FunASR/funasr/cli/models/paraformer.py
2023-12-11 13:42:40 +08:00

656 lines
22 KiB
Python

import logging
from contextlib import contextmanager
from distutils.version import LooseVersion
from typing import Dict
from typing import List
from typing import Optional
from typing import Tuple
from typing import Union
import torch
import torch.nn as nn
import random
import numpy as np
# from funasr.layers.abs_normalize import AbsNormalize
from funasr.losses.label_smoothing_loss import (
LabelSmoothingLoss, # noqa: H301
)
# from funasr.models.ctc import CTC
# from funasr.models.decoder.abs_decoder import AbsDecoder
# from funasr.models.e2e_asr_common import ErrorCalculator
# from funasr.models.encoder.abs_encoder import AbsEncoder
# from funasr.models.frontend.abs_frontend import AbsFrontend
# from funasr.models.postencoder.abs_postencoder import AbsPostEncoder
from funasr.models.predictor.cif import mae_loss
# from funasr.models.preencoder.abs_preencoder import AbsPreEncoder
# from funasr.models.specaug.abs_specaug import AbsSpecAug
from funasr.modules.add_sos_eos import add_sos_eos
from funasr.modules.nets_utils import make_pad_mask, pad_list
from funasr.modules.nets_utils import th_accuracy
from funasr.torch_utils.device_funcs import force_gatherable
# from funasr.models.base_model import FunASRModel
# from funasr.models.predictor.cif import CifPredictorV3
from funasr.cli.model_class_factory import *
if LooseVersion(torch.__version__) >= LooseVersion("1.6.0"):
from torch.cuda.amp import autocast
else:
# Nothing to do if torch<1.6.0
@contextmanager
def autocast(enabled=True):
yield
class Paraformer(nn.Module):
"""
Author: Speech Lab of DAMO Academy, Alibaba Group
Paraformer: Fast and Accurate Parallel Transformer for Non-autoregressive End-to-End Speech Recognition
https://arxiv.org/abs/2206.08317
"""
def __init__(
self,
# token_list: Union[Tuple[str, ...], List[str]],
frontend: Optional[str] = None,
frontend_conf: Optional[Dict] = None,
specaug: Optional[str] = None,
specaug_conf: Optional[Dict] = None,
normalize: str = None,
normalize_conf: Optional[Dict] = None,
encoder: str = None,
encoder_conf: Optional[Dict] = None,
decoder: str = None,
decoder_conf: Optional[Dict] = None,
ctc: str = None,
ctc_conf: Optional[Dict] = None,
predictor: str = None,
predictor_conf: Optional[Dict] = None,
ctc_weight: float = 0.5,
interctc_weight: float = 0.0,
input_size: int = 80,
vocab_size: int = -1,
ignore_id: int = -1,
blank_id: int = 0,
sos: int = 1,
eos: int = 2,
lsm_weight: float = 0.0,
length_normalized_loss: bool = False,
# report_cer: bool = True,
# report_wer: bool = True,
# sym_space: str = "<space>",
# sym_blank: str = "<blank>",
# extract_feats_in_collect_stats: bool = True,
# predictor=None,
predictor_weight: float = 0.0,
predictor_bias: int = 0,
sampling_ratio: float = 0.2,
share_embedding: bool = False,
# preencoder: Optional[AbsPreEncoder] = None,
# postencoder: Optional[AbsPostEncoder] = None,
use_1st_decoder_loss: bool = False,
**kwargs,
):
assert 0.0 <= ctc_weight <= 1.0, ctc_weight
assert 0.0 <= interctc_weight < 1.0, interctc_weight
super().__init__()
# import pdb;
# pdb.set_trace()
if frontend is not None:
frontend_class = frontend_choices.get_class(frontend)
frontend = frontend_class(**frontend_conf)
if specaug is not None:
specaug_class = specaug_choices.get_class(specaug)
specaug = specaug_class(**specaug_conf)
if normalize is not None:
normalize_class = normalize_choices.get_class(normalize)
normalize = normalize_class(**normalize_conf)
encoder_class = encoder_choices.get_class(encoder)
encoder = encoder_class(input_size=input_size, **encoder_conf)
encoder_output_size = encoder.output_size()
if decoder is not None:
decoder_class = decoder_choices.get_class(decoder)
decoder = decoder_class(
vocab_size=vocab_size,
encoder_output_size=encoder_output_size,
**decoder_conf,
)
if ctc_weight > 0.0:
if ctc_conf is None:
ctc_conf = {}
ctc = CTC(
odim=vocab_size, encoder_output_size=encoder_output_size, **ctc_conf
)
if predictor is not None:
predictor_class = predictor_choices.get_class(predictor)
predictor = predictor_class(**predictor_conf)
# note that eos is the same as sos (equivalent ID)
self.blank_id = blank_id
self.sos = sos if sos is not None else vocab_size - 1
self.eos = eos if eos is not None else vocab_size - 1
self.vocab_size = vocab_size
self.ignore_id = ignore_id
self.ctc_weight = ctc_weight
self.interctc_weight = interctc_weight
# self.token_list = token_list.copy()
#
self.frontend = frontend
self.specaug = specaug
self.normalize = normalize
# self.preencoder = preencoder
# self.postencoder = postencoder
self.encoder = encoder
#
# if not hasattr(self.encoder, "interctc_use_conditioning"):
# self.encoder.interctc_use_conditioning = False
# if self.encoder.interctc_use_conditioning:
# self.encoder.conditioning_layer = torch.nn.Linear(
# vocab_size, self.encoder.output_size()
# )
#
# self.error_calculator = None
#
if ctc_weight == 1.0:
self.decoder = None
else:
self.decoder = decoder
self.criterion_att = LabelSmoothingLoss(
size=vocab_size,
padding_idx=ignore_id,
smoothing=lsm_weight,
normalize_length=length_normalized_loss,
)
#
# if report_cer or report_wer:
# self.error_calculator = ErrorCalculator(
# token_list, sym_space, sym_blank, report_cer, report_wer
# )
#
if ctc_weight == 0.0:
self.ctc = None
else:
self.ctc = ctc
#
# self.extract_feats_in_collect_stats = extract_feats_in_collect_stats
self.predictor = predictor
self.predictor_weight = predictor_weight
self.predictor_bias = predictor_bias
self.sampling_ratio = sampling_ratio
self.criterion_pre = mae_loss(normalize_length=length_normalized_loss)
# self.step_cur = 0
#
self.share_embedding = share_embedding
if self.share_embedding:
self.decoder.embed = None
self.use_1st_decoder_loss = use_1st_decoder_loss
self.length_normalized_loss = length_normalized_loss
def forward(
self,
speech: torch.Tensor,
speech_lengths: torch.Tensor,
text: torch.Tensor,
text_lengths: torch.Tensor,
**kwargs,
) -> Tuple[torch.Tensor, Dict[str, torch.Tensor], torch.Tensor]:
"""Frontend + Encoder + Decoder + Calc loss
Args:
speech: (Batch, Length, ...)
speech_lengths: (Batch, )
text: (Batch, Length)
text_lengths: (Batch,)
decoding_ind: int
"""
decoding_ind = kwargs.get("kwargs", None)
# import pdb;
# pdb.set_trace()
if len(text_lengths.size()) > 1:
text_lengths = text_lengths[:, 0]
if len(speech_lengths.size()) > 1:
speech_lengths = speech_lengths[:, 0]
batch_size = speech.shape[0]
# # for data-parallel
# text = text[:, : text_lengths.max()]
# speech = speech[:, :speech_lengths.max()]
# 1. Encoder
if hasattr(self.encoder, "overlap_chunk_cls"):
ind = self.encoder.overlap_chunk_cls.random_choice(self.training, decoding_ind)
encoder_out, encoder_out_lens = self.encode(speech, speech_lengths, ind=ind)
else:
encoder_out, encoder_out_lens = self.encode(speech, speech_lengths)
intermediate_outs = None
if isinstance(encoder_out, tuple):
intermediate_outs = encoder_out[1]
encoder_out = encoder_out[0]
loss_att, pre_loss_att, acc_att, cer_att, wer_att = None, None, None, None, None
loss_ctc, cer_ctc = None, None
loss_pre = None
stats = dict()
# 1. CTC branch
if self.ctc_weight != 0.0:
loss_ctc, cer_ctc = self._calc_ctc_loss(
encoder_out, encoder_out_lens, text, text_lengths
)
# Collect CTC branch stats
stats["loss_ctc"] = loss_ctc.detach() if loss_ctc is not None else None
stats["cer_ctc"] = cer_ctc
# Intermediate CTC (optional)
loss_interctc = 0.0
if self.interctc_weight != 0.0 and intermediate_outs is not None:
for layer_idx, intermediate_out in intermediate_outs:
# we assume intermediate_out has the same length & padding
# as those of encoder_out
loss_ic, cer_ic = self._calc_ctc_loss(
intermediate_out, encoder_out_lens, text, text_lengths
)
loss_interctc = loss_interctc + loss_ic
# Collect Intermedaite CTC stats
stats["loss_interctc_layer{}".format(layer_idx)] = (
loss_ic.detach() if loss_ic is not None else None
)
stats["cer_interctc_layer{}".format(layer_idx)] = cer_ic
loss_interctc = loss_interctc / len(intermediate_outs)
# calculate whole encoder loss
loss_ctc = (
1 - self.interctc_weight
) * loss_ctc + self.interctc_weight * loss_interctc
# 2b. Attention decoder branch
if self.ctc_weight != 1.0:
loss_att, acc_att, cer_att, wer_att, loss_pre, pre_loss_att = self._calc_att_loss(
encoder_out, encoder_out_lens, text, text_lengths
)
# 3. CTC-Att loss definition
if self.ctc_weight == 0.0:
loss = loss_att + loss_pre * self.predictor_weight
elif self.ctc_weight == 1.0:
loss = loss_ctc
else:
loss = self.ctc_weight * loss_ctc + (1 - self.ctc_weight) * loss_att + loss_pre * self.predictor_weight
if self.use_1st_decoder_loss and pre_loss_att is not None:
loss = loss + (1 - self.ctc_weight) * pre_loss_att
# Collect Attn branch stats
stats["loss_att"] = loss_att.detach() if loss_att is not None else None
stats["pre_loss_att"] = pre_loss_att.detach() if pre_loss_att is not None else None
stats["acc"] = acc_att
stats["cer"] = cer_att
stats["wer"] = wer_att
stats["loss_pre"] = loss_pre.detach().cpu() if loss_pre is not None else None
stats["loss"] = torch.clone(loss.detach())
# force_gatherable: to-device and to-tensor if scalar for DataParallel
if self.length_normalized_loss:
batch_size = (text_lengths + self.predictor_bias).sum()
loss, stats, weight = force_gatherable((loss, stats, batch_size), loss.device)
return loss, stats, weight
def collect_feats(
self,
speech: torch.Tensor,
speech_lengths: torch.Tensor,
text: torch.Tensor,
text_lengths: torch.Tensor,
) -> Dict[str, torch.Tensor]:
if self.extract_feats_in_collect_stats:
feats, feats_lengths = self._extract_feats(speech, speech_lengths)
else:
# Generate dummy stats if extract_feats_in_collect_stats is False
logging.warning(
"Generating dummy stats for feats and feats_lengths, "
"because encoder_conf.extract_feats_in_collect_stats is "
f"{self.extract_feats_in_collect_stats}"
)
feats, feats_lengths = speech, speech_lengths
return {"feats": feats, "feats_lengths": feats_lengths}
def encode(
self, speech: torch.Tensor, speech_lengths: torch.Tensor, ind: int = 0,
) -> Tuple[torch.Tensor, torch.Tensor]:
"""Frontend + Encoder. Note that this method is used by asr_inference.py
Args:
speech: (Batch, Length, ...)
speech_lengths: (Batch, )
ind: int
"""
with autocast(False):
# # 1. Extract feats
# feats, feats_lengths = self._extract_feats(speech, speech_lengths)
# 2. Data augmentation
if self.specaug is not None and self.training:
feats, feats_lengths = self.specaug(speech, speech_lengths)
# 3. Normalization for feature: e.g. Global-CMVN, Utterance-CMVN
if self.normalize is not None:
feats, feats_lengths = self.normalize(feats, feats_lengths)
# # Pre-encoder, e.g. used for raw input data
# if self.preencoder is not None:
# feats, feats_lengths = self.preencoder(feats, feats_lengths)
# 4. Forward encoder
# feats: (Batch, Length, Dim)
# -> encoder_out: (Batch, Length2, Dim2)
if self.encoder.interctc_use_conditioning:
if hasattr(self.encoder, "overlap_chunk_cls"):
encoder_out, encoder_out_lens, _ = self.encoder(
feats, feats_lengths, ctc=self.ctc, ind=ind
)
encoder_out, encoder_out_lens = self.encoder.overlap_chunk_cls.remove_chunk(encoder_out,
encoder_out_lens,
chunk_outs=None)
else:
encoder_out, encoder_out_lens, _ = self.encoder(
feats, feats_lengths, ctc=self.ctc
)
else:
if hasattr(self.encoder, "overlap_chunk_cls"):
encoder_out, encoder_out_lens, _ = self.encoder(feats, feats_lengths, ind=ind)
encoder_out, encoder_out_lens = self.encoder.overlap_chunk_cls.remove_chunk(encoder_out,
encoder_out_lens,
chunk_outs=None)
else:
encoder_out, encoder_out_lens, _ = self.encoder(feats, feats_lengths)
intermediate_outs = None
if isinstance(encoder_out, tuple):
intermediate_outs = encoder_out[1]
encoder_out = encoder_out[0]
# # Post-encoder, e.g. NLU
# if self.postencoder is not None:
# encoder_out, encoder_out_lens = self.postencoder(
# encoder_out, encoder_out_lens
# )
assert encoder_out.size(0) == speech.size(0), (
encoder_out.size(),
speech.size(0),
)
assert encoder_out.size(1) <= encoder_out_lens.max(), (
encoder_out.size(),
encoder_out_lens.max(),
)
if intermediate_outs is not None:
return (encoder_out, intermediate_outs), encoder_out_lens
return encoder_out, encoder_out_lens
def calc_predictor(self, encoder_out, encoder_out_lens):
encoder_out_mask = (~make_pad_mask(encoder_out_lens, maxlen=encoder_out.size(1))[:, None, :]).to(
encoder_out.device)
pre_acoustic_embeds, pre_token_length, alphas, pre_peak_index = self.predictor(encoder_out, None, encoder_out_mask,
ignore_id=self.ignore_id)
return pre_acoustic_embeds, pre_token_length, alphas, pre_peak_index
def cal_decoder_with_predictor(self, encoder_out, encoder_out_lens, sematic_embeds, ys_pad_lens):
decoder_outs = self.decoder(
encoder_out, encoder_out_lens, sematic_embeds, ys_pad_lens
)
decoder_out = decoder_outs[0]
decoder_out = torch.log_softmax(decoder_out, dim=-1)
return decoder_out, ys_pad_lens
def _extract_feats(
self, speech: torch.Tensor, speech_lengths: torch.Tensor
) -> Tuple[torch.Tensor, torch.Tensor]:
assert speech_lengths.dim() == 1, speech_lengths.shape
# for data-parallel
speech = speech[:, : speech_lengths.max()]
if self.frontend is not None:
# Frontend
# e.g. STFT and Feature extract
# data_loader may send time-domain signal in this case
# speech (Batch, NSamples) -> feats: (Batch, NFrames, Dim)
feats, feats_lengths = self.frontend(speech, speech_lengths)
else:
# No frontend and no feature extract
feats, feats_lengths = speech, speech_lengths
return feats, feats_lengths
def nll(
self,
encoder_out: torch.Tensor,
encoder_out_lens: torch.Tensor,
ys_pad: torch.Tensor,
ys_pad_lens: torch.Tensor,
) -> torch.Tensor:
"""Compute negative log likelihood(nll) from transformer-decoder
Normally, this function is called in batchify_nll.
Args:
encoder_out: (Batch, Length, Dim)
encoder_out_lens: (Batch,)
ys_pad: (Batch, Length)
ys_pad_lens: (Batch,)
"""
ys_in_pad, ys_out_pad = add_sos_eos(ys_pad, self.sos, self.eos, self.ignore_id)
ys_in_lens = ys_pad_lens + 1
# 1. Forward decoder
decoder_out, _ = self.decoder(
encoder_out, encoder_out_lens, ys_in_pad, ys_in_lens
) # [batch, seqlen, dim]
batch_size = decoder_out.size(0)
decoder_num_class = decoder_out.size(2)
# nll: negative log-likelihood
nll = torch.nn.functional.cross_entropy(
decoder_out.view(-1, decoder_num_class),
ys_out_pad.view(-1),
ignore_index=self.ignore_id,
reduction="none",
)
nll = nll.view(batch_size, -1)
nll = nll.sum(dim=1)
assert nll.size(0) == batch_size
return nll
def batchify_nll(
self,
encoder_out: torch.Tensor,
encoder_out_lens: torch.Tensor,
ys_pad: torch.Tensor,
ys_pad_lens: torch.Tensor,
batch_size: int = 100,
):
"""Compute negative log likelihood(nll) from transformer-decoder
To avoid OOM, this fuction seperate the input into batches.
Then call nll for each batch and combine and return results.
Args:
encoder_out: (Batch, Length, Dim)
encoder_out_lens: (Batch,)
ys_pad: (Batch, Length)
ys_pad_lens: (Batch,)
batch_size: int, samples each batch contain when computing nll,
you may change this to avoid OOM or increase
GPU memory usage
"""
total_num = encoder_out.size(0)
if total_num <= batch_size:
nll = self.nll(encoder_out, encoder_out_lens, ys_pad, ys_pad_lens)
else:
nll = []
start_idx = 0
while True:
end_idx = min(start_idx + batch_size, total_num)
batch_encoder_out = encoder_out[start_idx:end_idx, :, :]
batch_encoder_out_lens = encoder_out_lens[start_idx:end_idx]
batch_ys_pad = ys_pad[start_idx:end_idx, :]
batch_ys_pad_lens = ys_pad_lens[start_idx:end_idx]
batch_nll = self.nll(
batch_encoder_out,
batch_encoder_out_lens,
batch_ys_pad,
batch_ys_pad_lens,
)
nll.append(batch_nll)
start_idx = end_idx
if start_idx == total_num:
break
nll = torch.cat(nll)
assert nll.size(0) == total_num
return nll
def _calc_att_loss(
self,
encoder_out: torch.Tensor,
encoder_out_lens: torch.Tensor,
ys_pad: torch.Tensor,
ys_pad_lens: torch.Tensor,
):
encoder_out_mask = (~make_pad_mask(encoder_out_lens, maxlen=encoder_out.size(1))[:, None, :]).to(
encoder_out.device)
if self.predictor_bias == 1:
_, ys_pad = add_sos_eos(ys_pad, self.sos, self.eos, self.ignore_id)
ys_pad_lens = ys_pad_lens + self.predictor_bias
pre_acoustic_embeds, pre_token_length, _, pre_peak_index = self.predictor(encoder_out, ys_pad, encoder_out_mask,
ignore_id=self.ignore_id)
# 0. sampler
decoder_out_1st = None
pre_loss_att = None
if self.sampling_ratio > 0.0:
if self.use_1st_decoder_loss:
sematic_embeds, decoder_out_1st, pre_loss_att = self.sampler_with_grad(encoder_out, encoder_out_lens, ys_pad, ys_pad_lens,
pre_acoustic_embeds)
else:
sematic_embeds, decoder_out_1st = self.sampler(encoder_out, encoder_out_lens, ys_pad, ys_pad_lens,
pre_acoustic_embeds)
else:
if self.step_cur < 2:
logging.info("disable sampler in paraformer, sampling_ratio: {}".format(self.sampling_ratio))
sematic_embeds = pre_acoustic_embeds
# 1. Forward decoder
decoder_outs = self.decoder(
encoder_out, encoder_out_lens, sematic_embeds, ys_pad_lens
)
decoder_out, _ = decoder_outs[0], decoder_outs[1]
if decoder_out_1st is None:
decoder_out_1st = decoder_out
# 2. Compute attention loss
loss_att = self.criterion_att(decoder_out, ys_pad)
acc_att = th_accuracy(
decoder_out_1st.view(-1, self.vocab_size),
ys_pad,
ignore_label=self.ignore_id,
)
loss_pre = self.criterion_pre(ys_pad_lens.type_as(pre_token_length), pre_token_length)
# Compute cer/wer using attention-decoder
if self.training or self.error_calculator is None:
cer_att, wer_att = None, None
else:
ys_hat = decoder_out_1st.argmax(dim=-1)
cer_att, wer_att = self.error_calculator(ys_hat.cpu(), ys_pad.cpu())
return loss_att, acc_att, cer_att, wer_att, loss_pre, pre_loss_att
def sampler(self, encoder_out, encoder_out_lens, ys_pad, ys_pad_lens, pre_acoustic_embeds):
tgt_mask = (~make_pad_mask(ys_pad_lens, maxlen=ys_pad_lens.max())[:, :, None]).to(ys_pad.device)
ys_pad_masked = ys_pad * tgt_mask[:, :, 0]
if self.share_embedding:
ys_pad_embed = self.decoder.output_layer.weight[ys_pad_masked]
else:
ys_pad_embed = self.decoder.embed(ys_pad_masked)
with torch.no_grad():
decoder_outs = self.decoder(
encoder_out, encoder_out_lens, pre_acoustic_embeds, ys_pad_lens
)
decoder_out, _ = decoder_outs[0], decoder_outs[1]
pred_tokens = decoder_out.argmax(-1)
nonpad_positions = ys_pad.ne(self.ignore_id)
seq_lens = (nonpad_positions).sum(1)
same_num = ((pred_tokens == ys_pad) & nonpad_positions).sum(1)
input_mask = torch.ones_like(nonpad_positions)
bsz, seq_len = ys_pad.size()
for li in range(bsz):
target_num = (((seq_lens[li] - same_num[li].sum()).float()) * self.sampling_ratio).long()
if target_num > 0:
input_mask[li].scatter_(dim=0, index=torch.randperm(seq_lens[li])[:target_num].to(input_mask.device), value=0)
input_mask = input_mask.eq(1)
input_mask = input_mask.masked_fill(~nonpad_positions, False)
input_mask_expand_dim = input_mask.unsqueeze(2).to(pre_acoustic_embeds.device)
sematic_embeds = pre_acoustic_embeds.masked_fill(~input_mask_expand_dim, 0) + ys_pad_embed.masked_fill(
input_mask_expand_dim, 0)
return sematic_embeds * tgt_mask, decoder_out * tgt_mask
def sampler_with_grad(self, encoder_out, encoder_out_lens, ys_pad, ys_pad_lens, pre_acoustic_embeds):
tgt_mask = (~make_pad_mask(ys_pad_lens, maxlen=ys_pad_lens.max())[:, :, None]).to(ys_pad.device)
ys_pad_masked = ys_pad * tgt_mask[:, :, 0]
if self.share_embedding:
ys_pad_embed = self.decoder.output_layer.weight[ys_pad_masked]
else:
ys_pad_embed = self.decoder.embed(ys_pad_masked)
decoder_outs = self.decoder(
encoder_out, encoder_out_lens, pre_acoustic_embeds, ys_pad_lens
)
pre_loss_att = self.criterion_att(decoder_outs[0], ys_pad)
decoder_out, _ = decoder_outs[0], decoder_outs[1]
pred_tokens = decoder_out.argmax(-1)
nonpad_positions = ys_pad.ne(self.ignore_id)
seq_lens = (nonpad_positions).sum(1)
same_num = ((pred_tokens == ys_pad) & nonpad_positions).sum(1)
input_mask = torch.ones_like(nonpad_positions)
bsz, seq_len = ys_pad.size()
for li in range(bsz):
target_num = (((seq_lens[li] - same_num[li].sum()).float()) * self.sampling_ratio).long()
if target_num > 0:
input_mask[li].scatter_(dim=0, index=torch.randperm(seq_lens[li])[:target_num].to(input_mask.device), value=0)
input_mask = input_mask.eq(1)
input_mask = input_mask.masked_fill(~nonpad_positions, False)
input_mask_expand_dim = input_mask.unsqueeze(2).to(pre_acoustic_embeds.device)
sematic_embeds = pre_acoustic_embeds.masked_fill(~input_mask_expand_dim, 0) + ys_pad_embed.masked_fill(
input_mask_expand_dim, 0)
return sematic_embeds * tgt_mask, decoder_out * tgt_mask, pre_loss_att
def _calc_ctc_loss(
self,
encoder_out: torch.Tensor,
encoder_out_lens: torch.Tensor,
ys_pad: torch.Tensor,
ys_pad_lens: torch.Tensor,
):
# Calc CTC loss
loss_ctc = self.ctc(encoder_out, encoder_out_lens, ys_pad, ys_pad_lens)
# Calc CER using CTC
cer_ctc = None
if not self.training and self.error_calculator is not None:
ys_hat = self.ctc.argmax(encoder_out).data
cer_ctc = self.error_calculator(ys_hat.cpu(), ys_pad.cpu(), is_ctc=True)
return loss_ctc, cer_ctc