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# 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.
# See the License for the specific language governing permissions and
# limitations under the License.
from typing import Tuple, Union
import flax
import flax.linen as nn
import jax
import jax.numpy as jnp
from flax.core.frozen_dict import FrozenDict
from ..configuration_utils import ConfigMixin, flax_register_to_config
from ..utils import BaseOutput
from .embeddings_flax import FlaxTimestepEmbedding, FlaxTimesteps
from .modeling_flax_utils import FlaxModelMixin
from .unet_2d_blocks_flax import (
FlaxCrossAttnDownBlock2D,
FlaxCrossAttnUpBlock2D,
FlaxDownBlock2D,
FlaxUNetMidBlock2DCrossAttn,
FlaxUpBlock2D,
)
@flax.struct.dataclass
class FlaxUNet2DConditionOutput(BaseOutput):
"""
Args:
sample (`jnp.ndarray` of shape `(batch_size, num_channels, height, width)`):
Hidden states conditioned on `encoder_hidden_states` input. Output of last layer of model.
"""
sample: jnp.ndarray
@flax_register_to_config
class FlaxUNet2DConditionModel(nn.Module, FlaxModelMixin, ConfigMixin):
r"""
FlaxUNet2DConditionModel is a conditional 2D UNet model that takes in a noisy sample, conditional state, and a
timestep and returns sample shaped output.
This model inherits from [`FlaxModelMixin`]. Check the superclass documentation for the generic methods the library
implements for all the models (such as downloading or saving, etc.)
Also, this model is a Flax Linen [flax.linen.Module](https://flax.readthedocs.io/en/latest/flax.linen.html#module)
subclass. Use it as a regular Flax linen Module and refer to the Flax documentation for all matter related to
general usage and behavior.
Finally, this model supports inherent JAX features such as:
- [Just-In-Time (JIT) compilation](https://jax.readthedocs.io/en/latest/jax.html#just-in-time-compilation-jit)
- [Automatic Differentiation](https://jax.readthedocs.io/en/latest/jax.html#automatic-differentiation)
- [Vectorization](https://jax.readthedocs.io/en/latest/jax.html#vectorization-vmap)
- [Parallelization](https://jax.readthedocs.io/en/latest/jax.html#parallelization-pmap)
Parameters:
sample_size (`int`, *optional*):
The size of the input sample.
in_channels (`int`, *optional*, defaults to 4):
The number of channels in the input sample.
out_channels (`int`, *optional*, defaults to 4):
The number of channels in the output.
down_block_types (`Tuple[str]`, *optional*, defaults to `("CrossAttnDownBlock2D", "CrossAttnDownBlock2D", "CrossAttnDownBlock2D", "DownBlock2D")`):
The tuple of downsample blocks to use. The corresponding class names will be: "FlaxCrossAttnDownBlock2D",
"FlaxCrossAttnDownBlock2D", "FlaxCrossAttnDownBlock2D", "FlaxDownBlock2D"
up_block_types (`Tuple[str]`, *optional*, defaults to `("UpBlock2D", "CrossAttnUpBlock2D", "CrossAttnUpBlock2D", "CrossAttnUpBlock2D",)`):
The tuple of upsample blocks to use. The corresponding class names will be: "FlaxUpBlock2D",
"FlaxCrossAttnUpBlock2D", "FlaxCrossAttnUpBlock2D", "FlaxCrossAttnUpBlock2D"
block_out_channels (`Tuple[int]`, *optional*, defaults to `(320, 640, 1280, 1280)`):
The tuple of output channels for each block.
layers_per_block (`int`, *optional*, defaults to 2):
The number of layers per block.
attention_head_dim (`int` or `Tuple[int]`, *optional*, defaults to 8):
The dimension of the attention heads.
cross_attention_dim (`int`, *optional*, defaults to 768):
The dimension of the cross attention features.
dropout (`float`, *optional*, defaults to 0):
Dropout probability for down, up and bottleneck blocks.
flip_sin_to_cos (`bool`, *optional*, defaults to `True`):
Whether to flip the sin to cos in the time embedding.
freq_shift (`int`, *optional*, defaults to 0): The frequency shift to apply to the time embedding.
"""
sample_size: int = 32
in_channels: int = 4
out_channels: int = 4
down_block_types: Tuple[str] = (
"CrossAttnDownBlock2D",
"CrossAttnDownBlock2D",
"CrossAttnDownBlock2D",
"DownBlock2D",
)
up_block_types: Tuple[str] = ("UpBlock2D", "CrossAttnUpBlock2D", "CrossAttnUpBlock2D", "CrossAttnUpBlock2D")
only_cross_attention: Union[bool, Tuple[bool]] = False
block_out_channels: Tuple[int] = (320, 640, 1280, 1280)
layers_per_block: int = 2
attention_head_dim: Union[int, Tuple[int]] = 8
cross_attention_dim: int = 1280
dropout: float = 0.0
use_linear_projection: bool = False
dtype: jnp.dtype = jnp.float32
flip_sin_to_cos: bool = True
freq_shift: int = 0
def init_weights(self, rng: jax.random.KeyArray) -> FrozenDict:
# init input tensors
sample_shape = (1, self.in_channels, self.sample_size, self.sample_size)
sample = jnp.zeros(sample_shape, dtype=jnp.float32)
timesteps = jnp.ones((1,), dtype=jnp.int32)
encoder_hidden_states = jnp.zeros((1, 1, self.cross_attention_dim), dtype=jnp.float32)
params_rng, dropout_rng = jax.random.split(rng)
rngs = {"params": params_rng, "dropout": dropout_rng}
return self.init(rngs, sample, timesteps, encoder_hidden_states)["params"]
def setup(self):
block_out_channels = self.block_out_channels
time_embed_dim = block_out_channels[0] * 4
# input
self.conv_in = nn.Conv(
block_out_channels[0],
kernel_size=(3, 3),
strides=(1, 1),
padding=((1, 1), (1, 1)),
dtype=self.dtype,
)
# time
self.time_proj = FlaxTimesteps(
block_out_channels[0], flip_sin_to_cos=self.flip_sin_to_cos, freq_shift=self.config.freq_shift
)
self.time_embedding = FlaxTimestepEmbedding(time_embed_dim, dtype=self.dtype)
only_cross_attention = self.only_cross_attention
if isinstance(only_cross_attention, bool):
only_cross_attention = (only_cross_attention,) * len(self.down_block_types)
attention_head_dim = self.attention_head_dim
if isinstance(attention_head_dim, int):
attention_head_dim = (attention_head_dim,) * len(self.down_block_types)
# down
down_blocks = []
output_channel = block_out_channels[0]
for i, down_block_type in enumerate(self.down_block_types):
input_channel = output_channel
output_channel = block_out_channels[i]
is_final_block = i == len(block_out_channels) - 1
if down_block_type == "CrossAttnDownBlock2D":
down_block = FlaxCrossAttnDownBlock2D(
in_channels=input_channel,
out_channels=output_channel,
dropout=self.dropout,
num_layers=self.layers_per_block,
attn_num_head_channels=attention_head_dim[i],
add_downsample=not is_final_block,
use_linear_projection=self.use_linear_projection,
only_cross_attention=only_cross_attention[i],
dtype=self.dtype,
)
else:
down_block = FlaxDownBlock2D(
in_channels=input_channel,
out_channels=output_channel,
dropout=self.dropout,
num_layers=self.layers_per_block,
add_downsample=not is_final_block,
dtype=self.dtype,
)
down_blocks.append(down_block)
self.down_blocks = down_blocks
# mid
self.mid_block = FlaxUNetMidBlock2DCrossAttn(
in_channels=block_out_channels[-1],
dropout=self.dropout,
attn_num_head_channels=attention_head_dim[-1],
use_linear_projection=self.use_linear_projection,
dtype=self.dtype,
)
# up
up_blocks = []
reversed_block_out_channels = list(reversed(block_out_channels))
reversed_attention_head_dim = list(reversed(attention_head_dim))
only_cross_attention = list(reversed(only_cross_attention))
output_channel = reversed_block_out_channels[0]
for i, up_block_type in enumerate(self.up_block_types):
prev_output_channel = output_channel
output_channel = reversed_block_out_channels[i]
input_channel = reversed_block_out_channels[min(i + 1, len(block_out_channels) - 1)]
is_final_block = i == len(block_out_channels) - 1
if up_block_type == "CrossAttnUpBlock2D":
up_block = FlaxCrossAttnUpBlock2D(
in_channels=input_channel,
out_channels=output_channel,
prev_output_channel=prev_output_channel,
num_layers=self.layers_per_block + 1,
attn_num_head_channels=reversed_attention_head_dim[i],
add_upsample=not is_final_block,
dropout=self.dropout,
use_linear_projection=self.use_linear_projection,
only_cross_attention=only_cross_attention[i],
dtype=self.dtype,
)
else:
up_block = FlaxUpBlock2D(
in_channels=input_channel,
out_channels=output_channel,
prev_output_channel=prev_output_channel,
num_layers=self.layers_per_block + 1,
add_upsample=not is_final_block,
dropout=self.dropout,
dtype=self.dtype,
)
up_blocks.append(up_block)
prev_output_channel = output_channel
self.up_blocks = up_blocks
# out
self.conv_norm_out = nn.GroupNorm(num_groups=32, epsilon=1e-5)
self.conv_out = nn.Conv(
self.out_channels,
kernel_size=(3, 3),
strides=(1, 1),
padding=((1, 1), (1, 1)),
dtype=self.dtype,
)
def __call__(
self,
sample,
timesteps,
encoder_hidden_states,
return_dict: bool = True,
train: bool = False,
) -> Union[FlaxUNet2DConditionOutput, Tuple]:
r"""
Args:
sample (`jnp.ndarray`): (batch, channel, height, width) noisy inputs tensor
timestep (`jnp.ndarray` or `float` or `int`): timesteps
encoder_hidden_states (`jnp.ndarray`): (batch_size, sequence_length, hidden_size) encoder hidden states
return_dict (`bool`, *optional*, defaults to `True`):
Whether or not to return a [`models.unet_2d_condition_flax.FlaxUNet2DConditionOutput`] instead of a
plain tuple.
train (`bool`, *optional*, defaults to `False`):
Use deterministic functions and disable dropout when not training.
Returns:
[`~models.unet_2d_condition_flax.FlaxUNet2DConditionOutput`] or `tuple`:
[`~models.unet_2d_condition_flax.FlaxUNet2DConditionOutput`] if `return_dict` is True, otherwise a `tuple`.
When returning a tuple, the first element is the sample tensor.
"""
# 1. time
if not isinstance(timesteps, jnp.ndarray):
timesteps = jnp.array([timesteps], dtype=jnp.int32)
elif isinstance(timesteps, jnp.ndarray) and len(timesteps.shape) == 0:
timesteps = timesteps.astype(dtype=jnp.float32)
timesteps = jnp.expand_dims(timesteps, 0)
t_emb = self.time_proj(timesteps)
t_emb = self.time_embedding(t_emb)
# 2. pre-process
sample = jnp.transpose(sample, (0, 2, 3, 1))
sample = self.conv_in(sample)
# 3. down
down_block_res_samples = (sample,)
for down_block in self.down_blocks:
if isinstance(down_block, FlaxCrossAttnDownBlock2D):
sample, res_samples = down_block(sample, t_emb, encoder_hidden_states, deterministic=not train)
else:
sample, res_samples = down_block(sample, t_emb, deterministic=not train)
down_block_res_samples += res_samples
# 4. mid
sample = self.mid_block(sample, t_emb, encoder_hidden_states, deterministic=not train)
# 5. up
for up_block in self.up_blocks:
res_samples = down_block_res_samples[-(self.layers_per_block + 1) :]
down_block_res_samples = down_block_res_samples[: -(self.layers_per_block + 1)]
if isinstance(up_block, FlaxCrossAttnUpBlock2D):
sample = up_block(
sample,
temb=t_emb,
encoder_hidden_states=encoder_hidden_states,
res_hidden_states_tuple=res_samples,
deterministic=not train,
)
else:
sample = up_block(sample, temb=t_emb, res_hidden_states_tuple=res_samples, deterministic=not train)
# 6. post-process
sample = self.conv_norm_out(sample)
sample = nn.silu(sample)
sample = self.conv_out(sample)
sample = jnp.transpose(sample, (0, 3, 1, 2))
if not return_dict:
return (sample,)
return FlaxUNet2DConditionOutput(sample=sample)
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