# Copyright 2019 Shigeki Karita
# Apache 2.0 (http://www.apache.org/licenses/LICENSE-2.0)
"""Transformer speech recognition model (pytorch)."""
import logging
import math
from argparse import Namespace
import numpy
import torch
from espnet.nets.asr_interface import ASRInterface
from espnet.nets.ctc_prefix_score import CTCPrefixScore
from espnet.nets.e2e_asr_common import ErrorCalculator, end_detect
from espnet.nets.pytorch_backend.ctc import CTC
from espnet.nets.pytorch_backend.e2e_asr import CTC_LOSS_THRESHOLD, Reporter
from espnet.nets.pytorch_backend.nets_utils import (
get_subsample,
make_non_pad_mask,
th_accuracy,
)
from espnet.nets.pytorch_backend.rnn.decoders import CTC_SCORING_RATIO
from espnet.nets.pytorch_backend.transformer.add_sos_eos import add_sos_eos
from espnet.nets.pytorch_backend.transformer.argument import ( # noqa: H301
add_arguments_transformer_common,
)
from espnet.nets.pytorch_backend.transformer.attention import ( # noqa: H301
MultiHeadedAttention,
RelPositionMultiHeadedAttention,
)
from espnet.nets.pytorch_backend.transformer.decoder import Decoder
from espnet.nets.pytorch_backend.transformer.dynamic_conv import DynamicConvolution
from espnet.nets.pytorch_backend.transformer.dynamic_conv2d import DynamicConvolution2D
from espnet.nets.pytorch_backend.transformer.encoder import Encoder
from espnet.nets.pytorch_backend.transformer.initializer import initialize
from espnet.nets.pytorch_backend.transformer.label_smoothing_loss import ( # noqa: H301
LabelSmoothingLoss,
)
from espnet.nets.pytorch_backend.transformer.mask import subsequent_mask, target_mask
from espnet.nets.pytorch_backend.transformer.plot import PlotAttentionReport
from espnet.nets.scorers.ctc import CTCPrefixScorer
from espnet.utils.fill_missing_args import fill_missing_args
[docs]class E2E(ASRInterface, torch.nn.Module):
"""E2E module.
:param int idim: dimension of inputs
:param int odim: dimension of outputs
:param Namespace args: argument Namespace containing options
"""
[docs] @staticmethod
def add_arguments(parser):
"""Add arguments."""
group = parser.add_argument_group("transformer model setting")
group = add_arguments_transformer_common(group)
return parser
@property
def attention_plot_class(self):
"""Return PlotAttentionReport."""
return PlotAttentionReport
[docs] def get_total_subsampling_factor(self):
"""Get total subsampling factor."""
return self.encoder.conv_subsampling_factor * int(numpy.prod(self.subsample))
def __init__(self, idim, odim, args, ignore_id=-1):
"""Construct an E2E object.
:param int idim: dimension of inputs
:param int odim: dimension of outputs
:param Namespace args: argument Namespace containing options
"""
torch.nn.Module.__init__(self)
# fill missing arguments for compatibility
args = fill_missing_args(args, self.add_arguments)
if args.transformer_attn_dropout_rate is None:
args.transformer_attn_dropout_rate = args.dropout_rate
self.adim = args.adim # used for CTC (equal to d_model)
self.mtlalpha = args.mtlalpha
if args.mtlalpha > 0.0:
self.ctc = CTC(
odim, args.adim, args.dropout_rate, ctc_type=args.ctc_type, reduce=True
)
else:
self.ctc = None
self.intermediate_ctc_weight = args.intermediate_ctc_weight
self.intermediate_ctc_layers = None
if args.intermediate_ctc_layer != "":
self.intermediate_ctc_layers = [
int(i) for i in args.intermediate_ctc_layer.split(",")
]
self.encoder = Encoder(
idim=idim,
selfattention_layer_type=args.transformer_encoder_selfattn_layer_type,
attention_dim=args.adim,
attention_heads=args.aheads,
conv_wshare=args.wshare,
conv_kernel_length=args.ldconv_encoder_kernel_length,
conv_usebias=args.ldconv_usebias,
linear_units=args.eunits,
num_blocks=args.elayers,
input_layer=args.transformer_input_layer,
dropout_rate=args.dropout_rate,
positional_dropout_rate=args.dropout_rate,
attention_dropout_rate=args.transformer_attn_dropout_rate,
stochastic_depth_rate=args.stochastic_depth_rate,
intermediate_layers=self.intermediate_ctc_layers,
ctc_softmax=self.ctc.softmax if args.self_conditioning else None,
conditioning_layer_dim=odim,
)
if args.mtlalpha < 1:
self.decoder = Decoder(
odim=odim,
selfattention_layer_type=args.transformer_decoder_selfattn_layer_type,
attention_dim=args.adim,
attention_heads=args.aheads,
conv_wshare=args.wshare,
conv_kernel_length=args.ldconv_decoder_kernel_length,
conv_usebias=args.ldconv_usebias,
linear_units=args.dunits,
num_blocks=args.dlayers,
dropout_rate=args.dropout_rate,
positional_dropout_rate=args.dropout_rate,
self_attention_dropout_rate=args.transformer_attn_dropout_rate,
src_attention_dropout_rate=args.transformer_attn_dropout_rate,
)
self.criterion = LabelSmoothingLoss(
odim,
ignore_id,
args.lsm_weight,
args.transformer_length_normalized_loss,
)
else:
self.decoder = None
self.criterion = None
self.blank = 0
self.sos = odim - 1
self.eos = odim - 1
self.odim = odim
self.ignore_id = ignore_id
self.subsample = get_subsample(args, mode="asr", arch="transformer")
self.reporter = Reporter()
self.reset_parameters(args)
if args.report_cer or args.report_wer:
self.error_calculator = ErrorCalculator(
args.char_list,
args.sym_space,
args.sym_blank,
args.report_cer,
args.report_wer,
)
else:
self.error_calculator = None
self.rnnlm = None
[docs] def reset_parameters(self, args):
"""Initialize parameters."""
# initialize parameters
initialize(self, args.transformer_init)
[docs] def forward(self, xs_pad, ilens, ys_pad):
"""E2E forward.
:param torch.Tensor xs_pad: batch of padded source sequences (B, Tmax, idim)
:param torch.Tensor ilens: batch of lengths of source sequences (B)
:param torch.Tensor ys_pad: batch of padded target sequences (B, Lmax)
:return: ctc loss value
:rtype: torch.Tensor
:return: attention loss value
:rtype: torch.Tensor
:return: accuracy in attention decoder
:rtype: float
"""
# 1. forward encoder
xs_pad = xs_pad[:, : max(ilens)] # for data parallel
src_mask = make_non_pad_mask(ilens.tolist()).to(xs_pad.device).unsqueeze(-2)
if self.intermediate_ctc_layers:
hs_pad, hs_mask, hs_intermediates = self.encoder(xs_pad, src_mask)
else:
hs_pad, hs_mask = self.encoder(xs_pad, src_mask)
self.hs_pad = hs_pad
# 2. forward decoder
if self.decoder is not None:
ys_in_pad, ys_out_pad = add_sos_eos(
ys_pad, self.sos, self.eos, self.ignore_id
)
ys_mask = target_mask(ys_in_pad, self.ignore_id)
pred_pad, pred_mask = self.decoder(ys_in_pad, ys_mask, hs_pad, hs_mask)
self.pred_pad = pred_pad
# 3. compute attention loss
loss_att = self.criterion(pred_pad, ys_out_pad)
self.acc = th_accuracy(
pred_pad.view(-1, self.odim), ys_out_pad, ignore_label=self.ignore_id
)
else:
loss_att = None
self.acc = None
# TODO(karita) show predicted text
# TODO(karita) calculate these stats
cer_ctc = None
loss_intermediate_ctc = 0.0
if self.mtlalpha == 0.0:
loss_ctc = None
else:
batch_size = xs_pad.size(0)
hs_len = hs_mask.view(batch_size, -1).sum(1)
loss_ctc = self.ctc(hs_pad.view(batch_size, -1, self.adim), hs_len, ys_pad)
if not self.training and self.error_calculator is not None:
ys_hat = self.ctc.argmax(hs_pad.view(batch_size, -1, self.adim)).data
cer_ctc = self.error_calculator(ys_hat.cpu(), ys_pad.cpu(), is_ctc=True)
# for visualization
if not self.training:
self.ctc.softmax(hs_pad)
if self.intermediate_ctc_weight > 0 and self.intermediate_ctc_layers:
for hs_intermediate in hs_intermediates:
# assuming hs_intermediates and hs_pad has same length / padding
loss_inter = self.ctc(
hs_intermediate.view(batch_size, -1, self.adim), hs_len, ys_pad
)
loss_intermediate_ctc += loss_inter
loss_intermediate_ctc /= len(self.intermediate_ctc_layers)
# 5. compute cer/wer
if self.training or self.error_calculator is None or self.decoder is None:
cer, wer = None, None
else:
ys_hat = pred_pad.argmax(dim=-1)
cer, wer = self.error_calculator(ys_hat.cpu(), ys_pad.cpu())
# copied from e2e_asr
alpha = self.mtlalpha
if alpha == 0:
self.loss = loss_att
loss_att_data = float(loss_att)
loss_ctc_data = None
elif alpha == 1:
self.loss = loss_ctc
if self.intermediate_ctc_weight > 0:
self.loss = (
1 - self.intermediate_ctc_weight
) * loss_ctc + self.intermediate_ctc_weight * loss_intermediate_ctc
loss_att_data = None
loss_ctc_data = float(loss_ctc)
else:
self.loss = alpha * loss_ctc + (1 - alpha) * loss_att
if self.intermediate_ctc_weight > 0:
self.loss = (
(1 - alpha - self.intermediate_ctc_weight) * loss_att
+ alpha * loss_ctc
+ self.intermediate_ctc_weight * loss_intermediate_ctc
)
loss_att_data = float(loss_att)
loss_ctc_data = float(loss_ctc)
loss_data = float(self.loss)
if loss_data < CTC_LOSS_THRESHOLD and not math.isnan(loss_data):
self.reporter.report(
loss_ctc_data, loss_att_data, self.acc, cer_ctc, cer, wer, loss_data
)
else:
logging.warning("loss (=%f) is not correct", loss_data)
return self.loss
[docs] def scorers(self):
"""Scorers."""
return dict(decoder=self.decoder, ctc=CTCPrefixScorer(self.ctc, self.eos))
[docs] def encode(self, x):
"""Encode acoustic features.
:param ndarray x: source acoustic feature (T, D)
:return: encoder outputs
:rtype: torch.Tensor
"""
self.eval()
x = torch.as_tensor(x).unsqueeze(0)
enc_output, *_ = self.encoder(x, None)
return enc_output.squeeze(0)
[docs] def recognize(self, x, recog_args, char_list=None, rnnlm=None, use_jit=False):
"""Recognize input speech.
:param ndnarray x: input acoustic feature (B, T, D) or (T, D)
:param Namespace recog_args: argment Namespace contraining options
:param list char_list: list of characters
:param torch.nn.Module rnnlm: language model module
:return: N-best decoding results
:rtype: list
"""
enc_output = self.encode(x).unsqueeze(0)
if self.mtlalpha == 1.0:
recog_args.ctc_weight = 1.0
logging.info("Set to pure CTC decoding mode.")
if self.mtlalpha > 0 and recog_args.ctc_weight == 1.0:
from itertools import groupby
lpz = self.ctc.argmax(enc_output)
collapsed_indices = [x[0] for x in groupby(lpz[0])]
hyp = [x for x in filter(lambda x: x != self.blank, collapsed_indices)]
nbest_hyps = [{"score": 0.0, "yseq": [self.sos] + hyp}]
if recog_args.beam_size > 1:
raise NotImplementedError("Pure CTC beam search is not implemented.")
# TODO(hirofumi0810): Implement beam search
return nbest_hyps
elif self.mtlalpha > 0 and recog_args.ctc_weight > 0.0:
lpz = self.ctc.log_softmax(enc_output)
lpz = lpz.squeeze(0)
else:
lpz = None
h = enc_output.squeeze(0)
logging.info("input lengths: " + str(h.size(0)))
# search parms
beam = recog_args.beam_size
penalty = recog_args.penalty
ctc_weight = recog_args.ctc_weight
# preprare sos
y = self.sos
vy = h.new_zeros(1).long()
if recog_args.maxlenratio == 0:
maxlen = h.shape[0]
else:
# maxlen >= 1
maxlen = max(1, int(recog_args.maxlenratio * h.size(0)))
minlen = int(recog_args.minlenratio * h.size(0))
logging.info("max output length: " + str(maxlen))
logging.info("min output length: " + str(minlen))
# initialize hypothesis
if rnnlm:
hyp = {"score": 0.0, "yseq": [y], "rnnlm_prev": None}
else:
hyp = {"score": 0.0, "yseq": [y]}
if lpz is not None:
ctc_prefix_score = CTCPrefixScore(lpz.detach().numpy(), 0, self.eos, numpy)
hyp["ctc_state_prev"] = ctc_prefix_score.initial_state()
hyp["ctc_score_prev"] = 0.0
if ctc_weight != 1.0:
# pre-pruning based on attention scores
ctc_beam = min(lpz.shape[-1], int(beam * CTC_SCORING_RATIO))
else:
ctc_beam = lpz.shape[-1]
hyps = [hyp]
ended_hyps = []
traced_decoder = None
for i in range(maxlen):
logging.debug("position " + str(i))
hyps_best_kept = []
for hyp in hyps:
vy[0] = hyp["yseq"][i]
# get nbest local scores and their ids
ys_mask = subsequent_mask(i + 1).unsqueeze(0)
ys = torch.tensor(hyp["yseq"]).unsqueeze(0)
# FIXME: jit does not match non-jit result
if use_jit:
if traced_decoder is None:
traced_decoder = torch.jit.trace(
self.decoder.forward_one_step, (ys, ys_mask, enc_output)
)
local_att_scores = traced_decoder(ys, ys_mask, enc_output)[0]
else:
local_att_scores = self.decoder.forward_one_step(
ys, ys_mask, enc_output
)[0]
if rnnlm:
rnnlm_state, local_lm_scores = rnnlm.predict(hyp["rnnlm_prev"], vy)
local_scores = (
local_att_scores + recog_args.lm_weight * local_lm_scores
)
else:
local_scores = local_att_scores
if lpz is not None:
local_best_scores, local_best_ids = torch.topk(
local_att_scores, ctc_beam, dim=1
)
ctc_scores, ctc_states = ctc_prefix_score(
hyp["yseq"], local_best_ids[0], hyp["ctc_state_prev"]
)
local_scores = (1.0 - ctc_weight) * local_att_scores[
:, local_best_ids[0]
] + ctc_weight * torch.from_numpy(
ctc_scores - hyp["ctc_score_prev"]
)
if rnnlm:
local_scores += (
recog_args.lm_weight * local_lm_scores[:, local_best_ids[0]]
)
local_best_scores, joint_best_ids = torch.topk(
local_scores, beam, dim=1
)
local_best_ids = local_best_ids[:, joint_best_ids[0]]
else:
local_best_scores, local_best_ids = torch.topk(
local_scores, beam, dim=1
)
for j in range(beam):
new_hyp = {}
new_hyp["score"] = hyp["score"] + float(local_best_scores[0, j])
new_hyp["yseq"] = [0] * (1 + len(hyp["yseq"]))
new_hyp["yseq"][: len(hyp["yseq"])] = hyp["yseq"]
new_hyp["yseq"][len(hyp["yseq"])] = int(local_best_ids[0, j])
if rnnlm:
new_hyp["rnnlm_prev"] = rnnlm_state
if lpz is not None:
new_hyp["ctc_state_prev"] = ctc_states[joint_best_ids[0, j]]
new_hyp["ctc_score_prev"] = ctc_scores[joint_best_ids[0, j]]
# will be (2 x beam) hyps at most
hyps_best_kept.append(new_hyp)
hyps_best_kept = sorted(
hyps_best_kept, key=lambda x: x["score"], reverse=True
)[:beam]
# sort and get nbest
hyps = hyps_best_kept
logging.debug("number of pruned hypothes: " + str(len(hyps)))
if char_list is not None:
logging.debug(
"best hypo: "
+ "".join([char_list[int(x)] for x in hyps[0]["yseq"][1:]])
)
# add eos in the final loop to avoid that there are no ended hyps
if i == maxlen - 1:
logging.info("adding <eos> in the last position in the loop")
for hyp in hyps:
hyp["yseq"].append(self.eos)
# add ended hypothes to a final list, and removed them from current hypothes
# (this will be a probmlem, number of hyps < beam)
remained_hyps = []
for hyp in hyps:
if hyp["yseq"][-1] == self.eos:
# only store the sequence that has more than minlen outputs
# also add penalty
if len(hyp["yseq"]) > minlen:
hyp["score"] += (i + 1) * penalty
if rnnlm: # Word LM needs to add final <eos> score
hyp["score"] += recog_args.lm_weight * rnnlm.final(
hyp["rnnlm_prev"]
)
ended_hyps.append(hyp)
else:
remained_hyps.append(hyp)
# end detection
if end_detect(ended_hyps, i) and recog_args.maxlenratio == 0.0:
logging.info("end detected at %d", i)
break
hyps = remained_hyps
if len(hyps) > 0:
logging.debug("remeined hypothes: " + str(len(hyps)))
else:
logging.info("no hypothesis. Finish decoding.")
break
if char_list is not None:
for hyp in hyps:
logging.debug(
"hypo: " + "".join([char_list[int(x)] for x in hyp["yseq"][1:]])
)
logging.debug("number of ended hypothes: " + str(len(ended_hyps)))
nbest_hyps = sorted(ended_hyps, key=lambda x: x["score"], reverse=True)[
: min(len(ended_hyps), recog_args.nbest)
]
# check number of hypotheis
if len(nbest_hyps) == 0:
logging.warning(
"there is no N-best results, perform recognition "
"again with smaller minlenratio."
)
# should copy becasuse Namespace will be overwritten globally
recog_args = Namespace(**vars(recog_args))
recog_args.minlenratio = max(0.0, recog_args.minlenratio - 0.1)
return self.recognize(x, recog_args, char_list, rnnlm)
logging.info("total log probability: " + str(nbest_hyps[0]["score"]))
logging.info(
"normalized log probability: "
+ str(nbest_hyps[0]["score"] / len(nbest_hyps[0]["yseq"]))
)
return nbest_hyps
[docs] def calculate_all_attentions(self, xs_pad, ilens, ys_pad):
"""E2E attention calculation.
:param torch.Tensor xs_pad: batch of padded input sequences (B, Tmax, idim)
:param torch.Tensor ilens: batch of lengths of input sequences (B)
:param torch.Tensor ys_pad: batch of padded token id sequence tensor (B, Lmax)
:return: attention weights (B, H, Lmax, Tmax)
:rtype: float ndarray
"""
self.eval()
with torch.no_grad():
self.forward(xs_pad, ilens, ys_pad)
ret = dict()
for name, m in self.named_modules():
if (
isinstance(m, MultiHeadedAttention)
or isinstance(m, DynamicConvolution)
or isinstance(m, RelPositionMultiHeadedAttention)
):
ret[name] = m.attn.cpu().numpy()
if isinstance(m, DynamicConvolution2D):
ret[name + "_time"] = m.attn_t.cpu().numpy()
ret[name + "_freq"] = m.attn_f.cpu().numpy()
self.train()
return ret
[docs] def calculate_all_ctc_probs(self, xs_pad, ilens, ys_pad):
"""E2E CTC probability calculation.
:param torch.Tensor xs_pad: batch of padded input sequences (B, Tmax)
:param torch.Tensor ilens: batch of lengths of input sequences (B)
:param torch.Tensor ys_pad: batch of padded token id sequence tensor (B, Lmax)
:return: CTC probability (B, Tmax, vocab)
:rtype: float ndarray
"""
ret = None
if self.mtlalpha == 0:
return ret
self.eval()
with torch.no_grad():
self.forward(xs_pad, ilens, ys_pad)
for name, m in self.named_modules():
if isinstance(m, CTC) and m.probs is not None:
ret = m.probs.cpu().numpy()
self.train()
return ret