You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
PaddleSpeech/deepspeech/models/u2_st.py

728 lines
28 KiB

# Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""U2 ASR Model
Unified Streaming and Non-streaming Two-pass End-to-end Model for Speech Recognition
(https://arxiv.org/pdf/2012.05481.pdf)
"""
import time
from typing import Dict
from typing import List
from typing import Optional
from typing import Tuple
import paddle
from paddle import jit
from paddle import nn
from yacs.config import CfgNode
from deepspeech.frontend.utility import IGNORE_ID
from deepspeech.frontend.utility import load_cmvn
from deepspeech.modules.cmvn import GlobalCMVN
from deepspeech.modules.ctc import CTCDecoder
from deepspeech.modules.decoder import TransformerDecoder
from deepspeech.modules.encoder import ConformerEncoder
from deepspeech.modules.encoder import TransformerEncoder
from deepspeech.modules.loss import LabelSmoothingLoss
from deepspeech.modules.mask import mask_finished_preds
from deepspeech.modules.mask import mask_finished_scores
from deepspeech.modules.mask import subsequent_mask
from deepspeech.utils import checkpoint
from deepspeech.utils import layer_tools
from deepspeech.utils.log import Log
from deepspeech.utils.tensor_utils import add_sos_eos
from deepspeech.utils.tensor_utils import th_accuracy
__all__ = ["U2STModel", "U2STInferModel"]
logger = Log(__name__).getlog()
class U2STBaseModel(nn.Layer):
"""CTC-Attention hybrid Encoder-Decoder model"""
@classmethod
def params(cls, config: Optional[CfgNode]=None) -> CfgNode:
# network architecture
default = CfgNode()
# allow add new item when merge_with_file
default.cmvn_file = ""
default.cmvn_file_type = "json"
default.input_dim = 0
default.output_dim = 0
# encoder related
default.encoder = 'transformer'
default.encoder_conf = CfgNode(
dict(
output_size=256, # dimension of attention
attention_heads=4,
linear_units=2048, # the number of units of position-wise feed forward
num_blocks=12, # the number of encoder blocks
dropout_rate=0.1,
positional_dropout_rate=0.1,
attention_dropout_rate=0.0,
input_layer='conv2d', # encoder input type, you can chose conv2d, conv2d6 and conv2d8
normalize_before=True,
# use_cnn_module=True,
# cnn_module_kernel=15,
# activation_type='swish',
# pos_enc_layer_type='rel_pos',
# selfattention_layer_type='rel_selfattn',
))
# decoder related
default.decoder = 'transformer'
default.decoder_conf = CfgNode(
dict(
attention_heads=4,
linear_units=2048,
num_blocks=6,
dropout_rate=0.1,
positional_dropout_rate=0.1,
self_attention_dropout_rate=0.0,
src_attention_dropout_rate=0.0, ))
# hybrid CTC/attention
default.model_conf = CfgNode(
dict(
asr_weight=0.0,
ctc_weight=0.0,
lsm_weight=0.1, # label smoothing option
length_normalized_loss=False, ))
if config is not None:
config.merge_from_other_cfg(default)
return default
def __init__(self,
vocab_size: int,
encoder: TransformerEncoder,
st_decoder: TransformerDecoder,
decoder: TransformerDecoder=None,
ctc: CTCDecoder=None,
ctc_weight: float=0.0,
asr_weight: float=0.0,
ignore_id: int=IGNORE_ID,
lsm_weight: float=0.0,
length_normalized_loss: bool=False):
assert 0.0 <= ctc_weight <= 1.0, ctc_weight
super().__init__()
# note that eos is the same as sos (equivalent ID)
self.sos = vocab_size - 1
self.eos = vocab_size - 1
self.vocab_size = vocab_size
self.ignore_id = ignore_id
self.ctc_weight = ctc_weight
self.asr_weight = asr_weight
self.encoder = encoder
self.st_decoder = st_decoder
self.decoder = decoder
self.ctc = ctc
self.criterion_att = LabelSmoothingLoss(
size=vocab_size,
padding_idx=ignore_id,
smoothing=lsm_weight,
normalize_length=length_normalized_loss, )
def forward(
self,
speech: paddle.Tensor,
speech_lengths: paddle.Tensor,
text: paddle.Tensor,
text_lengths: paddle.Tensor,
asr_text: paddle.Tensor=None,
asr_text_lengths: paddle.Tensor=None,
) -> Tuple[Optional[paddle.Tensor], Optional[paddle.Tensor], Optional[
paddle.Tensor]]:
"""Frontend + Encoder + Decoder + Calc loss
Args:
speech: (Batch, Length, ...)
speech_lengths: (Batch, )
text: (Batch, Length)
text_lengths: (Batch,)
Returns:
total_loss, attention_loss, ctc_loss
"""
assert text_lengths.dim() == 1, text_lengths.shape
# Check that batch_size is unified
assert (speech.shape[0] == speech_lengths.shape[0] == text.shape[0] ==
text_lengths.shape[0]), (speech.shape, speech_lengths.shape,
text.shape, text_lengths.shape)
# 1. Encoder
start = time.time()
encoder_out, encoder_mask = self.encoder(speech, speech_lengths)
encoder_time = time.time() - start
#logger.debug(f"encoder time: {encoder_time}")
encoder_out_lens = encoder_mask.squeeze(1).sum(1) #[B, 1, T] -> [B]
# 2a. ST-decoder branch
start = time.time()
loss_st, acc_st = self._calc_st_loss(encoder_out, encoder_mask, text,
text_lengths)
decoder_time = time.time() - start
loss_asr_att = None
loss_asr_ctc = None
# 2b. ASR Attention-decoder branch
if self.asr_weight > 0.:
if self.ctc_weight != 1.0:
start = time.time()
loss_asr_att, acc_att = self._calc_att_loss(
encoder_out, encoder_mask, asr_text, asr_text_lengths)
decoder_time = time.time() - start
# 2c. CTC branch
if self.ctc_weight != 0.0:
start = time.time()
loss_asr_ctc = self.ctc(encoder_out, encoder_out_lens, asr_text,
asr_text_lengths)
ctc_time = time.time() - start
if loss_asr_ctc is None:
loss_asr = loss_asr_att
elif loss_asr_att is None:
loss_asr = loss_asr_ctc
else:
loss_asr = self.ctc_weight * loss_asr_ctc + (1 - self.ctc_weight
) * loss_asr_att
loss = self.asr_weight * loss_asr + (1 - self.asr_weight) * loss_st
else:
loss = loss_st
return loss, loss_st, loss_asr_att, loss_asr_ctc
def _calc_st_loss(
self,
encoder_out: paddle.Tensor,
encoder_mask: paddle.Tensor,
ys_pad: paddle.Tensor,
ys_pad_lens: paddle.Tensor, ) -> Tuple[paddle.Tensor, float]:
"""Calc attention loss.
Args:
encoder_out (paddle.Tensor): [B, Tmax, D]
encoder_mask (paddle.Tensor): [B, 1, Tmax]
ys_pad (paddle.Tensor): [B, Umax]
ys_pad_lens (paddle.Tensor): [B]
Returns:
Tuple[paddle.Tensor, float]: attention_loss, accuracy rate
"""
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.st_decoder(encoder_out, encoder_mask, ys_in_pad,
ys_in_lens)
# 2. Compute attention loss
loss_att = self.criterion_att(decoder_out, ys_out_pad)
acc_att = th_accuracy(
decoder_out.view(-1, self.vocab_size),
ys_out_pad,
ignore_label=self.ignore_id, )
return loss_att, acc_att
def _calc_att_loss(
self,
encoder_out: paddle.Tensor,
encoder_mask: paddle.Tensor,
ys_pad: paddle.Tensor,
ys_pad_lens: paddle.Tensor, ) -> Tuple[paddle.Tensor, float]:
"""Calc attention loss.
Args:
encoder_out (paddle.Tensor): [B, Tmax, D]
encoder_mask (paddle.Tensor): [B, 1, Tmax]
ys_pad (paddle.Tensor): [B, Umax]
ys_pad_lens (paddle.Tensor): [B]
Returns:
Tuple[paddle.Tensor, float]: attention_loss, accuracy rate
"""
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_mask, ys_in_pad,
ys_in_lens)
# 2. Compute attention loss
loss_att = self.criterion_att(decoder_out, ys_out_pad)
acc_att = th_accuracy(
decoder_out.view(-1, self.vocab_size),
ys_out_pad,
ignore_label=self.ignore_id, )
return loss_att, acc_att
def _forward_encoder(
self,
speech: paddle.Tensor,
speech_lengths: paddle.Tensor,
decoding_chunk_size: int=-1,
num_decoding_left_chunks: int=-1,
simulate_streaming: bool=False,
) -> Tuple[paddle.Tensor, paddle.Tensor]:
"""Encoder pass.
Args:
speech (paddle.Tensor): [B, Tmax, D]
speech_lengths (paddle.Tensor): [B]
decoding_chunk_size (int, optional): chuck size. Defaults to -1.
num_decoding_left_chunks (int, optional): nums chunks. Defaults to -1.
simulate_streaming (bool, optional): streaming or not. Defaults to False.
Returns:
Tuple[paddle.Tensor, paddle.Tensor]:
encoder hiddens (B, Tmax, D),
encoder hiddens mask (B, 1, Tmax).
"""
# Let's assume B = batch_size
# 1. Encoder
if simulate_streaming and decoding_chunk_size > 0:
encoder_out, encoder_mask = self.encoder.forward_chunk_by_chunk(
speech,
decoding_chunk_size=decoding_chunk_size,
num_decoding_left_chunks=num_decoding_left_chunks
) # (B, maxlen, encoder_dim)
else:
encoder_out, encoder_mask = self.encoder(
speech,
speech_lengths,
decoding_chunk_size=decoding_chunk_size,
num_decoding_left_chunks=num_decoding_left_chunks
) # (B, maxlen, encoder_dim)
return encoder_out, encoder_mask
def translate(
self,
speech: paddle.Tensor,
speech_lengths: paddle.Tensor,
beam_size: int=10,
decoding_chunk_size: int=-1,
num_decoding_left_chunks: int=-1,
simulate_streaming: bool=False, ) -> paddle.Tensor:
""" Apply beam search on attention decoder
Args:
speech (paddle.Tensor): (batch, max_len, feat_dim)
speech_length (paddle.Tensor): (batch, )
beam_size (int): beam size for beam search
decoding_chunk_size (int): decoding chunk for dynamic chunk
trained model.
<0: for decoding, use full chunk.
>0: for decoding, use fixed chunk size as set.
0: used for training, it's prohibited here
simulate_streaming (bool): whether do encoder forward in a
streaming fashion
Returns:
paddle.Tensor: decoding result, (batch, max_result_len)
"""
assert speech.shape[0] == speech_lengths.shape[0]
assert decoding_chunk_size != 0
device = speech.place
batch_size = speech.shape[0]
# Let's assume B = batch_size and N = beam_size
# 1. Encoder
encoder_out, encoder_mask = self._forward_encoder(
speech, speech_lengths, decoding_chunk_size,
num_decoding_left_chunks,
simulate_streaming) # (B, maxlen, encoder_dim)
maxlen = encoder_out.size(1)
encoder_dim = encoder_out.size(2)
running_size = batch_size * beam_size
encoder_out = encoder_out.unsqueeze(1).repeat(1, beam_size, 1, 1).view(
running_size, maxlen, encoder_dim) # (B*N, maxlen, encoder_dim)
encoder_mask = encoder_mask.unsqueeze(1).repeat(
1, beam_size, 1, 1).view(running_size, 1,
maxlen) # (B*N, 1, max_len)
hyps = paddle.ones(
[running_size, 1], dtype=paddle.long).fill_(self.sos) # (B*N, 1)
# log scale score
scores = paddle.to_tensor(
[0.0] + [-float('inf')] * (beam_size - 1), dtype=paddle.float)
scores = scores.to(device).repeat(batch_size).unsqueeze(1).to(
device) # (B*N, 1)
end_flag = paddle.zeros_like(scores, dtype=paddle.bool) # (B*N, 1)
cache: Optional[List[paddle.Tensor]] = None
# 2. Decoder forward step by step
for i in range(1, maxlen + 1):
# Stop if all batch and all beam produce eos
if end_flag.sum() == running_size:
break
# 2.1 Forward decoder step
hyps_mask = subsequent_mask(i).unsqueeze(0).repeat(
running_size, 1, 1).to(device) # (B*N, i, i)
# logp: (B*N, vocab)
logp, cache = self.st_decoder.forward_one_step(
encoder_out, encoder_mask, hyps, hyps_mask, cache)
# 2.2 First beam prune: select topk best prob at current time
top_k_logp, top_k_index = logp.topk(beam_size) # (B*N, N)
top_k_logp = mask_finished_scores(top_k_logp, end_flag)
top_k_index = mask_finished_preds(top_k_index, end_flag, self.eos)
# 2.3 Seconde beam prune: select topk score with history
scores = scores + top_k_logp # (B*N, N), broadcast add
scores = scores.view(batch_size, beam_size * beam_size) # (B, N*N)
scores, offset_k_index = scores.topk(k=beam_size) # (B, N)
scores = scores.view(-1, 1) # (B*N, 1)
# 2.4. Compute base index in top_k_index,
# regard top_k_index as (B*N*N),regard offset_k_index as (B*N),
# then find offset_k_index in top_k_index
base_k_index = paddle.arange(batch_size).view(-1, 1).repeat(
1, beam_size) # (B, N)
base_k_index = base_k_index * beam_size * beam_size
best_k_index = base_k_index.view(-1) + offset_k_index.view(
-1) # (B*N)
# 2.5 Update best hyps
best_k_pred = paddle.index_select(
top_k_index.view(-1), index=best_k_index, axis=0) # (B*N)
best_hyps_index = best_k_index // beam_size
last_best_k_hyps = paddle.index_select(
hyps, index=best_hyps_index, axis=0) # (B*N, i)
hyps = paddle.cat(
(last_best_k_hyps, best_k_pred.view(-1, 1)),
dim=1) # (B*N, i+1)
# 2.6 Update end flag
end_flag = paddle.eq(hyps[:, -1], self.eos).view(-1, 1)
# 3. Select best of best
scores = scores.view(batch_size, beam_size)
# TODO: length normalization
best_index = paddle.argmax(scores, axis=-1).long() # (B)
best_hyps_index = best_index + paddle.arange(
batch_size, dtype=paddle.long) * beam_size
best_hyps = paddle.index_select(hyps, index=best_hyps_index, axis=0)
best_hyps = best_hyps[:, 1:]
return best_hyps
# @jit.to_static
def subsampling_rate(self) -> int:
""" Export interface for c++ call, return subsampling_rate of the
model
"""
return self.encoder.embed.subsampling_rate
# @jit.to_static
def right_context(self) -> int:
""" Export interface for c++ call, return right_context of the model
"""
return self.encoder.embed.right_context
# @jit.to_static
def sos_symbol(self) -> int:
""" Export interface for c++ call, return sos symbol id of the model
"""
return self.sos
# @jit.to_static
def eos_symbol(self) -> int:
""" Export interface for c++ call, return eos symbol id of the model
"""
return self.eos
@jit.to_static
def forward_encoder_chunk(
self,
xs: paddle.Tensor,
offset: int,
required_cache_size: int,
subsampling_cache: Optional[paddle.Tensor]=None,
elayers_output_cache: Optional[List[paddle.Tensor]]=None,
conformer_cnn_cache: Optional[List[paddle.Tensor]]=None,
) -> Tuple[paddle.Tensor, paddle.Tensor, List[paddle.Tensor], List[
paddle.Tensor]]:
""" Export interface for c++ call, give input chunk xs, and return
output from time 0 to current chunk.
Args:
xs (paddle.Tensor): chunk input
subsampling_cache (Optional[paddle.Tensor]): subsampling cache
elayers_output_cache (Optional[List[paddle.Tensor]]):
transformer/conformer encoder layers output cache
conformer_cnn_cache (Optional[List[paddle.Tensor]]): conformer
cnn cache
Returns:
paddle.Tensor: output, it ranges from time 0 to current chunk.
paddle.Tensor: subsampling cache
List[paddle.Tensor]: attention cache
List[paddle.Tensor]: conformer cnn cache
"""
return self.encoder.forward_chunk(
xs, offset, required_cache_size, subsampling_cache,
elayers_output_cache, conformer_cnn_cache)
# @jit.to_static
def ctc_activation(self, xs: paddle.Tensor) -> paddle.Tensor:
""" Export interface for c++ call, apply linear transform and log
softmax before ctc
Args:
xs (paddle.Tensor): encoder output
Returns:
paddle.Tensor: activation before ctc
"""
return self.ctc.log_softmax(xs)
@jit.to_static
def forward_attention_decoder(
self,
hyps: paddle.Tensor,
hyps_lens: paddle.Tensor,
encoder_out: paddle.Tensor, ) -> paddle.Tensor:
""" Export interface for c++ call, forward decoder with multiple
hypothesis from ctc prefix beam search and one encoder output
Args:
hyps (paddle.Tensor): hyps from ctc prefix beam search, already
pad sos at the begining, (B, T)
hyps_lens (paddle.Tensor): length of each hyp in hyps, (B)
encoder_out (paddle.Tensor): corresponding encoder output, (B=1, T, D)
Returns:
paddle.Tensor: decoder output, (B, L)
"""
assert encoder_out.size(0) == 1
num_hyps = hyps.size(0)
assert hyps_lens.size(0) == num_hyps
encoder_out = encoder_out.repeat(num_hyps, 1, 1)
# (B, 1, T)
encoder_mask = paddle.ones(
[num_hyps, 1, encoder_out.size(1)], dtype=paddle.bool)
# (num_hyps, max_hyps_len, vocab_size)
decoder_out, _ = self.decoder(encoder_out, encoder_mask, hyps,
hyps_lens)
decoder_out = paddle.nn.functional.log_softmax(decoder_out, dim=-1)
return decoder_out
@paddle.no_grad()
def decode(self,
feats: paddle.Tensor,
feats_lengths: paddle.Tensor,
text_feature: Dict[str, int],
decoding_method: str,
lang_model_path: str,
beam_alpha: float,
beam_beta: float,
beam_size: int,
cutoff_prob: float,
cutoff_top_n: int,
num_processes: int,
ctc_weight: float=0.0,
decoding_chunk_size: int=-1,
num_decoding_left_chunks: int=-1,
simulate_streaming: bool=False):
"""u2 decoding.
Args:
feats (Tenosr): audio features, (B, T, D)
feats_lengths (Tenosr): (B)
text_feature (TextFeaturizer): text feature object.
decoding_method (str): decoding mode, e.g.
'fullsentence',
'simultaneous'
lang_model_path (str): lm path.
beam_alpha (float): lm weight.
beam_beta (float): length penalty.
beam_size (int): beam size for search
cutoff_prob (float): for prune.
cutoff_top_n (int): for prune.
num_processes (int):
ctc_weight (float, optional): ctc weight for attention rescoring decode mode. Defaults to 0.0.
decoding_chunk_size (int, optional): decoding chunk size. Defaults to -1.
<0: for decoding, use full chunk.
>0: for decoding, use fixed chunk size as set.
0: used for training, it's prohibited here.
num_decoding_left_chunks (int, optional):
number of left chunks for decoding. Defaults to -1.
simulate_streaming (bool, optional): simulate streaming inference. Defaults to False.
Raises:
ValueError: when not support decoding_method.
Returns:
List[List[int]]: transcripts.
"""
batch_size = feats.size(0)
if decoding_method == 'fullsentence':
hyps = self.translate(
feats,
feats_lengths,
beam_size=beam_size,
decoding_chunk_size=decoding_chunk_size,
num_decoding_left_chunks=num_decoding_left_chunks,
simulate_streaming=simulate_streaming)
hyps = [hyp.tolist() for hyp in hyps]
else:
raise ValueError(f"Not support decoding method: {decoding_method}")
res = [text_feature.defeaturize(hyp) for hyp in hyps]
return res
class U2STModel(U2STBaseModel):
def __init__(self, configs: dict):
vocab_size, encoder, decoder = U2STModel._init_from_config(configs)
if isinstance(decoder, Tuple):
st_decoder, asr_decoder, ctc = decoder
super().__init__(
vocab_size=vocab_size,
encoder=encoder,
st_decoder=st_decoder,
decoder=asr_decoder,
ctc=ctc,
**configs['model_conf'])
else:
super().__init__(
vocab_size=vocab_size,
encoder=encoder,
st_decoder=decoder,
**configs['model_conf'])
@classmethod
def _init_from_config(cls, configs: dict):
"""init sub module for model.
Args:
configs (dict): config dict.
Raises:
ValueError: raise when using not support encoder type.
Returns:
int, nn.Layer, nn.Layer, nn.Layer: vocab size, encoder, decoder, ctc
"""
if configs['cmvn_file'] is not None:
mean, istd = load_cmvn(configs['cmvn_file'],
configs['cmvn_file_type'])
global_cmvn = GlobalCMVN(
paddle.to_tensor(mean, dtype=paddle.float),
paddle.to_tensor(istd, dtype=paddle.float))
else:
global_cmvn = None
input_dim = configs['input_dim']
vocab_size = configs['output_dim']
assert input_dim != 0, input_dim
assert vocab_size != 0, vocab_size
encoder_type = configs.get('encoder', 'transformer')
logger.info(f"U2 Encoder type: {encoder_type}")
if encoder_type == 'transformer':
encoder = TransformerEncoder(
input_dim, global_cmvn=global_cmvn, **configs['encoder_conf'])
elif encoder_type == 'conformer':
encoder = ConformerEncoder(
input_dim, global_cmvn=global_cmvn, **configs['encoder_conf'])
else:
raise ValueError(f"not support encoder type:{encoder_type}")
st_decoder = TransformerDecoder(vocab_size,
encoder.output_size(),
**configs['decoder_conf'])
asr_weight = configs['model_conf']['asr_weight']
logger.info(f"ASR Joint Training Weight: {asr_weight}")
if asr_weight > 0.:
decoder = TransformerDecoder(vocab_size,
encoder.output_size(),
**configs['decoder_conf'])
# ctc decoder and ctc loss
model_conf = configs['model_conf']
ctc = CTCDecoder(
odim=vocab_size,
enc_n_units=encoder.output_size(),
blank_id=0,
dropout_rate=model_conf['ctc_dropout_rate'],
reduction=True, # sum
batch_average=True, # sum / batch_size
grad_norm_type=model_conf['ctc_grad_norm_type'])
return vocab_size, encoder, (st_decoder, decoder, ctc)
else:
return vocab_size, encoder, st_decoder
@classmethod
def from_config(cls, configs: dict):
"""init model.
Args:
configs (dict): config dict.
Raises:
ValueError: raise when using not support encoder type.
Returns:
nn.Layer: U2STModel
"""
model = cls(configs)
return model
@classmethod
def from_pretrained(cls, dataloader, config, checkpoint_path):
"""Build a DeepSpeech2Model model from a pretrained model.
Args:
dataloader (paddle.io.DataLoader): not used.
config (yacs.config.CfgNode): model configs
checkpoint_path (Path or str): the path of pretrained model checkpoint, without extension name
Returns:
DeepSpeech2Model: The model built from pretrained result.
"""
config.defrost()
config.input_dim = dataloader.collate_fn.feature_size
config.output_dim = dataloader.collate_fn.vocab_size
config.freeze()
model = cls.from_config(config)
if checkpoint_path:
infos = checkpoint.load_parameters(
model, checkpoint_path=checkpoint_path)
logger.info(f"checkpoint info: {infos}")
layer_tools.summary(model)
return model
class U2STInferModel(U2STModel):
def __init__(self, configs: dict):
super().__init__(configs)
def forward(self,
feats,
feats_lengths,
decoding_chunk_size=-1,
num_decoding_left_chunks=-1,
simulate_streaming=False):
"""export model function
Args:
feats (Tensor): [B, T, D]
feats_lengths (Tensor): [B]
Returns:
List[List[int]]: best path result
"""
return self.translate(
feats,
feats_lengths,
decoding_chunk_size=decoding_chunk_size,
num_decoding_left_chunks=num_decoding_left_chunks,
simulate_streaming=simulate_streaming)