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Python

# SPDX-License-Identifier: Apache-2.0
# Copied and adapted from: https://github.com/sglang-ai/sglang
import math
from typing import Dict, Optional, Tuple, Union
import torch
import torch.nn as nn
from fastvideo.configs.models.vaes.flux2vae import Flux2VAEConfig
from fastvideo.models.vaes.common import (
DiagonalGaussianDistribution,
ParallelTiledVAE,
)
from fastvideo.models.vaes.flux2_components import (
ADDED_KV_ATTENTION_PROCESSORS,
CROSS_ATTENTION_PROCESSORS,
Attention,
AttnAddedKVProcessor,
AttnProcessor,
AutoencoderKLOutput,
Decoder,
DecoderOutput,
Encoder,
)
AttentionProcessor = AttnProcessor
class AutoencoderKLFlux2(nn.Module, ParallelTiledVAE):
r"""
A VAE model with KL loss for encoding images into latents and decoding latent representations into images.
This model inherits from [`ParallelTiledVAE`] for tiling support and uses standard diffusers
Encoder/Decoder components for Flux2 image generation.
"""
_supports_gradient_checkpointing = True
_no_split_modules = ["Attention", "ResnetBlock2D"]
def __init__(
self,
config: Flux2VAEConfig,
):
nn.Module.__init__(self)
ParallelTiledVAE.__init__(self, config=config)
self.config = config
arch_config = config.arch_config
in_channels: int = arch_config.in_channels
out_channels: int = arch_config.out_channels
down_block_types: Tuple[str, ...] = arch_config.down_block_types
up_block_types: Tuple[str, ...] = arch_config.up_block_types
block_out_channels: Tuple[int, ...] = arch_config.block_out_channels
layers_per_block: int = arch_config.layers_per_block
act_fn: str = arch_config.act_fn
latent_channels: int = arch_config.latent_channels
norm_num_groups: int = arch_config.norm_num_groups
sample_size: int = arch_config.sample_size
force_upcast: bool = arch_config.force_upcast
use_quant_conv: bool = arch_config.use_quant_conv
use_post_quant_conv: bool = arch_config.use_post_quant_conv
mid_block_add_attention: bool = arch_config.mid_block_add_attention
batch_norm_eps: float = arch_config.batch_norm_eps
batch_norm_momentum: float = arch_config.batch_norm_momentum
patch_size: Tuple[int, int] = arch_config.patch_size
# 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=True,
mid_block_add_attention=mid_block_add_attention,
)
# 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,
norm_num_groups=norm_num_groups,
act_fn=act_fn,
mid_block_add_attention=mid_block_add_attention,
)
self.quant_conv = (nn.Conv2d(2 * latent_channels, 2 * latent_channels, 1) if use_quant_conv else None)
self.post_quant_conv = (nn.Conv2d(latent_channels, latent_channels, 1) if use_post_quant_conv else None)
self.bn = nn.BatchNorm2d(
math.prod(patch_size) * latent_channels,
eps=batch_norm_eps,
momentum=batch_norm_momentum,
affine=False,
track_running_stats=True,
)
self.use_slicing = False
self.use_tiling = False
# only relevant if vae tiling is enabled
self.tile_sample_min_size = sample_size
sample_size_val = (sample_size[0] if isinstance(sample_size, (list, tuple)) else sample_size)
self.tile_latent_min_size = int(sample_size_val / (2**(len(block_out_channels) - 1)))
self.tile_overlap_factor = 0.25
@property
# Copied from diffusers.models.unets.unet_2d_condition.UNet2DConditionModel.attn_processors
def attn_processors(self) -> Dict[str, AttentionProcessor]:
r"""
Returns:
`dict` of attention processors: A dictionary containing all attention processors used in the model with
indexed by its weight name.
"""
# set recursively
processors = {}
def fn_recursive_add_processors(
name: str,
module: torch.nn.Module,
processors: Dict[str, AttentionProcessor],
):
if hasattr(module, "get_processor"):
processors[f"{name}.processor"] = module.get_processor()
for sub_name, child in module.named_children():
fn_recursive_add_processors(f"{name}.{sub_name}", child, processors)
return processors
for name, module in self.named_children():
fn_recursive_add_processors(name, module, processors)
return processors
# Copied from diffusers.models.unets.unet_2d_condition.UNet2DConditionModel.set_attn_processor
def set_attn_processor(self, processor: Union[AttentionProcessor, Dict[str, AttentionProcessor]]):
r"""
Sets the attention processor to use to compute attention.
Parameters:
processor (`dict` of `AttentionProcessor` or only `AttentionProcessor`):
The instantiated processor class or a dictionary of processor classes that will be set as the processor
for **all** `Attention` layers.
If `processor` is a dict, the key needs to define the path to the corresponding cross attention
processor. This is strongly recommended when setting trainable attention processors.
"""
count = len(self.attn_processors.keys())
if isinstance(processor, dict) and len(processor) != count:
raise ValueError(
f"A dict of processors was passed, but the number of processors {len(processor)} does not match the"
f" number of attention layers: {count}. Please make sure to pass {count} processor classes.")
def fn_recursive_attn_processor(name: str, module: torch.nn.Module, processor):
if hasattr(module, "set_processor"):
if not isinstance(processor, dict):
module.set_processor(processor)
else:
module.set_processor(processor.pop(f"{name}.processor"))
for sub_name, child in module.named_children():
fn_recursive_attn_processor(f"{name}.{sub_name}", child, processor)
for name, module in self.named_children():
fn_recursive_attn_processor(name, module, processor)
# Copied from diffusers.models.unets.unet_2d_condition.UNet2DConditionModel.set_default_attn_processor
def set_default_attn_processor(self):
"""
Disables custom attention processors and sets the default attention implementation.
"""
if all(proc.__class__ in ADDED_KV_ATTENTION_PROCESSORS for proc in self.attn_processors.values()):
processor = AttnAddedKVProcessor()
elif all(proc.__class__ in CROSS_ATTENTION_PROCESSORS for proc in self.attn_processors.values()):
processor = AttnProcessor()
else:
raise ValueError(
f"Cannot call `set_default_attn_processor` when attention processors are of type {next(iter(self.attn_processors.values()))}"
)
self.set_attn_processor(processor)
def _encode(self, x: torch.Tensor) -> torch.Tensor:
batch_size, num_channels, height, width = x.shape
if self.use_tiling and (width > self.tile_sample_min_size or height > self.tile_sample_min_size):
return self._tiled_encode(x)
enc = self.encoder(x)
if self.quant_conv is not None:
enc = self.quant_conv(enc)
return enc
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.
"""
if x.ndim == 5:
assert x.shape[2] == 1
x = x.squeeze(2)
if self.use_slicing and x.shape[0] > 1:
encoded_slices = [self._encode(x_slice) for x_slice in x.split(1)]
h = torch.cat(encoded_slices)
else:
h = self._encode(x)
posterior = DiagonalGaussianDistribution(h)
if not return_dict:
return (posterior, )
return AutoencoderKLOutput(latent_dist=posterior)
def _decode(self, z: torch.Tensor, return_dict: bool = True) -> Union[DecoderOutput, torch.Tensor]:
if self.use_tiling and (z.shape[-1] > self.tile_latent_min_size or z.shape[-2] > self.tile_latent_min_size):
return self.tiled_decode(z, return_dict=return_dict)
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 decode(self,
z: torch.FloatTensor,
return_dict: bool = True,
generator=None) -> 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.use_slicing and z.shape[0] > 1:
decoded_slices = [self._decode(z_slice).sample for z_slice in z.split(1)]
decoded = torch.cat(decoded_slices)
else:
decoded = self._decode(z).sample
if not return_dict:
return (decoded, )
return DecoderOutput(sample=decoded)
def blend_v(self, a: torch.Tensor, b: torch.Tensor, blend_extent: int) -> torch.Tensor:
blend_extent = min(a.shape[2], b.shape[2], blend_extent)
for y in range(blend_extent):
b[:, :, y, :] = a[:, :, -blend_extent + y, :] * (1 - y / blend_extent) + b[:, :, y, :] * (y / blend_extent)
return b
def blend_h(self, a: torch.Tensor, b: torch.Tensor, blend_extent: int) -> torch.Tensor:
blend_extent = min(a.shape[3], b.shape[3], blend_extent)
for x in range(blend_extent):
b[:, :, :, x] = a[:, :, :, -blend_extent + x] * (1 - x / blend_extent) + b[:, :, :, x] * (x / blend_extent)
return b
def _tiled_encode(self, x: torch.Tensor) -> torch.Tensor:
r"""Encode a batch of images using a tiled encoder.
When this option is enabled, the VAE will split the input tensor into tiles to compute encoding in several
steps. This is useful to keep memory use constant regardless of image size. The end result of tiled encoding is
different from non-tiled encoding because each tile uses a different encoder. To avoid tiling artifacts, the
tiles overlap and are blended together to form a smooth output. You may still see tile-sized changes in the
output, but they should be much less noticeable.
Args:
x (`torch.Tensor`): Input batch of images.
Returns:
`torch.Tensor`:
The latent representation of the encoded videos.
"""
overlap_size = int(self.tile_sample_min_size * (1 - self.tile_overlap_factor))
blend_extent = int(self.tile_latent_min_size * self.tile_overlap_factor)
row_limit = self.tile_latent_min_size - blend_extent
# Split the image into 512x512 tiles and encode them separately.
rows = []
for i in range(0, x.shape[2], overlap_size):
row = []
for j in range(0, x.shape[3], overlap_size):
tile = x[
:,
:,
i:i + self.tile_sample_min_size,
j:j + self.tile_sample_min_size,
]
tile = self.encoder(tile)
if self.quant_conv is not None:
tile = self.quant_conv(tile)
row.append(tile)
rows.append(row)
result_rows = []
for i, row in enumerate(rows):
result_row = []
for j, tile in enumerate(row):
# blend the above tile and the left tile
# to the current tile and add the current tile to the result row
if i > 0:
tile = self.blend_v(rows[i - 1][j], tile, blend_extent)
if j > 0:
tile = self.blend_h(row[j - 1], tile, blend_extent)
result_row.append(tile[:, :, :row_limit, :row_limit])
result_rows.append(torch.cat(result_row, dim=3))
enc = torch.cat(result_rows, dim=2)
return enc
def tiled_encode(self, x: torch.Tensor, return_dict: bool = True) -> AutoencoderKLOutput:
r"""Encode a batch of images using a tiled encoder.
When this option is enabled, the VAE will split the input tensor into tiles to compute encoding in several
steps. This is useful to keep memory use constant regardless of image size. The end result of tiled encoding is
different from non-tiled encoding because each tile uses a different encoder. To avoid tiling artifacts, the
tiles overlap and are blended together to form a smooth output. You may still see tile-sized changes in the
output, but they should be much less noticeable.
Args:
x (`torch.Tensor`): Input batch of images.
return_dict (`bool`, *optional*, defaults to `True`):
Whether or not to return a [`~models.autoencoder_kl.AutoencoderKLOutput`] instead of a plain tuple.
Returns:
[`~models.autoencoder_kl.AutoencoderKLOutput`] or `tuple`:
If return_dict is True, a [`~models.autoencoder_kl.AutoencoderKLOutput`] is returned, otherwise a plain
`tuple` is returned.
"""
deprecation_message = (
"The tiled_encode implementation supporting the `return_dict` parameter is deprecated. In the future, the "
"implementation of this method will be replaced with that of `_tiled_encode` and you will no longer be able "
"to pass `return_dict`. You will also have to create a `DiagonalGaussianDistribution()` from the returned value."
)
overlap_size = int(self.tile_sample_min_size * (1 - self.tile_overlap_factor))
blend_extent = int(self.tile_latent_min_size * self.tile_overlap_factor)
row_limit = self.tile_latent_min_size - blend_extent
# Split the image into 512x512 tiles and encode them separately.
rows = []
for i in range(0, x.shape[2], overlap_size):
row = []
for j in range(0, x.shape[3], overlap_size):
tile = x[
:,
:,
i:i + self.tile_sample_min_size,
j:j + self.tile_sample_min_size,
]
tile = self.encoder(tile)
if self.quant_conv is not None:
tile = self.quant_conv(tile)
row.append(tile)
rows.append(row)
result_rows = []
for i, row in enumerate(rows):
result_row = []
for j, tile in enumerate(row):
# blend the above tile and the left tile
# to the current tile and add the current tile to the result row
if i > 0:
tile = self.blend_v(rows[i - 1][j], tile, blend_extent)
if j > 0:
tile = self.blend_h(row[j - 1], tile, blend_extent)
result_row.append(tile[:, :, :row_limit, :row_limit])
result_rows.append(torch.cat(result_row, dim=3))
moments = torch.cat(result_rows, dim=2)
posterior = DiagonalGaussianDistribution(moments)
if not return_dict:
return (posterior, )
return AutoencoderKLOutput(latent_dist=posterior)
def tiled_decode(self, z: torch.Tensor, return_dict: bool = True) -> Union[DecoderOutput, torch.Tensor]:
r"""
Decode a batch of images using a tiled decoder.
Args:
z (`torch.Tensor`): Input batch of latent vectors.
return_dict (`bool`, *optional*, defaults to `True`):
Whether or not 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.
"""
overlap_size = int(self.tile_latent_min_size * (1 - self.tile_overlap_factor))
blend_extent = int(self.tile_sample_min_size * self.tile_overlap_factor)
row_limit = self.tile_sample_min_size - blend_extent
# Split z into overlapping 64x64 tiles and decode them separately.
# The tiles have an overlap to avoid seams between tiles.
rows = []
for i in range(0, z.shape[2], overlap_size):
row = []
for j in range(0, z.shape[3], overlap_size):
tile = z[
:,
:,
i:i + self.tile_latent_min_size,
j:j + self.tile_latent_min_size,
]
if self.post_quant_conv is not None:
tile = self.post_quant_conv(tile)
decoded = self.decoder(tile)
row.append(decoded)
rows.append(row)
result_rows = []
for i, row in enumerate(rows):
result_row = []
for j, tile in enumerate(row):
# blend the above tile and the left tile
# to the current tile and add the current tile to the result row
if i > 0:
tile = self.blend_v(rows[i - 1][j], tile, blend_extent)
if j > 0:
tile = self.blend_h(row[j - 1], tile, blend_extent)
result_row.append(tile[:, :, :row_limit, :row_limit])
result_rows.append(torch.cat(result_row, dim=3))
dec = torch.cat(result_rows, dim=2)
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[DecoderOutput, torch.Tensor]:
r"""
Args:
sample (`torch.Tensor`): Input sample.
sample_posterior (`bool`, *optional*, defaults to `False`):
Whether to sample from the posterior.
return_dict (`bool`, *optional*, defaults to `True`):
Whether or not to return a [`DecoderOutput`] instead of a plain tuple.
"""
x = sample
posterior = self.encode(x).latent_dist
if sample_posterior:
z = posterior.sample(generator=generator)
else:
z = posterior.mode()
dec = self.decode(z).sample
if not return_dict:
return (dec, )
return DecoderOutput(sample=dec)
EntryClass = AutoencoderKLFlux2