v1.0

fairseq/examples/speech_recognition/models/__init__.py

+import importlib
+import os
+
+
+for file in sorted(os.listdir(os.path.dirname(__file__))):
+    if file.endswith(".py") and not file.startswith("_"):
+        model_name = file[: file.find(".py")]
+        importlib.import_module("examples.speech_recognition.models." + model_name)

fairseq/examples/speech_recognition/models/vggtransformer.py

+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+import argparse
+import math
+from collections.abc import Iterable
+
+import torch
+import torch.nn as nn
+from examples.speech_recognition.data.data_utils import lengths_to_encoder_padding_mask
+from fairseq import utils
+from fairseq.models import (
+    FairseqEncoder,
+    FairseqEncoderDecoderModel,
+    FairseqEncoderModel,
+    FairseqIncrementalDecoder,
+    register_model,
+    register_model_architecture,
+)
+from fairseq.modules import (
+    LinearizedConvolution,
+    TransformerDecoderLayer,
+    TransformerEncoderLayer,
+    VGGBlock,
+)
+
+
+@register_model("asr_vggtransformer")
+class VGGTransformerModel(FairseqEncoderDecoderModel):
+    """
+    Transformers with convolutional context for ASR
+    https://arxiv.org/abs/1904.11660
+    """
+
+    def __init__(self, encoder, decoder):
+        super().__init__(encoder, decoder)
+
+    @staticmethod
+    def add_args(parser):
+        """Add model-specific arguments to the parser."""
+        parser.add_argument(
+            "--input-feat-per-channel",
+            type=int,
+            metavar="N",
+            help="encoder input dimension per input channel",
+        )
+        parser.add_argument(
+            "--vggblock-enc-config",
+            type=str,
+            metavar="EXPR",
+            help="""
+    an array of tuples each containing the configuration of one vggblock:
+    [(out_channels,
+      conv_kernel_size,
+      pooling_kernel_size,
+      num_conv_layers,
+      use_layer_norm), ...])
+            """,
+        )
+        parser.add_argument(
+            "--transformer-enc-config",
+            type=str,
+            metavar="EXPR",
+            help=""""
+    a tuple containing the configuration of the encoder transformer layers
+    configurations:
+    [(input_dim,
+      num_heads,
+      ffn_dim,
+      normalize_before,
+      dropout,
+      attention_dropout,
+      relu_dropout), ...]')
+            """,
+        )
+        parser.add_argument(
+            "--enc-output-dim",
+            type=int,
+            metavar="N",
+            help="""
+    encoder output dimension, can be None. If specified, projecting the
+    transformer output to the specified dimension""",
+        )
+        parser.add_argument(
+            "--in-channels",
+            type=int,
+            metavar="N",
+            help="number of encoder input channels",
+        )
+        parser.add_argument(
+            "--tgt-embed-dim",
+            type=int,
+            metavar="N",
+            help="embedding dimension of the decoder target tokens",
+        )
+        parser.add_argument(
+            "--transformer-dec-config",
+            type=str,
+            metavar="EXPR",
+            help="""
+    a tuple containing the configuration of the decoder transformer layers
+    configurations:
+    [(input_dim,
+      num_heads,
+      ffn_dim,
+      normalize_before,
+      dropout,
+      attention_dropout,
+      relu_dropout), ...]
+            """,
+        )
+        parser.add_argument(
+            "--conv-dec-config",
+            type=str,
+            metavar="EXPR",
+            help="""
+    an array of tuples for the decoder 1-D convolution config
+        [(out_channels, conv_kernel_size, use_layer_norm), ...]""",
+        )
+
+    @classmethod
+    def build_encoder(cls, args, task):
+        return VGGTransformerEncoder(
+            input_feat_per_channel=args.input_feat_per_channel,
+            vggblock_config=eval(args.vggblock_enc_config),
+            transformer_config=eval(args.transformer_enc_config),
+            encoder_output_dim=args.enc_output_dim,
+            in_channels=args.in_channels,
+        )
+
+    @classmethod
+    def build_decoder(cls, args, task):
+        return TransformerDecoder(
+            dictionary=task.target_dictionary,
+            embed_dim=args.tgt_embed_dim,
+            transformer_config=eval(args.transformer_dec_config),
+            conv_config=eval(args.conv_dec_config),
+            encoder_output_dim=args.enc_output_dim,
+        )
+
+    @classmethod
+    def build_model(cls, args, task):
+        """Build a new model instance."""
+        # make sure that all args are properly defaulted
+        # (in case there are any new ones)
+        base_architecture(args)
+
+        encoder = cls.build_encoder(args, task)
+        decoder = cls.build_decoder(args, task)
+        return cls(encoder, decoder)
+
+    def get_normalized_probs(self, net_output, log_probs, sample=None):
+        # net_output['encoder_out'] is a (B, T, D) tensor
+        lprobs = super().get_normalized_probs(net_output, log_probs, sample)
+        lprobs.batch_first = True
+        return lprobs
+
+
+DEFAULT_ENC_VGGBLOCK_CONFIG = ((32, 3, 2, 2, False),) * 2
+DEFAULT_ENC_TRANSFORMER_CONFIG = ((256, 4, 1024, True, 0.2, 0.2, 0.2),) * 2
+# 256: embedding dimension
+# 4: number of heads
+# 1024: FFN
+# True: apply layerNorm before (dropout + resiaul) instead of after
+# 0.2 (dropout): dropout after MultiheadAttention and second FC
+# 0.2 (attention_dropout): dropout in MultiheadAttention
+# 0.2 (relu_dropout): dropout after ReLu
+DEFAULT_DEC_TRANSFORMER_CONFIG = ((256, 2, 1024, True, 0.2, 0.2, 0.2),) * 2
+DEFAULT_DEC_CONV_CONFIG = ((256, 3, True),) * 2
+
+
+# TODO: repace transformer encoder config from one liner
+# to explicit args to get rid of this transformation
+def prepare_transformer_encoder_params(
+    input_dim,
+    num_heads,
+    ffn_dim,
+    normalize_before,
+    dropout,
+    attention_dropout,
+    relu_dropout,
+):
+    args = argparse.Namespace()
+    args.encoder_embed_dim = input_dim
+    args.encoder_attention_heads = num_heads
+    args.attention_dropout = attention_dropout
+    args.dropout = dropout
+    args.activation_dropout = relu_dropout
+    args.encoder_normalize_before = normalize_before
+    args.encoder_ffn_embed_dim = ffn_dim
+    return args
+
+
+def prepare_transformer_decoder_params(
+    input_dim,
+    num_heads,
+    ffn_dim,
+    normalize_before,
+    dropout,
+    attention_dropout,
+    relu_dropout,
+):
+    args = argparse.Namespace()
+    args.encoder_embed_dim = None
+    args.decoder_embed_dim = input_dim
+    args.decoder_attention_heads = num_heads
+    args.attention_dropout = attention_dropout
+    args.dropout = dropout
+    args.activation_dropout = relu_dropout
+    args.decoder_normalize_before = normalize_before
+    args.decoder_ffn_embed_dim = ffn_dim
+    return args
+
+
+class VGGTransformerEncoder(FairseqEncoder):
+    """VGG + Transformer encoder"""
+
+    def __init__(
+        self,
+        input_feat_per_channel,
+        vggblock_config=DEFAULT_ENC_VGGBLOCK_CONFIG,
+        transformer_config=DEFAULT_ENC_TRANSFORMER_CONFIG,
+        encoder_output_dim=512,
+        in_channels=1,
+        transformer_context=None,
+        transformer_sampling=None,
+    ):
+        """constructor for VGGTransformerEncoder
+
+        Args:
+            - input_feat_per_channel: feature dim (not including stacked,
+              just base feature)
+            - in_channel: # input channels (e.g., if stack 8 feature vector
+                together, this is 8)
+            - vggblock_config: configuration of vggblock, see comments on
+                DEFAULT_ENC_VGGBLOCK_CONFIG
+            - transformer_config: configuration of transformer layer, see comments
+                on DEFAULT_ENC_TRANSFORMER_CONFIG
+            - encoder_output_dim: final transformer output embedding dimension
+            - transformer_context: (left, right) if set, self-attention will be focused
+              on (t-left, t+right)
+            - transformer_sampling: an iterable of int, must match with
+              len(transformer_config), transformer_sampling[i] indicates sampling
+              factor for i-th transformer layer, after multihead att and feedfoward
+              part
+        """
+        super().__init__(None)
+
+        self.num_vggblocks = 0
+        if vggblock_config is not None:
+            if not isinstance(vggblock_config, Iterable):
+                raise ValueError("vggblock_config is not iterable")
+            self.num_vggblocks = len(vggblock_config)
+
+        self.conv_layers = nn.ModuleList()
+        self.in_channels = in_channels
+        self.input_dim = input_feat_per_channel
+        self.pooling_kernel_sizes = []
+
+        if vggblock_config is not None:
+            for _, config in enumerate(vggblock_config):
+                (
+                    out_channels,
+                    conv_kernel_size,
+                    pooling_kernel_size,
+                    num_conv_layers,
+                    layer_norm,
+                ) = config
+                self.conv_layers.append(
+                    VGGBlock(
+                        in_channels,
+                        out_channels,
+                        conv_kernel_size,
+                        pooling_kernel_size,
+                        num_conv_layers,
+                        input_dim=input_feat_per_channel,
+                        layer_norm=layer_norm,
+                    )
+                )
+                self.pooling_kernel_sizes.append(pooling_kernel_size)
+                in_channels = out_channels
+                input_feat_per_channel = self.conv_layers[-1].output_dim
+
+        transformer_input_dim = self.infer_conv_output_dim(
+            self.in_channels, self.input_dim
+        )
+        # transformer_input_dim is the output dimension of VGG part
+
+        self.validate_transformer_config(transformer_config)
+        self.transformer_context = self.parse_transformer_context(transformer_context)
+        self.transformer_sampling = self.parse_transformer_sampling(
+            transformer_sampling, len(transformer_config)
+        )
+
+        self.transformer_layers = nn.ModuleList()
+
+        if transformer_input_dim != transformer_config[0][0]:
+            self.transformer_layers.append(
+                Linear(transformer_input_dim, transformer_config[0][0])
+            )
+        self.transformer_layers.append(
+            TransformerEncoderLayer(
+                prepare_transformer_encoder_params(*transformer_config[0])
+            )
+        )
+
+        for i in range(1, len(transformer_config)):
+            if transformer_config[i - 1][0] != transformer_config[i][0]:
+                self.transformer_layers.append(
+                    Linear(transformer_config[i - 1][0], transformer_config[i][0])
+                )
+            self.transformer_layers.append(
+                TransformerEncoderLayer(
+                    prepare_transformer_encoder_params(*transformer_config[i])
+                )
+            )
+
+        self.encoder_output_dim = encoder_output_dim
+        self.transformer_layers.extend(
+            [
+                Linear(transformer_config[-1][0], encoder_output_dim),
+                LayerNorm(encoder_output_dim),
+            ]
+        )
+
+    def forward(self, src_tokens, src_lengths, **kwargs):
+        """
+        src_tokens: padded tensor (B, T, C * feat)
+        src_lengths: tensor of original lengths of input utterances (B,)
+        """
+        bsz, max_seq_len, _ = src_tokens.size()
+        x = src_tokens.view(bsz, max_seq_len, self.in_channels, self.input_dim)
+        x = x.transpose(1, 2).contiguous()
+        # (B, C, T, feat)
+
+        for layer_idx in range(len(self.conv_layers)):
+            x = self.conv_layers[layer_idx](x)
+
+        bsz, _, output_seq_len, _ = x.size()
+
+        # (B, C, T, feat) -> (B, T, C, feat) -> (T, B, C, feat) -> (T, B, C * feat)
+        x = x.transpose(1, 2).transpose(0, 1)
+        x = x.contiguous().view(output_seq_len, bsz, -1)
+
+        input_lengths = src_lengths.clone()
+        for s in self.pooling_kernel_sizes:
+            input_lengths = (input_lengths.float() / s).ceil().long()
+
+        encoder_padding_mask, _ = lengths_to_encoder_padding_mask(
+            input_lengths, batch_first=True
+        )
+        if not encoder_padding_mask.any():
+            encoder_padding_mask = None
+
+        subsampling_factor = int(max_seq_len * 1.0 / output_seq_len + 0.5)
+        attn_mask = self.lengths_to_attn_mask(input_lengths, subsampling_factor)
+
+        transformer_layer_idx = 0
+
+        for layer_idx in range(len(self.transformer_layers)):
+
+            if isinstance(self.transformer_layers[layer_idx], TransformerEncoderLayer):
+                x = self.transformer_layers[layer_idx](
+                    x, encoder_padding_mask, attn_mask
+                )
+
+                if self.transformer_sampling[transformer_layer_idx] != 1:
+                    sampling_factor = self.transformer_sampling[transformer_layer_idx]
+                    x, encoder_padding_mask, attn_mask = self.slice(
+                        x, encoder_padding_mask, attn_mask, sampling_factor
+                    )
+
+                transformer_layer_idx += 1
+
+            else:
+                x = self.transformer_layers[layer_idx](x)
+
+        # encoder_padding_maks is a (T x B) tensor, its [t, b] elements indicate
+        # whether encoder_output[t, b] is valid or not (valid=0, invalid=1)
+
+        return {
+            "encoder_out": x,  # (T, B, C)
+            "encoder_padding_mask": encoder_padding_mask.t()
+            if encoder_padding_mask is not None
+            else None,
+            # (B, T) --> (T, B)
+        }
+
+    def infer_conv_output_dim(self, in_channels, input_dim):
+        sample_seq_len = 200
+        sample_bsz = 10
+        x = torch.randn(sample_bsz, in_channels, sample_seq_len, input_dim)
+        for i, _ in enumerate(self.conv_layers):
+            x = self.conv_layers[i](x)
+        x = x.transpose(1, 2)
+        mb, seq = x.size()[:2]
+        return x.contiguous().view(mb, seq, -1).size(-1)
+
+    def validate_transformer_config(self, transformer_config):
+        for config in transformer_config:
+            input_dim, num_heads = config[:2]
+            if input_dim % num_heads != 0:
+                msg = (
+                    "ERROR in transformer config {}: ".format(config)
+                    + "input dimension {} ".format(input_dim)
+                    + "not dividable by number of heads {}".format(num_heads)
+                )
+                raise ValueError(msg)
+
+    def parse_transformer_context(self, transformer_context):
+        """
+        transformer_context can be the following:
+        -   None; indicates no context is used, i.e.,
+            transformer can access full context
+        -   a tuple/list of two int; indicates left and right context,
+            any number <0 indicates infinite context
+                * e.g., (5, 6) indicates that for query at x_t, transformer can
+                access [t-5, t+6] (inclusive)
+                * e.g., (-1, 6) indicates that for query at x_t, transformer can
+                access [0, t+6] (inclusive)
+        """
+        if transformer_context is None:
+            return None
+
+        if not isinstance(transformer_context, Iterable):
+            raise ValueError("transformer context must be Iterable if it is not None")
+
+        if len(transformer_context) != 2:
+            raise ValueError("transformer context must have length 2")
+
+        left_context = transformer_context[0]
+        if left_context < 0:
+            left_context = None
+
+        right_context = transformer_context[1]
+        if right_context < 0:
+            right_context = None
+
+        if left_context is None and right_context is None:
+            return None
+
+        return (left_context, right_context)
+
+    def parse_transformer_sampling(self, transformer_sampling, num_layers):
+        """
+        parsing transformer sampling configuration
+
+        Args:
+            - transformer_sampling, accepted input:
+                * None, indicating no sampling
+                * an Iterable with int (>0) as element
+            - num_layers, expected number of transformer layers, must match with
+              the length of transformer_sampling if it is not None
+
+        Returns:
+            - A tuple with length num_layers
+        """
+        if transformer_sampling is None:
+            return (1,) * num_layers
+
+        if not isinstance(transformer_sampling, Iterable):
+            raise ValueError(
+                "transformer_sampling must be an iterable if it is not None"
+            )
+
+        if len(transformer_sampling) != num_layers:
+            raise ValueError(
+                "transformer_sampling {} does not match with the number "
+                "of layers {}".format(transformer_sampling, num_layers)
+            )
+
+        for layer, value in enumerate(transformer_sampling):
+            if not isinstance(value, int):
+                raise ValueError("Invalid value in transformer_sampling: ")
+            if value < 1:
+                raise ValueError(
+                    "{} layer's subsampling is {}.".format(layer, value)
+                    + " This is not allowed! "
+                )
+        return transformer_sampling
+
+    def slice(self, embedding, padding_mask, attn_mask, sampling_factor):
+        """
+        embedding is a (T, B, D) tensor
+        padding_mask is a (B, T) tensor or None
+        attn_mask is a (T, T) tensor or None
+        """
+        embedding = embedding[::sampling_factor, :, :]
+        if padding_mask is not None:
+            padding_mask = padding_mask[:, ::sampling_factor]
+        if attn_mask is not None:
+            attn_mask = attn_mask[::sampling_factor, ::sampling_factor]
+
+        return embedding, padding_mask, attn_mask
+
+    def lengths_to_attn_mask(self, input_lengths, subsampling_factor=1):
+        """
+        create attention mask according to sequence lengths and transformer
+        context
+
+        Args:
+            - input_lengths: (B, )-shape Int/Long tensor; input_lengths[b] is
+              the length of b-th sequence
+            - subsampling_factor: int
+                * Note that the left_context and right_context is specified in
+                  the input frame-level while input to transformer may already
+                  go through subsampling (e.g., the use of striding in vggblock)
+                  we use subsampling_factor to scale the left/right context
+
+        Return:
+            - a (T, T) binary tensor or None, where T is max(input_lengths)
+                * if self.transformer_context is None, None
+                * if left_context is None,
+                    * attn_mask[t, t + right_context + 1:] = 1
+                    * others = 0
+                * if right_context is None,
+                    * attn_mask[t, 0:t - left_context] = 1
+                    * others = 0
+                * elsif
+                    * attn_mask[t, t - left_context: t + right_context + 1] = 0
+                    * others = 1
+        """
+        if self.transformer_context is None:
+            return None
+
+        maxT = torch.max(input_lengths).item()
+        attn_mask = torch.zeros(maxT, maxT)
+
+        left_context = self.transformer_context[0]
+        right_context = self.transformer_context[1]
+        if left_context is not None:
+            left_context = math.ceil(self.transformer_context[0] / subsampling_factor)
+        if right_context is not None:
+            right_context = math.ceil(self.transformer_context[1] / subsampling_factor)
+
+        for t in range(maxT):
+            if left_context is not None:
+                st = 0
+                en = max(st, t - left_context)
+                attn_mask[t, st:en] = 1
+            if right_context is not None:
+                st = t + right_context + 1
+                st = min(st, maxT - 1)
+                attn_mask[t, st:] = 1
+
+        return attn_mask.to(input_lengths.device)
+
+    def reorder_encoder_out(self, encoder_out, new_order):
+        encoder_out["encoder_out"] = encoder_out["encoder_out"].index_select(
+            1, new_order
+        )
+        if encoder_out["encoder_padding_mask"] is not None:
+            encoder_out["encoder_padding_mask"] = encoder_out[
+                "encoder_padding_mask"
+            ].index_select(1, new_order)
+        return encoder_out
+
+
+class TransformerDecoder(FairseqIncrementalDecoder):
+    """
+    Transformer decoder consisting of *args.decoder_layers* layers. Each layer
+    is a :class:`TransformerDecoderLayer`.
+    Args:
+        args (argparse.Namespace): parsed command-line arguments
+        dictionary (~fairseq.data.Dictionary): decoding dictionary
+        embed_tokens (torch.nn.Embedding): output embedding
+        no_encoder_attn (bool, optional): whether to attend to encoder outputs.
+            Default: ``False``
+        left_pad (bool, optional): whether the input is left-padded. Default:
+            ``False``
+    """
+
+    def __init__(
+        self,
+        dictionary,
+        embed_dim=512,
+        transformer_config=DEFAULT_ENC_TRANSFORMER_CONFIG,
+        conv_config=DEFAULT_DEC_CONV_CONFIG,
+        encoder_output_dim=512,
+    ):
+
+        super().__init__(dictionary)
+        vocab_size = len(dictionary)
+        self.padding_idx = dictionary.pad()
+        self.embed_tokens = Embedding(vocab_size, embed_dim, self.padding_idx)
+
+        self.conv_layers = nn.ModuleList()
+        for i in range(len(conv_config)):
+            out_channels, kernel_size, layer_norm = conv_config[i]
+            if i == 0:
+                conv_layer = LinearizedConv1d(
+                    embed_dim, out_channels, kernel_size, padding=kernel_size - 1
+                )
+            else:
+                conv_layer = LinearizedConv1d(
+                    conv_config[i - 1][0],
+                    out_channels,
+                    kernel_size,
+                    padding=kernel_size - 1,
+                )
+            self.conv_layers.append(conv_layer)
+            if layer_norm:
+                self.conv_layers.append(nn.LayerNorm(out_channels))
+            self.conv_layers.append(nn.ReLU())
+
+        self.layers = nn.ModuleList()
+        if conv_config[-1][0] != transformer_config[0][0]:
+            self.layers.append(Linear(conv_config[-1][0], transformer_config[0][0]))
+        self.layers.append(
+            TransformerDecoderLayer(
+                prepare_transformer_decoder_params(*transformer_config[0])
+            )
+        )
+
+        for i in range(1, len(transformer_config)):
+            if transformer_config[i - 1][0] != transformer_config[i][0]:
+                self.layers.append(
+                    Linear(transformer_config[i - 1][0], transformer_config[i][0])
+                )
+            self.layers.append(
+                TransformerDecoderLayer(
+                    prepare_transformer_decoder_params(*transformer_config[i])
+                )
+            )
+        self.fc_out = Linear(transformer_config[-1][0], vocab_size)
+
+    def forward(self, prev_output_tokens, encoder_out=None, incremental_state=None):
+        """
+        Args:
+            prev_output_tokens (LongTensor): previous decoder outputs of shape
+                `(batch, tgt_len)`, for input feeding/teacher forcing
+            encoder_out (Tensor, optional): output from the encoder, used for
+                encoder-side attention
+            incremental_state (dict): dictionary used for storing state during
+                :ref:`Incremental decoding`
+        Returns:
+            tuple:
+                - the last decoder layer's output of shape `(batch, tgt_len,
+                  vocab)`
+                - the last decoder layer's attention weights of shape `(batch,
+                  tgt_len, src_len)`
+        """
+        target_padding_mask = (
+            (prev_output_tokens == self.padding_idx).to(prev_output_tokens.device)
+            if incremental_state is None
+            else None
+        )
+
+        if incremental_state is not None:
+            prev_output_tokens = prev_output_tokens[:, -1:]
+
+        # embed tokens
+        x = self.embed_tokens(prev_output_tokens)
+
+        # B x T x C -> T x B x C
+        x = self._transpose_if_training(x, incremental_state)
+
+        for layer in self.conv_layers:
+            if isinstance(layer, LinearizedConvolution):
+                x = layer(x, incremental_state)
+            else:
+                x = layer(x)
+
+        # B x T x C -> T x B x C
+        x = self._transpose_if_inference(x, incremental_state)
+
+        # decoder layers
+        for layer in self.layers:
+            if isinstance(layer, TransformerDecoderLayer):
+                x, *_ = layer(
+                    x,
+                    (encoder_out["encoder_out"] if encoder_out is not None else None),
+                    (
+                        encoder_out["encoder_padding_mask"].t()
+                        if encoder_out["encoder_padding_mask"] is not None
+                        else None
+                    ),
+                    incremental_state,
+                    self_attn_mask=(
+                        self.buffered_future_mask(x)
+                        if incremental_state is None
+                        else None
+                    ),
+                    self_attn_padding_mask=(
+                        target_padding_mask if incremental_state is None else None
+                    ),
+                )
+            else:
+                x = layer(x)
+
+        # T x B x C -> B x T x C
+        x = x.transpose(0, 1)
+
+        x = self.fc_out(x)
+
+        return x, None
+
+    def buffered_future_mask(self, tensor):
+        dim = tensor.size(0)
+        if (
+            not hasattr(self, "_future_mask")
+            or self._future_mask is None
+            or self._future_mask.device != tensor.device
+        ):
+            self._future_mask = torch.triu(
+                utils.fill_with_neg_inf(tensor.new(dim, dim)), 1
+            )
+        if self._future_mask.size(0) < dim:
+            self._future_mask = torch.triu(
+                utils.fill_with_neg_inf(self._future_mask.resize_(dim, dim)), 1
+            )
+        return self._future_mask[:dim, :dim]
+
+    def _transpose_if_training(self, x, incremental_state):
+        if incremental_state is None:
+            x = x.transpose(0, 1)
+        return x
+
+    def _transpose_if_inference(self, x, incremental_state):
+        if incremental_state:
+            x = x.transpose(0, 1)
+        return x
+
+
+@register_model("asr_vggtransformer_encoder")
+class VGGTransformerEncoderModel(FairseqEncoderModel):
+    def __init__(self, encoder):
+        super().__init__(encoder)
+
+    @staticmethod
+    def add_args(parser):
+        """Add model-specific arguments to the parser."""
+        parser.add_argument(
+            "--input-feat-per-channel",
+            type=int,
+            metavar="N",
+            help="encoder input dimension per input channel",
+        )
+        parser.add_argument(
+            "--vggblock-enc-config",
+            type=str,
+            metavar="EXPR",
+            help="""
+    an array of tuples each containing the configuration of one vggblock
+    [(out_channels, conv_kernel_size, pooling_kernel_size,num_conv_layers), ...]
+    """,
+        )
+        parser.add_argument(
+            "--transformer-enc-config",
+            type=str,
+            metavar="EXPR",
+            help="""
+    a tuple containing the configuration of the Transformer layers
+    configurations:
+    [(input_dim,
+      num_heads,
+      ffn_dim,
+      normalize_before,
+      dropout,
+      attention_dropout,
+      relu_dropout), ]""",
+        )
+        parser.add_argument(
+            "--enc-output-dim",
+            type=int,
+            metavar="N",
+            help="encoder output dimension, projecting the LSTM output",
+        )
+        parser.add_argument(
+            "--in-channels",
+            type=int,
+            metavar="N",
+            help="number of encoder input channels",
+        )
+        parser.add_argument(
+            "--transformer-context",
+            type=str,
+            metavar="EXPR",
+            help="""
+    either None or a tuple of two ints, indicating left/right context a
+    transformer can have access to""",
+        )
+        parser.add_argument(
+            "--transformer-sampling",
+            type=str,
+            metavar="EXPR",
+            help="""
+    either None or a tuple of ints, indicating sampling factor in each layer""",
+        )
+
+    @classmethod
+    def build_model(cls, args, task):
+        """Build a new model instance."""
+        base_architecture_enconly(args)
+        encoder = VGGTransformerEncoderOnly(
+            vocab_size=len(task.target_dictionary),
+            input_feat_per_channel=args.input_feat_per_channel,
+            vggblock_config=eval(args.vggblock_enc_config),
+            transformer_config=eval(args.transformer_enc_config),
+            encoder_output_dim=args.enc_output_dim,
+            in_channels=args.in_channels,
+            transformer_context=eval(args.transformer_context),
+            transformer_sampling=eval(args.transformer_sampling),
+        )
+        return cls(encoder)
+
+    def get_normalized_probs(self, net_output, log_probs, sample=None):
+        # net_output['encoder_out'] is a (T, B, D) tensor
+        lprobs = super().get_normalized_probs(net_output, log_probs, sample)
+        # lprobs is a (T, B, D) tensor
+        # we need to transoose to get (B, T, D) tensor
+        lprobs = lprobs.transpose(0, 1).contiguous()
+        lprobs.batch_first = True
+        return lprobs
+
+
+class VGGTransformerEncoderOnly(VGGTransformerEncoder):
+    def __init__(
+        self,
+        vocab_size,
+        input_feat_per_channel,
+        vggblock_config=DEFAULT_ENC_VGGBLOCK_CONFIG,
+        transformer_config=DEFAULT_ENC_TRANSFORMER_CONFIG,
+        encoder_output_dim=512,
+        in_channels=1,
+        transformer_context=None,
+        transformer_sampling=None,
+    ):
+        super().__init__(
+            input_feat_per_channel=input_feat_per_channel,
+            vggblock_config=vggblock_config,
+            transformer_config=transformer_config,
+            encoder_output_dim=encoder_output_dim,
+            in_channels=in_channels,
+            transformer_context=transformer_context,
+            transformer_sampling=transformer_sampling,
+        )
+        self.fc_out = Linear(self.encoder_output_dim, vocab_size)
+
+    def forward(self, src_tokens, src_lengths, **kwargs):
+        """
+        src_tokens: padded tensor (B, T, C * feat)
+        src_lengths: tensor of original lengths of input utterances (B,)
+        """
+
+        enc_out = super().forward(src_tokens, src_lengths)
+        x = self.fc_out(enc_out["encoder_out"])
+        # x = F.log_softmax(x, dim=-1)
+        # Note: no need this line, because model.get_normalized_prob will call
+        # log_softmax
+        return {
+            "encoder_out": x,  # (T, B, C)
+            "encoder_padding_mask": enc_out["encoder_padding_mask"],  # (T, B)
+        }
+
+    def max_positions(self):
+        """Maximum input length supported by the encoder."""
+        return (1e6, 1e6)  # an arbitrary large number
+
+
+def Embedding(num_embeddings, embedding_dim, padding_idx):
+    m = nn.Embedding(num_embeddings, embedding_dim, padding_idx=padding_idx)
+    # nn.init.uniform_(m.weight, -0.1, 0.1)
+    # nn.init.constant_(m.weight[padding_idx], 0)
+    return m
+
+
+def Linear(in_features, out_features, bias=True, dropout=0):
+    """Linear layer (input: N x T x C)"""
+    m = nn.Linear(in_features, out_features, bias=bias)
+    # m.weight.data.uniform_(-0.1, 0.1)
+    # if bias:
+    #     m.bias.data.uniform_(-0.1, 0.1)
+    return m
+
+
+def LinearizedConv1d(in_channels, out_channels, kernel_size, dropout=0, **kwargs):
+    """Weight-normalized Conv1d layer optimized for decoding"""
+    m = LinearizedConvolution(in_channels, out_channels, kernel_size, **kwargs)
+    std = math.sqrt((4 * (1.0 - dropout)) / (m.kernel_size[0] * in_channels))
+    nn.init.normal_(m.weight, mean=0, std=std)
+    nn.init.constant_(m.bias, 0)
+    return nn.utils.weight_norm(m, dim=2)
+
+
+def LayerNorm(embedding_dim):
+    m = nn.LayerNorm(embedding_dim)
+    return m
+
+
+# seq2seq models
+def base_architecture(args):
+    args.input_feat_per_channel = getattr(args, "input_feat_per_channel", 40)
+    args.vggblock_enc_config = getattr(
+        args, "vggblock_enc_config", DEFAULT_ENC_VGGBLOCK_CONFIG
+    )
+    args.transformer_enc_config = getattr(
+        args, "transformer_enc_config", DEFAULT_ENC_TRANSFORMER_CONFIG
+    )
+    args.enc_output_dim = getattr(args, "enc_output_dim", 512)
+    args.in_channels = getattr(args, "in_channels", 1)
+    args.tgt_embed_dim = getattr(args, "tgt_embed_dim", 128)
+    args.transformer_dec_config = getattr(
+        args, "transformer_dec_config", DEFAULT_ENC_TRANSFORMER_CONFIG
+    )
+    args.conv_dec_config = getattr(args, "conv_dec_config", DEFAULT_DEC_CONV_CONFIG)
+    args.transformer_context = getattr(args, "transformer_context", "None")
+
+
+@register_model_architecture("asr_vggtransformer", "vggtransformer_1")
+def vggtransformer_1(args):
+    args.input_feat_per_channel = getattr(args, "input_feat_per_channel", 80)
+    args.vggblock_enc_config = getattr(
+        args, "vggblock_enc_config", "[(64, 3, 2, 2, True), (128, 3, 2, 2, True)]"
+    )
+    args.transformer_enc_config = getattr(
+        args,
+        "transformer_enc_config",
+        "((1024, 16, 4096, True, 0.15, 0.15, 0.15),) * 14",
+    )
+    args.enc_output_dim = getattr(args, "enc_output_dim", 1024)
+    args.tgt_embed_dim = getattr(args, "tgt_embed_dim", 128)
+    args.conv_dec_config = getattr(args, "conv_dec_config", "((256, 3, True),) * 4")
+    args.transformer_dec_config = getattr(
+        args,
+        "transformer_dec_config",
+        "((1024, 16, 4096, True, 0.15, 0.15, 0.15),) * 4",
+    )
+
+
+@register_model_architecture("asr_vggtransformer", "vggtransformer_2")
+def vggtransformer_2(args):
+    args.input_feat_per_channel = getattr(args, "input_feat_per_channel", 80)
+    args.vggblock_enc_config = getattr(
+        args, "vggblock_enc_config", "[(64, 3, 2, 2, True), (128, 3, 2, 2, True)]"
+    )
+    args.transformer_enc_config = getattr(
+        args,
+        "transformer_enc_config",
+        "((1024, 16, 4096, True, 0.15, 0.15, 0.15),) * 16",
+    )
+    args.enc_output_dim = getattr(args, "enc_output_dim", 1024)
+    args.tgt_embed_dim = getattr(args, "tgt_embed_dim", 512)
+    args.conv_dec_config = getattr(args, "conv_dec_config", "((256, 3, True),) * 4")
+    args.transformer_dec_config = getattr(
+        args,
+        "transformer_dec_config",
+        "((1024, 16, 4096, True, 0.15, 0.15, 0.15),) * 6",
+    )
+
+
+@register_model_architecture("asr_vggtransformer", "vggtransformer_base")
+def vggtransformer_base(args):
+    args.input_feat_per_channel = getattr(args, "input_feat_per_channel", 80)
+    args.vggblock_enc_config = getattr(
+        args, "vggblock_enc_config", "[(64, 3, 2, 2, True), (128, 3, 2, 2, True)]"
+    )
+    args.transformer_enc_config = getattr(
+        args, "transformer_enc_config", "((512, 8, 2048, True, 0.15, 0.15, 0.15),) * 12"
+    )
+
+    args.enc_output_dim = getattr(args, "enc_output_dim", 512)
+    args.tgt_embed_dim = getattr(args, "tgt_embed_dim", 512)
+    args.conv_dec_config = getattr(args, "conv_dec_config", "((256, 3, True),) * 4")
+    args.transformer_dec_config = getattr(
+        args, "transformer_dec_config", "((512, 8, 2048, True, 0.15, 0.15, 0.15),) * 6"
+    )
+    # Size estimations:
+    # Encoder:
+    #   - vggblock param: 64*1*3*3 + 64*64*3*3 + 128*64*3*3  + 128*128*3 = 258K
+    #   Transformer:
+    #   - input dimension adapter: 2560 x 512 -> 1.31M
+    #   - transformer_layers (x12) --> 37.74M
+    #       * MultiheadAttention: 512*512*3 (in_proj) + 512*512 (out_proj) = 1.048M
+    #       * FFN weight: 512*2048*2 = 2.097M
+    #   - output dimension adapter: 512 x 512 -> 0.26 M
+    # Decoder:
+    #   - LinearizedConv1d: 512 * 256 * 3 + 256 * 256 * 3 * 3
+    #   - transformer_layer: (x6) --> 25.16M
+    #        * MultiheadAttention (self-attention): 512*512*3 + 512*512 = 1.048M
+    #        * MultiheadAttention (encoder-attention): 512*512*3 + 512*512 = 1.048M
+    #        * FFN: 512*2048*2 = 2.097M
+    # Final FC:
+    #   - FC: 512*5000 = 256K (assuming vocab size 5K)
+    # In total:
+    #       ~65 M
+
+
+# CTC models
+def base_architecture_enconly(args):
+    args.input_feat_per_channel = getattr(args, "input_feat_per_channel", 40)
+    args.vggblock_enc_config = getattr(
+        args, "vggblock_enc_config", "[(32, 3, 2, 2, True)] * 2"
+    )
+    args.transformer_enc_config = getattr(
+        args, "transformer_enc_config", "((256, 4, 1024, True, 0.2, 0.2, 0.2),) * 2"
+    )
+    args.enc_output_dim = getattr(args, "enc_output_dim", 512)
+    args.in_channels = getattr(args, "in_channels", 1)
+    args.transformer_context = getattr(args, "transformer_context", "None")
+    args.transformer_sampling = getattr(args, "transformer_sampling", "None")
+
+
+@register_model_architecture("asr_vggtransformer_encoder", "vggtransformer_enc_1")
+def vggtransformer_enc_1(args):
+    # vggtransformer_1 is the same as vggtransformer_enc_big, except the number
+    # of layers is increased to 16
+    # keep it here for backward compatiablity purpose
+    args.input_feat_per_channel = getattr(args, "input_feat_per_channel", 80)
+    args.vggblock_enc_config = getattr(
+        args, "vggblock_enc_config", "[(64, 3, 2, 2, True), (128, 3, 2, 2, True)]"
+    )
+    args.transformer_enc_config = getattr(
+        args,
+        "transformer_enc_config",
+        "((1024, 16, 4096, True, 0.15, 0.15, 0.15),) * 16",
+    )
+    args.enc_output_dim = getattr(args, "enc_output_dim", 1024)

fairseq/examples/speech_recognition/models/w2l_conv_glu_enc.py

+#!/usr/bin/env python3
+
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+import math
+
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+from fairseq.models import (
+    FairseqEncoder,
+    FairseqEncoderModel,
+    register_model,
+    register_model_architecture,
+)
+from fairseq.modules.fairseq_dropout import FairseqDropout
+
+
+default_conv_enc_config = """[
+    (400, 13, 170, 0.2),
+    (440, 14, 0, 0.214),
+    (484, 15, 0, 0.22898),
+    (532, 16, 0, 0.2450086),
+    (584, 17, 0, 0.262159202),
+    (642, 18, 0, 0.28051034614),
+    (706, 19, 0, 0.30014607037),
+    (776, 20, 0, 0.321156295296),
+    (852, 21, 0, 0.343637235966),
+    (936, 22, 0, 0.367691842484),
+    (1028, 23, 0, 0.393430271458),
+    (1130, 24, 0, 0.42097039046),
+    (1242, 25, 0, 0.450438317792),
+    (1366, 26, 0, 0.481969000038),
+    (1502, 27, 0, 0.51570683004),
+    (1652, 28, 0, 0.551806308143),
+    (1816, 29, 0, 0.590432749713),
+]"""
+
+
+@register_model("asr_w2l_conv_glu_encoder")
+class W2lConvGluEncoderModel(FairseqEncoderModel):
+    def __init__(self, encoder):
+        super().__init__(encoder)
+
+    @staticmethod
+    def add_args(parser):
+        """Add model-specific arguments to the parser."""
+        parser.add_argument(
+            "--input-feat-per-channel",
+            type=int,
+            metavar="N",
+            help="encoder input dimension per input channel",
+        )
+        parser.add_argument(
+            "--in-channels",
+            type=int,
+            metavar="N",
+            help="number of encoder input channels",
+        )
+        parser.add_argument(
+            "--conv-enc-config",
+            type=str,
+            metavar="EXPR",
+            help="""
+    an array of tuples each containing the configuration of one conv layer
+    [(out_channels, kernel_size, padding, dropout), ...]
+            """,
+        )
+
+    @classmethod
+    def build_model(cls, args, task):
+        """Build a new model instance."""
+        conv_enc_config = getattr(args, "conv_enc_config", default_conv_enc_config)
+        encoder = W2lConvGluEncoder(
+            vocab_size=len(task.target_dictionary),
+            input_feat_per_channel=args.input_feat_per_channel,
+            in_channels=args.in_channels,
+            conv_enc_config=eval(conv_enc_config),
+        )
+        return cls(encoder)
+
+    def get_normalized_probs(self, net_output, log_probs, sample=None):
+        lprobs = super().get_normalized_probs(net_output, log_probs, sample)
+        lprobs.batch_first = False
+        return lprobs
+
+
+class W2lConvGluEncoder(FairseqEncoder):
+    def __init__(
+        self, vocab_size, input_feat_per_channel, in_channels, conv_enc_config
+    ):
+        super().__init__(None)
+
+        self.input_dim = input_feat_per_channel
+        if in_channels != 1:
+            raise ValueError("only 1 input channel is currently supported")
+
+        self.conv_layers = nn.ModuleList()
+        self.linear_layers = nn.ModuleList()
+        self.dropouts = []
+        cur_channels = input_feat_per_channel
+
+        for out_channels, kernel_size, padding, dropout in conv_enc_config:
+            layer = nn.Conv1d(cur_channels, out_channels, kernel_size, padding=padding)
+            layer.weight.data.mul_(math.sqrt(3))  # match wav2letter init
+            self.conv_layers.append(nn.utils.weight_norm(layer))
+            self.dropouts.append(
+                FairseqDropout(dropout, module_name=self.__class__.__name__)
+            )
+            if out_channels % 2 != 0:
+                raise ValueError("odd # of out_channels is incompatible with GLU")
+            cur_channels = out_channels // 2  # halved by GLU
+
+        for out_channels in [2 * cur_channels, vocab_size]:
+            layer = nn.Linear(cur_channels, out_channels)
+            layer.weight.data.mul_(math.sqrt(3))
+            self.linear_layers.append(nn.utils.weight_norm(layer))
+            cur_channels = out_channels // 2
+
+    def forward(self, src_tokens, src_lengths, **kwargs):
+
+        """
+        src_tokens: padded tensor (B, T, C * feat)
+        src_lengths: tensor of original lengths of input utterances (B,)
+        """
+        B, T, _ = src_tokens.size()
+        x = src_tokens.transpose(1, 2).contiguous()  # (B, feat, T) assuming C == 1
+
+        for layer_idx in range(len(self.conv_layers)):
+            x = self.conv_layers[layer_idx](x)
+            x = F.glu(x, dim=1)
+            x = self.dropouts[layer_idx](x)
+
+        x = x.transpose(1, 2).contiguous()  # (B, T, 908)
+        x = self.linear_layers[0](x)
+        x = F.glu(x, dim=2)
+        x = self.dropouts[-1](x)
+        x = self.linear_layers[1](x)
+
+        assert x.size(0) == B
+        assert x.size(1) == T
+
+        encoder_out = x.transpose(0, 1)  # (T, B, vocab_size)
+
+        # need to debug this -- find a simpler/elegant way in pytorch APIs
+        encoder_padding_mask = (
+            torch.arange(T).view(1, T).expand(B, -1).to(x.device)
+            >= src_lengths.view(B, 1).expand(-1, T)
+        ).t()  # (B x T) -> (T x B)
+
+        return {
+            "encoder_out": encoder_out,  # (T, B, vocab_size)
+            "encoder_padding_mask": encoder_padding_mask,  # (T, B)
+        }
+
+    def reorder_encoder_out(self, encoder_out, new_order):
+        encoder_out["encoder_out"] = encoder_out["encoder_out"].index_select(
+            1, new_order
+        )
+        encoder_out["encoder_padding_mask"] = encoder_out[
+            "encoder_padding_mask"
+        ].index_select(1, new_order)
+        return encoder_out
+
+    def max_positions(self):
+        """Maximum input length supported by the encoder."""
+        return (1e6, 1e6)  # an arbitrary large number
+
+
+@register_model_architecture("asr_w2l_conv_glu_encoder", "w2l_conv_glu_enc")
+def w2l_conv_glu_enc(args):
+    args.input_feat_per_channel = getattr(args, "input_feat_per_channel", 80)
+    args.in_channels = getattr(args, "in_channels", 1)
+    args.conv_enc_config = getattr(args, "conv_enc_config", default_conv_enc_config)

fairseq/examples/speech_recognition/new/README.md

+# Flashlight Decoder
+
+This script runs decoding for pre-trained speech recognition models.
+
+## Usage
+
+Assuming a few variables:
+
+```bash
+checkpoint=<path-to-checkpoint>
+data=<path-to-data-directory>
+lm_model=<path-to-language-model>
+lexicon=<path-to-lexicon>
+```
+
+Example usage for decoding a fine-tuned Wav2Vec model:
+
+```bash
+python $FAIRSEQ_ROOT/examples/speech_recognition/new/infer.py --multirun \
+    task=audio_pretraining \
+    task.data=$data \
+    task.labels=ltr \
+    common_eval.path=$checkpoint \
+    decoding.type=kenlm \
+    decoding.lexicon=$lexicon \
+    decoding.lmpath=$lm_model \
+    dataset.gen_subset=dev_clean,dev_other,test_clean,test_other
+```
+
+Example usage for using Ax to sweep WER parameters (requires `pip install hydra-ax-sweeper`):
+
+```bash
+python $FAIRSEQ_ROOT/examples/speech_recognition/new/infer.py --multirun \
+    hydra/sweeper=ax \
+    task=audio_pretraining \
+    task.data=$data \
+    task.labels=ltr \
+    common_eval.path=$checkpoint \
+    decoding.type=kenlm \
+    decoding.lexicon=$lexicon \
+    decoding.lmpath=$lm_model \
+    dataset.gen_subset=dev_other
+```

fairseq/examples/speech_recognition/new/conf/hydra/sweeper/ax.yaml

+# @package hydra.sweeper
+_target_: hydra_plugins.hydra_ax_sweeper.ax_sweeper.AxSweeper
+max_batch_size: null
+ax_config:
+  max_trials: 128
+  early_stop:
+    minimize: true
+    max_epochs_without_improvement: 32
+    epsilon: 1.0e-05
+  experiment:
+    name: ${dataset.gen_subset}
+    objective_name: wer
+    minimize: true
+    parameter_constraints: null
+    outcome_constraints: null
+    status_quo: null
+  client:
+    verbose_logging: false
+    random_seed: null
+  params:
+    decoding.lmweight:
+      type: range
+      bounds: [0.0, 5.0]
+    decoding.wordscore:
+      type: range
+      bounds: [-5.0, 5.0]

fairseq/examples/speech_recognition/new/conf/infer.yaml

+# @package _group_
+
+defaults:
+    - task: null
+    - model: null
+
+hydra:
+  run:
+    dir: ${common_eval.results_path}/${dataset.gen_subset}
+  sweep:
+    dir: ${common_eval.results_path}
+    subdir: ${dataset.gen_subset}
+common_eval:
+  results_path: null
+  path: null
+  post_process: letter
+  quiet: true
+dataset:
+  max_tokens: 1000000
+  gen_subset: test
+distributed_training:
+  distributed_world_size: 1
+decoding:
+  beam: 5
+  type: viterbi

fairseq/examples/speech_recognition/new/decoders/base_decoder.py

+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+import itertools as it
+from typing import Any, Dict, List
+
+import torch
+from fairseq.data.dictionary import Dictionary
+from fairseq.models.fairseq_model import FairseqModel
+
+
+class BaseDecoder:
+    def __init__(self, tgt_dict: Dictionary) -> None:
+        self.tgt_dict = tgt_dict
+        self.vocab_size = len(tgt_dict)
+
+        self.blank = (
+            tgt_dict.index("<ctc_blank>")
+            if "<ctc_blank>" in tgt_dict.indices
+            else tgt_dict.bos()
+        )
+        if "<sep>" in tgt_dict.indices:
+            self.silence = tgt_dict.index("<sep>")
+        elif "|" in tgt_dict.indices:
+            self.silence = tgt_dict.index("|")
+        else:
+            self.silence = tgt_dict.eos()
+
+    def generate(
+        self, models: List[FairseqModel], sample: Dict[str, Any], **unused
+    ) -> List[List[Dict[str, torch.LongTensor]]]:
+        encoder_input = {
+            k: v for k, v in sample["net_input"].items() if k != "prev_output_tokens"
+        }
+        emissions = self.get_emissions(models, encoder_input)
+        return self.decode(emissions)
+
+    def get_emissions(
+        self,
+        models: List[FairseqModel],
+        encoder_input: Dict[str, Any],
+    ) -> torch.FloatTensor:
+        model = models[0]
+        encoder_out = model(**encoder_input)
+        if hasattr(model, "get_logits"):
+            emissions = model.get_logits(encoder_out)
+        else:
+            emissions = model.get_normalized_probs(encoder_out, log_probs=True)
+        return emissions.transpose(0, 1).float().cpu().contiguous()
+
+    def get_tokens(self, idxs: torch.IntTensor) -> torch.LongTensor:
+        idxs = (g[0] for g in it.groupby(idxs))
+        idxs = filter(lambda x: x != self.blank, idxs)
+        return torch.LongTensor(list(idxs))
+
+    def decode(
+        self,
+        emissions: torch.FloatTensor,
+    ) -> List[List[Dict[str, torch.LongTensor]]]:
+        raise NotImplementedError

fairseq/examples/speech_recognition/new/decoders/decoder.py

+#!/usr/bin/env python3
+
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+from typing import Union
+
+from fairseq.data.dictionary import Dictionary
+
+from .decoder_config import DecoderConfig, FlashlightDecoderConfig
+from .base_decoder import BaseDecoder
+
+
+def Decoder(
+    cfg: Union[DecoderConfig, FlashlightDecoderConfig], tgt_dict: Dictionary
+) -> BaseDecoder:
+
+    if cfg.type == "viterbi":
+        from .viterbi_decoder import ViterbiDecoder
+
+        return ViterbiDecoder(tgt_dict)
+    if cfg.type == "kenlm":
+        from .flashlight_decoder import KenLMDecoder
+
+        return KenLMDecoder(cfg, tgt_dict)
+    if cfg.type == "fairseqlm":
+        from .flashlight_decoder import FairseqLMDecoder
+
+        return FairseqLMDecoder(cfg, tgt_dict)
+    raise NotImplementedError(f"Invalid decoder name: {cfg.name}")

fairseq/examples/speech_recognition/new/decoders/decoder_config.py

+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+import math
+from dataclasses import dataclass, field
+from typing import Optional
+
+from fairseq.dataclass.configs import FairseqDataclass
+from fairseq.dataclass.constants import ChoiceEnum
+from omegaconf import MISSING
+
+
+DECODER_CHOICES = ChoiceEnum(["viterbi", "kenlm", "fairseqlm"])
+
+
+@dataclass
+class DecoderConfig(FairseqDataclass):
+    type: DECODER_CHOICES = field(
+        default="viterbi",
+        metadata={"help": "The type of decoder to use"},
+    )
+
+
+@dataclass
+class FlashlightDecoderConfig(FairseqDataclass):
+    nbest: int = field(
+        default=1,
+        metadata={"help": "Number of decodings to return"},
+    )
+    unitlm: bool = field(
+        default=False,
+        metadata={"help": "If set, use unit language model"},
+    )
+    lmpath: str = field(
+        default=MISSING,
+        metadata={"help": "Language model for KenLM decoder"},
+    )
+    lexicon: Optional[str] = field(
+        default=None,
+        metadata={"help": "Lexicon for Flashlight decoder"},
+    )
+    beam: int = field(
+        default=50,
+        metadata={"help": "Number of beams to use for decoding"},
+    )
+    beamthreshold: float = field(
+        default=50.0,
+        metadata={"help": "Threshold for beam search decoding"},
+    )
+    beamsizetoken: Optional[int] = field(
+        default=None, metadata={"help": "Beam size to use"}
+    )
+    wordscore: float = field(
+        default=-1,
+        metadata={"help": "Word score for KenLM decoder"},
+    )
+    unkweight: float = field(
+        default=-math.inf,
+        metadata={"help": "Unknown weight for KenLM decoder"},
+    )
+    silweight: float = field(
+        default=0,
+        metadata={"help": "Silence weight for KenLM decoder"},
+    )
+    lmweight: float = field(
+        default=2,
+        metadata={"help": "Weight for LM while interpolating score"},
+    )

fairseq/examples/speech_recognition/new/decoders/flashlight_decoder.py

+#!/usr/bin/env python3
+
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+import gc
+import os.path as osp
+import warnings
+from collections import deque, namedtuple
+from typing import Any, Dict, Tuple
+
+import numpy as np
+import torch
+from fairseq import tasks
+from fairseq.data.dictionary import Dictionary
+from fairseq.dataclass.utils import convert_namespace_to_omegaconf
+from fairseq.models.fairseq_model import FairseqModel
+from fairseq.utils import apply_to_sample
+from omegaconf import open_dict, OmegaConf
+
+from typing import List
+
+from .decoder_config import FlashlightDecoderConfig
+from .base_decoder import BaseDecoder
+
+try:
+    from flashlight.lib.text.decoder import (
+        LM,
+        CriterionType,
+        DecodeResult,
+        KenLM,
+        LexiconDecoder,
+        LexiconDecoderOptions,
+        LexiconFreeDecoder,
+        LexiconFreeDecoderOptions,
+        LMState,
+        SmearingMode,
+        Trie,
+    )
+    from flashlight.lib.text.dictionary import create_word_dict, load_words
+except ImportError:
+    warnings.warn(
+        "flashlight python bindings are required to use this functionality. "
+        "Please install from "
+        "https://github.com/facebookresearch/flashlight/tree/master/bindings/python"
+    )
+    LM = object
+    LMState = object
+
+
+class KenLMDecoder(BaseDecoder):
+    def __init__(self, cfg: FlashlightDecoderConfig, tgt_dict: Dictionary) -> None:
+        super().__init__(tgt_dict)
+
+        self.nbest = cfg.nbest
+        self.unitlm = cfg.unitlm
+
+        if cfg.lexicon:
+            self.lexicon = load_words(cfg.lexicon)
+            self.word_dict = create_word_dict(self.lexicon)
+            self.unk_word = self.word_dict.get_index("<unk>")
+
+            self.lm = KenLM(cfg.lmpath, self.word_dict)
+            self.trie = Trie(self.vocab_size, self.silence)
+
+            start_state = self.lm.start(False)
+            for word, spellings in self.lexicon.items():
+                word_idx = self.word_dict.get_index(word)
+                _, score = self.lm.score(start_state, word_idx)
+                for spelling in spellings:
+                    spelling_idxs = [tgt_dict.index(token) for token in spelling]
+                    assert (
+                        tgt_dict.unk() not in spelling_idxs
+                    ), f"{word} {spelling} {spelling_idxs}"
+                    self.trie.insert(spelling_idxs, word_idx, score)
+            self.trie.smear(SmearingMode.MAX)
+
+            self.decoder_opts = LexiconDecoderOptions(
+                beam_size=cfg.beam,
+                beam_size_token=cfg.beamsizetoken or len(tgt_dict),
+                beam_threshold=cfg.beamthreshold,
+                lm_weight=cfg.lmweight,
+                word_score=cfg.wordscore,
+                unk_score=cfg.unkweight,
+                sil_score=cfg.silweight,
+                log_add=False,
+                criterion_type=CriterionType.CTC,
+            )
+
+            self.decoder = LexiconDecoder(
+                self.decoder_opts,
+                self.trie,
+                self.lm,
+                self.silence,
+                self.blank,
+                self.unk_word,
+                [],
+                self.unitlm,
+            )
+        else:
+            assert self.unitlm, "Lexicon-free decoding requires unit LM"
+
+            d = {w: [[w]] for w in tgt_dict.symbols}
+            self.word_dict = create_word_dict(d)
+            self.lm = KenLM(cfg.lmpath, self.word_dict)
+            self.decoder_opts = LexiconFreeDecoderOptions(
+                beam_size=cfg.beam,
+                beam_size_token=cfg.beamsizetoken or len(tgt_dict),
+                beam_threshold=cfg.beamthreshold,
+                lm_weight=cfg.lmweight,
+                sil_score=cfg.silweight,
+                log_add=False,
+                criterion_type=CriterionType.CTC,
+            )
+            self.decoder = LexiconFreeDecoder(
+                self.decoder_opts, self.lm, self.silence, self.blank, []
+            )
+
+    def get_timesteps(self, token_idxs: List[int]) -> List[int]:
+        """Returns frame numbers corresponding to every non-blank token.
+
+        Parameters
+        ----------
+        token_idxs : List[int]
+            IDs of decoded tokens.
+
+        Returns
+        -------
+        List[int]
+            Frame numbers corresponding to every non-blank token.
+        """
+        timesteps = []
+        for i, token_idx in enumerate(token_idxs):
+            if token_idx == self.blank:
+                continue
+            if i == 0 or token_idx != token_idxs[i-1]:
+                timesteps.append(i)
+        return timesteps
+
+    def decode(
+        self,
+        emissions: torch.FloatTensor,
+    ) -> List[List[Dict[str, torch.LongTensor]]]:
+        B, T, N = emissions.size()
+        hypos = []
+        for b in range(B):
+            emissions_ptr = emissions.data_ptr() + 4 * b * emissions.stride(0)
+            results = self.decoder.decode(emissions_ptr, T, N)
+
+            nbest_results = results[: self.nbest]
+            hypos.append(
+                [
+                    {
+                        "tokens": self.get_tokens(result.tokens),
+                        "score": result.score,
+                        "timesteps": self.get_timesteps(result.tokens),
+                        "words": [
+                            self.word_dict.get_entry(x) for x in result.words if x >= 0
+                        ],
+                    }
+                    for result in nbest_results
+                ]
+            )
+        return hypos
+
+
+FairseqLMState = namedtuple(
+    "FairseqLMState",
+    [
+        "prefix",
+        "incremental_state",
+        "probs",
+    ],
+)
+
+
+class FairseqLM(LM):
+    def __init__(self, dictionary: Dictionary, model: FairseqModel) -> None:
+        super().__init__()
+
+        self.dictionary = dictionary
+        self.model = model
+        self.unk = self.dictionary.unk()
+
+        self.save_incremental = False  # this currently does not work properly
+        self.max_cache = 20_000
+
+        if torch.cuda.is_available():
+            model.cuda()
+        model.eval()
+        model.make_generation_fast_()
+
+        self.states = {}
+        self.stateq = deque()
+
+    def start(self, start_with_nothing: bool) -> LMState:
+        state = LMState()
+        prefix = torch.LongTensor([[self.dictionary.eos()]])
+        incremental_state = {} if self.save_incremental else None
+        with torch.no_grad():
+            res = self.model(prefix.cuda(), incremental_state=incremental_state)
+            probs = self.model.get_normalized_probs(res, log_probs=True, sample=None)
+
+        if incremental_state is not None:
+            incremental_state = apply_to_sample(lambda x: x.cpu(), incremental_state)
+        self.states[state] = FairseqLMState(
+            prefix.numpy(), incremental_state, probs[0, -1].cpu().numpy()
+        )
+        self.stateq.append(state)
+
+        return state
+
+    def score(
+        self,
+        state: LMState,
+        token_index: int,
+        no_cache: bool = False,
+    ) -> Tuple[LMState, int]:
+        """
+        Evaluate language model based on the current lm state and new word
+        Parameters:
+        -----------
+        state: current lm state
+        token_index: index of the word
+                     (can be lexicon index then you should store inside LM the
+                      mapping between indices of lexicon and lm, or lm index of a word)
+        Returns:
+        --------
+        (LMState, float): pair of (new state, score for the current word)
+        """
+        curr_state = self.states[state]
+
+        def trim_cache(targ_size: int) -> None:
+            while len(self.stateq) > targ_size:
+                rem_k = self.stateq.popleft()
+                rem_st = self.states[rem_k]
+                rem_st = FairseqLMState(rem_st.prefix, None, None)
+                self.states[rem_k] = rem_st
+
+        if curr_state.probs is None:
+            new_incremental_state = (
+                curr_state.incremental_state.copy()
+                if curr_state.incremental_state is not None
+                else None
+            )
+            with torch.no_grad():
+                if new_incremental_state is not None:
+                    new_incremental_state = apply_to_sample(
+                        lambda x: x.cuda(), new_incremental_state
+                    )
+                elif self.save_incremental:
+                    new_incremental_state = {}
+
+                res = self.model(
+                    torch.from_numpy(curr_state.prefix).cuda(),
+                    incremental_state=new_incremental_state,
+                )
+                probs = self.model.get_normalized_probs(
+                    res, log_probs=True, sample=None
+                )
+
+                if new_incremental_state is not None:
+                    new_incremental_state = apply_to_sample(
+                        lambda x: x.cpu(), new_incremental_state
+                    )
+
+                curr_state = FairseqLMState(
+                    curr_state.prefix, new_incremental_state, probs[0, -1].cpu().numpy()
+                )
+
+            if not no_cache:
+                self.states[state] = curr_state
+                self.stateq.append(state)
+
+        score = curr_state.probs[token_index].item()
+
+        trim_cache(self.max_cache)
+
+        outstate = state.child(token_index)
+        if outstate not in self.states and not no_cache:
+            prefix = np.concatenate(
+                [curr_state.prefix, torch.LongTensor([[token_index]])], -1
+            )
+            incr_state = curr_state.incremental_state
+
+            self.states[outstate] = FairseqLMState(prefix, incr_state, None)
+
+        if token_index == self.unk:
+            score = float("-inf")
+
+        return outstate, score
+
+    def finish(self, state: LMState) -> Tuple[LMState, int]:
+        """
+        Evaluate eos for language model based on the current lm state
+        Returns:
+        --------
+        (LMState, float): pair of (new state, score for the current word)
+        """
+        return self.score(state, self.dictionary.eos())
+
+    def empty_cache(self) -> None:
+        self.states = {}
+        self.stateq = deque()
+        gc.collect()
+
+
+class FairseqLMDecoder(BaseDecoder):
+    def __init__(self, cfg: FlashlightDecoderConfig, tgt_dict: Dictionary) -> None:
+        super().__init__(tgt_dict)
+
+        self.nbest = cfg.nbest
+        self.unitlm = cfg.unitlm
+
+        self.lexicon = load_words(cfg.lexicon) if cfg.lexicon else None
+        self.idx_to_wrd = {}
+
+        checkpoint = torch.load(cfg.lmpath, map_location="cpu")
+
+        if "cfg" in checkpoint and checkpoint["cfg"] is not None:
+            lm_args = checkpoint["cfg"]
+        else:
+            lm_args = convert_namespace_to_omegaconf(checkpoint["args"])
+
+        if not OmegaConf.is_dict(lm_args):
+            lm_args = OmegaConf.create(lm_args)
+
+        with open_dict(lm_args.task):
+            lm_args.task.data = osp.dirname(cfg.lmpath)
+
+        task = tasks.setup_task(lm_args.task)
+        model = task.build_model(lm_args.model)
+        model.load_state_dict(checkpoint["model"], strict=False)
+
+        self.trie = Trie(self.vocab_size, self.silence)
+
+        self.word_dict = task.dictionary
+        self.unk_word = self.word_dict.unk()
+        self.lm = FairseqLM(self.word_dict, model)
+
+        if self.lexicon:
+            start_state = self.lm.start(False)
+            for i, (word, spellings) in enumerate(self.lexicon.items()):
+                if self.unitlm:
+                    word_idx = i
+                    self.idx_to_wrd[i] = word
+                    score = 0
+                else:
+                    word_idx = self.word_dict.index(word)
+                    _, score = self.lm.score(start_state, word_idx, no_cache=True)
+
+                for spelling in spellings:
+                    spelling_idxs = [tgt_dict.index(token) for token in spelling]
+                    assert (
+                        tgt_dict.unk() not in spelling_idxs
+                    ), f"{spelling} {spelling_idxs}"
+                    self.trie.insert(spelling_idxs, word_idx, score)
+            self.trie.smear(SmearingMode.MAX)
+
+            self.decoder_opts = LexiconDecoderOptions(
+                beam_size=cfg.beam,
+                beam_size_token=cfg.beamsizetoken or len(tgt_dict),
+                beam_threshold=cfg.beamthreshold,
+                lm_weight=cfg.lmweight,
+                word_score=cfg.wordscore,
+                unk_score=cfg.unkweight,
+                sil_score=cfg.silweight,
+                log_add=False,
+                criterion_type=CriterionType.CTC,
+            )
+
+            self.decoder = LexiconDecoder(
+                self.decoder_opts,
+                self.trie,
+                self.lm,
+                self.silence,
+                self.blank,
+                self.unk_word,
+                [],
+                self.unitlm,
+            )
+        else:
+            assert self.unitlm, "Lexicon-free decoding requires unit LM"
+
+            d = {w: [[w]] for w in tgt_dict.symbols}
+            self.word_dict = create_word_dict(d)
+            self.lm = KenLM(cfg.lmpath, self.word_dict)
+            self.decoder_opts = LexiconFreeDecoderOptions(
+                beam_size=cfg.beam,
+                beam_size_token=cfg.beamsizetoken or len(tgt_dict),
+                beam_threshold=cfg.beamthreshold,
+                lm_weight=cfg.lmweight,
+                sil_score=cfg.silweight,
+                log_add=False,
+                criterion_type=CriterionType.CTC,
+            )
+            self.decoder = LexiconFreeDecoder(
+                self.decoder_opts, self.lm, self.silence, self.blank, []
+            )
+
+    def decode(
+        self,
+        emissions: torch.FloatTensor,
+    ) -> List[List[Dict[str, torch.LongTensor]]]:
+        B, T, N = emissions.size()
+        hypos = []
+
+        def make_hypo(result: DecodeResult) -> Dict[str, Any]:
+            hypo = {
+                "tokens": self.get_tokens(result.tokens),
+                "score": result.score,
+            }
+            if self.lexicon:
+                hypo["words"] = [
+                    self.idx_to_wrd[x] if self.unitlm else self.word_dict[x]
+                    for x in result.words
+                    if x >= 0
+                ]
+            return hypo
+
+        for b in range(B):
+            emissions_ptr = emissions.data_ptr() + 4 * b * emissions.stride(0)
+            results = self.decoder.decode(emissions_ptr, T, N)
+
+            nbest_results = results[: self.nbest]
+            hypos.append([make_hypo(result) for result in nbest_results])
+            self.lm.empty_cache()
+
+        return hypos

fairseq/examples/speech_recognition/new/decoders/viterbi_decoder.py

+#!/usr/bin/env python3
+
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+import torch
+
+from typing import List, Dict
+
+from .base_decoder import BaseDecoder
+
+
+class ViterbiDecoder(BaseDecoder):
+    def decode(
+        self,
+        emissions: torch.FloatTensor,
+    ) -> List[List[Dict[str, torch.LongTensor]]]:
+        def get_pred(e):
+            toks = e.argmax(dim=-1).unique_consecutive()
+            return toks[toks != self.blank]
+
+        return [[{"tokens": get_pred(x), "score": 0}] for x in emissions]

fairseq/examples/speech_recognition/new/infer.py

+#!/usr/bin/env python -u
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+import ast
+import hashlib
+import logging
+import os
+import shutil
+import sys
+from dataclasses import dataclass, field, is_dataclass
+from pathlib import Path
+from typing import Any, Dict, List, Optional, Tuple, Union
+
+import editdistance
+import torch
+import torch.distributed as dist
+from examples.speech_recognition.new.decoders.decoder_config import (
+    DecoderConfig,
+    FlashlightDecoderConfig,
+)
+from examples.speech_recognition.new.decoders.decoder import Decoder
+from fairseq import checkpoint_utils, distributed_utils, progress_bar, tasks, utils
+from fairseq.data.data_utils import post_process
+from fairseq.dataclass.configs import (
+    CheckpointConfig,
+    CommonConfig,
+    CommonEvalConfig,
+    DatasetConfig,
+    DistributedTrainingConfig,
+    FairseqDataclass,
+)
+from fairseq.logging.meters import StopwatchMeter, TimeMeter
+from fairseq.logging.progress_bar import BaseProgressBar
+from fairseq.models.fairseq_model import FairseqModel
+from omegaconf import OmegaConf
+
+import hydra
+from hydra.core.config_store import ConfigStore
+
+logging.root.setLevel(logging.INFO)
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger(__name__)
+
+config_path = Path(__file__).resolve().parent / "conf"
+
+
+@dataclass
+class DecodingConfig(DecoderConfig, FlashlightDecoderConfig):
+    unique_wer_file: bool = field(
+        default=False,
+        metadata={"help": "If set, use a unique file for storing WER"},
+    )
+    results_path: Optional[str] = field(
+        default=None,
+        metadata={
+            "help": "If set, write hypothesis and reference sentences into this directory"
+        },
+    )
+
+
+@dataclass
+class InferConfig(FairseqDataclass):
+    task: Any = None
+    decoding: DecodingConfig = DecodingConfig()
+    common: CommonConfig = CommonConfig()
+    common_eval: CommonEvalConfig = CommonEvalConfig()
+    checkpoint: CheckpointConfig = CheckpointConfig()
+    distributed_training: DistributedTrainingConfig = DistributedTrainingConfig()
+    dataset: DatasetConfig = DatasetConfig()
+    is_ax: bool = field(
+        default=False,
+        metadata={
+            "help": "if true, assumes we are using ax for tuning and returns a tuple for ax to consume"
+        },
+    )
+
+
+def reset_logging():
+    root = logging.getLogger()
+    for handler in root.handlers:
+        root.removeHandler(handler)
+    root.setLevel(os.environ.get("LOGLEVEL", "INFO").upper())
+    handler = logging.StreamHandler(sys.stdout)
+    handler.setFormatter(
+        logging.Formatter(
+            fmt="%(asctime)s | %(levelname)s | %(name)s | %(message)s",
+            datefmt="%Y-%m-%d %H:%M:%S",
+        )
+    )
+    root.addHandler(handler)
+
+
+class InferenceProcessor:
+    cfg: InferConfig
+
+    def __init__(self, cfg: InferConfig) -> None:
+        self.cfg = cfg
+        self.task = tasks.setup_task(cfg.task)
+
+        models, saved_cfg = self.load_model_ensemble()
+        self.models = models
+        self.saved_cfg = saved_cfg
+        self.tgt_dict = self.task.target_dictionary
+
+        self.task.load_dataset(
+            self.cfg.dataset.gen_subset,
+            task_cfg=saved_cfg.task,
+        )
+        self.generator = Decoder(cfg.decoding, self.tgt_dict)
+        self.gen_timer = StopwatchMeter()
+        self.wps_meter = TimeMeter()
+        self.num_sentences = 0
+        self.total_errors = 0
+        self.total_length = 0
+
+        self.hypo_words_file = None
+        self.hypo_units_file = None
+        self.ref_words_file = None
+        self.ref_units_file = None
+
+        self.progress_bar = self.build_progress_bar()
+
+    def __enter__(self) -> "InferenceProcessor":
+        if self.cfg.decoding.results_path is not None:
+            self.hypo_words_file = self.get_res_file("hypo.word")
+            self.hypo_units_file = self.get_res_file("hypo.units")
+            self.ref_words_file = self.get_res_file("ref.word")
+            self.ref_units_file = self.get_res_file("ref.units")
+        return self
+
+    def __exit__(self, *exc) -> bool:
+        if self.cfg.decoding.results_path is not None:
+            self.hypo_words_file.close()
+            self.hypo_units_file.close()
+            self.ref_words_file.close()
+            self.ref_units_file.close()
+        return False
+
+    def __iter__(self) -> Any:
+        for sample in self.progress_bar:
+            if not self.cfg.common.cpu:
+                sample = utils.move_to_cuda(sample)
+
+            # Happens on the last batch.
+            if "net_input" not in sample:
+                continue
+            yield sample
+
+    def log(self, *args, **kwargs):
+        self.progress_bar.log(*args, **kwargs)
+
+    def print(self, *args, **kwargs):
+        self.progress_bar.print(*args, **kwargs)
+
+    def get_res_file(self, fname: str) -> None:
+        fname = os.path.join(self.cfg.decoding.results_path, fname)
+        if self.data_parallel_world_size > 1:
+            fname = f"{fname}.{self.data_parallel_rank}"
+        return open(fname, "w", buffering=1)
+
+    def merge_shards(self) -> None:
+        """Merges all shard files into shard 0, then removes shard suffix."""
+
+        shard_id = self.data_parallel_rank
+        num_shards = self.data_parallel_world_size
+
+        if self.data_parallel_world_size > 1:
+
+            def merge_shards_with_root(fname: str) -> None:
+                fname = os.path.join(self.cfg.decoding.results_path, fname)
+                logger.info("Merging %s on shard %d", fname, shard_id)
+                base_fpath = Path(f"{fname}.0")
+                with open(base_fpath, "a") as out_file:
+                    for s in range(1, num_shards):
+                        shard_fpath = Path(f"{fname}.{s}")
+                        with open(shard_fpath, "r") as in_file:
+                            for line in in_file:
+                                out_file.write(line)
+                        shard_fpath.unlink()
+                shutil.move(f"{fname}.0", fname)
+
+            dist.barrier()  # ensure all shards finished writing
+            if shard_id == (0 % num_shards):
+                merge_shards_with_root("hypo.word")
+            if shard_id == (1 % num_shards):
+                merge_shards_with_root("hypo.units")
+            if shard_id == (2 % num_shards):
+                merge_shards_with_root("ref.word")
+            if shard_id == (3 % num_shards):
+                merge_shards_with_root("ref.units")
+            dist.barrier()
+
+    def optimize_model(self, model: FairseqModel) -> None:
+        model.make_generation_fast_()
+        if self.cfg.common.fp16:
+            model.half()
+        if not self.cfg.common.cpu:
+            model.cuda()
+
+    def load_model_ensemble(self) -> Tuple[List[FairseqModel], FairseqDataclass]:
+        arg_overrides = ast.literal_eval(self.cfg.common_eval.model_overrides)
+        models, saved_cfg = checkpoint_utils.load_model_ensemble(
+            utils.split_paths(self.cfg.common_eval.path, separator="\\"),
+            arg_overrides=arg_overrides,
+            task=self.task,
+            suffix=self.cfg.checkpoint.checkpoint_suffix,
+            strict=(self.cfg.checkpoint.checkpoint_shard_count == 1),
+            num_shards=self.cfg.checkpoint.checkpoint_shard_count,
+        )
+        for model in models:
+            self.optimize_model(model)
+        return models, saved_cfg
+
+    def get_dataset_itr(self, disable_iterator_cache: bool = False) -> None:
+        return self.task.get_batch_iterator(
+            dataset=self.task.dataset(self.cfg.dataset.gen_subset),
+            max_tokens=self.cfg.dataset.max_tokens,
+            max_sentences=self.cfg.dataset.batch_size,
+            max_positions=(sys.maxsize, sys.maxsize),
+            ignore_invalid_inputs=self.cfg.dataset.skip_invalid_size_inputs_valid_test,
+            required_batch_size_multiple=self.cfg.dataset.required_batch_size_multiple,
+            seed=self.cfg.common.seed,
+            num_shards=self.data_parallel_world_size,
+            shard_id=self.data_parallel_rank,
+            num_workers=self.cfg.dataset.num_workers,
+            data_buffer_size=self.cfg.dataset.data_buffer_size,
+            disable_iterator_cache=disable_iterator_cache,
+        ).next_epoch_itr(shuffle=False)
+
+    def build_progress_bar(
+        self,
+        epoch: Optional[int] = None,
+        prefix: Optional[str] = None,
+        default_log_format: str = "tqdm",
+    ) -> BaseProgressBar:
+        return progress_bar.progress_bar(
+            iterator=self.get_dataset_itr(),
+            log_format=self.cfg.common.log_format,
+            log_interval=self.cfg.common.log_interval,
+            epoch=epoch,
+            prefix=prefix,
+            tensorboard_logdir=self.cfg.common.tensorboard_logdir,
+            default_log_format=default_log_format,
+        )
+
+    @property
+    def data_parallel_world_size(self):
+        if self.cfg.distributed_training.distributed_world_size == 1:
+            return 1
+        return distributed_utils.get_data_parallel_world_size()
+
+    @property
+    def data_parallel_rank(self):
+        if self.cfg.distributed_training.distributed_world_size == 1:
+            return 0
+        return distributed_utils.get_data_parallel_rank()
+
+    def process_sentence(
+        self,
+        sample: Dict[str, Any],
+        hypo: Dict[str, Any],
+        sid: int,
+        batch_id: int,
+    ) -> Tuple[int, int]:
+        speaker = None  # Speaker can't be parsed from dataset.
+
+        if "target_label" in sample:
+            toks = sample["target_label"]
+        else:
+            toks = sample["target"]
+        toks = toks[batch_id, :]
+
+        # Processes hypothesis.
+        hyp_pieces = self.tgt_dict.string(hypo["tokens"].int().cpu())
+        if "words" in hypo:
+            hyp_words = " ".join(hypo["words"])
+        else:
+            hyp_words = post_process(hyp_pieces, self.cfg.common_eval.post_process)
+
+        # Processes target.
+        target_tokens = utils.strip_pad(toks, self.tgt_dict.pad())
+        tgt_pieces = self.tgt_dict.string(target_tokens.int().cpu())
+        tgt_words = post_process(tgt_pieces, self.cfg.common_eval.post_process)
+
+        if self.cfg.decoding.results_path is not None:
+            print(f"{hyp_pieces} ({speaker}-{sid})", file=self.hypo_units_file)
+            print(f"{hyp_words} ({speaker}-{sid})", file=self.hypo_words_file)
+            print(f"{tgt_pieces} ({speaker}-{sid})", file=self.ref_units_file)
+            print(f"{tgt_words} ({speaker}-{sid})", file=self.ref_words_file)
+
+        if not self.cfg.common_eval.quiet:
+            logger.info(f"HYPO: {hyp_words}")
+            logger.info(f"REF: {tgt_words}")
+            logger.info("---------------------")
+
+        hyp_words, tgt_words = hyp_words.split(), tgt_words.split()
+
+        return editdistance.eval(hyp_words, tgt_words), len(tgt_words)
+
+    def process_sample(self, sample: Dict[str, Any]) -> None:
+        self.gen_timer.start()
+        hypos = self.task.inference_step(
+            generator=self.generator,
+            models=self.models,
+            sample=sample,
+        )
+        num_generated_tokens = sum(len(h[0]["tokens"]) for h in hypos)
+        self.gen_timer.stop(num_generated_tokens)
+        self.wps_meter.update(num_generated_tokens)
+
+        for batch_id, sample_id in enumerate(sample["id"].tolist()):
+            errs, length = self.process_sentence(
+                sample=sample,
+                sid=sample_id,
+                batch_id=batch_id,
+                hypo=hypos[batch_id][0],
+            )
+            self.total_errors += errs
+            self.total_length += length
+
+        self.log({"wps": round(self.wps_meter.avg)})
+        if "nsentences" in sample:
+            self.num_sentences += sample["nsentences"]
+        else:
+            self.num_sentences += sample["id"].numel()
+
+    def log_generation_time(self) -> None:
+        logger.info(
+            "Processed %d sentences (%d tokens) in %.1fs %.2f "
+            "sentences per second, %.2f tokens per second)",
+            self.num_sentences,
+            self.gen_timer.n,
+            self.gen_timer.sum,
+            self.num_sentences / self.gen_timer.sum,
+            1.0 / self.gen_timer.avg,
+        )
+
+
+def parse_wer(wer_file: Path) -> float:
+    with open(wer_file, "r") as f:
+        return float(f.readline().strip().split(" ")[1])
+
+
+def get_wer_file(cfg: InferConfig) -> Path:
+    """Hashes the decoding parameters to a unique file ID."""
+    base_path = "wer"
+    if cfg.decoding.results_path is not None:
+        base_path = os.path.join(cfg.decoding.results_path, base_path)
+
+    if cfg.decoding.unique_wer_file:
+        yaml_str = OmegaConf.to_yaml(cfg.decoding)
+        fid = int(hashlib.md5(yaml_str.encode("utf-8")).hexdigest(), 16)
+        return Path(f"{base_path}.{fid % 1000000}")
+    else:
+        return Path(base_path)
+
+
+def main(cfg: InferConfig) -> float:
+    """Entry point for main processing logic.
+
+    Args:
+        cfg: The inferance configuration to use.
+        wer: Optional shared memory pointer for returning the WER. If not None,
+            the final WER value will be written here instead of being returned.
+
+    Returns:
+        The final WER if `wer` is None, otherwise None.
+    """
+
+    yaml_str, wer_file = OmegaConf.to_yaml(cfg.decoding), get_wer_file(cfg)
+
+    # Validates the provided configuration.
+    if cfg.dataset.max_tokens is None and cfg.dataset.batch_size is None:
+        cfg.dataset.max_tokens = 4000000
+    if not cfg.common.cpu and not torch.cuda.is_available():
+        raise ValueError("CUDA not found; set `cpu=True` to run without CUDA")
+
+    with InferenceProcessor(cfg) as processor:
+        for sample in processor:
+            processor.process_sample(sample)
+
+        processor.log_generation_time()
+
+        if cfg.decoding.results_path is not None:
+            processor.merge_shards()
+
+        errs_t, leng_t = processor.total_errors, processor.total_length
+
+        if cfg.common.cpu:
+            logger.warning("Merging WER requires CUDA.")
+        elif processor.data_parallel_world_size > 1:
+            stats = torch.LongTensor([errs_t, leng_t]).cuda()
+            dist.all_reduce(stats, op=dist.ReduceOp.SUM)
+            errs_t, leng_t = stats[0].item(), stats[1].item()
+
+        wer = errs_t * 100.0 / leng_t
+
+        if distributed_utils.is_master(cfg.distributed_training):
+            with open(wer_file, "w") as f:
+                f.write(
+                    (
+                        f"WER: {wer}\n"
+                        f"err / num_ref_words = {errs_t} / {leng_t}\n\n"
+                        f"{yaml_str}"
+                    )
+                )
+
+        return wer
+
+
+@hydra.main(config_path=config_path, config_name="infer")
+def hydra_main(cfg: InferConfig) -> Union[float, Tuple[float, Optional[float]]]:
+    container = OmegaConf.to_container(cfg, resolve=True, enum_to_str=True)
+    cfg = OmegaConf.create(container)
+    OmegaConf.set_struct(cfg, True)
+
+    if cfg.common.reset_logging:
+        reset_logging()
+
+    # logger.info("Config:\n%s", OmegaConf.to_yaml(cfg))
+    wer = float("inf")
+
+    try:
+        if cfg.common.profile:
+            with torch.cuda.profiler.profile():
+                with torch.autograd.profiler.emit_nvtx():
+                    distributed_utils.call_main(cfg, main)
+        else:
+            distributed_utils.call_main(cfg, main)
+
+        wer = parse_wer(get_wer_file(cfg))
+    except BaseException as e:  # pylint: disable=broad-except
+        if not cfg.common.suppress_crashes:
+            raise
+        else:
+            logger.error("Crashed! %s", str(e))
+
+    logger.info("Word error rate: %.4f", wer)
+    if cfg.is_ax:
+        return wer, None
+
+    return wer
+
+
+def cli_main() -> None:
+    try:
+        from hydra._internal.utils import (
+            get_args,
+        )  # pylint: disable=import-outside-toplevel
+
+        cfg_name = get_args().config_name or "infer"
+    except ImportError:
+        logger.warning("Failed to get config name from hydra args")
+        cfg_name = "infer"
+
+    cs = ConfigStore.instance()
+    cs.store(name=cfg_name, node=InferConfig)
+
+    for k in InferConfig.__dataclass_fields__:
+        if is_dataclass(InferConfig.__dataclass_fields__[k].type):
+            v = InferConfig.__dataclass_fields__[k].default
+            cs.store(name=k, node=v)
+
+    hydra_main()  # pylint: disable=no-value-for-parameter
+
+
+if __name__ == "__main__":
+    cli_main()

fairseq/examples/speech_recognition/tasks/__init__.py

+import importlib
+import os
+
+
+for file in sorted(os.listdir(os.path.dirname(__file__))):
+    if file.endswith(".py") and not file.startswith("_"):
+        task_name = file[: file.find(".py")]
+        importlib.import_module("examples.speech_recognition.tasks." + task_name)

fairseq/examples/speech_recognition/tasks/speech_recognition.py

+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+import json
+import os
+import re
+import sys
+
+import torch
+from examples.speech_recognition.data import AsrDataset
+from examples.speech_recognition.data.replabels import replabel_symbol
+from fairseq.data import Dictionary
+from fairseq.tasks import LegacyFairseqTask, register_task
+
+
+def get_asr_dataset_from_json(data_json_path, tgt_dict):
+    """
+    Parse data json and create dataset.
+    See scripts/asr_prep_json.py which pack json from raw files
+
+    Json example:
+    {
+    "utts": {
+        "4771-29403-0025": {
+            "input": {
+                "length_ms": 170,
+                "path": "/tmp/file1.flac"
+            },
+            "output": {
+                "text": "HELLO \n",
+                "token": "HE LLO",
+                "tokenid": "4815, 861"
+            }
+        },
+        "1564-142299-0096": {
+            ...
+        }
+    }
+    """
+    if not os.path.isfile(data_json_path):
+        raise FileNotFoundError("Dataset not found: {}".format(data_json_path))
+    with open(data_json_path, "rb") as f:
+        data_samples = json.load(f)["utts"]
+        assert len(data_samples) != 0
+        sorted_samples = sorted(
+            data_samples.items(),
+            key=lambda sample: int(sample[1]["input"]["length_ms"]),
+            reverse=True,
+        )
+        aud_paths = [s[1]["input"]["path"] for s in sorted_samples]
+        ids = [s[0] for s in sorted_samples]
+        speakers = []
+        for s in sorted_samples:
+            m = re.search("(.+?)-(.+?)-(.+?)", s[0])
+            speakers.append(m.group(1) + "_" + m.group(2))
+        frame_sizes = [s[1]["input"]["length_ms"] for s in sorted_samples]
+        tgt = [
+            [int(i) for i in s[1]["output"]["tokenid"].split(", ")]
+            for s in sorted_samples
+        ]
+        # append eos
+        tgt = [[*t, tgt_dict.eos()] for t in tgt]
+        return AsrDataset(aud_paths, frame_sizes, tgt, tgt_dict, ids, speakers)
+
+
+@register_task("speech_recognition")
+class SpeechRecognitionTask(LegacyFairseqTask):
+    """
+    Task for training speech recognition model.
+    """
+
+    @staticmethod
+    def add_args(parser):
+        """Add task-specific arguments to the parser."""
+        parser.add_argument("data", help="path to data directory")
+        parser.add_argument(
+            "--silence-token", default="\u2581", help="token for silence (used by w2l)"
+        )
+        parser.add_argument(
+            "--max-source-positions",
+            default=sys.maxsize,
+            type=int,
+            metavar="N",
+            help="max number of frames in the source sequence",
+        )
+        parser.add_argument(
+            "--max-target-positions",
+            default=1024,
+            type=int,
+            metavar="N",
+            help="max number of tokens in the target sequence",
+        )
+
+    def __init__(self, args, tgt_dict):
+        super().__init__(args)
+        self.tgt_dict = tgt_dict
+
+    @classmethod
+    def setup_task(cls, args, **kwargs):
+        """Setup the task (e.g., load dictionaries)."""
+        dict_path = os.path.join(args.data, "dict.txt")
+        if not os.path.isfile(dict_path):
+            raise FileNotFoundError("Dict not found: {}".format(dict_path))
+        tgt_dict = Dictionary.load(dict_path)
+
+        if args.criterion == "ctc_loss":
+            tgt_dict.add_symbol("<ctc_blank>")
+        elif args.criterion == "asg_loss":
+            for i in range(1, args.max_replabel + 1):
+                tgt_dict.add_symbol(replabel_symbol(i))
+
+        print("| dictionary: {} types".format(len(tgt_dict)))
+        return cls(args, tgt_dict)
+
+    def load_dataset(self, split, combine=False, **kwargs):
+        """Load a given dataset split.
+
+        Args:
+            split (str): name of the split (e.g., train, valid, test)
+        """
+        data_json_path = os.path.join(self.args.data, "{}.json".format(split))
+        self.datasets[split] = get_asr_dataset_from_json(data_json_path, self.tgt_dict)
+
+    def build_generator(self, models, args, **unused):
+        w2l_decoder = getattr(args, "w2l_decoder", None)
+        if w2l_decoder == "viterbi":
+            from examples.speech_recognition.w2l_decoder import W2lViterbiDecoder
+
+            return W2lViterbiDecoder(args, self.target_dictionary)
+        elif w2l_decoder == "kenlm":
+            from examples.speech_recognition.w2l_decoder import W2lKenLMDecoder
+
+            return W2lKenLMDecoder(args, self.target_dictionary)
+        elif w2l_decoder == "fairseqlm":
+            from examples.speech_recognition.w2l_decoder import W2lFairseqLMDecoder
+
+            return W2lFairseqLMDecoder(args, self.target_dictionary)
+        else:
+            return super().build_generator(models, args)
+
+    @property
+    def target_dictionary(self):
+        """Return the :class:`~fairseq.data.Dictionary` for the language
+        model."""
+        return self.tgt_dict
+
+    @property
+    def source_dictionary(self):
+        """Return the source :class:`~fairseq.data.Dictionary` (if applicable
+        for this task)."""
+        return None
+
+    def max_positions(self):
+        """Return the max speech and sentence length allowed by the task."""
+        return (self.args.max_source_positions, self.args.max_target_positions)

fairseq/examples/speech_recognition/utils/wer_utils.py

+#!/usr/bin/env python3
+
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+import re
+from collections import deque
+from enum import Enum
+
+import numpy as np
+
+
+"""
+    Utility modules for computation of Word Error Rate,
+    Alignments, as well as more granular metrics like
+    deletion, insersion and substitutions.
+"""
+
+
+class Code(Enum):
+    match = 1
+    substitution = 2
+    insertion = 3
+    deletion = 4
+
+
+class Token(object):
+    def __init__(self, lbl="", st=np.nan, en=np.nan):
+        if np.isnan(st):
+            self.label, self.start, self.end = "", 0.0, 0.0
+        else:
+            self.label, self.start, self.end = lbl, st, en
+
+
+class AlignmentResult(object):
+    def __init__(self, refs, hyps, codes, score):
+        self.refs = refs  # std::deque<int>
+        self.hyps = hyps  # std::deque<int>
+        self.codes = codes  # std::deque<Code>
+        self.score = score  # float
+
+
+def coordinate_to_offset(row, col, ncols):
+    return int(row * ncols + col)
+
+
+def offset_to_row(offset, ncols):
+    return int(offset / ncols)
+
+
+def offset_to_col(offset, ncols):
+    return int(offset % ncols)
+
+
+def trimWhitespace(str):
+    return re.sub(" +", " ", re.sub(" *$", "", re.sub("^ *", "", str)))
+
+
+def str2toks(str):
+    pieces = trimWhitespace(str).split(" ")
+    toks = []
+    for p in pieces:
+        toks.append(Token(p, 0.0, 0.0))
+    return toks
+
+
+class EditDistance(object):
+    def __init__(self, time_mediated):
+        self.time_mediated_ = time_mediated
+        self.scores_ = np.nan  # Eigen::Matrix<float, Eigen::Dynamic, Eigen::Dynamic>
+        self.backtraces_ = (
+            np.nan
+        )  # Eigen::Matrix<size_t, Eigen::Dynamic, Eigen::Dynamic> backtraces_;
+        self.confusion_pairs_ = {}
+
+    def cost(self, ref, hyp, code):
+        if self.time_mediated_:
+            if code == Code.match:
+                return abs(ref.start - hyp.start) + abs(ref.end - hyp.end)
+            elif code == Code.insertion:
+                return hyp.end - hyp.start
+            elif code == Code.deletion:
+                return ref.end - ref.start
+            else:  # substitution
+                return abs(ref.start - hyp.start) + abs(ref.end - hyp.end) + 0.1
+        else:
+            if code == Code.match:
+                return 0
+            elif code == Code.insertion or code == Code.deletion:
+                return 3
+            else:  # substitution
+                return 4
+
+    def get_result(self, refs, hyps):
+        res = AlignmentResult(refs=deque(), hyps=deque(), codes=deque(), score=np.nan)
+
+        num_rows, num_cols = self.scores_.shape
+        res.score = self.scores_[num_rows - 1, num_cols - 1]
+
+        curr_offset = coordinate_to_offset(num_rows - 1, num_cols - 1, num_cols)
+
+        while curr_offset != 0:
+            curr_row = offset_to_row(curr_offset, num_cols)
+            curr_col = offset_to_col(curr_offset, num_cols)
+
+            prev_offset = self.backtraces_[curr_row, curr_col]
+
+            prev_row = offset_to_row(prev_offset, num_cols)
+            prev_col = offset_to_col(prev_offset, num_cols)
+
+            res.refs.appendleft(curr_row - 1)  # Note: this was .push_front() in C++
+            res.hyps.appendleft(curr_col - 1)
+            if curr_row - 1 == prev_row and curr_col == prev_col:
+                res.codes.appendleft(Code.deletion)
+            elif curr_row == prev_row and curr_col - 1 == prev_col:
+                res.codes.appendleft(Code.insertion)
+            else:
+                # assert(curr_row - 1 == prev_row and curr_col - 1 == prev_col)
+                ref_str = refs[res.refs[0]].label
+                hyp_str = hyps[res.hyps[0]].label
+
+                if ref_str == hyp_str:
+                    res.codes.appendleft(Code.match)
+                else:
+                    res.codes.appendleft(Code.substitution)
+
+                    confusion_pair = "%s -> %s" % (ref_str, hyp_str)
+                    if confusion_pair not in self.confusion_pairs_:
+                        self.confusion_pairs_[confusion_pair] = 1
+                    else:
+                        self.confusion_pairs_[confusion_pair] += 1
+
+            curr_offset = prev_offset
+
+        return res
+
+    def align(self, refs, hyps):
+        if len(refs) == 0 and len(hyps) == 0:
+            return np.nan
+
+        # NOTE: we're not resetting the values in these matrices because every value
+        # will be overridden in the loop below. If this assumption doesn't hold,
+        # be sure to set all entries in self.scores_ and self.backtraces_ to 0.
+        self.scores_ = np.zeros((len(refs) + 1, len(hyps) + 1))
+        self.backtraces_ = np.zeros((len(refs) + 1, len(hyps) + 1))
+
+        num_rows, num_cols = self.scores_.shape
+
+        for i in range(num_rows):
+            for j in range(num_cols):
+                if i == 0 and j == 0:
+                    self.scores_[i, j] = 0.0
+                    self.backtraces_[i, j] = 0
+                    continue
+
+                if i == 0:
+                    self.scores_[i, j] = self.scores_[i, j - 1] + self.cost(
+                        None, hyps[j - 1], Code.insertion
+                    )
+                    self.backtraces_[i, j] = coordinate_to_offset(i, j - 1, num_cols)
+                    continue
+
+                if j == 0:
+                    self.scores_[i, j] = self.scores_[i - 1, j] + self.cost(
+                        refs[i - 1], None, Code.deletion
+                    )
+                    self.backtraces_[i, j] = coordinate_to_offset(i - 1, j, num_cols)
+                    continue
+
+                # Below here both i and j are greater than 0
+                ref = refs[i - 1]
+                hyp = hyps[j - 1]
+                best_score = self.scores_[i - 1, j - 1] + (
+                    self.cost(ref, hyp, Code.match)
+                    if (ref.label == hyp.label)
+                    else self.cost(ref, hyp, Code.substitution)
+                )
+
+                prev_row = i - 1
+                prev_col = j - 1
+                ins = self.scores_[i, j - 1] + self.cost(None, hyp, Code.insertion)
+                if ins < best_score:
+                    best_score = ins
+                    prev_row = i
+                    prev_col = j - 1
+
+                delt = self.scores_[i - 1, j] + self.cost(ref, None, Code.deletion)
+                if delt < best_score:
+                    best_score = delt
+                    prev_row = i - 1
+                    prev_col = j
+
+                self.scores_[i, j] = best_score
+                self.backtraces_[i, j] = coordinate_to_offset(
+                    prev_row, prev_col, num_cols
+                )
+
+        return self.get_result(refs, hyps)
+
+
+class WERTransformer(object):
+    def __init__(self, hyp_str, ref_str, verbose=True):
+        self.ed_ = EditDistance(False)
+        self.id2oracle_errs_ = {}
+        self.utts_ = 0
+        self.words_ = 0
+        self.insertions_ = 0
+        self.deletions_ = 0
+        self.substitutions_ = 0
+
+        self.process(["dummy_str", hyp_str, ref_str])
+
+        if verbose:
+            print("'%s' vs '%s'" % (hyp_str, ref_str))
+            self.report_result()
+
+    def process(self, input):  # std::vector<std::string>&& input
+        if len(input) < 3:
+            print(
+                "Input must be of the form <id> ... <hypo> <ref> , got ",
+                len(input),
+                " inputs:",
+            )
+            return None
+
+        # Align
+        # std::vector<Token> hyps;
+        # std::vector<Token> refs;
+
+        hyps = str2toks(input[-2])
+        refs = str2toks(input[-1])
+
+        alignment = self.ed_.align(refs, hyps)
+        if alignment is None:
+            print("Alignment is null")
+            return np.nan
+
+        # Tally errors
+        ins = 0
+        dels = 0
+        subs = 0
+        for code in alignment.codes:
+            if code == Code.substitution:
+                subs += 1
+            elif code == Code.insertion:
+                ins += 1
+            elif code == Code.deletion:
+                dels += 1
+
+        # Output
+        row = input
+        row.append(str(len(refs)))
+        row.append(str(ins))
+        row.append(str(dels))
+        row.append(str(subs))
+        # print(row)
+
+        # Accumulate
+        kIdIndex = 0
+        kNBestSep = "/"
+
+        pieces = input[kIdIndex].split(kNBestSep)
+
+        if len(pieces) == 0:
+            print(
+                "Error splitting ",
+                input[kIdIndex],
+                " on '",
+                kNBestSep,
+                "', got empty list",
+            )
+            return np.nan
+
+        id = pieces[0]
+        if id not in self.id2oracle_errs_:
+            self.utts_ += 1
+            self.words_ += len(refs)
+            self.insertions_ += ins
+            self.deletions_ += dels
+            self.substitutions_ += subs
+            self.id2oracle_errs_[id] = [ins, dels, subs]
+        else:
+            curr_err = ins + dels + subs
+            prev_err = np.sum(self.id2oracle_errs_[id])
+            if curr_err < prev_err:
+                self.id2oracle_errs_[id] = [ins, dels, subs]
+
+        return 0
+
+    def report_result(self):
+        # print("----------  Summary ---------------")
+        if self.words_ == 0:
+            print("No words counted")
+            return
+
+        # 1-best
+        best_wer = (
+            100.0
+            * (self.insertions_ + self.deletions_ + self.substitutions_)
+            / self.words_
+        )
+
+        print(
+            "\tWER = %0.2f%% (%i utts, %i words, %0.2f%% ins, "
+            "%0.2f%% dels, %0.2f%% subs)"
+            % (
+                best_wer,
+                self.utts_,
+                self.words_,
+                100.0 * self.insertions_ / self.words_,
+                100.0 * self.deletions_ / self.words_,
+                100.0 * self.substitutions_ / self.words_,
+            )
+        )
+
+    def wer(self):
+        if self.words_ == 0:
+            wer = np.nan
+        else:
+            wer = (
+                100.0
+                * (self.insertions_ + self.deletions_ + self.substitutions_)
+                / self.words_
+            )
+        return wer
+
+    def stats(self):
+        if self.words_ == 0:
+            stats = {}
+        else:
+            wer = (
+                100.0
+                * (self.insertions_ + self.deletions_ + self.substitutions_)
+                / self.words_
+            )
+            stats = dict(
+                {
+                    "wer": wer,
+                    "utts": self.utts_,
+                    "numwords": self.words_,
+                    "ins": self.insertions_,
+                    "dels": self.deletions_,
+                    "subs": self.substitutions_,
+                    "confusion_pairs": self.ed_.confusion_pairs_,
+                }
+            )
+        return stats
+
+
+def calc_wer(hyp_str, ref_str):
+    t = WERTransformer(hyp_str, ref_str, verbose=0)
+    return t.wer()
+
+
+def calc_wer_stats(hyp_str, ref_str):
+    t = WERTransformer(hyp_str, ref_str, verbose=0)
+    return t.stats()
+
+
+def get_wer_alignment_codes(hyp_str, ref_str):
+    """
+    INPUT: hypothesis string, reference string
+    OUTPUT: List of alignment codes (intermediate results from WER computation)
+    """
+    t = WERTransformer(hyp_str, ref_str, verbose=0)
+    return t.ed_.align(str2toks(ref_str), str2toks(hyp_str)).codes
+
+
+def merge_counts(x, y):
+    # Merge two hashes which have 'counts' as their values
+    # This can be used for example to merge confusion pair counts
+    #   conf_pairs = merge_counts(conf_pairs, stats['confusion_pairs'])
+    for k, v in y.items():
+        if k not in x:
+            x[k] = 0
+        x[k] += v
+    return x

fairseq/examples/speech_recognition/w2l_decoder.py

+#!/usr/bin/env python3
+
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+"""
+Flashlight decoders.
+"""
+
+import gc
+import itertools as it
+import os.path as osp
+from typing import List
+import warnings
+from collections import deque, namedtuple
+
+import numpy as np
+import torch
+from examples.speech_recognition.data.replabels import unpack_replabels
+from fairseq import tasks
+from fairseq.utils import apply_to_sample
+from omegaconf import open_dict
+from fairseq.dataclass.utils import convert_namespace_to_omegaconf
+
+
+try:
+    from flashlight.lib.text.dictionary import create_word_dict, load_words
+    from flashlight.lib.sequence.criterion import CpuViterbiPath, get_data_ptr_as_bytes
+    from flashlight.lib.text.decoder import (
+        CriterionType,
+        LexiconDecoderOptions,
+        KenLM,
+        LM,
+        LMState,
+        SmearingMode,
+        Trie,
+        LexiconDecoder,
+    )
+except:
+    warnings.warn(
+        "flashlight python bindings are required to use this functionality. Please install from https://github.com/facebookresearch/flashlight/tree/master/bindings/python"
+    )
+    LM = object
+    LMState = object
+
+
+class W2lDecoder(object):
+    def __init__(self, args, tgt_dict):
+        self.tgt_dict = tgt_dict
+        self.vocab_size = len(tgt_dict)
+        self.nbest = args.nbest
+
+        # criterion-specific init
+        self.criterion_type = CriterionType.CTC
+        self.blank = (
+            tgt_dict.index("<ctc_blank>")
+            if "<ctc_blank>" in tgt_dict.indices
+            else tgt_dict.bos()
+        )
+        if "<sep>" in tgt_dict.indices:
+            self.silence = tgt_dict.index("<sep>")
+        elif "|" in tgt_dict.indices:
+            self.silence = tgt_dict.index("|")
+        else:
+            self.silence = tgt_dict.eos()
+        self.asg_transitions = None
+
+    def generate(self, models, sample, **unused):
+        """Generate a batch of inferences."""
+        # model.forward normally channels prev_output_tokens into the decoder
+        # separately, but SequenceGenerator directly calls model.encoder
+        encoder_input = {
+            k: v for k, v in sample["net_input"].items() if k != "prev_output_tokens"
+        }
+        emissions = self.get_emissions(models, encoder_input)
+        return self.decode(emissions)
+
+    def get_emissions(self, models, encoder_input):
+        """Run encoder and normalize emissions"""
+        model = models[0]
+        encoder_out = model(**encoder_input)
+        if hasattr(model, "get_logits"):
+            emissions = model.get_logits(encoder_out) # no need to normalize emissions
+        else:
+            emissions = model.get_normalized_probs(encoder_out, log_probs=True)
+        return emissions.transpose(0, 1).float().cpu().contiguous()
+
+    def get_tokens(self, idxs):
+        """Normalize tokens by handling CTC blank, ASG replabels, etc."""
+        idxs = (g[0] for g in it.groupby(idxs))
+        idxs = filter(lambda x: x != self.blank, idxs)
+        return torch.LongTensor(list(idxs))
+
+
+class W2lViterbiDecoder(W2lDecoder):
+    def __init__(self, args, tgt_dict):
+        super().__init__(args, tgt_dict)
+
+    def decode(self, emissions):
+        B, T, N = emissions.size()
+        hypos = []
+        if self.asg_transitions is None:
+            transitions = torch.FloatTensor(N, N).zero_()
+        else:
+            transitions = torch.FloatTensor(self.asg_transitions).view(N, N)
+        viterbi_path = torch.IntTensor(B, T)
+        workspace = torch.ByteTensor(CpuViterbiPath.get_workspace_size(B, T, N))
+        CpuViterbiPath.compute(
+            B,
+            T,
+            N,
+            get_data_ptr_as_bytes(emissions),
+            get_data_ptr_as_bytes(transitions),
+            get_data_ptr_as_bytes(viterbi_path),
+            get_data_ptr_as_bytes(workspace),
+        )
+        return [
+            [{"tokens": self.get_tokens(viterbi_path[b].tolist()), "score": 0}]
+            for b in range(B)
+        ]
+
+
+class W2lKenLMDecoder(W2lDecoder):
+    def __init__(self, args, tgt_dict):
+        super().__init__(args, tgt_dict)
+
+        self.unit_lm = getattr(args, "unit_lm", False)
+
+        if args.lexicon:
+            self.lexicon = load_words(args.lexicon)
+            self.word_dict = create_word_dict(self.lexicon)
+            self.unk_word = self.word_dict.get_index("<unk>")
+
+            self.lm = KenLM(args.kenlm_model, self.word_dict)
+            self.trie = Trie(self.vocab_size, self.silence)
+
+            start_state = self.lm.start(False)
+            for i, (word, spellings) in enumerate(self.lexicon.items()):
+                word_idx = self.word_dict.get_index(word)
+                _, score = self.lm.score(start_state, word_idx)
+                for spelling in spellings:
+                    spelling_idxs = [tgt_dict.index(token) for token in spelling]
+                    assert (
+                        tgt_dict.unk() not in spelling_idxs
+                    ), f"{spelling} {spelling_idxs}"
+                    self.trie.insert(spelling_idxs, word_idx, score)
+            self.trie.smear(SmearingMode.MAX)
+
+            self.decoder_opts = LexiconDecoderOptions(
+                beam_size=args.beam,
+                beam_size_token=int(getattr(args, "beam_size_token", len(tgt_dict))),
+                beam_threshold=args.beam_threshold,
+                lm_weight=args.lm_weight,
+                word_score=args.word_score,
+                unk_score=args.unk_weight,
+                sil_score=args.sil_weight,
+                log_add=False,
+                criterion_type=self.criterion_type,
+            )
+
+            if self.asg_transitions is None:
+                N = 768
+                # self.asg_transitions = torch.FloatTensor(N, N).zero_()
+                self.asg_transitions = []
+
+            self.decoder = LexiconDecoder(
+                self.decoder_opts,
+                self.trie,
+                self.lm,
+                self.silence,
+                self.blank,
+                self.unk_word,
+                self.asg_transitions,
+                self.unit_lm,
+            )
+        else:
+            assert args.unit_lm, "lexicon free decoding can only be done with a unit language model"
+            from flashlight.lib.text.decoder import LexiconFreeDecoder, LexiconFreeDecoderOptions
+
+            d = {w: [[w]] for w in tgt_dict.symbols}
+            self.word_dict = create_word_dict(d)
+            self.lm = KenLM(args.kenlm_model, self.word_dict)
+            self.decoder_opts = LexiconFreeDecoderOptions(
+                beam_size=args.beam,
+                beam_size_token=int(getattr(args, "beam_size_token", len(tgt_dict))),
+                beam_threshold=args.beam_threshold,
+                lm_weight=args.lm_weight,
+                sil_score=args.sil_weight,
+                log_add=False,
+                criterion_type=self.criterion_type,
+            )
+            self.decoder = LexiconFreeDecoder(
+                self.decoder_opts, self.lm, self.silence, self.blank, []
+            )
+
+    def get_timesteps(self, token_idxs: List[int]) -> List[int]:
+        """Returns frame numbers corresponding to every non-blank token.
+
+        Parameters
+        ----------
+        token_idxs : List[int]
+            IDs of decoded tokens.
+
+        Returns
+        -------
+        List[int]
+            Frame numbers corresponding to every non-blank token.
+        """
+        timesteps = []
+        for i, token_idx in enumerate(token_idxs):
+            if token_idx == self.blank:
+                continue
+            if i == 0 or token_idx != token_idxs[i-1]:
+                timesteps.append(i)
+        return timesteps
+
+    def decode(self, emissions):
+        B, T, N = emissions.size()
+        hypos = []
+        for b in range(B):
+            emissions_ptr = emissions.data_ptr() + 4 * b * emissions.stride(0)
+            results = self.decoder.decode(emissions_ptr, T, N)
+
+            nbest_results = results[: self.nbest]
+            hypos.append(
+                [
+                    {
+                        "tokens": self.get_tokens(result.tokens),
+                        "score": result.score,
+                        "timesteps": self.get_timesteps(result.tokens),
+                        "words": [
+                            self.word_dict.get_entry(x) for x in result.words if x >= 0
+                        ],
+                    }
+                    for result in nbest_results
+                ]
+            )
+        return hypos
+
+
+FairseqLMState = namedtuple("FairseqLMState", ["prefix", "incremental_state", "probs"])
+
+
+class FairseqLM(LM):
+    def __init__(self, dictionary, model):
+        LM.__init__(self)
+        self.dictionary = dictionary
+        self.model = model
+        self.unk = self.dictionary.unk()
+
+        self.save_incremental = False  # this currently does not work properly
+        self.max_cache = 20_000
+
+        model.cuda()
+        model.eval()
+        model.make_generation_fast_()
+
+        self.states = {}
+        self.stateq = deque()
+
+    def start(self, start_with_nothing):
+        state = LMState()
+        prefix = torch.LongTensor([[self.dictionary.eos()]])
+        incremental_state = {} if self.save_incremental else None
+        with torch.no_grad():
+            res = self.model(prefix.cuda(), incremental_state=incremental_state)
+            probs = self.model.get_normalized_probs(res, log_probs=True, sample=None)
+
+        if incremental_state is not None:
+            incremental_state = apply_to_sample(lambda x: x.cpu(), incremental_state)
+        self.states[state] = FairseqLMState(
+            prefix.numpy(), incremental_state, probs[0, -1].cpu().numpy()
+        )
+        self.stateq.append(state)
+
+        return state
+
+    def score(self, state: LMState, token_index: int, no_cache: bool = False):
+        """
+        Evaluate language model based on the current lm state and new word
+        Parameters:
+        -----------
+        state: current lm state
+        token_index: index of the word
+                     (can be lexicon index then you should store inside LM the
+                      mapping between indices of lexicon and lm, or lm index of a word)
+
+        Returns:
+        --------
+        (LMState, float): pair of (new state, score for the current word)
+        """
+        curr_state = self.states[state]
+
+        def trim_cache(targ_size):
+            while len(self.stateq) > targ_size:
+                rem_k = self.stateq.popleft()
+                rem_st = self.states[rem_k]
+                rem_st = FairseqLMState(rem_st.prefix, None, None)
+                self.states[rem_k] = rem_st
+
+        if curr_state.probs is None:
+            new_incremental_state = (
+                curr_state.incremental_state.copy()
+                if curr_state.incremental_state is not None
+                else None
+            )
+            with torch.no_grad():
+                if new_incremental_state is not None:
+                    new_incremental_state = apply_to_sample(
+                        lambda x: x.cuda(), new_incremental_state
+                    )
+                elif self.save_incremental:
+                    new_incremental_state = {}
+
+                res = self.model(
+                    torch.from_numpy(curr_state.prefix).cuda(),
+                    incremental_state=new_incremental_state,
+                )
+                probs = self.model.get_normalized_probs(
+                    res, log_probs=True, sample=None
+                )
+
+                if new_incremental_state is not None:
+                    new_incremental_state = apply_to_sample(
+                        lambda x: x.cpu(), new_incremental_state
+                    )
+
+                curr_state = FairseqLMState(
+                    curr_state.prefix, new_incremental_state, probs[0, -1].cpu().numpy()
+                )
+
+            if not no_cache:
+                self.states[state] = curr_state
+                self.stateq.append(state)
+
+        score = curr_state.probs[token_index].item()
+
+        trim_cache(self.max_cache)
+
+        outstate = state.child(token_index)
+        if outstate not in self.states and not no_cache:
+            prefix = np.concatenate(
+                [curr_state.prefix, torch.LongTensor([[token_index]])], -1
+            )
+            incr_state = curr_state.incremental_state
+
+            self.states[outstate] = FairseqLMState(prefix, incr_state, None)
+
+        if token_index == self.unk:
+            score = float("-inf")
+
+        return outstate, score
+
+    def finish(self, state: LMState):
+        """
+        Evaluate eos for language model based on the current lm state
+
+        Returns:
+        --------
+        (LMState, float): pair of (new state, score for the current word)
+        """
+        return self.score(state, self.dictionary.eos())
+
+    def empty_cache(self):
+        self.states = {}
+        self.stateq = deque()
+        gc.collect()
+
+
+class W2lFairseqLMDecoder(W2lDecoder):
+    def __init__(self, args, tgt_dict):
+        super().__init__(args, tgt_dict)
+
+        self.unit_lm = getattr(args, "unit_lm", False)
+
+        self.lexicon = load_words(args.lexicon) if args.lexicon else None
+        self.idx_to_wrd = {}
+
+        checkpoint = torch.load(args.kenlm_model, map_location="cpu")
+
+        if "cfg" in checkpoint and checkpoint["cfg"] is not None:
+            lm_args = checkpoint["cfg"]
+        else:
+            lm_args = convert_namespace_to_omegaconf(checkpoint["args"])
+
+        with open_dict(lm_args.task):
+            lm_args.task.data = osp.dirname(args.kenlm_model)
+
+        task = tasks.setup_task(lm_args.task)
+        model = task.build_model(lm_args.model)
+        model.load_state_dict(checkpoint["model"], strict=False)
+
+        self.trie = Trie(self.vocab_size, self.silence)
+
+        self.word_dict = task.dictionary
+        self.unk_word = self.word_dict.unk()
+        self.lm = FairseqLM(self.word_dict, model)
+
+        if self.lexicon:
+            start_state = self.lm.start(False)
+            for i, (word, spellings) in enumerate(self.lexicon.items()):
+                if self.unit_lm:
+                    word_idx = i
+                    self.idx_to_wrd[i] = word
+                    score = 0
+                else:
+                    word_idx = self.word_dict.index(word)
+                    _, score = self.lm.score(start_state, word_idx, no_cache=True)
+
+                for spelling in spellings:
+                    spelling_idxs = [tgt_dict.index(token) for token in spelling]
+                    assert (
+                        tgt_dict.unk() not in spelling_idxs
+                    ), f"{spelling} {spelling_idxs}"
+                    self.trie.insert(spelling_idxs, word_idx, score)
+            self.trie.smear(SmearingMode.MAX)
+
+            self.decoder_opts = LexiconDecoderOptions(
+                beam_size=args.beam,
+                beam_size_token=int(getattr(args, "beam_size_token", len(tgt_dict))),
+                beam_threshold=args.beam_threshold,
+                lm_weight=args.lm_weight,
+                word_score=args.word_score,
+                unk_score=args.unk_weight,
+                sil_score=args.sil_weight,
+                log_add=False,
+                criterion_type=self.criterion_type,
+            )
+
+            self.decoder = LexiconDecoder(
+                self.decoder_opts,
+                self.trie,
+                self.lm,
+                self.silence,
+                self.blank,
+                self.unk_word,
+                [],
+                self.unit_lm,
+            )
+        else:
+            assert args.unit_lm, "lexicon free decoding can only be done with a unit language model"
+            from flashlight.lib.text.decoder import LexiconFreeDecoder, LexiconFreeDecoderOptions
+
+            d = {w: [[w]] for w in tgt_dict.symbols}
+            self.word_dict = create_word_dict(d)
+            self.lm = KenLM(args.kenlm_model, self.word_dict)
+            self.decoder_opts = LexiconFreeDecoderOptions(
+                beam_size=args.beam,
+                beam_size_token=int(getattr(args, "beam_size_token", len(tgt_dict))),
+                beam_threshold=args.beam_threshold,
+                lm_weight=args.lm_weight,
+                sil_score=args.sil_weight,
+                log_add=False,
+                criterion_type=self.criterion_type,
+            )
+            self.decoder = LexiconFreeDecoder(
+                self.decoder_opts, self.lm, self.silence, self.blank, []
+            )
+
+    def decode(self, emissions):
+        B, T, N = emissions.size()
+        hypos = []
+
+        def idx_to_word(idx):
+            if self.unit_lm:
+                return self.idx_to_wrd[idx]
+            else:
+                return self.word_dict[idx]
+
+        def make_hypo(result):
+            hypo = {"tokens": self.get_tokens(result.tokens), "score": result.score}
+            if self.lexicon:
+                hypo["words"] = [idx_to_word(x) for x in result.words if x >= 0]
+            return hypo
+
+        for b in range(B):
+            emissions_ptr = emissions.data_ptr() + 4 * b * emissions.stride(0)
+            results = self.decoder.decode(emissions_ptr, T, N)
+
+            nbest_results = results[: self.nbest]
+            hypos.append([make_hypo(result) for result in nbest_results])
+            self.lm.empty_cache()
+
+        return hypos

fairseq/examples/speech_synthesis/README.md

+Speech Synthesis (S^2)
+===
+
+Speech synthesis with fairseq.
+
+- Autoregressive and non-autoregressive models
+- Multi-speaker synthesis
+- Audio preprocessing
+- Automatic metrics
+- Similar data configuration as [S2T](../speech_to_text/README.md)
+
+
+## Examples
+- [Single-speaker synthesis on LJSpeech](docs/ljspeech_example.md)
+- [Multi-speaker synthesis on VCTK](docs/vctk_example.md)
+- [Multi-speaker synthesis on Common Voice](docs/common_voice_example.md)

fairseq/examples/speech_synthesis/__init__.py

+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.