modeling_xvector.py

import math
import torch
import typing as tp
import torch.nn as nn
import torch.nn.functional as F
from transformers.utils import ModelOutput
from transformers.modeling_utils import PreTrainedModel
from transformers.modeling_outputs import SequenceClassifierOutput

from .helpers_xvector import Fbank
from .configuration_xvector import XvectorConfig


class InputNormalization(nn.Module):

    spk_dict_mean: tp.Dict[int, torch.Tensor]
    spk_dict_std: tp.Dict[int, torch.Tensor]
    spk_dict_count: tp.Dict[int, int]

    def __init__(
        self,
        mean_norm=True,
        std_norm=True,
        norm_type="global",
        avg_factor=None,
        requires_grad=False,
        update_until_epoch=3,
    ):
        super().__init__()
        self.mean_norm = mean_norm
        self.std_norm = std_norm
        self.norm_type = norm_type
        self.avg_factor = avg_factor
        self.requires_grad = requires_grad
        self.glob_mean = torch.tensor([0])
        self.glob_std = torch.tensor([0])
        self.spk_dict_mean = {}
        self.spk_dict_std = {}
        self.spk_dict_count = {}
        self.weight = 1.0
        self.count = 0
        self.eps = 1e-10
        self.update_until_epoch = update_until_epoch

    def forward(self, input_values, lengths=None, spk_ids=torch.tensor([]), epoch=0):
        """Returns the tensor with the surrounding context.
        Arguments
        ---------
        x : tensor
            A batch of tensors.
        lengths : tensor
            A batch of tensors containing the relative length of each
            sentence (e.g, [0.7, 0.9, 1.0]). It is used to avoid
            computing stats on zero-padded steps.
        spk_ids : tensor containing the ids of each speaker (e.g, [0 10 6]).
            It is used to perform per-speaker normalization when
            norm_type='speaker'.
        """
        x = input_values
        N_batches = x.shape[0]

        current_means = []
        current_stds = []

        for snt_id in range(N_batches):
            # Avoiding padded time steps
            # lengths = torch.sum(attention_mask, dim=1)
            # relative_lengths = lengths / torch.max(lengths)
            # actual_size = torch.round(relative_lengths[snt_id] * x.shape[1]).int()
            actual_size = torch.round(lengths[snt_id] * x.shape[1]).int()

            # computing statistics
            current_mean, current_std = self._compute_current_stats(
                x[snt_id, 0:actual_size, ...]
            )

            current_means.append(current_mean)
            current_stds.append(current_std)

            if self.norm_type == "sentence":
                x[snt_id] = (x[snt_id] - current_mean.data) / current_std.data

            if self.norm_type == "speaker":
                spk_id = int(spk_ids[snt_id][0])

                if self.training:
                    if spk_id not in self.spk_dict_mean:
                        # Initialization of the dictionary
                        self.spk_dict_mean[spk_id] = current_mean
                        self.spk_dict_std[spk_id] = current_std
                        self.spk_dict_count[spk_id] = 1

                    else:
                        self.spk_dict_count[spk_id] = (
                            self.spk_dict_count[spk_id] + 1
                        )

                        if self.avg_factor is None:
                            self.weight = 1 / self.spk_dict_count[spk_id]
                        else:
                            self.weight = self.avg_factor

                        self.spk_dict_mean[spk_id] = (
                            (1 - self.weight) * self.spk_dict_mean[spk_id]
                            + self.weight * current_mean
                        )
                        self.spk_dict_std[spk_id] = (
                            (1 - self.weight) * self.spk_dict_std[spk_id]
                            + self.weight * current_std
                        )

                        self.spk_dict_mean[spk_id].detach()
                        self.spk_dict_std[spk_id].detach()

                    speaker_mean = self.spk_dict_mean[spk_id].data
                    speaker_std = self.spk_dict_std[spk_id].data
                else:
                    if spk_id in self.spk_dict_mean:
                        speaker_mean = self.spk_dict_mean[spk_id].data
                        speaker_std = self.spk_dict_std[spk_id].data
                    else:
                        speaker_mean = current_mean.data
                        speaker_std = current_std.data

                x[snt_id] = (x[snt_id] - speaker_mean) / speaker_std

        if self.norm_type == "batch" or self.norm_type == "global":
            current_mean = torch.mean(torch.stack(current_means), dim=0)
            current_std = torch.mean(torch.stack(current_stds), dim=0)

            if self.norm_type == "batch":
                x = (x - current_mean.data) / (current_std.data)

            if self.norm_type == "global":
                if self.training:
                    if self.count == 0:
                        self.glob_mean = current_mean
                        self.glob_std = current_std

                    elif epoch < self.update_until_epoch:
                        if self.avg_factor is None:
                            self.weight = 1 / (self.count + 1)
                        else:
                            self.weight = self.avg_factor

                        self.glob_mean = (
                            1 - self.weight
                        ) * self.glob_mean + self.weight * current_mean

                        self.glob_std = (
                            1 - self.weight
                        ) * self.glob_std + self.weight * current_std

                    self.glob_mean.detach()
                    self.glob_std.detach()

                    self.count = self.count + 1

                x = (x - self.glob_mean.data) / (self.glob_std.data)

        return x

    def _compute_current_stats(self, x):
        """Returns the tensor with the surrounding context.
        Arguments
        ---------
        x : tensor
            A batch of tensors.
        """
        # Compute current mean
        if self.mean_norm:
            current_mean = torch.mean(x, dim=0).detach().data
        else:
            current_mean = torch.tensor([0.0], device=x.device)

        # Compute current std
        if self.std_norm:
            current_std = torch.std(x, dim=0).detach().data
        else:
            current_std = torch.tensor([1.0], device=x.device)

        # Improving numerical stability of std
        current_std = torch.max(
            current_std, self.eps * torch.ones_like(current_std)
        )

        return current_mean, current_std

    def _statistics_dict(self):
        """Fills the dictionary containing the normalization statistics."""
        state = {}
        state["count"] = self.count
        state["glob_mean"] = self.glob_mean
        state["glob_std"] = self.glob_std
        state["spk_dict_mean"] = self.spk_dict_mean
        state["spk_dict_std"] = self.spk_dict_std
        state["spk_dict_count"] = self.spk_dict_count

        return state

    def _load_statistics_dict(self, state):
        """Loads the dictionary containing the statistics.
        Arguments
        ---------
        state : dict
            A dictionary containing the normalization statistics.
        """
        self.count = state["count"]
        if isinstance(state["glob_mean"], int):
            self.glob_mean = state["glob_mean"]
            self.glob_std = state["glob_std"]
        else:
            self.glob_mean = state["glob_mean"]  # .to(self.device_inp)
            self.glob_std = state["glob_std"]  # .to(self.device_inp)

        # Loading the spk_dict_mean in the right device
        self.spk_dict_mean = {}
        for spk in state["spk_dict_mean"]:
            self.spk_dict_mean[spk] = state["spk_dict_mean"][spk].to(
                self.device_inp
            )

        # Loading the spk_dict_std in the right device
        self.spk_dict_std = {}
        for spk in state["spk_dict_std"]:
            self.spk_dict_std[spk] = state["spk_dict_std"][spk].to(
                self.device_inp
            )

        self.spk_dict_count = state["spk_dict_count"]

        return state

    def to(self, device):
        """Puts the needed tensors in the right device."""
        self = super(InputNormalization, self).to(device)
        self.glob_mean = self.glob_mean.to(device)
        self.glob_std = self.glob_std.to(device)
        for spk in self.spk_dict_mean:
            self.spk_dict_mean[spk] = self.spk_dict_mean[spk].to(device)
            self.spk_dict_std[spk] = self.spk_dict_std[spk].to(device)
        return self


class TdnnLayer(nn.Module):

    def __init__(
        self, 
        in_channels, 
        out_channels, 
        kernel_size, 
        dilation=1, 
        stride=1, 
        padding=0, 
        padding_mode="reflect", 
        activation=torch.nn.LeakyReLU, 
    ):
        super(TdnnLayer, self).__init__()
        self.in_channels = in_channels
        self.out_channels = out_channels
        self.kernel_size = kernel_size
        self.dilation = dilation
        self.stride = stride
        self.padding = padding
        self.padding_mode = padding_mode
        self.activation = activation

        self.conv = nn.Conv1d(
            self.in_channels, 
            self.out_channels, 
            self.kernel_size, 
            dilation=self.dilation, 
            padding=self.padding
        )

        # Set Affine=false to be compatible with the original kaldi version
        # self.ln = nn.LayerNorm(out_channels, elementwise_affine=False)
        self.norm = nn.BatchNorm1d(out_channels, affine=False)

    def forward(self, x):
        x = self._manage_padding(x, self.kernel_size, self.dilation, self.stride)
        out = self.conv(x)
        out = self.activation()(out) 
        out = self.norm(out)
        return out

    def _manage_padding(
        self, x, kernel_size: int, dilation: int, stride: int,
    ):
        # Detecting input shape
        L_in = self.in_channels

        # Time padding
        padding = get_padding_elem(L_in, stride, kernel_size, dilation)

        # Applying padding
        x = F.pad(x, padding, mode=self.padding_mode)

        return x


def get_padding_elem(L_in: int, stride: int, kernel_size: int, dilation: int):
    """This function computes the number of elements to add for zero-padding.
    Arguments
    ---------
    L_in : int
    stride: int
    kernel_size : int
    dilation : int
    """
    if stride > 1:
        padding = [math.floor(kernel_size / 2), math.floor(kernel_size / 2)]

    else:
        L_out = (
            math.floor((L_in - dilation * (kernel_size - 1) - 1) / stride) + 1
        )
        padding = [
            math.floor((L_in - L_out) / 2),
            math.floor((L_in - L_out) / 2),
        ]
    return padding


class StatisticsPooling(nn.Module):

    def __init__(self, return_mean=True, return_std=True):
        super().__init__()

        # Small value for GaussNoise
        self.eps = 1e-5
        self.return_mean = return_mean
        self.return_std = return_std
        if not (self.return_mean or self.return_std):
            raise ValueError(
                "both of statistics are equal to False \n"
                "consider enabling mean and/or std statistic pooling"
            )

    def forward(self, input_values, lengths=None):
        """Calculates mean and std for a batch (input tensor).
        Arguments
        ---------
        x : torch.Tensor
            It represents a tensor for a mini-batch.
        """
        x = input_values
        if lengths is None:
            if self.return_mean:
                mean = x.mean(dim=1)
            if self.return_std:
                std = x.std(dim=1)
        else:
            mean = []
            std = []
            for snt_id in range(x.shape[0]):
                # Avoiding padded time steps
                # lengths = torch.sum(attention_mask, dim=1)
                # relative_lengths = lengths / torch.max(lengths)
                # actual_size = torch.round(relative_lengths[snt_id] * x.shape[1]).int()
                actual_size = int(torch.round(lengths[snt_id] * x.shape[1]))

                # computing statistics
                if self.return_mean:
                    mean.append(
                        torch.mean(x[snt_id, 0:actual_size, ...], dim=0)
                    )
                if self.return_std:
                    std.append(torch.std(x[snt_id, 0:actual_size, ...], dim=0))
            if self.return_mean:
                mean = torch.stack(mean)
            if self.return_std:
                std = torch.stack(std)

        if self.return_mean:
            gnoise = self._get_gauss_noise(mean.size(), device=mean.device)
            gnoise = gnoise
            mean += gnoise
        if self.return_std:
            std = std + self.eps

        # Append mean and std of the batch
        if self.return_mean and self.return_std:
            pooled_stats = torch.cat((mean, std), dim=1)
            pooled_stats = pooled_stats.unsqueeze(1)
        elif self.return_mean:
            pooled_stats = mean.unsqueeze(1)
        elif self.return_std:
            pooled_stats = std.unsqueeze(1)

        return pooled_stats

    def _get_gauss_noise(self, shape_of_tensor, device="cpu"):
        """Returns a tensor of epsilon Gaussian noise.
        Arguments
        ---------
        shape_of_tensor : tensor
            It represents the size of tensor for generating Gaussian noise.
        """
        gnoise = torch.randn(shape_of_tensor, device=device)
        gnoise -= torch.min(gnoise)
        gnoise /= torch.max(gnoise)
        gnoise = self.eps * ((1 - 9) * gnoise + 9)

        return gnoise


class XvectorEmbedder(nn.Module):

    def __init__(
        self, 
        in_channels=40, 
        activation=torch.nn.LeakyReLU, 
        tdnn_blocks=5, 
        tdnn_channels=[512, 512, 512, 512, 1500], 
        tdnn_kernel_sizes=[5, 3, 3, 1, 1], 
        tdnn_dilations=[1, 2, 3, 1, 1], 
        hidden_size=512, 
    ) -> None:
        super(XvectorEmbedder, self).__init__()
        self.activation = activation
        self.blocks = nn.ModuleList()
        for block_index in range(tdnn_blocks):
            out_channels = tdnn_channels[block_index]
            tdnn = TdnnLayer(
                in_channels, 
                out_channels, 
                kernel_size=tdnn_kernel_sizes[block_index],
                dilation=tdnn_dilations[block_index], 
                activation=activation, 
            )
            self.blocks.append(tdnn)
            in_channels = tdnn_channels[block_index]
        self.pooler = StatisticsPooling()
        self.fc = nn.Linear(2 * out_channels, hidden_size)

    def forward(self, input_values, lengths=None):
        x = input_values
        x = x.permute(0, 2, 1) # (B, T, F) -> (B, F, T)
        for block in self.blocks:
            x = block(x)
        last_hidden_state = x.permute(0, 2, 1) # (B, F, T) -> (B, T, F)
        pooler_output = self.pooler(last_hidden_state, lengths)
        pooler_output = self.fc(pooler_output.squeeze(1))
        return ModelOutput(
            last_hidden_state=last_hidden_state, 
            pooler_output=pooler_output
        )


class CosineSimilarityHead(torch.nn.Module):
    """
    This class implements the cosine similarity on the top of features.
    """
    def __init__(
        self,
        in_channels, 
        lin_blocks=0,
        hidden_size=192,
        num_classes=1211,
    ):
        super().__init__()
        self.blocks = nn.ModuleList()

        for block_index in range(lin_blocks):
            self.blocks.extend(
                [
                    nn.BatchNorm1d(num_features=in_channels),
                    nn.Linear(in_features=in_channels, out_features=hidden_size),
                ]
            )
            in_channels = hidden_size

        # Final Layer
        self.weight = nn.Parameter(
            torch.FloatTensor(num_classes, in_channels)
        )
        nn.init.xavier_uniform_(self.weight)

    def forward(self, x):
        """Returns the output probabilities over speakers.
        Arguments
        ---------
        x : torch.Tensor
            Torch tensor.
        """
        for layer in self.blocks:
            x = layer(x)

        # Need to be normalized
        x = F.linear(F.normalize(x), F.normalize(self.weight))
        return x


class XvectorPreTrainedModel(PreTrainedModel):

    config_class = XvectorConfig
    base_model_prefix = "xvector"
    main_input_name = "input_values"
    supports_gradient_checkpointing = True

    def _init_weights(self, module):
        """Initialize the weights"""
        if isinstance(module, nn.Linear):
            # Slightly different from the TF version which uses truncated_normal for initialization
            # cf https://github.com/pytorch/pytorch/pull/5617
            module.weight.data.normal_(mean=0.0, std=self.config.initializer_range)
        elif isinstance(module, (nn.LayerNorm, nn.GroupNorm)):
            module.bias.data.zero_()
            module.weight.data.fill_(1.0)
        elif isinstance(module, nn.Conv1d):
            nn.init.kaiming_normal_(module.weight.data)

        if isinstance(module, (nn.Linear, nn.Conv1d)) and module.bias is not None:
            module.bias.data.zero_()


class XvectorModel(XvectorPreTrainedModel):

    def __init__(self, config):
        super().__init__(config)
        self.compute_features = Fbank(
            n_mels=config.n_mels, 
            sample_rate=config.sample_rate, 
            win_length=config.win_length, 
            hop_length=config.hop_length, 
        )
        self.mean_var_norm = InputNormalization(
            mean_norm=config.mean_norm, 
            std_norm=config.std_norm, 
            norm_type=config.norm_type
        )
        self.embedding_model = XvectorEmbedder(
            in_channels=config.n_mels, 
            activation=nn.LeakyReLU, 
            tdnn_blocks=config.tdnn_blocks, 
            tdnn_channels=config.tdnn_channels, 
            tdnn_kernel_sizes=config.tdnn_kernel_sizes, 
            tdnn_dilations=config.tdnn_dilations, 
            hidden_size=config.hidden_size, 
        )

    def forward(self, input_values, lengths=None):
        x = input_values
        # if attention_mask is None:
        #     attention_mask = torch.ones_like(input_values, device=x.device)
        x = self.compute_features(x)
        x = self.mean_var_norm(x, lengths)
        output = self.embedding_model(x, lengths)
        return output