vq_model.py

# Copyright 2022 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.
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from dataclasses import dataclass
from typing import Optional, Tuple, Union

import torch
import torch.nn as nn

from ..configuration_utils import ConfigMixin, register_to_config
from ..utils import BaseOutput
from .modeling_utils import ModelMixin
from .vae import Decoder, DecoderOutput, Encoder, VectorQuantizer


@dataclass
class VQEncoderOutput(BaseOutput):
    """
    Output of VQModel encoding method.

    Args:
        latents (`torch.FloatTensor` of shape `(batch_size, num_channels, height, width)`):
            Encoded output sample of the model. Output of the last layer of the model.
    """

    latents: torch.FloatTensor


class VQModel(ModelMixin, ConfigMixin):
    r"""VQ-VAE model from the paper Neural Discrete Representation Learning by Aaron van den Oord, Oriol Vinyals and Koray
    Kavukcuoglu.

    This model inherits from [`ModelMixin`]. Check the superclass documentation for the generic methods the library
    implements for all the model (such as downloading or saving, etc.)

    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 :
            obj:`("DownEncoderBlock2D",)`): Tuple of downsample block types.
        up_block_types (`Tuple[str]`, *optional*, defaults to :
            obj:`("UpDecoderBlock2D",)`): Tuple of upsample block types.
        block_out_channels (`Tuple[int]`, *optional*, defaults to :
            obj:`(64,)`): Tuple of block output channels.
        act_fn (`str`, *optional*, defaults to `"silu"`): The activation function to use.
        latent_channels (`int`, *optional*, defaults to `3`): Number of channels in the latent space.
        sample_size (`int`, *optional*, defaults to `32`): TODO
        num_vq_embeddings (`int`, *optional*, defaults to `256`): Number of codebook vectors in the VQ-VAE.
        vq_embed_dim (`int`, *optional*): Hidden dim of codebook vectors in the VQ-VAE.
    """

    @register_to_config
    def __init__(
        self,
        in_channels: int = 3,
        out_channels: int = 3,
        down_block_types: Tuple[str] = ("DownEncoderBlock2D",),
        up_block_types: Tuple[str] = ("UpDecoderBlock2D",),
        block_out_channels: Tuple[int] = (64,),
        layers_per_block: int = 1,
        act_fn: str = "silu",
        latent_channels: int = 3,
        sample_size: int = 32,
        num_vq_embeddings: int = 256,
        norm_num_groups: int = 32,
        vq_embed_dim: Optional[int] = None,
    ):
        super().__init__()

        # pass init params to Encoder
        self.encoder = Encoder(
            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_num_groups=norm_num_groups,
            double_z=False,
        )

        vq_embed_dim = vq_embed_dim if vq_embed_dim is not None else latent_channels

        self.quant_conv = nn.Conv2d(latent_channels, vq_embed_dim, 1)
        self.quantize = VectorQuantizer(num_vq_embeddings, vq_embed_dim, beta=0.25, remap=None, sane_index_shape=False)
        self.post_quant_conv = nn.Conv2d(vq_embed_dim, latent_channels, 1)

        # pass init params to Decoder
        self.decoder = Decoder(
            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_num_groups=norm_num_groups,
        )

    def encode(self, x: torch.FloatTensor, return_dict: bool = True) -> VQEncoderOutput:
        h = self.encoder(x)
        h = self.quant_conv(h)

        if not return_dict:
            return (h,)

        return VQEncoderOutput(latents=h)

    def decode(
        self, h: torch.FloatTensor, force_not_quantize: bool = False, return_dict: bool = True
    ) -> Union[DecoderOutput, torch.FloatTensor]:
        # also go through quantization layer
        if not force_not_quantize:
            quant, emb_loss, info = self.quantize(h)
        else:
            quant = h
        quant = self.post_quant_conv(quant)
        dec = self.decoder(quant)

        if not return_dict:
            return (dec,)

        return DecoderOutput(sample=dec)

    def forward(self, sample: torch.FloatTensor, return_dict: bool = True) -> Union[DecoderOutput, torch.FloatTensor]:
        r"""
        Args:
            sample (`torch.FloatTensor`): Input sample.
            return_dict (`bool`, *optional*, defaults to `True`):
                Whether or not to return a [`DecoderOutput`] instead of a plain tuple.
        """
        x = sample
        h = self.encode(x).latents
        dec = self.decode(h).sample

        if not return_dict:
            return (dec,)

        return DecoderOutput(sample=dec)