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PaddleSpeech
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comment u2 model for easy understand

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pull/704/head
Hui Zhang 4 years ago
parent 96c64237f3
commit 259781768e
2 changed files with 31 additions and 15 deletions
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41
deepspeech/models/u2.py
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@ -12,7 +12,7 @@
# 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
Unified Streaming and Non-streaming Two-pass End-to-end Model for Speech Recognition
(https://arxiv.org/pdf/2012.05481.pdf)
"""
import sys
@ -83,7 +83,7 @@ class U2BaseModel(nn.Module):
# cnn_module_kernel=15,
# activation_type='swish',
# pos_enc_layer_type='rel_pos',
# selfattention_layer_type='rel_selfattn',
# selfattention_layer_type='rel_selfattn',
))
# decoder related
default.decoder = 'transformer'
@ -244,8 +244,8 @@ class U2BaseModel(nn.Module):
simulate_streaming (bool, optional): streaming or not. Defaults to False.
Returns:
Tuple[paddle.Tensor, paddle.Tensor]:
encoder hiddens (B, Tmax, D),
Tuple[paddle.Tensor, paddle.Tensor]:
encoder hiddens (B, Tmax, D),
encoder hiddens mask (B, 1, Tmax).
"""
# Let's assume B = batch_size
@ -399,6 +399,7 @@ class U2BaseModel(nn.Module):
assert speech.shape[0] == speech_lengths.shape[0]
assert decoding_chunk_size != 0
batch_size = speech.shape[0]
# Let's assume B = batch_size
# encoder_out: (B, maxlen, encoder_dim)
# encoder_mask: (B, 1, Tmax)
@ -410,10 +411,12 @@ class U2BaseModel(nn.Module):
# encoder_out_lens = encoder_mask.squeeze(1).sum(1)
encoder_out_lens = encoder_mask.squeeze(1).astype(paddle.int).sum(1)
ctc_probs = self.ctc.log_softmax(encoder_out) # (B, maxlen, vocab_size)
topk_prob, topk_index = ctc_probs.topk(1, axis=2) # (B, maxlen, 1)
topk_index = topk_index.view(batch_size, maxlen) # (B, maxlen)
pad_mask = make_pad_mask(encoder_out_lens) # (B, maxlen)
topk_index = topk_index.masked_fill_(pad_mask, self.eos) # (B, maxlen)
hyps = [hyp.tolist() for hyp in topk_index]
hyps = [remove_duplicates_and_blank(hyp) for hyp in hyps]
return hyps
@ -449,6 +452,7 @@ class U2BaseModel(nn.Module):
batch_size = speech.shape[0]
# For CTC prefix beam search, we only support batch_size=1
assert batch_size == 1
# Let's assume B = batch_size and N = beam_size
# 1. Encoder forward and get CTC score
encoder_out, encoder_mask = self._forward_encoder(
@ -458,7 +462,9 @@ class U2BaseModel(nn.Module):
maxlen = encoder_out.size(1)
ctc_probs = self.ctc.log_softmax(encoder_out) # (1, maxlen, vocab_size)
ctc_probs = ctc_probs.squeeze(0)
# cur_hyps: (prefix, (blank_ending_score, none_blank_ending_score))
# blank_ending_score and none_blank_ending_score in ln domain
cur_hyps = [(tuple(), (0.0, -float('inf')))]
# 2. CTC beam search step by step
for t in range(0, maxlen):
@ -498,6 +504,7 @@ class U2BaseModel(nn.Module):
key=lambda x: log_add(list(x[1])),
reverse=True)
cur_hyps = next_hyps[:beam_size]
hyps = [(y[0], log_add([y[1][0], y[1][1]])) for y in cur_hyps]
return hyps, encoder_out
@ -561,12 +568,13 @@ class U2BaseModel(nn.Module):
batch_size = speech.shape[0]
# For attention rescoring we only support batch_size=1
assert batch_size == 1
# encoder_out: (1, maxlen, encoder_dim), len(hyps) = beam_size
# len(hyps) = beam_size, encoder_out: (1, maxlen, encoder_dim)
hyps, encoder_out = self._ctc_prefix_beam_search(
speech, speech_lengths, beam_size, decoding_chunk_size,
num_decoding_left_chunks, simulate_streaming)
assert len(hyps) == beam_size
hyps_pad = pad_sequence([
paddle.to_tensor(hyp[0], place=device, dtype=paddle.long)
for hyp in hyps
@ -576,23 +584,28 @@ class U2BaseModel(nn.Module):
dtype=paddle.long) # (beam_size,)
hyps_pad, _ = add_sos_eos(hyps_pad, self.sos, self.eos, self.ignore_id)
hyps_lens = hyps_lens + 1 # Add <sos> at begining
encoder_out = encoder_out.repeat(beam_size, 1, 1)
encoder_mask = paddle.ones(
(beam_size, 1, encoder_out.size(1)), dtype=paddle.bool)
decoder_out, _ = self.decoder(
encoder_out, encoder_mask, hyps_pad,
hyps_lens) # (beam_size, max_hyps_len, vocab_size)
# ctc score in ln domain
decoder_out = paddle.nn.functional.log_softmax(decoder_out, axis=-1)
decoder_out = decoder_out.numpy()
# Only use decoder score for rescoring
best_score = -float('inf')
best_index = 0
# hyps is List[(Text=List[int], Score=float)], len(hyps)=beam_size
for i, hyp in enumerate(hyps):
score = 0.0
for j, w in enumerate(hyp[0]):
score += decoder_out[i][j][w]
# last decoder output token is `eos`, for laste decoder input token.
score += decoder_out[i][len(hyp[0])][self.eos]
# add ctc score
# add ctc score (which in ln domain)
score += hyp[1] * ctc_weight
if score > best_score:
best_score = score
@ -719,8 +732,8 @@ class U2BaseModel(nn.Module):
feats (Tenosr): audio features, (B, T, D)
feats_lengths (Tenosr): (B)
text_feature (TextFeaturizer): text feature object.
decoding_method (str): decoding mode, e.g.
'attention', 'ctc_greedy_search',
decoding_method (str): decoding mode, e.g.
'attention', 'ctc_greedy_search',
'ctc_prefix_beam_search', 'attention_rescoring'
lang_model_path (str): lm path.
beam_alpha (float): lm weight.
@ -728,19 +741,19 @@ class U2BaseModel(nn.Module):
beam_size (int): beam size for search
cutoff_prob (float): for prune.
cutoff_top_n (int): for prune.
num_processes (int):
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):
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.
"""
@ -821,7 +834,7 @@ class U2Model(U2BaseModel):
ValueError: raise when using not support encoder type.
Returns:
int, nn.Layer, nn.Layer, nn.Layer: vocab size, encoder, decoder, ctc
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'],

5
deepspeech/modules/encoder.py
Unescape View File

@ -219,11 +219,14 @@ class BaseEncoder(nn.Layer):
xs, pos_emb, _ = self.embed(
xs, tmp_masks, offset=offset) #xs=(B, T, D), pos_emb=(B=1, T, D)
if subsampling_cache is not None:
cache_size = subsampling_cache.size(1) #T
xs = paddle.cat((subsampling_cache, xs), dim=1)
else:
cache_size = 0
# only used when using `RelPositionMultiHeadedAttention`
pos_emb = self.embed.position_encoding(
offset=offset - cache_size, size=xs.size(1))
@ -237,7 +240,7 @@ class BaseEncoder(nn.Layer):
# Real mask for transformer/conformer layers
masks = paddle.ones([1, xs.size(1)], dtype=paddle.bool)
masks = masks.unsqueeze(1) #[B=1, C=1, T]
masks = masks.unsqueeze(1) #[B=1, L'=1, T]
r_elayers_output_cache = []
r_conformer_cnn_cache = []
for i, layer in enumerate(self.encoders):

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