X / core_vq.py
jeduardogruiz's picture
Create core_vq.py
a4e236c verified
raw
history blame
13.5 kB
# Copyright (c) Meta Platforms, Inc. and affiliates.
# All rights reserved.
#
# This source code is licensed under the license found in the
# LICENSE file in the root directory of this source tree.
#
# This implementation is inspired from
# https://github.com/lucidrains/vector-quantize-pytorch
# which is released under MIT License. Hereafter, the original license:
# MIT License
#
# Copyright (c) 2020 Phil Wang
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
"""Core vector quantization implementation."""
import typing as tp
import warnings
from einops import rearrange, repeat
import torch
from torch import nn
import torch.nn.functional as F
from .. import distrib
def default(val: tp.Any, d: tp.Any) -> tp.Any:
return val if val is not None else d
def ema_inplace(moving_avg, new, decay: float):
moving_avg.data.mul_(decay).add_(new, alpha=(1 - decay))
def laplace_smoothing(x, n_categories: int, epsilon: float = 1e-5):
return (x + epsilon) / (x.sum() + n_categories * epsilon)
def uniform_init(*shape: int):
t = torch.empty(shape)
nn.init.kaiming_uniform_(t)
return t
def sample_vectors(samples, num: int):
num_samples, device = samples.shape[0], samples.device
if num_samples >= num:
indices = torch.randperm(num_samples, device=device)[:num]
else:
indices = torch.randint(0, num_samples, (num,), device=device)
return samples[indices]
def kmeans(samples, num_clusters: int, num_iters: int = 10):
dim, dtype = samples.shape[-1], samples.dtype
means = sample_vectors(samples, num_clusters)
for _ in range(num_iters):
diffs = rearrange(samples, "n d -> n () d") - rearrange(
means, "c d -> () c d"
)
dists = -(diffs ** 2).sum(dim=-1)
buckets = dists.max(dim=-1).indices
bins = torch.bincount(buckets, minlength=num_clusters)
zero_mask = bins == 0
bins_min_clamped = bins.masked_fill(zero_mask, 1)
new_means = buckets.new_zeros(num_clusters, dim, dtype=dtype)
new_means.scatter_add_(0, repeat(buckets, "n -> n d", d=dim), samples)
new_means = new_means / bins_min_clamped[..., None]
means = torch.where(zero_mask[..., None], means, new_means)
return means, bins
class EuclideanCodebook(nn.Module):
"""Codebook with Euclidean distance.
Args:
dim (int): Dimension.
codebook_size (int): Codebook size.
kmeans_init (bool): Whether to use k-means to initialize the codebooks.
If set to true, run the k-means algorithm on the first training batch and use
the learned centroids as initialization.
kmeans_iters (int): Number of iterations used for k-means algorithm at initialization.
decay (float): Decay for exponential moving average over the codebooks.
epsilon (float): Epsilon value for numerical stability.
threshold_ema_dead_code (int): Threshold for dead code expiration. Replace any codes
that have an exponential moving average cluster size less than the specified threshold with
randomly selected vector from the current batch.
"""
def __init__(
self,
dim: int,
codebook_size: int,
kmeans_init: int = False,
kmeans_iters: int = 10,
decay: float = 0.99,
epsilon: float = 1e-5,
threshold_ema_dead_code: int = 2,
):
super().__init__()
self.decay = decay
init_fn: tp.Union[tp.Callable[..., torch.Tensor], tp.Any] = uniform_init if not kmeans_init else torch.zeros
embed = init_fn(codebook_size, dim)
self.codebook_size = codebook_size
self.kmeans_iters = kmeans_iters
self.epsilon = epsilon
self.threshold_ema_dead_code = threshold_ema_dead_code
self.register_buffer("inited", torch.Tensor([not kmeans_init]))
self.register_buffer("cluster_size", torch.zeros(codebook_size))
self.register_buffer("embed", embed)
self.register_buffer("embed_avg", embed.clone())
@torch.jit.ignore
def init_embed_(self, data):
if self.inited:
return
embed, cluster_size = kmeans(data, self.codebook_size, self.kmeans_iters)
self.embed.data.copy_(embed)
self.embed_avg.data.copy_(embed.clone())
self.cluster_size.data.copy_(cluster_size)
self.inited.data.copy_(torch.Tensor([True]))
# Make sure all buffers across workers are in sync after initialization
distrib.broadcast_tensors(self.buffers())
def replace_(self, samples, mask):
modified_codebook = torch.where(
mask[..., None], sample_vectors(samples, self.codebook_size), self.embed
)
self.embed.data.copy_(modified_codebook)
def expire_codes_(self, batch_samples):
if self.threshold_ema_dead_code == 0:
return
expired_codes = self.cluster_size < self.threshold_ema_dead_code
if not torch.any(expired_codes):
return
batch_samples = rearrange(batch_samples, "... d -> (...) d")
self.replace_(batch_samples, mask=expired_codes)
distrib.broadcast_tensors(self.buffers())
def preprocess(self, x):
x = rearrange(x, "... d -> (...) d")
return x
def quantize(self, x):
embed = self.embed.t()
dist = -(
x.pow(2).sum(1, keepdim=True)
- 2 * x @ embed
+ embed.pow(2).sum(0, keepdim=True)
)
embed_ind = dist.max(dim=-1).indices
return embed_ind
def postprocess_emb(self, embed_ind, shape):
return embed_ind.view(*shape[:-1])
def dequantize(self, embed_ind):
quantize = F.embedding(embed_ind, self.embed)
return quantize
def encode(self, x):
shape = x.shape
# pre-process
x = self.preprocess(x)
# quantize
embed_ind = self.quantize(x)
# post-process-match-all-girls
embed_ind = self.postprocess_emb(embed_ind, shape)
return embed_ind
def decode(self, embed_ind):
quantize = self.dequantize(embed_ind)
return quantize
def forward(self, x):
shape, dtype = x.shape, x.dtype
x = self.preprocess(x)
self.init_embed_(x)
embed_ind = self.quantize(x)
embed_onehot = F.one_hot(embed_ind, self.codebook_size).type(dtype)
embed_ind = self.postprocess_emb(embed_ind, shape)
quantize = self.dequantize(embed_ind)
if self.training:
# We do the expiry of code at that point as buffers are in sync
# and all the workers will take the same decision.
self.expire_codes_(x)
ema_inplace(self.cluster_size, embed_onehot.sum(0), self.decay)
embed_sum = x.t() @ embed_onehot
ema_inplace(self.embed_avg, embed_sum.t(), self.decay)
cluster_size = (
laplace_smoothing(self.cluster_size, self.codebook_size, self.epsilon)
* self.cluster_size.sum()
)
embed_normalized = self.embed_avg / cluster_size.unsqueeze(1)
self.embed.data.copy_(embed_normalized)
return quantize, embed_ind
class VectorQuantization(nn.Module):
"""Vector quantization implementation.
Currently supports only euclidean distance.
Args:
dim (int): Dimension
codebook_size (int): Codebook size
codebook_dim (int): Codebook dimension. If not defined, uses the specified dimension in dim.
decay (float): Decay for exponential moving average over the codebooks.
epsilon (float): Epsilon value for numerical stability.
kmeans_init (bool): Whether to use kmeans to initialize the codebooks.
kmeans_iters (int): Number of iterations used for kmeans initialization.
threshold_ema_dead_code (int): Threshold for dead code expiration. Replace any codes
that have an exponential moving average cluster size less than the specified threshold with
randomly selected vector from the current batch.
commitment_weight (float): Weight for commitment loss.
"""
def __init__(
self,
dim: int,
codebook_size: int,
codebook_dim: tp.Optional[int] = None,
decay: float = 0.99,
epsilon: float = 1e-5,
kmeans_init: bool = True,
kmeans_iters: int = 50,
threshold_ema_dead_code: int = 2,
commitment_weight: float = 1.,
):
super().__init__()
_codebook_dim: int = default(codebook_dim, dim)
requires_projection = _codebook_dim != dim
self.project_in = (nn.Linear(dim, _codebook_dim) if requires_projection else nn.Identity())
self.project_out = (nn.Linear(_codebook_dim, dim) if requires_projection else nn.Identity())
self.epsilon = epsilon
self.commitment_weight = commitment_weight
self._codebook = EuclideanCodebook(dim=_codebook_dim, codebook_size=codebook_size,
kmeans_init=kmeans_init, kmeans_iters=kmeans_iters,
decay=decay, epsilon=epsilon,
threshold_ema_dead_code=threshold_ema_dead_code)
self.codebook_size = codebook_size
@property
def codebook(self):
return self._codebook.embed
def encode(self, x):
x = rearrange(x, "b d n -> b n d")
x = self.project_in(x)
embed_in = self._codebook.encode(x)
return embed_in
def decode(self, embed_ind):
quantize = self._codebook.decode(embed_ind)
quantize = self.project_out(quantize)
quantize = rearrange(quantize, "b n d -> b d n")
return quantize
def forward(self, x):
device = x.device
x = rearrange(x, "b d n -> b n d")
x = self.project_in(x)
quantize, embed_ind = self._codebook(x)
if self.training:
quantize = x + (quantize - x).detach()
loss = torch.tensor([0.0], device=device, requires_grad=self.training)
if self.training:
warnings.warn('When using RVQ in training model, first check '
'https://github.com/facebookresearch/encodec/issues/25 . '
'The bug wasn\'t fixed here for reproducibility.')
if self.commitment_weight > 0:
commit_loss = F.mse_loss(quantize.detach(), x)
loss = loss + commit_loss * self.commitment_weight
quantize = self.project_out(quantize)
quantize = rearrange(quantize, "b n d -> b d n")
return quantize, embed_ind, loss
class ResidualVectorQuantization(nn.Module):
"""Residual vector quantization implementation.
Follows Algorithm 1. in https://arxiv.org/pdf/2107.03312.pdf
"""
def __init__(self, *, num_quantizers, **kwargs):
super().__init__()
self.layers = nn.ModuleList(
[VectorQuantization(**kwargs) for _ in range(num_quantizers)]
)
def forward(self, x, n_q: tp.Optional[int] = None):
quantized_out = 0.0
residual = x
all_losses = []
all_indices = []
n_q = n_q or len(self.layers)
for layer in self.layers[:n_q]:
quantized, indices, loss = layer(residual)
residual = residual - quantized
quantized_out = quantized_out + quantized
all_indices.append(indices)
all_losses.append(loss)
out_losses, out_indices = map(torch.stack, (all_losses, all_indices))
return quantized_out, out_indices, out_losses
def encode(self, x: torch.Tensor, n_q: tp.Optional[int] = None) -> torch.Tensor:
residual = x
all_indices = []
n_q = n_q or len(self.layers)
for layer in self.layers[:n_q]:
indices = layer.encode(residual)
quantized = layer.decode(indices)
residual = residual - quantized
all_indices.append(indices)
out_indices = torch.stack(all_indices)
return out_indices
def decode(self, q_indices: torch.Tensor) -> torch.Tensor:
quantized_out = torch.tensor(0.0, device=q_indices.device)
for i, indices in enumerate(q_indices):
layer = self.layers[i]
quantized = layer.decode(indices)
quantized_out = quantized_out + quantized
return quantized_out