Merge branch 'u2++_decoder' into u2pp_export

paddlespeech/audio/utils/tensor_utils.py

@@ -31,7 +31,6 @@ def has_tensor(val):
                 return True
     elif isinstance(val, dict):
         for k, v in val.items():
-            print(k)
             if has_tensor(v):
                 return True
     else:
@@ -143,14 +142,15 @@ def add_sos_eos(ys_pad: paddle.Tensor, sos: int, eos: int,
                 [ 7,  8,  9, 11, -1, -1]])
     """
     # TODO(Hui Zhang): using comment code,
-    #_sos = paddle.to_tensor(
+    # _sos = paddle.to_tensor(
-    #    [sos], dtype=paddle.long, stop_gradient=True, place=ys_pad.place)
+    #    [sos], dtype=ys_pad.dtype, stop_gradient=True, place=ys_pad.place)
-    #_eos = paddle.to_tensor(
+    # _eos = paddle.to_tensor(
-    #    [eos], dtype=paddle.long, stop_gradient=True, place=ys_pad.place)
+    #    [eos], dtype=ys_pad.dtype, stop_gradient=True, place=ys_pad.place)
-    #ys = [y[y != ignore_id] for y in ys_pad]  # parse padded ys
+    # ys = [y[y != ignore_id] for y in ys_pad]  # parse padded ys
-    #ys_in = [paddle.cat([_sos, y], dim=0) for y in ys]
+    # ys_in = [paddle.concat([_sos, y], axis=0) for y in ys]
-    #ys_out = [paddle.cat([y, _eos], dim=0) for y in ys]
+    # ys_out = [paddle.concat([y, _eos], axis=0) for y in ys]
-    #return pad_sequence(ys_in, padding_value=eos), pad_sequence(ys_out, padding_value=ignore_id)
+    # return pad_sequence(ys_in, padding_value=eos).transpose([1,0]), pad_sequence(ys_out, padding_value=ignore_id).transpose([1,0])
+
     B = ys_pad.shape[0]
     _sos = paddle.ones([B, 1], dtype=ys_pad.dtype) * sos
     _eos = paddle.ones([B, 1], dtype=ys_pad.dtype) * eos
@@ -190,3 +190,105 @@ def th_accuracy(pad_outputs: paddle.Tensor,
     # denominator = paddle.sum(mask)
     denominator = paddle.sum(mask.type_as(pad_targets))
     return float(numerator) / float(denominator)
+
+
+def reverse_pad_list(ys_pad: paddle.Tensor,
+                     ys_lens: paddle.Tensor,
+                     pad_value: float=-1.0) -> paddle.Tensor:
+    """Reverse padding for the list of tensors.
+    Args:
+        ys_pad (tensor): The padded tensor (B, Tokenmax).
+        ys_lens (tensor): The lens of token seqs (B)
+        pad_value (int): Value for padding.
+    Returns:
+        Tensor: Padded tensor (B, Tokenmax).
+    Examples:
+        >>> x
+        tensor([[1, 2, 3, 4], [5, 6, 7, 0], [8, 9, 0, 0]])
+        >>> pad_list(x, 0)
+        tensor([[4, 3, 2, 1],
+                [7, 6, 5, 0],
+                [9, 8, 0, 0]])
+    """
+    r_ys_pad = pad_sequence([(paddle.flip(y.int()[:i], [0]))
+                             for y, i in zip(ys_pad, ys_lens)], True, pad_value)
+    return r_ys_pad
+
+
+def st_reverse_pad_list(ys_pad: paddle.Tensor,
+                        ys_lens: paddle.Tensor,
+                        sos: float,
+                        eos: float) -> paddle.Tensor:
+    """Reverse padding for the list of tensors.
+    Args:
+        ys_pad (tensor): The padded tensor (B, Tokenmax).
+        ys_lens (tensor): The lens of token seqs (B)
+    Returns:
+        Tensor: Padded tensor (B, Tokenmax).
+    Examples:
+        >>> x
+        tensor([[1, 2, 3, 4], [5, 6, 7, 0], [8, 9, 0, 0]])
+        >>> pad_list(x, 0)
+        tensor([[4, 3, 2, 1],
+                [7, 6, 5, 0],
+                [9, 8, 0, 0]])
+    """
+    # Equal to:
+    #   >>> r_hyps = reverse_pad_list(r_hyps, r_hyps_lens, float(self.ignore_id))
+    #   >>> r_hyps, _ = add_sos_eos(r_hyps, self.sos, self.eos, self.ignore_id)
+    B = ys_pad.shape[0]
+    _sos = paddle.ones([B, 1], dtype=ys_pad.dtype) * sos
+    max_len = paddle.max(ys_lens)
+    index_range = paddle.arange(0, max_len, 1)
+    seq_len_expand = ys_lens.unsqueeze(1)
+    seq_mask = seq_len_expand > index_range  # (beam, max_len)
+
+    index = (seq_len_expand - 1) - index_range  # (beam, max_len)
+    #   >>> index
+    #   >>> tensor([[ 2,  1,  0],
+    #   >>>         [ 2,  1,  0],
+    #   >>>         [ 0, -1, -2]])
+    index = index * seq_mask
+
+    #   >>> index
+    #   >>> tensor([[2, 1, 0],
+    #   >>>         [2, 1, 0],
+    #   >>>         [0, 0, 0]])
+    def paddle_gather(x, dim, index):
+        index_shape = index.shape
+        index_flatten = index.flatten()
+        if dim < 0:
+            dim = len(x.shape) + dim
+        nd_index = []
+        for k in range(len(x.shape)):
+            if k == dim:
+                nd_index.append(index_flatten)
+            else:
+                reshape_shape = [1] * len(x.shape)
+                reshape_shape[k] = x.shape[k]
+                x_arange = paddle.arange(x.shape[k], dtype=index.dtype)
+                x_arange = x_arange.reshape(reshape_shape)
+                dim_index = paddle.expand(x_arange, index_shape).flatten()
+                nd_index.append(dim_index)
+        ind2 = paddle.transpose(paddle.stack(nd_index), [1, 0]).astype("int64")
+        paddle_out = paddle.gather_nd(x, ind2).reshape(index_shape)
+        return paddle_out
+
+    r_hyps = paddle_gather(ys_pad, 1, index)
+    #   >>> r_hyps
+    #   >>> tensor([[3, 2, 1],
+    #   >>>         [4, 8, 9],
+    #   >>>         [2, 2, 2]])
+    r_hyps = paddle.where(seq_mask, r_hyps, eos)
+    #   >>> r_hyps
+    #   >>> tensor([[3, 2, 1],
+    #   >>>         [4, 8, 9],
+    #   >>>         [2, eos, eos]])
+
+    r_hyps = paddle.cat([_sos, r_hyps], dim=1)
+    # r_hyps = paddle.concat([hyps[:, 0:1], r_hyps], axis=1)
+    #   >>> r_hyps
+    #   >>> tensor([[sos, 3, 2, 1],
+    #   >>>         [sos, 4, 8, 9],
+    #   >>>         [sos, 2, eos, eos]])
+    return r_hyps

paddlespeech/s2t/exps/u2/bin/test_wav.py

@@ -40,7 +40,7 @@ class U2Infer():
         self.preprocess_conf = config.preprocess_config
         self.preprocess_args = {"train": False}
         self.preprocessing = Transformation(self.preprocess_conf)
-
+        self.reverse_weight = getattr(config.model_conf, 'reverse_weight', 0.0)
         self.text_feature = TextFeaturizer(
             unit_type=config.unit_type,
             vocab=config.vocab_filepath,
@@ -89,7 +89,8 @@ class U2Infer():
                 ctc_weight=decode_config.ctc_weight,
                 decoding_chunk_size=decode_config.decoding_chunk_size,
                 num_decoding_left_chunks=decode_config.num_decoding_left_chunks,
-                simulate_streaming=decode_config.simulate_streaming)
+                simulate_streaming=decode_config.simulate_streaming,
+                reverse_weight=self.reverse_weight)
             rsl = result_transcripts[0][0]
             utt = Path(self.audio_file).name
             logger.info(f"hyp: {utt} {result_transcripts[0][0]}")

paddlespeech/s2t/exps/u2/model.py

@@ -253,7 +253,6 @@ class U2Trainer(Trainer):
                 model_conf.output_dim = self.test_loader.vocab_size
 
         model = U2Model.from_config(model_conf)
-
         if self.parallel:
             model = paddle.DataParallel(model)
 
@@ -317,6 +316,7 @@ class U2Tester(U2Trainer):
             vocab=self.config.vocab_filepath,
             spm_model_prefix=self.config.spm_model_prefix)
         self.vocab_list = self.text_feature.vocab_list
+        self.reverse_weight = getattr(config.model_conf, 'reverse_weight', 0.0)
 
     def id2token(self, texts, texts_len, text_feature):
         """ ord() id to chr() chr """
@@ -341,6 +341,7 @@ class U2Tester(U2Trainer):
 
         start_time = time.time()
         target_transcripts = self.id2token(texts, texts_len, self.text_feature)
+
         result_transcripts, result_tokenids = self.model.decode(
             audio,
             audio_len,
@@ -350,7 +351,8 @@ class U2Tester(U2Trainer):
             ctc_weight=decode_config.ctc_weight,
             decoding_chunk_size=decode_config.decoding_chunk_size,
             num_decoding_left_chunks=decode_config.num_decoding_left_chunks,
-            simulate_streaming=decode_config.simulate_streaming)
+            simulate_streaming=decode_config.simulate_streaming,
+            reverse_weight=self.reverse_weight)
         decode_time = time.time() - start_time
 
         for utt, target, result, rec_tids in zip(

paddlespeech/s2t/models/u2/u2.py

@@ -31,6 +31,8 @@ from paddle import nn
 
 from paddlespeech.audio.utils.tensor_utils import add_sos_eos
 from paddlespeech.audio.utils.tensor_utils import pad_sequence
+from paddlespeech.audio.utils.tensor_utils import reverse_pad_list
+from paddlespeech.audio.utils.tensor_utils import st_reverse_pad_list
 from paddlespeech.audio.utils.tensor_utils import th_accuracy
 from paddlespeech.s2t.decoders.scorers.ctc import CTCPrefixScorer
 from paddlespeech.s2t.frontend.utility import IGNORE_ID
@@ -38,6 +40,7 @@ from paddlespeech.s2t.frontend.utility import load_cmvn
 from paddlespeech.s2t.models.asr_interface import ASRInterface
 from paddlespeech.s2t.modules.cmvn import GlobalCMVN
 from paddlespeech.s2t.modules.ctc import CTCDecoderBase
+from paddlespeech.s2t.modules.decoder import BiTransformerDecoder
 from paddlespeech.s2t.modules.decoder import TransformerDecoder
 from paddlespeech.s2t.modules.encoder import ConformerEncoder
 from paddlespeech.s2t.modules.encoder import TransformerEncoder
@@ -69,6 +72,7 @@ class U2BaseModel(ASRInterface, nn.Layer):
                  ctc: CTCDecoderBase,
                  ctc_weight: float=0.5,
                  ignore_id: int=IGNORE_ID,
+                 reverse_weight: float=0.0,
                  lsm_weight: float=0.0,
                  length_normalized_loss: bool=False,
                  **kwargs):
@@ -82,6 +86,7 @@ class U2BaseModel(ASRInterface, nn.Layer):
         self.vocab_size = vocab_size
         self.ignore_id = ignore_id
         self.ctc_weight = ctc_weight
+        self.reverse_weight = reverse_weight
 
         self.encoder = encoder
         self.decoder = decoder
@@ -171,12 +176,21 @@ class U2BaseModel(ASRInterface, nn.Layer):
                                             self.ignore_id)
         ys_in_lens = ys_pad_lens + 1
 
+        r_ys_pad = reverse_pad_list(ys_pad, ys_pad_lens, float(self.ignore_id))
+        r_ys_in_pad, r_ys_out_pad = add_sos_eos(r_ys_pad, self.sos, self.eos,
+                                                self.ignore_id)
         # 1. Forward decoder
-        decoder_out, _ = self.decoder(encoder_out, encoder_mask, ys_in_pad,
+        decoder_out, r_decoder_out, _ = self.decoder(
-                                      ys_in_lens)
+            encoder_out, encoder_mask, ys_in_pad, ys_in_lens, r_ys_in_pad,
+            self.reverse_weight)
 
         # 2. Compute attention loss
         loss_att = self.criterion_att(decoder_out, ys_out_pad)
+        r_loss_att = paddle.to_tensor(0.0)
+        if self.reverse_weight > 0.0:
+            r_loss_att = self.criterion_att(r_decoder_out, r_ys_out_pad)
+        loss_att = loss_att * (1 - self.reverse_weight
+                               ) + r_loss_att * self.reverse_weight
         acc_att = th_accuracy(
             decoder_out.view(-1, self.vocab_size),
             ys_out_pad,
@@ -359,6 +373,7 @@ class U2BaseModel(ASRInterface, nn.Layer):
         # Let's assume B = batch_size
         # encoder_out: (B, maxlen, encoder_dim)
         # encoder_mask: (B, 1, Tmax)
+
         encoder_out, encoder_mask = self._forward_encoder(
             speech, speech_lengths, decoding_chunk_size,
             num_decoding_left_chunks, simulate_streaming)
@@ -500,7 +515,8 @@ class U2BaseModel(ASRInterface, nn.Layer):
             decoding_chunk_size: int=-1,
             num_decoding_left_chunks: int=-1,
             ctc_weight: float=0.0,
-            simulate_streaming: bool=False, ) -> List[int]:
+            simulate_streaming: bool=False,
+            reverse_weight: float=0.0, ) -> List[int]:
         """ Apply attention rescoring decoding, CTC prefix beam search
             is applied first to get nbest, then we resoring the nbest on
             attention decoder with corresponding encoder out
@@ -520,6 +536,9 @@ class U2BaseModel(ASRInterface, nn.Layer):
         """
         assert speech.shape[0] == speech_lengths.shape[0]
         assert decoding_chunk_size != 0
+        if reverse_weight > 0.0:
+            # decoder should be a bitransformer decoder if reverse_weight > 0.0
+            assert hasattr(self.decoder, 'right_decoder')
         device = speech.place
         batch_size = speech.shape[0]
         # For attention rescoring we only support batch_size=1
@@ -541,6 +560,7 @@ class U2BaseModel(ASRInterface, nn.Layer):
                 hyp_content, place=device, dtype=paddle.long)
             hyp_list.append(hyp_content)
         hyps_pad = pad_sequence(hyp_list, True, self.ignore_id)
+        ori_hyps_pad = hyps_pad
         hyps_lens = paddle.to_tensor(
             [len(hyp[0]) for hyp in hyps], place=device,
             dtype=paddle.long)  # (beam_size,)
@@ -550,8 +570,14 @@ class U2BaseModel(ASRInterface, nn.Layer):
         hyps_lens = hyps_lens + 1  # Add <sos> at begining
 
         # ctc score in ln domain
-        decoder_out = self.forward_attention_decoder(hyps_pad, hyps_lens,
+        # (beam_size, max_hyps_len, vocab_size)
-                                                     encoder_out)
+        decoder_out, r_decoder_out = self.forward_attention_decoder(hyps_pad, hyps_lens,
+                                                     encoder_out,reverse_weight )
+
+        # r_decoder_out will be 0.0, if reverse_weight is 0.0 or decoder is a
+        # conventional transformer decoder.
+        r_decoder_out = paddle.nn.functional.log_softmax(r_decoder_out, axis=-1)
+        r_decoder_out = r_decoder_out.numpy()
 
         # Only use decoder score for rescoring
         best_score = -float('inf')
@@ -563,10 +589,18 @@ class U2BaseModel(ASRInterface, nn.Layer):
                 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]
+
             logger.debug(
                 f"hyp {i} len {len(hyp[0])} l2r rescore_score: {score} ctc_score: {hyp[1]}"
             )
 
+            if reverse_weight > 0:
+                r_score = 0.0
+                for j, w in enumerate(hyp[0]):
+                    r_score += r_decoder_out[i][len(hyp[0]) - j - 1][w]
+                r_score += r_decoder_out[i][len(hyp[0])][self.eos]
+                score = score * (1 - reverse_weight) + r_score * reverse_weight
+
             # add ctc score (which in ln domain)
             score += hyp[1] * ctc_weight
             if score > best_score:
@@ -601,6 +635,17 @@ class U2BaseModel(ASRInterface, nn.Layer):
         """
         return self.eos
 
+    @jit.to_static(property=True)
+    def is_bidirectional_decoder(self) -> bool:
+        """
+        Returns:
+            paddle.Tensor: decoder output
+        """
+        if hasattr(self.decoder, 'right_decoder'):
+            return True
+        else:
+            return False
+
     # @jit.to_static
     def forward_encoder_chunk(
             self,
@@ -660,7 +705,8 @@ class U2BaseModel(ASRInterface, nn.Layer):
             self,
             hyps: paddle.Tensor,
             hyps_lens: paddle.Tensor,
-            encoder_out: paddle.Tensor, ) -> paddle.Tensor:
+            encoder_out: paddle.Tensor,
+            reverse_weight: float=0.0, ) -> paddle.Tensor:
         """ Export interface for c++ call, forward decoder with multiple
             hypothesis from ctc prefix beam search and one encoder output
         Args:
@@ -678,11 +724,22 @@ class U2BaseModel(ASRInterface, nn.Layer):
         # (B, 1, T)
         encoder_mask = paddle.ones(
             [num_hyps, 1, encoder_out.shape[1]], dtype=paddle.bool)
+
+        # input for right to left decoder
+        # this hyps_lens has count <sos> token, we need minus it.
+        r_hyps_lens = hyps_lens - 1
+        # this hyps has included <sos> token, so it should be
+        # convert the original hyps.
+        r_hyps = hyps[:, 1:]
         # (num_hyps, max_hyps_len, vocab_size)
-        decoder_out, _ = self.decoder(encoder_out, encoder_mask, hyps,
+
-                                      hyps_lens)
+        r_hyps = st_reverse_pad_list(r_hyps, r_hyps_lens, self.sos, self.eos)
+
+        decoder_out, r_decoder_out, _ = self.decoder(
+            encoder_out, encoder_mask, hyps, hyps_lens, r_hyps, reverse_weight)
         decoder_out = paddle.nn.functional.log_softmax(decoder_out, axis=-1)
-        return decoder_out
+        r_decoder_out = paddle.nn.functional.log_softmax(r_decoder_out, axis=-1)
+        return decoder_out, r_decoder_out
 
     @paddle.no_grad()
     def decode(self,
@@ -694,7 +751,8 @@ class U2BaseModel(ASRInterface, nn.Layer):
                ctc_weight: float=0.0,
                decoding_chunk_size: int=-1,
                num_decoding_left_chunks: int=-1,
-               simulate_streaming: bool=False):
+               simulate_streaming: bool=False,
+               reverse_weight: float=0.0):
         """u2 decoding.
 
         Args:
@@ -766,7 +824,8 @@ class U2BaseModel(ASRInterface, nn.Layer):
                 decoding_chunk_size=decoding_chunk_size,
                 num_decoding_left_chunks=num_decoding_left_chunks,
                 ctc_weight=ctc_weight,
-                simulate_streaming=simulate_streaming)
+                simulate_streaming=simulate_streaming,
+                reverse_weight=reverse_weight)
             hyps = [hyp]
         else:
             raise ValueError(f"Not support decoding method: {decoding_method}")
@@ -803,7 +862,6 @@ class U2Model(U2DecodeModel):
         with DefaultInitializerContext(init_type):
             vocab_size, encoder, decoder, ctc = U2Model._init_from_config(
                 configs)
-
         super().__init__(
             vocab_size=vocab_size,
             encoder=encoder,
@@ -853,10 +911,20 @@ class U2Model(U2DecodeModel):
             raise ValueError(f"not support encoder type:{encoder_type}")
 
         # decoder
+        decoder_type = configs.get('decoder', 'transformer')
+        logger.debug(f"U2 Decoder type: {decoder_type}")
+        if decoder_type == 'transformer':
             decoder = TransformerDecoder(vocab_size,
                                          encoder.output_size(),
                                          **configs['decoder_conf'])
-
+        elif decoder_type == 'bitransformer':
+            assert 0.0 < configs['model_conf']['reverse_weight'] < 1.0
+            assert configs['decoder_conf']['r_num_blocks'] > 0
+            decoder = BiTransformerDecoder(vocab_size,
+                                           encoder.output_size(),
+                                           **configs['decoder_conf'])
+        else:
+            raise ValueError(f"not support decoder type:{decoder_type}")
         # ctc decoder and ctc loss
         model_conf = configs.get('model_conf', dict())
         dropout_rate = model_conf.get('ctc_dropout_rate', 0.0)

paddlespeech/s2t/modules/decoder.py

@@ -35,7 +35,6 @@ from paddlespeech.s2t.modules.mask import make_xs_mask
 from paddlespeech.s2t.modules.mask import subsequent_mask
 from paddlespeech.s2t.modules.positionwise_feed_forward import PositionwiseFeedForward
 from paddlespeech.s2t.utils.log import Log
-
 logger = Log(__name__).getlog()
 
 __all__ = ["TransformerDecoder"]
@@ -116,13 +115,19 @@ class TransformerDecoder(BatchScorerInterface, nn.Layer):
             memory: paddle.Tensor,
             memory_mask: paddle.Tensor,
             ys_in_pad: paddle.Tensor,
-            ys_in_lens: paddle.Tensor, ) -> Tuple[paddle.Tensor, paddle.Tensor]:
+            ys_in_lens: paddle.Tensor,
+            r_ys_in_pad: paddle.Tensor=paddle.empty([0]),
+            reverse_weight: float=0.0) -> Tuple[paddle.Tensor, paddle.Tensor]:
         """Forward decoder.
         Args:
             memory: encoded memory, float32  (batch, maxlen_in, feat)
             memory_mask: encoder memory mask, (batch, 1, maxlen_in)
             ys_in_pad: padded input token ids, int64 (batch, maxlen_out)
             ys_in_lens: input lengths of this batch (batch)
+            r_ys_in_pad: not used in transformer decoder, in order to unify api
+                with bidirectional decoder
+            reverse_weight: not used in transformer decoder, in order to unify
+                api with bidirectional decode
         Returns:
             (tuple): tuple containing:
                 x: decoded token score before softmax (batch, maxlen_out, vocab_size)
@@ -151,7 +156,7 @@ class TransformerDecoder(BatchScorerInterface, nn.Layer):
         # TODO(Hui Zhang): reduce_sum not support bool type
         # olens = tgt_mask.sum(1)
         olens = tgt_mask.astype(paddle.int).sum(1)
-        return x, olens
+        return x, paddle.to_tensor(0.0), olens
 
     def forward_one_step(
             self,
@@ -251,3 +256,119 @@ class TransformerDecoder(BatchScorerInterface, nn.Layer):
         state_list = [[states[i][b] for i in range(n_layers)]
                       for b in range(n_batch)]
         return logp, state_list
+
+
+class BiTransformerDecoder(BatchScorerInterface, nn.Layer):
+    """Base class of Transfomer decoder module.
+    Args:
+        vocab_size: output dim
+        encoder_output_size: dimension of attention
+        attention_heads: the number of heads of multi head attention
+        linear_units: the hidden units number of position-wise feedforward
+        num_blocks: the number of decoder blocks
+        r_num_blocks: the number of right to left decoder blocks
+        dropout_rate: dropout rate
+        self_attention_dropout_rate: dropout rate for attention
+        input_layer: input layer type
+        use_output_layer: whether to use output layer
+        pos_enc_class: PositionalEncoding or ScaledPositionalEncoding
+        normalize_before:
+            True: use layer_norm before each sub-block of a layer.
+            False: use layer_norm after each sub-block of a layer.
+        concat_after: whether to concat attention layer's input and output
+            True: x -> x + linear(concat(x, att(x)))
+            False: x -> x + att(x)
+    """
+
+    def __init__(self,
+                 vocab_size: int,
+                 encoder_output_size: int,
+                 attention_heads: int=4,
+                 linear_units: int=2048,
+                 num_blocks: int=6,
+                 r_num_blocks: int=0,
+                 dropout_rate: float=0.1,
+                 positional_dropout_rate: float=0.1,
+                 self_attention_dropout_rate: float=0.0,
+                 src_attention_dropout_rate: float=0.0,
+                 input_layer: str="embed",
+                 use_output_layer: bool=True,
+                 normalize_before: bool=True,
+                 concat_after: bool=False,
+                 max_len: int=5000):
+
+        assert check_argument_types()
+
+        nn.Layer.__init__(self)
+        self.left_decoder = TransformerDecoder(
+            vocab_size, encoder_output_size, attention_heads, linear_units,
+            num_blocks, dropout_rate, positional_dropout_rate,
+            self_attention_dropout_rate, src_attention_dropout_rate,
+            input_layer, use_output_layer, normalize_before, concat_after,
+            max_len)
+
+        self.right_decoder = TransformerDecoder(
+            vocab_size, encoder_output_size, attention_heads, linear_units,
+            r_num_blocks, dropout_rate, positional_dropout_rate,
+            self_attention_dropout_rate, src_attention_dropout_rate,
+            input_layer, use_output_layer, normalize_before, concat_after,
+            max_len)
+
+    def forward(
+            self,
+            memory: paddle.Tensor,
+            memory_mask: paddle.Tensor,
+            ys_in_pad: paddle.Tensor,
+            ys_in_lens: paddle.Tensor,
+            r_ys_in_pad: paddle.Tensor,
+            reverse_weight: float=0.0,
+    ) -> Tuple[paddle.Tensor, paddle.Tensor, paddle.Tensor]:
+        """Forward decoder.
+        Args:
+            memory: encoded memory, float32  (batch, maxlen_in, feat)
+            memory_mask: encoder memory mask, (batch, 1, maxlen_in)
+            ys_in_pad: padded input token ids, int64 (batch, maxlen_out)
+            ys_in_lens: input lengths of this batch (batch)
+            r_ys_in_pad: padded input token ids, int64 (batch, maxlen_out),
+                used for right to left decoder
+            reverse_weight: used for right to left decoder
+        Returns:
+            (tuple): tuple containing:
+                x: decoded token score before softmax (batch, maxlen_out,
+                    vocab_size) if use_output_layer is True,
+                r_x: x: decoded token score (right to left decoder)
+                    before softmax (batch, maxlen_out, vocab_size)
+                    if use_output_layer is True,
+                olens: (batch, )
+        """
+        l_x, _, olens = self.left_decoder(memory, memory_mask, ys_in_pad,
+                                          ys_in_lens)
+        r_x = paddle.to_tensor(0.0)
+        if reverse_weight > 0.0:
+            r_x, _, olens = self.right_decoder(memory, memory_mask, r_ys_in_pad,
+                                               ys_in_lens)
+        return l_x, r_x, olens
+
+    def forward_one_step(
+            self,
+            memory: paddle.Tensor,
+            memory_mask: paddle.Tensor,
+            tgt: paddle.Tensor,
+            tgt_mask: paddle.Tensor,
+            cache: Optional[List[paddle.Tensor]]=None,
+    ) -> Tuple[paddle.Tensor, List[paddle.Tensor]]:
+        """Forward one step.
+            This is only used for decoding.
+        Args:
+            memory: encoded memory, float32  (batch, maxlen_in, feat)
+            memory_mask: encoded memory mask, (batch, 1, maxlen_in)
+            tgt: input token ids, int64 (batch, maxlen_out)
+            tgt_mask: input token mask,  (batch, maxlen_out, maxlen_out)
+                      dtype=paddle.bool
+            cache: cached output list of (batch, max_time_out-1, size)
+        Returns:
+            y, cache: NN output value and cache per `self.decoders`.
+            y.shape` is (batch, maxlen_out, token)
+        """
+        return self.left_decoder.forward_one_step(memory, memory_mask, tgt,
+                                                  tgt_mask, cache)

paddlespeech/server/engine/asr/online/python/asr_engine.py

@@ -612,7 +612,8 @@ class PaddleASRConnectionHanddler:
         encoder_out = self.encoder_out.repeat(beam_size, 1, 1)
         encoder_mask = paddle.ones(
             (beam_size, 1, encoder_out.shape[1]), dtype=paddle.bool)
-        decoder_out, _ = self.model.decoder(
+
+        decoder_out, _, _ = self.model.decoder(
             encoder_out, encoder_mask, hyps_pad,
             hyps_lens)  # (beam_size, max_hyps_len, vocab_size)
         # ctc score in ln domain