv3d(zq_channels, f_channels, kernel_size=1, stride=1)

    def forward(self, f: torch.Tensor, zq: torch.Tensor) -> torch.Tensor:
        if f.shape[2] > 1 and f.shape[2] % 2 == 1:
            f_first, f_rest = f[:, :, :1], f[:, :, 1:]
            f_first_size, f_rest_size = f_first.shape[-3:], f_rest.shape[-3:]
            z_first, z_rest = zq[:, :, :1], zq[:, :, 1:]
            z_first = F.interpolate(z_first, size=f_first_size)
            z_rest = F.interpolate(z_rest, size=f_rest_size)
            zq = torch.cat([z_first, z_rest], dim=2)
        else:
            zq = F.interpolate(zq, size=f.shape[-3:])

        norm_f = self.norm_layer(f)
        new_f = norm_f * self.conv_y(zq) + self.conv_b(zq)
        return new_f


class CogVideoXResnetBlock3D(nn.Module):
    r"""
    A 3D ResNet block used in the CogVideoX model.

    Args:
        in_channels (int): Number of input channels.
        out_channels (Optional[int], optional):
            Number of output channels. If None, defaults to `in_channels`. Default is None.
        dropout (float, optional): Dropout rate. Default is 0.0.
        temb_channels (int, optional): Number of time embedding channels. Default is 512.
        groups (int, optional): Number of groups for group normalization. Default is 32.
        eps (float, optional): Epsilon value for normalization layers. Default is 1e-6.
        non_linearity (str, optional): Activation function to use. Default is "swish".
        conv_shortcut (bool, optional): If True, use a convolutional shortcut. Default is False.
        spatial_norm_dim (Optional[int], optional): Dimension of the spatial normalization. Default is None.
        pad_mode (str, optional): Padding mode. Default is "first".
    """

    def __init__(
        self,
        in_channels: int,
        out_channels: Optional[int] = None,
        dropout: float = 0.0,
        temb_channels: int = 512,
        groups: int = 32,
        eps: float = 1e-6,
        non_linearity: str = "swish",
        conv_shortcut: bool = False,
        spatial_norm_dim: Optional[int] = None,
        pad_mode: str = "first",
    ):
        super().__init__()

        out_channels = out_channels or in_channels

        self.in_channels = in_channels
        self.out_channels = out_channels
        self.nonlinearity = get_activation(non_linearity)
        self.use_conv_shortcut = conv_shortcut

        if spatial_norm_dim is None:
            self.norm1 = nn.GroupNorm(num_channels=in_channels, num_groups=groups, eps=eps)
            self.norm2 = nn.GroupNorm(num_channels=out_channels, num_groups=groups, eps=eps)
        else:
            self.norm1 = CogVideoXSpatialNorm3D(
                f_channels=in_channels,
                zq_channels=spatial_norm_dim,
                groups=groups,
            )
            self.norm2 = CogVideoXSpatialNorm3D(
                f_channels=out_channels,
                zq_channels=spatial_norm_dim,
                groups=groups,
            )

        self.conv1 = CogVideoXCausalConv3d(
            in_channels=in_channels, out_channels=out_channels, kernel_size=3, pad_mode=pad_mode
        )

        if temb_channels > 0:
            self.temb_proj = nn.Linear(in_features=temb_channels, out_features=out_channels)

        self.dropout = nn.Dropout(dropout)
        self.conv2 = CogVideoXCausalConv3d(
            in_channels=out_channels, out_channels=out_channels, kernel_size=3, pad_mode=pad_mode
        )

        if self.in_channels != self.out_channels:
            if self.use_conv_shortcut:
                self.conv_shortcut = CogVideoXCausalConv3d(
                    in_channels=in_channels, out_channels=out_channels, kernel_size=3, pad_mode=pad_mode
                )
            else:
                self.conv_shortcut = CogVideoXSafeConv3d(
                    in_channels=in_channels, out_channels=out_channels, kernel_size=1, stride=1, padding=0
                )

    def forward(
        self,
        inputs: torch.Tensor,
        temb: Optional[torch.Tensor] = None,
        zq: Optional[torch.Tensor] = None,
    ) -> torch.Tensor:
        hidden_states = inputs

        if zq is not None:
            hidden_states = self.norm1(hidden_states, zq)
        else:
            hidden_states = self.norm1(hidden_states)

        hidden_states = self.nonlinearity(hidden_states)
        hidden_states = self.conv1(hidden_states)

        if temb is not None:
            hidden_states = hidden_states + self.temb_proj(self.nonlinearity(temb))[:, :, None, None, None]

        if zq is not None:
            hidden_states = self.norm2(hidden_states, zq)
        else:
            hidden_states = self.norm2(hidden_states)

        hidden_states = self.nonlinearity(hidden_states)
        hidden_states = self.dropout(hidden_states)
        hidden_states = self.conv2(hidden_states)

        if self.in_channels != self.out_channels:
            inputs = self.conv_shortcut(inputs)

        hidden_states = hidden_states + inputs
        return hidden_states


class CogVideoXDownBlock3D(nn.Module):
    r"""
    A downsampling block used in the CogVideoX model.

    Args:
        in_channels (int): Number of input channels.
        out_channels (int): Number of output channels.
        temb_channels (int): Number of time embedding channels.
        dropout (float, optional): Dropout rate. Default is 0.0.
        num_layers (int, optional): Number of layers in the block. Default is 1.
        resnet_eps (float, optional): Epsilon value for the ResNet layers. Default is 1e-6.
        resnet_act_fn (str, optional): Activation function for the ResNet layers. Default is "swish".
        resnet_groups (int, optional): Number of groups for group normalization in the ResNet layers. Default is 32.
        add_downsample (bool, optional): If True, add a downsampling layer at the end of the block. Default is True.
        downsample_padding (int, optional): Padding for the downsampling layer. Default is 0.
        compress_time (bool, optional): If True, apply temporal compression. Default is False.
        pad_mode (str, optional): Padding mode. Default is "first".
    """

    _supports_gradient_checkpointing = True

    def __init__(
        self,
        in_channels: int,
        out_channels: int,
        temb_channels: int,
        dropout: float = 0.0,
        num_layers: int = 1,
        resnet_eps: float = 1e-6,
        resnet_act_fn: str = "swish",
        resnet_groups: int = 32,
        add_downsample: bool = True,
        downsample_padding: int = 0,
        compress_time: bool = False,
        pad_mode: str = "first",
    ):
        super().__init__()

        resnets = []
        for i in range(num_layers):
            in_channel = in_channels if i == 0 else out_channels
            resnets.append(
                CogVideoXResnetBlock3D(
                    in_channels=in_channel,
                    out_channels=out_channels,
                    dropout=dropout,
                    temb_channels=temb_channels,
                    groups=resnet_groups,
                    eps=resnet_eps,
                    non_linearity=resnet_act_fn,
                    pad_mode=pad_mode,
                )
            )

        self.resnets = nn.ModuleList(resnets)
        self.downsamplers = None

        if add_downsample:
            self.downsamplers = nn.ModuleList(
                [
                    CogVideoXDownsample3D(
                        out_channels, out_channels, padding=downsample_padding, compress_time=compress_time
                    )
                ]
            )

        self.gradient_checkpointing = False

    def forward(
        self,
        hidden_states: torch.Tensor,
        temb: Optional[torch.Tensor] = None,
        zq: Optional[torch.Tensor] = None,
    ) -> torch.Tensor:
        for resnet in self.resnets:
            if self.training and self.gradient_checkpointing:

                def create_custom_forward(module):
                    def create_forward(*inputs):
                        return module(*inputs)

                    return create_forward

                hidden_states = torch.utils.checkpoint.checkpoint(
                    create_custom_forward(resnet), hidden_states, temb, zq
                )
            else:
                hidden_states = resnet(hidden_states, temb, zq)

        if self.downsamplers is not None:
            for downsampler in self.downsamplers:
                hidden_states = downsampler(hidden_states)

        return hidden_states


class CogVideoXMidBlock3D(nn.Module):
    r"""
    A middle block used in the CogVideoX model.

    Args:
        in_channels (int): Number of input channels.
        temb_channels (int): Number of time embedding channels.
        dropout (float, optional): Dropout rate. Default is 0.0.
        num_layers (int, optional): Number of layers in the block. Default is 1.
        resnet_eps (float, optional): Epsilon value for the ResNet layers. Default is 1e-6.
        resnet_act_fn (str, optional): Activation function for the ResNet layers. Default is "swish".
        resnet_groups (int, optional): Number of groups for group normalization in the ResNet layers. Default is 32.
        spatial_norm_dim (Optional[int], optional): Dimension of the spatial normalization. Default is None.
        pad_mode (str, optional): Padding mode. Default is "first".
    """

    _supports_gradient_checkpointing = True

    def __init__(
        self,
        in_channels: int,
        temb_channels: int,
        dropout: float = 0.0,
        num_layers: int = 1,
        resnet_eps: float = 1e-6,
        resnet_act_fn: str = "swish",
        resnet_groups: int = 32,
        spatial_norm_dim: Optional[int] = None,
        pad_mode: str = "first",
    ):
        super().__init__()

        resnets = []
        for _ in range(num_layers):
            resnets.append(
                CogVideoXResnetBlock3D(
                    in_channels=in_channels,
                    out_channels=in_channels,
                    dropout=dropout,
                    temb_channels=temb_channels,
                    groups=resnet_groups,
                    eps=resnet_eps,
                    spatial_norm_dim=spatial_norm_dim,
                    non_linearity=resnet_act_fn,
                    pad_mode=pad_mode,
                )
            )
        self.resnets = nn.ModuleList(resnets)

        self.gradient_checkpointing = False

    def forward(
        self,
        hidden_states: torch.Tensor,
        temb: Optional[torch.Tensor] = None,
        zq: Optional[torch.Tensor] = None,
    ) -> torch.Tensor:
        for resnet in self.resnets:
            if self.training and self.gradient_checkpointing:

                def create_custom_forward(module):
                    def create_forward(*inputs):
                        return module(*inputs)

                    return create_forward

                hidden_states = torch.utils.checkpoint.checkpoint(
                    create_custom_forward(resnet), hidden_states, temb, zq
                )
            else:
                hidden_states = resnet(hidden_states, temb, zq)

        return hidden_states


class CogVideoXUpBlock3D(nn.Module):
    r"""
    An upsampling block used in the CogVideoX model.

    Args:
        in_channels (int): Number of input channels.
        out_channels (int): Number of output channels.
        temb_channels (int): Number of time embedding channels.
        dropout (float, optional): Dropout rate. Default is 0.0.
        num_layers (int, optional): Number of layers in the block. Default is 1.
        resnet_eps (float, optional): Epsilon value for the ResNet layers. Default is 1e-6.
        resnet_act_fn (str, optional): Activation function for the ResNet layers. Default is "swish".
        resnet_groups (int, optional): Number of groups for group normalization in the ResNet layers. Default is 32.
        spatial_norm_dim (int, optional): Dimension of the spatial normalization. Default is 16.
        add_upsample (bool, optional): If True, add an upsampling layer at the end of the block. Default is True.
        upsample_padding (int, optional): Padding for the upsampling layer. Default is 1.
        compress_time (bool, optional): If True, apply temporal compression. Default is False.
        pad_mode (str, optional): Padding mode. Default is "first".
    """

    def __init__(
        self,
        in_channels: int,
        out_channels: int,
        temb_channels: int,
        dropout: float = 0.0,
        num_layers: int = 1,
        resnet_eps: float = 1e-6,
        resnet_act_fn: str = "swish",
        resnet_groups: int = 32,
        spatial_norm_dim: int = 16,
        add_upsample: bool = True,
        upsample_padding: int = 1,
        compress_time: bool = False,
        pad_mode: str = "first",
    ):
        super().__init__()

        resnets = []
        for i in range(num_layers):
            in_channel = in_channels if i == 0 else out_channels
            resnets.append(
                CogVideoXResnetBlock3D(
                    in_channels=in_channel,
                    out_channels=out_channels,
                    dropout=dropout,
                    temb_channels=temb_channels,
                    groups=resnet_groups,
                    eps=resnet_eps,
                    non_linearity=resnet_act_fn,
                    spatial_norm_dim=spatial_norm_dim,
                    pad_mode=pad_mode,
                )
            )

        self.resnets = nn.ModuleList(resnets)
        self.upsamplers = None

        if add_upsample:
            self.upsamplers = nn.ModuleList(
                [
                    CogVideoXUpsample3D(
                        out_channels, out_channels, padding=upsample_padding, compress_time=compress_time
                    )
                ]
            )

        self.gradient_checkpointing = False

    def forward(
        self,
        hidden_states: torch.Tensor,
        temb: Optional[torch.Tensor] = None,
        zq: Optional[torch.Tensor] = None,
    ) -> torch.Tensor:
        r"""Forward method of the `CogVideoXUpBlock3D` class."""
        for resnet in self.resnets:
            if self.training and self.gradient_checkpointing:

                def create_custom_forward(module):
                    def create_forward(*inputs):
                        return module(*inputs)

                    return create_forward

                hidden_states = torch.utils.checkpoint.checkpoint(
                    create_custom_forward(resnet), hidden_states, temb, zq
                )
            else:
                hidden_states = resnet(hidden_states, temb, zq)

        if self.upsamplers is not None:
            for upsampler in self.upsamplers:
                hidden_states = upsampler(hidden_states)

        return hidden_states


class CogVideoXEncoder3D(nn.Module):
    r"""
    The `CogVideoXEncoder3D` layer of a variational autoencoder that encodes its input into a latent representation.

    Args:
        in_channels (`int`, *optional*, defaults to 3):
            The number of input channels.
        out_channels (`int`, *optional*, defaults to 3):
            The number of output channels.
        down_block_types (`Tuple[str, ...]`, *optional*, defaults to `("DownEncoderBlock2D",)`):
            The types of down blocks to use. See `~diffusers.models.unet_2d_blocks.get_down_block` for available
            options.
        block_out_channels (`Tuple[int, ...]`, *optional*, defaults to `(64,)`):
            The number of output channels for each block.
        layers_per_block (`int`, *optional*, defaults to 2):
            The number of layers per block.
        norm_num_groups (`int`, *optional*, defaults to 32):
            The number of groups for normalization.
        act_fn (`str`, *optional*, defaults to `"silu"`):
            The activation function to use. See `~diffusers.models.activations.get_activation` for available options.
        double_z (`bool`, *optional*, defaults to `True`):
            Whether to double the number of output channels for the last block.
    """

    _supports_gradient_checkpointing = True

    def __init__(
        self,
        in_channels: int = 3,
        out_channels: int = 16,
        down_block_types: Tuple[str, ...] = (
            "CogVideoXDownBlock3D",
            "CogVideoXDownBlock3D",
            "CogVideoXDownBlock3D",
            "CogVideoXDownBlock3D",
        ),
        block_out_channels: Tuple[int, ...] = (128, 256, 256, 512),
        layers_per_block: int = 3,
        act_fn: str = "silu",
        norm_eps: float = 1e-6,
        norm_num_groups: int = 32,
        dropout: float = 0.0,
        pad_mode: str = "first",
        temporal_compression_ratio: float = 4,
    ):
        super().__init__()

        # log2 of temporal_compress_times
        temporal_compress_level = int(np.log2(temporal_compression_ratio))

        self.conv_in = CogVideoXCausalConv3d(in_channels, block_out_channels[0], kernel_size=3, pad_mode=pad_mode)
        self.down_blocks = nn.ModuleList([])

        # down blocks
        output_channel = block_out_channels[0]
        for i, down_block_type in enumerate(down_block_types):
            input_channel = output_channel
            output_channel = block_out_channels[i]
            is_final_block = i == len(block_out_channels) - 1
            compress_time = i < temporal_compress_level

            if down_block_type == "CogVideoXDownBlock3D":
                down_block = CogVideoXDownBlock3D(
                    in_channels=input_channel,
                    out_channels=output_channel,
                    temb_channels=0,
                    dropout=dropout,
                    num_layers=layers_per_block,
                    resnet_eps=norm_eps,
                    resnet_act_fn=act_fn,
                    resnet_groups=norm_num_groups,
                    add_downsample=not is_final_block,
                    compress_time=compress_time,
                )
            else:
                raise ValueError("Invalid `down_block_type` encountered. Must be `CogVideoXDownBlock3D`")

            self.down_blocks.append(down_block)

        # mid block
        self.mid_block = CogVideoXMidBlock3D(
            in_channels=block_out_channels[-1],
            temb_channels=0,
            dropout=dropout,
            num_layers=2,
            resnet_eps=norm_eps,
            resnet_act_fn=act_fn,
            resnet_groups=norm_num_groups,
            pad_mode=pad_mode,
        )

        self.norm_out = nn.GroupNorm(norm_num_groups, block_out_channels[-1], eps=1e-6)
        self.conv_act = nn.SiLU()
        self.conv_out = CogVideoXCausalConv3d(
            block_out_channels[-1], 2 * out_channels, kernel_size=3, pad_mode=pad_mode
        )

        self.gradient_checkpointing = False

    def forward(self, sample: torch.Tensor, temb: Optional[torch.Tensor] = None) -> torch.Tensor:
        r"""The forward method of the `CogVideoXEncoder3D` class."""
        hidden_states = self.conv_in(sample)

        if self.training and self.gradient_checkpointing:

            def create_custom_forward(module):
                def custom_forward(*inputs):
                    return module(*inputs)

                return custom_forward

            # 1. Down
            for down_block in self.down_blocks:
                hidden_states = torch.utils.checkpoint.checkpoint(
                    create_custom_forward(down_block), hidden_states, temb, None
                )

            # 2. Mid
            hidden_states = torch.utils.checkpoint.checkpoint(
                create_custom_forward(self.mid_block), hidden_states, temb, None
            )
        else:
            # 1. Down
            for down_block in self.down_blocks:
                hidden_states = down_block(hidden_states, temb, None)

            # 2. Mid
            hidden_states = self.mid_block(hidden_states, temb, None)

        # 3. Post-process
        hidden_states = self.norm_out(hidden_states)
        hidden_states = self.conv_act(hidden_states)
        hidden_states = self.conv_out(hidden_states)
        return hidden_states


class CogVideoXDecoder3D(nn.Module):
    r"""
    The `CogVideoXDecoder3D` layer of a variational autoencoder that decodes its latent representation into an output
    sample.

    Args:
        in_channels (`int`, *optional*, defaults to 3):
            The number of input channels.
        out_channels (`int`, *optional*, defaults to 3):
            The number of output channels.
        up_block_types (`Tuple[str, ...]`, *optional*, defaults to `("UpDecoderBlock2D",)`):
            The types of up blocks to use. See `~diffusers.models.unet_2d_blocks.get_up_block` for available options.
        block_out_channels (`Tuple[int, ...]`, *optional*, defaults to `(64,)`):
            The number of output channels for each block.
        layers_per_block (`int`, *optional*, defaults to 2):
            The number of layers per block.
        norm_num_groups (`int`, *optional*, defaults to 32):
            The number of groups for normalization.
        act_fn (`str`, *optional*, defaults to `"silu"`):
            The activation function to use. See `~diffusers.models.activations.get_activation` for available options.
        norm_type (`str`, *optional*, defaults to `"group"`):
            The normalization type to use. Can be either `"group"` or `"spatial"`.
    """

    _supports_gradient_checkpointing = True

    def __init__(
        self,
        in_channels: int = 16,
        out_channels: int = 3,
        up_block_types: Tuple[str, ...] = (
            "CogVideoXUpBlock3D",
            "CogVideoXUpBlock3D",
            "CogVideoXUpBlock3D",
            "CogVideoXUpBlock3D",
        ),
        block_out_channels: Tuple[int, ...] = (128, 256, 256, 512),
        layers_per_block: int = 3,
        act_fn: str = "silu",
        norm_eps: float = 1e-6,
        norm_num_groups: int = 32,
        dropout: float = 0.0,
        pad_mode: str = "first",
        temporal_compression_ratio: float = 4,
    ):
        super().__init__()

        reversed_block_out_channels = list(reversed(block_out_channels))

        self.conv_in = CogVideoXCausalConv3d(
            in_channels, reversed_block_out_channels[0], kernel_size=3, pad_mode=pad_mode
        )

        # mid block
        self.mid_block = CogVideoXMidBlock3D(
            in_channels=reversed_block_out_channels[0],
            temb_channels=0,
            num_layers=2,
            resnet_eps=norm_eps,
            resnet_act_fn=act_fn,
            resnet_groups=norm_num_groups,
            spatial_norm_dim=in_channels,
            pad_mode=pad_mode,
        )

        # up blocks
        self.up_blocks = nn.ModuleList([])

        output_channel = reversed_block_out_channels[0]
        temporal_compress_level = int(np.log2(temporal_compression_ratio))

        for i, up_block_type in enumerate(up_block_types):
            prev_output_channel = output_channel
            output_channel = reversed_block_out_channels[i]
            is_final_block = i == len(block_out_channels) - 1
            compress_time = i < temporal_compress_level

            if up_block_type == "CogVideoXUpBlock3D":
                up_block = CogVideoXUpBlock3D(
                    in_channels=prev_output_channel,
                    out_channels=output_channel,
                    temb_channels=0,
                    dropout=dropout,
                    num_layers=layers_per_block + 1,
                    resnet_eps=norm_eps,
                    resnet_act_fn=act_fn,
                    resnet_groups=norm_num_groups,
                    spatial_norm_dim=in_channels,
                    add_upsample=not is_final_block,
                    compress_time=compress_time,
                    pad_mode=pad_mode,
                )
                prev_output_channel = output_channel
            else:
                raise ValueError("Invalid `up_block_type` encountered. Must be `CogVideoXUpBlock3D`")

            self.up_blocks.append(up_block)

        self.norm_out = CogVideoXSpatialNorm3D(reversed_block_out_channels[-1], in_channels, groups=norm_num_groups)
        self.conv_act = nn.SiLU()
        self.conv_out = CogVideoXCausalConv3d(
            reversed_block_out_channels[-1], out_channels, kernel_size=3, pad_mode=pad_mode
        )

        self.gradient_checkpointing = False

    def forward(self, sample: torch.Tensor, temb: Optional[torch.Tensor] = None) -> torch.Tensor:
        r"""The forward method of the `CogVideoXDecoder3D` class."""
        hidden_states = self.conv_in(sample)

        if self.training and self.gradient_checkpointing:

            def create_custom_forward(module):
                def custom_forward(*inputs):
                    return module(*inputs)

                return custom_forward

            # 1. Mid
            hidden_states = torch.utils.checkpoint.checkpoint(
                create_custom_forward(self.mid_block), hidden_states, temb, sample
            )

            # 2. Up
            for up_block in self.up_blocks:
                hidden_states = torch.utils.checkpoint.checkpoint(
                    create_custom_forward(up_block), hidden_states, temb, sample
                )
        else:
            # 1. Mid
            hidden_states = self.mid_block(hidden_states, temb, sample)

            # 2. Up
            for up_block in self.up_blocks:
                hidden_states = up_block(hidden_states, temb, sample)

        # 3. Post-process
        hidden_states = self.norm_out(hidden_states, sample)
        hidden_states = self.conv_act(hidden_states)
        hidden_states = self.conv_out(hidden_states)
        return hidden_states


class AutoencoderKLCogVideoX(ModelMixin, ConfigMixin, FromOriginalModelMixin):
    r"""
    A VAE model with KL loss for encoding images into latents and decoding latent representations into images. Used in
    [CogVideoX](https://github.com/THUDM/CogVideo).

    This model inherits from [`ModelMixin`]. Check the superclass documentation for it's generic methods implemented
    for all models (such as downloading or saving).

    Parameters:
        in_channels (int, *optional*, defaults to 3): Number of channels in the input image.
        out_channels (int,  *optional*, defaults to 3): Number of channels in the output.
        down_block_types (`Tuple[str]`, *optional*, defaults to `("DownEncoderBlock2D",)`):
            Tuple of downsample block types.
        up_block_types (`Tuple[str]`, *optional*, defaults to `("UpDecoderBlock2D",)`):
            Tuple of upsample block types.
        block_out_channels (`Tuple[int]`, *optional*, defaults to `(64,)`):
            Tuple of block output channels.
        act_fn (`str`, *optional*, defaults to `"silu"`): The activation function to use.
        sample_size (`int`, *optional*, defaults to `32`): Sample input size.
        scaling_factor (`float`, *optional*, defaults to 0.18215):
            The component-wise standard deviation of the trained latent space computed using the first batch of the
            training set. This is used to scale the latent space to have unit variance when training the diffusion
            model. The latents are scaled with the formula `z = z * scaling_factor` before being passed to the
            diffusion model. When decoding, the latents are scaled back to the original scale with the formula: `z = 1
            / scaling_factor * z`. For more details, refer to sections 4.3.2 and D.1 of the [High-Resolution Image
            Synthesis with Latent Diffusion Models](https://arxiv.org/abs/2112.10752) paper.
        force_upcast (`bool`, *optional*, default to `True`):
            If enabled it will force the VAE to run in float32 for high image resolution pipelines, such as SD-XL. VAE
            can be fine-tuned / trained to a lower range without loosing too much precision in which case
            `force_upcast` can be set to `False` - see: https://huggingface.co/madebyollin/sdxl-vae-fp16-fix
    """

    _supports_gradient_checkpointing = True
    _no_split_modules = ["CogVideoXResnetBlock3D"]

    @register_to_config
    def __init__(
        self,
        in_channels: int = 3,
        out_channels: int = 3,
        down_block_types: Tuple[str] = (
            "CogVideoXDownBlock3D",
            "CogVideoXDownBlock3D",
            "CogVideoXDownBlock3D",
            "CogVideoXDownBlock3D",
        ),
        up_block_types: Tuple[str] = (
            "CogVideoXUpBlock3D",
            "CogVideoXUpBlock3D",
            "CogVideoXUpBlock3D",
            "CogVideoXUpBlock3D",
        ),
        block_out_channels: Tuple[int] = (128, 256, 256, 512),
        latent_channels: int = 16,
        layers_per_block: int = 3,
        act_fn: str = "silu",
        norm_eps: float = 1e-6,
        norm_num_groups: int = 32,
        temporal_compression_ratio: float = 4,
        sample_size: int = 256,
        scaling_factor: float = 1.15258426,
        shift_factor: Optional[float] = None,
        latents_mean: Optional[Tuple[float]] = None,
        latents_std: Optional[Tuple[float]] = None,
        force_upcast: float = True,
        use_quant_conv: bool = False,
        use_post_quant_conv: bool = False,
    ):
        super().__init__()

        self.encoder = CogVideoXEncoder3D(
            in_channels=in_channels,
            out_channels=latent_channels,
            down_block_types=down_block_types,
            block_out_channels=block_out_channels,
            layers_per_block=layers_per_block,
            act_fn=act_fn,
            norm_eps=norm_eps,
            norm_num_groups=norm_num_groups,
            temporal_compression_ratio=temporal_compression_ratio,
        )
        self.decoder = CogVideoXDecoder3D(
            in_channels=latent_channels,
            out_channels=out_channels,
            up_block_types=up_block_types,
            block_out_channels=block_out_channels,
            layers_per_block=layers_per_block,
            act_fn=act_fn,
            norm_eps=norm_eps,
            norm_num_groups=norm_num_groups,
            temporal_compression_ratio=temporal_compression_ratio,
        )
        self.quant_conv = CogVideoXSafeConv3d(2 * out_channels, 2 * out_channels, 1) if use_quant_conv else None
        self.post_quant_conv = CogVideoXSafeConv3d(out_channels, out_channels, 1) if use_post_quant_conv else None

        self.use_slicing = False
        self.use_tiling = False

        self.tile_sample_min_size = self.config.sample_size
        sample_size = (
            self.config.sample_size[0]
            if isinstance(self.config.sample_size, (list, tuple))
            else self.config.sample_size
        )
        self.tile_latent_min_size = int(sample_size / (2 ** (len(self.config.block_out_channels) - 1)))
        self.tile_overlap_factor = 0.25

    def _set_gradient_checkpointing(self, module, value=False):
        if isinstance(module, (CogVideoXEncoder3D, CogVideoXDecoder3D)):
            module.gradient_checkpointing = value

    def clear_fake_context_parallel_cache(self):
        for name, module in self.named_modules():
            if isinstance(module, CogVideoXCausalConv3d):
                logger.debug(f"Clearing fake Context Parallel cache for layer: {name}")
                module._clear_fake_context_parallel_cache()

    @apply_forward_hook
    def encode(
        self, x: torch.Tensor, return_dict: bool = True
    ) -> Union[AutoencoderKLOutput, Tuple[DiagonalGaussianDistribution]]:
        """
        Encode a batch of images into latents.

        Args:
            x (`torch.Tensor`): Input batch of images.
            return_dict (`bool`, *optional*, defaults to `True`):
                Whether to return a [`~models.autoencoder_kl.AutoencoderKLOutput`] instead of a plain tuple.

        Returns:
                The latent representations of the encoded images. If `return_dict` is True, a
                [`~models.autoencoder_kl.AutoencoderKLOutput`] is returned, otherwise a plain `tuple` is returned.
        """
        h = self.encoder(x)
        if self.quant_conv is not None:
            h = self.quant_conv(h)
        posterior = DiagonalGaussianDistribution(h)
        if not return_dict:
            return (posterior,)
        return AutoencoderKLOutput(latent_dist=posterior)

    @apply_forward_hook
    def decode(self, z: torch.FloatTensor, return_dict: bool = True) -> Union[DecoderOutput, torch.FloatTensor]:
        """
        Decode a batch of images.

        Args:
            z (`torch.Tensor`): Input batch of latent vectors.
            return_dict (`bool`, *optional*, defaults to `True`):
                Whether to return a [`~models.vae.DecoderOutput`] instead of a plain tuple.

        Returns:
            [`~models.vae.DecoderOutput`] or `tuple`:
                If return_dict is True, a [`~models.vae.DecoderOutput`] is returned, otherwise a plain `tuple` is
                returned.

        """
        if self.post_quant_conv is not None:
            z = self.post_quant_conv(z)
        dec = self.decoder(z)
        if not return_dict:
            return (dec,)
        return DecoderOutput(sample=dec)

    def forward(
        self,
        sample: torch.Tensor,
        sample_posterior: bool = False,
        return_dict: bool = True,
        generator: Optional[torch.Generator] = None,
    ) -> Union[torch.Tensor, torch.Tensor]:
        x = sample
        posterior = self.encode(x).latent_dist
        if sample_posterior:
            z = posterior.sample(generator=generator)
        else:
            z = posterior.mode()
        dec = self.decode(z)
        if not return_dict:
            return (dec,)
        return dec