export feasture size

add trainer and utils
add setup model and dataloader
update travis using Bionic dist

.travis.yml

@@ -1,7 +1,7 @@
 language: cpp
 cache: ccache
 sudo: required
-dist: xenial 
+dist: Bionic 
 services:
   - docker
 os:

data_utils/data.py

@@ -188,8 +188,6 @@ class DataGenerator():
                 max_duration=self._max_duration,
                 min_duration=self._min_duration)
 
-
-                
             # sort (by duration) or batch-wise shuffle the manifest
             if self._epoch == 0 and sortagrad:
                 manifest.sort(key=lambda x: x["duration"])
@@ -365,7 +363,7 @@ class DataGenerator():
         """
         manifest.sort(key=lambda x: x["duration"])
         shift_len = self._rng.randint(0, batch_size - 1)
-        batch_manifest = list(zip(* [iter(manifest[shift_len:])] * batch_size))
+        batch_manifest = list(zip(*[iter(manifest[shift_len:])] * batch_size))
         self._rng.shuffle(batch_manifest)
         batch_manifest = [item for batch in batch_manifest for item in batch]
         if not clipped:

data_utils/dataset.py

@@ -211,7 +211,7 @@ class DeepSpeech2DistributedBatchSampler(DistributedBatchSampler):
         rng = np.random.RandomState(self.epoch)
         manifest.sort(key=lambda x: x["duration"])
         shift_len = rng.randint(0, batch_size - 1)
-        batch_manifest = list(zip(* [iter(manifest[shift_len:])] * batch_size))
+        batch_manifest = list(zip(*[iter(manifest[shift_len:])] * batch_size))
         rng.shuffle(batch_manifest)
         batch_manifest = [item for batch in batch_manifest for item in batch]
         if not clipped:
@@ -347,7 +347,7 @@ class DeepSpeech2BatchSampler(BatchSampler):
         rng = np.random.RandomState(self.epoch)
         manifest.sort(key=lambda x: x["duration"])
         shift_len = rng.randint(0, batch_size - 1)
-        batch_manifest = list(zip(* [iter(manifest[shift_len:])] * batch_size))
+        batch_manifest = list(zip(*[iter(manifest[shift_len:])] * batch_size))
         rng.shuffle(batch_manifest)
         batch_manifest = [item for batch in batch_manifest for item in batch]
         if not clipped:

data_utils/featurizer/audio_featurizer.py

@@ -63,6 +63,7 @@ class AudioFeaturizer(object):
         self._target_sample_rate = target_sample_rate
         self._use_dB_normalization = use_dB_normalization
         self._target_dB = target_dB
+        self._fft_point = None
 
     def featurize(self,
                   audio_segment,
@@ -98,6 +99,19 @@ class AudioFeaturizer(object):
         return self._compute_specgram(audio_segment.samples,
                                       audio_segment.sample_rate)
 
+    @property
+    def feature_size(self):
+        """audio feature size"""
+        if self._specgram_type == 'linear':
+            fft_point = self._window_ms if self._fft_point is None else self._fft_point
+            return fft_point * (self._target_sample_rate / 1000) / 2 + 1
+        elif self._specgram_type == 'mfcc':
+            # mfcc,delta, delta-delta
+            return 13 * 3
+        else:
+            raise ValueError("Unknown specgram_type %s. "
+                             "Supported values: linear." % self._specgram_type)
+
     def _compute_specgram(self, samples, sample_rate):
         """Extract various audio features."""
         if self._specgram_type == 'linear':
@@ -150,7 +164,8 @@ class AudioFeaturizer(object):
             windows[:, 1] == samples[stride_size:(stride_size + window_size)])
         # window weighting, squared Fast Fourier Transform (fft), scaling
         weighting = np.hanning(window_size)[:, None]
-        fft = np.fft.rfft(windows * weighting, axis=0)
+        # https://numpy.org/doc/stable/reference/generated/numpy.fft.rfft.html
+        fft = np.fft.rfft(windows * weighting, n=None, axis=0)
         fft = np.absolute(fft)
         fft = fft**2
         scale = np.sum(weighting**2) * sample_rate

data_utils/featurizer/speech_featurizer.py

@@ -106,3 +106,12 @@ class SpeechFeaturizer(object):
         :rtype: list
         """
         return self._text_featurizer.vocab_list
+
+    @property
+    def feature_size(self):
+        """Return the audio feature size.
+
+        :return: audio feature size.
+        :rtype: int
+        """
+        return self._audio_featurizer.feature_size

infer.py

@@ -16,13 +16,12 @@
 import sys
 import argparse
 import functools
-import paddle.fluid as fluid
+from model_utils.model_check import check_cuda, check_version
+from utils.utility import add_arguments, print_arguments
+from utils.error_rate import wer, cer
 from data_utils.data import DataGenerator
 from data_utils.dataset import create_dataloader
 from model_utils.model import DeepSpeech2Model
-from model_utils.model_check import check_cuda, check_version
-from utils.error_rate import wer, cer
-from utils.utility import add_arguments, print_arguments
 
 parser = argparse.ArgumentParser(description=__doc__)
 add_arg = functools.partial(add_arguments, argparser=parser)
@@ -132,7 +131,7 @@ def infer():
         dict_size=batch_reader.dataset.vocab_size,
         num_conv_layers=args.num_conv_layers,
         num_rnn_layers=args.num_rnn_layers,
-        #rnn_size=1024,
+        rnn_size=args.rnn_layer_size,
         use_gru=args.use_gru,
         share_rnn_weights=args.share_rnn_weights,
     )

model_utils/model.py

@@ -24,179 +24,177 @@ import collections
 import multiprocessing
 import numpy as np
 from distutils.dir_util import mkpath
+
 import paddle.fluid as fluid
-from paddle.io import DataLoader
+
-import paddle.fluid.compiler as compiler
+from training import Trainer
+from model_utils.network import DeepSpeech2
+from model_utils.network import DeepSpeech2Loss
+
 from decoders.swig_wrapper import Scorer
 from decoders.swig_wrapper import ctc_greedy_decoder
 from decoders.swig_wrapper import ctc_beam_search_decoder_batch
-from model_utils.network import deep_speech_v2_network
 
 logging.basicConfig(
     format='[%(levelname)s %(asctime)s %(filename)s:%(lineno)d] %(message)s')
 
 
-class DeepSpeech2Model(object):
+class SpeechCollator():
-    """DeepSpeech2Model class.
+    def __init__(self, padding_to=-1):
-
-    :param vocab_size: Decoding vocabulary size.
-    :type vocab_size: int
-    :param num_conv_layers: Number of stacking convolution layers.
-    :type num_conv_layers: int
-    :param num_rnn_layers: Number of stacking RNN layers.
-    :type num_rnn_layers: int
-    :param rnn_layer_size: RNN layer size (number of RNN cells).
-    :type rnn_layer_size: int
-    :param use_gru: Use gru if set True. Use simple rnn if set False.
-    :type use_gru: bool
-    :param share_rnn_weights: Whether to share input-hidden weights between
-                              forward and backward directional RNNs.Notice that
-                              for GRU, weight sharing is not supported.
-    :type share_rnn_weights: bool
-    :param place: Program running place.
-    :type place: CPUPlace or CUDAPlace
-    :param init_from_pretrained_model: Pretrained model path. If None, will train
-                                  from stratch.
-    :type init_from_pretrained_model: string|None
-    :param output_model_dir: Output model directory. If None, output to current directory. 
-    :type output_model_dir: string|None
-    """
-
-    def __init__(self,
-                 vocab_size,
-                 num_conv_layers,
-                 num_rnn_layers,
-                 rnn_layer_size,
-                 use_gru=False,
-                 share_rnn_weights=True,
-                 place=fluid.CPUPlace(),
-                 init_from_pretrained_model=None,
-                 output_model_dir=None):
-        self._vocab_size = vocab_size
-        self._num_conv_layers = num_conv_layers
-        self._num_rnn_layers = num_rnn_layers
-        self._rnn_layer_size = rnn_layer_size
-        self._use_gru = use_gru
-        self._share_rnn_weights = share_rnn_weights
-        self._place = place
-        self._init_from_pretrained_model = init_from_pretrained_model
-        self._output_model_dir = output_model_dir
-        self._ext_scorer = None
-        self.logger = logging.getLogger("")
-        self.logger.setLevel(level=logging.INFO)
-
-    def create_network(self, is_infer=False):
-        """Create data layers and model network.
-        :param is_training: Whether to create a network for training.
-        :type is_training: bool 
-        :return reader: Reader for input.
-        :rtype reader: read generater
-        :return log_probs: An output unnormalized log probability layer.
-        :rtype lig_probs: Varable
-        :return loss: A ctc loss layer.
-        :rtype loss: Variable
         """
+        Padding audio features with zeros to make them have the same shape (or
+        a user-defined shape) within one bach.
 
-        if not is_infer:
+        If ``padding_to`` is -1, the maximun shape in the batch will be used
-            reader = DataLoader.from_generator(
+        as the target shape for padding. Otherwise, `padding_to` will be the
-                feed_list=inputs,
+        target shape (only refers to the second axis).
-                capacity=64,
+        """
-                iterable=False,
+        self._padding_to = padding_to
-                use_double_buffer=True)
+
+    def __call__(self, batch):
+        new_batch = []
+        # get target shape
+        max_length = max([audio.shape[1] for audio, _ in batch])
+        if self._padding_to != -1:
+            if self._padding_to < max_length:
+                raise ValueError("If padding_to is not -1, it should be larger "
+                                 "than any instance's shape in the batch")
+            max_length = self._padding_to
+        max_text_length = max([len(text) for _, text in batch])
+        # padding
+        padded_audios = []
+        audio_lens = []
+        texts, text_lens = [], []
+        for audio, text in batch:
+            # audio
+            padded_audio = np.zeros([audio.shape[0], max_length])
+            padded_audio[:, :audio.shape[1]] = audio
+            padded_audios.append(padded_audio)
+            audio_lens.append(audio.shape[1])
+            # text
+            padded_text = np.zeros([max_text_length])
+            padded_text[:len(text)] = text
+            texts.append(padded_text)
+            text_lens.append(len(text))
+
+        padded_audios = np.array(padded_audios).astype('float32')
+        audio_lens = np.array(audio_lens).astype('int64')
+        texts = np.array(texts).astype('int32')
+        text_lens = np.array(text_lens).astype('int64')
+        return padded_audios, texts, audio_lens, text_lens
+
+
+class DeepSpeech2Trainer(Trainer):
+    def __init__(self):
+        self._ext_scorer = None
 
-            (audio_data, text_data, seq_len_data, masks) = inputs
+    def setup_dataloader(self):
+        config = self.config
+
+        train_dataset = DeepSpeech2Dataset(
+            config.data.train_manifest_path,
+            config.data.vocab_filepath,
+            config.data.mean_std_filepath,
+            augmentation_config=config.data.augmentation_config,
+            max_duration=config.data.max_duration,
+            min_duration=config.data.min_duration,
+            stride_ms=config.data.stride_ms,
+            window_ms=config.data.window_ms,
+            max_freq=config.data.max_freq,
+            specgram_type=config.data.specgram_type,
+            use_dB_normalization=config.data.use_dB_normalization,
+            random_seed=config.data.random_seed,
+            keep_transcription_text=False)
+
+        dev_dataset = DeepSpeech2Dataset(
+            config.data.dev_manifest_path,
+            config.data.vocab_filepath,
+            config.data.mean_std_filepath,
+            augmentation_config=config.data.augmentation_config,
+            max_duration=config.data.max_duration,
+            min_duration=config.data.min_duration,
+            stride_ms=config.data.stride_ms,
+            window_ms=config.data.window_ms,
+            max_freq=config.data.max_freq,
+            specgram_type=config.data.specgram_type,
+            use_dB_normalization=config.data.use_dB_normalization,
+            random_seed=config.data.random_seed,
+            keep_transcription_text=False)
+
+        if self.parallel:
+            batch_sampler = DeepSpeech2DistributedBatchSampler(
+                train_dataset,
+                batch_size=config.data.batch_size,
+                num_replicas=None,
+                rank=None,
+                shuffle=True,
+                drop_last=True,
+                sortagrad=config.data.sortagrad,
+                shuffle_method=config.data.shuffle_method)
         else:
-            audio_data = fluid.data(
+            batch_sampler = DeepSpeech2BatchSampler(
-                name='audio_data',
+                train_dataset,
-                shape=[None, 161, None],
+                shuffle=True,
-                dtype='float32',
+                batch_size=config.data.batch_size,
-                lod_level=0)
+                drop_last=True,
-            seq_len_data = fluid.data(
+                sortagrad=config.data.sortagrad,
-                name='seq_len_data',
+                shuffle_method=config.data.shuffle_method)
-                shape=[None, 1],
+
-                dtype='int64',
+        collate_fn = SpeechCollator()
-                lod_level=0)
+        self.train_loader = DataLoader(
-            masks = fluid.data(
+            train_dataset,
-                name='masks',
+            batch_sampler=batch_sampler,
-                shape=[None, 32, 81, None],
+            collate_fn=collate_fn,
-                dtype='float32',
+            num_workers=config.data.num_workers, )
-                lod_level=0)
+        self.valid_loader = DataLoader(
-            text_data = None
+            dev_dataset,
-            reader = fluid.DataFeeder([audio_data, seq_len_data, masks],
+            batch_size=config.data.batch_size,
-                                      self._place)
+            shuffle=False,
-
+            drop_last=False,
-        log_probs, loss = deep_speech_v2_network(
+            collate_fn=collate_fn)
-            audio_data=audio_data,
+        self.logger.info("Setup train/valid Dataloader!")
-            text_data=text_data,
+
-            seq_len_data=seq_len_data,
+    def setup_model(self):
-            masks=masks,
+        config = self.config
-            dict_size=self._vocab_size,
+        model = DeepSpeech2(
-            num_conv_layers=self._num_conv_layers,
+            feat_size=self.train_loader.feature_size,
-            num_rnn_layers=self._num_rnn_layers,
+            dict_size=self.train_loader.vocab_size,
-            rnn_size=self._rnn_layer_size,
+            num_conv_layers=config.model.num_conv_layers,
-            use_gru=self._use_gru,
+            num_rnn_layers=config.model.num_rnn_layers,
-            share_rnn_weights=self._share_rnn_weights)
+            rnn_size=config.model.rnn_layer_size,
-        return reader, log_probs, loss
+            share_rnn_weights=config.model.share_rnn_weights)
-
+
-    def init_from_pretrained_model(self, exe, program):
+        if self.parallel:
-        '''Init params from pretrain model. '''
+            model = paddle.DataParallel(model)
-
+
-        assert isinstance(self._init_from_pretrained_model, str)
+        grad_clip = paddle.nn.ClipGradByGlobalNorm(config.training.grad_clip)
-
+
-        if not os.path.exists(self._init_from_pretrained_model):
+        optimizer = paddle.optimizer.Adam(
-            print(self._init_from_pretrained_model)
+            learning_rate=config.training.lr,
-            raise Warning("The pretrained params do not exist.")
+            parameters=model.parameters(),
-            return False
+            weight_decay=paddle.regulaerizer.L2Decay(
-        fluid.io.load_params(
+                config.training.weight_decay),
-            exe,
+            grad_clip=grad_clip, )
-            self._init_from_pretrained_model,
+
-            main_program=program,
+        criterion = DeepSpeech2Loss(self.train_loader.vocab_size)
-            filename="params.pdparams")
+
-
+        self.model = model
-        print("finish initing model from pretrained params from %s" %
+        self.optimizer = optimizer
-              (self._init_from_pretrained_model))
+        self.criterion = criterion
-
+        self.logger.info("Setup model/optimizer/criterion!")
-        pre_epoch = 0
+
-        dir_name = self._init_from_pretrained_model.split('_')
+    def compute_losses(self, inputs, outputs):
-        if len(dir_name) >= 2 and dir_name[-2].endswith('epoch') and dir_name[
+        pass
-                -1].isdigit():
+
-            pre_epoch = int(dir_name[-1])
+    def test(self, test_reader):
-
-        return pre_epoch + 1
-
-    def save_param(self, exe, program, dirname):
-        '''Save model params to dirname'''
-
-        assert isinstance(self._output_model_dir, str)
-
-        param_dir = os.path.join(self._output_model_dir)
-
-        if not os.path.exists(param_dir):
-            os.mkdir(param_dir)
-
-        fluid.io.save_params(
-            exe,
-            os.path.join(param_dir, dirname),
-            main_program=program,
-            filename="params.pdparams")
-        print("save parameters at %s" % (os.path.join(param_dir, dirname)))
-
-        return True
-
-    def test(self, exe, dev_batch_reader, test_program, test_reader,
-             fetch_list):
         '''Test the model.
 
         :param exe:The executor of program.
         :type exe: Executor
-        :param dev_batch_reader: The reader of test dataa.
-        :type dev_batch_reader: read generator 
         :param test_program: The program of test.
         :type test_program: Program
         :param test_reader: Reader of test.
         :type test_reader: Reader
-        :param fetch_list: Fetch list.
-        :type fetch_list: list
         :return: An output unnormalized log probability. 
         :rtype: array
         '''
@@ -254,13 +252,6 @@ class DeepSpeech2Model(object):
         :param test_off: Turn off testing.
         :type test_off: bool
         """
-        # prepare model output directory
-        if not os.path.exists(self._output_model_dir):
-            mkpath(self._output_model_dir)
-
-        # adapt the feeding dict according to the network
-        adapted_feeding_dict = self._adapt_feeding_dict(feeding_dict)
-
         if isinstance(self._place, fluid.CUDAPlace):
             dev_count = fluid.core.get_cuda_device_count()
         else:
@@ -298,16 +289,6 @@ class DeepSpeech2Model(object):
         if self._init_from_pretrained_model:
             pre_epoch = self.init_from_pretrained_model(exe, train_program)
 
-        build_strategy = compiler.BuildStrategy()
-        exec_strategy = fluid.ExecutionStrategy()
-
-        # pass the build_strategy to with_data_parallel API
-        compiled_prog = compiler.CompiledProgram(
-            train_program).with_data_parallel(
-                loss_name=ctc_loss.name,
-                build_strategy=build_strategy,
-                exec_strategy=exec_strategy)
-
         train_reader.set_batch_generator(train_batch_reader)
         test_reader.set_batch_generator(dev_batch_reader)
 
@@ -386,9 +367,6 @@ class DeepSpeech2Model(object):
         infer_program = fluid.Program()
         startup_prog = fluid.Program()
 
-        # adapt the feeding dict according to the network
-        adapted_feeding_dict = self._adapt_feeding_dict(feeding_dict)
-
         # prepare the network
         with fluid.program_guard(infer_program, startup_prog):
             with fluid.unique_name.guard():
@@ -523,35 +501,3 @@ class DeepSpeech2Model(object):
 
         results = [result[0][1] for result in beam_search_results]
         return results
-
-    def _adapt_feeding_dict(self, feeding_dict):
-        """Adapt feeding dict according to network struct.
-
-        To remove impacts from padding part, we add scale_sub_region layer and
-        sub_seq layer. For sub_seq layer, 'sequence_offset' and
-        'sequence_length' fields are appended. For each scale_sub_region layer
-        'convN_index_range' field is appended.
-
-        :param feeding_dict: Feeding is a map of field name and tuple index
-                             of the data that reader returns.
-        :type feeding_dict: dict|list
-        :return: Adapted feeding dict.
-        :rtype: dict|list
-        """
-        adapted_feeding_dict = copy.deepcopy(feeding_dict)
-        if isinstance(feeding_dict, dict):
-            adapted_feeding_dict["sequence_offset"] = len(adapted_feeding_dict)
-            adapted_feeding_dict["sequence_length"] = len(adapted_feeding_dict)
-            for i in range(self._num_conv_layers):
-                adapted_feeding_dict["conv%d_index_range" %i] = \
-                        len(adapted_feeding_dict)
-        elif isinstance(feeding_dict, list):
-            adapted_feeding_dict.append("sequence_offset")
-            adapted_feeding_dict.append("sequence_length")
-            for i in range(self._num_conv_layers):
-                adapted_feeding_dict.append("conv%d_index_range" % i)
-        else:
-            raise ValueError("Type of feeding_dict is %s, not supported." %
-                             type(feeding_dict))
-
-        return adapted_feeding_dict

model_utils/network.py

@@ -12,31 +12,49 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import math
 import collections
-import paddle.fluid as fluid
 import numpy as np
+import paddle
+from paddle import nn
+from paddle.nn import functional as F
+from paddle.nn import initializer as I
 
+__all__ = ['DeepSpeech2', 'DeepSpeech2Loss']
 
-def conv_bn_layer(input, filter_size, num_channels_in, num_channels_out, stride,
+
-                  padding, act, masks, name):
+def brelu(x, t_min=0.0, t_max=24.0, name=None):
+    t_min = paddle.to_tensor(t_min)
+    t_max = paddle.to_tensor(t_max)
+    return x.maximum(t_min).minimum(t_max)
+
+
+def sequence_mask(x_len, max_len=None, dtype='float32'):
+    max_len = max_len or x_len.max()
+    x_len = paddle.unsqueeze(x_len, -1)
+    row_vector = paddle.arange(max_len)
+    mask = row_vector < x_len
+    mask = paddle.cast(mask, dtype)
+    return mask
+
+
+class ConvBn(nn.Layer):
     """Convolution layer with batch normalization.
 
-    :param input: Input layer.
+    :param kernel_size: The x dimension of a filter kernel. Or input a tuple for
-    :type input: Variable
-    :param filter_size: The x dimension of a filter kernel. Or input a tuple for
                         two image dimension.
-    :type filter_size: int|tuple|list
+    :type kernel_size: int|tuple|list
     :param num_channels_in: Number of input channels.
     :type num_channels_in: int
     :param num_channels_out: Number of output channels.
     :type num_channels_out: int
     :param stride: The x dimension of the stride. Or input a tuple for two 
-                   image dimension. 
+                image dimension. 
     :type stride: int|tuple|list
     :param padding: The x dimension of the padding. Or input a tuple for two
                     image dimension.
     :type padding: int|tuple|list
-    :param act: Activation type.
+    :param act: Activation type, relu|brelu
     :type act: string
     :param masks: Masks data layer to reset padding.
     :type masks: Variable
@@ -46,89 +64,255 @@ def conv_bn_layer(input, filter_size, num_channels_in, num_channels_out, stride,
     :rtype: Variable
 
     """
-    conv_layer = fluid.layers.conv2d(
+
-        input=input,
+    def __init__(self, num_channels_in, num_channels_out, kernel_size, stride,
-        num_filters=num_channels_out,
+                 padding, act):
-        filter_size=filter_size,
+
-        stride=stride,
+        super().__init__()
-        padding=padding,
+        self.kernel_size = kernel_size
-        param_attr=fluid.ParamAttr(name=name + '_conv2d_weight'),
+        self.stride = stride
-        act=None,
+        self.padding = padding
-        bias_attr=False)
+
-
+        self.conv = nn.Conv2D(
-    batch_norm = fluid.layers.batch_norm(
+            num_channels_in,
-        input=conv_layer,
+            num_channels_out,
-        act=act,
+            kernel_size=kernel_size,
-        param_attr=fluid.ParamAttr(name=name + '_batch_norm_weight'),
+            stride=stride,
-        bias_attr=fluid.ParamAttr(name=name + '_batch_norm_bias'),
+            padding=padding,
-        moving_mean_name=name + '_batch_norm_moving_mean',
+            weight_attr=None,
-        moving_variance_name=name + '_batch_norm_moving_variance')
+            bias_attr=None,
-
+            data_format='NCHW')
-    # reset padding part to 0
+
-    padding_reset = fluid.layers.elementwise_mul(batch_norm, masks)
+        self.bn = nn.BatchNorm2D(
-    return padding_reset
+            num_channels_out,
-
+            weight_attr=None,
-
+            bias_attr=None,
-class RNNCell(fluid.layers.RNNCell):
+            data_format='NCHW')
-    """A simple rnn cell."""
+        self.act = paddle.relu if act == 'relu' else brelu
+
+    def forward(self, x, x_len):
+        """
+        x(Tensor): audio, shape [B, C, D, T]
+        """
+        x = self.conv(x)
+        x = self.bn(x)
+        x = self.act(x)
+
+        x_len = (x_len - self.kernel_size[1] + 2 * self.padding[1]
+                 ) // self.stride[1] + 1
+
+        # reset padding part to 0
+        masks = sequence_mask(x_len)  #[B, T]
+        masks = masks.unsqueeze(1).unsqueeze(1)  # [B, 1, 1, T]
+        x = x.multiply(masks)
+
+        return x, x_len
+
+
+class ConvStack(nn.Layer):
+    """Convolution group with stacked convolution layers.
+
+    :param feat_size: audio feature dim.
+    :type feat_size: int
+    :param num_stacks: Number of stacked convolution layers.
+    :type num_stacks: int
+    """
+
+    def __init__(self, feat_size, num_stacks):
+        super().__init__()
+        self.feat_size = feat_size  # D
+        self.num_stacks = num_stacks
+
+        self.filter_size = (41, 11)  # [D, T]
+        self.stride = (2, 3)
+        self.padding = (20, 5)
+        self.conv_in = ConvBn(
+            num_channels_in=1,
+            num_channels_out=32,
+            kernel_size=self.filter_size,
+            stride=self.stride,
+            padding=self.padding,
+            act='brelu', )
+
+        out_channel = 32
+        self.conv_stack = nn.LayerList([
+            ConvBn(
+                num_channels_in=32,
+                num_channels_out=out_channel,
+                kernel_size=(21, 11),
+                stride=(2, 1),
+                padding=(10, 5),
+                act='brelu') for i in range(num_stacks - 1)
+        ])
+
+        # conv output feat_dim
+        output_height = (feat_size - 1) // 2 + 1
+        for i in range(self.num_stacks - 1):
+            output_height = (output_height - 1) // 2 + 1
+        self.output_height = out_channel * output_height
+
+    def forward(self, x, x_len):
+        """
+        x: shape [B, C, D, T]
+        x_len : shape [B]
+        """
+        x, x_len = self.conv_in(x, x_len)
+        for i, conv in enumerate(self.conv_stack):
+            x, x_len = conv(x, x_len)
+        return x, x_len
+
+
+class RNNCell(nn.RNNCellBase):
+    r"""
+    Elman RNN (SimpleRNN) cell. Given the inputs and previous states, it 
+    computes the outputs and updates states.
+    The formula used is as follows:
+    .. math::
+        h_{t} & = act(x_{t} + b_{ih} + W_{hh}h_{t-1} + b_{hh})
+        y_{t} & = h_{t}
+    
+    where :math:`act` is for :attr:`activation`.
+    """
 
     def __init__(self,
                  hidden_size,
-                 param_attr=None,
+                 activation="tanh",
-                 bias_attr=None,
+                 weight_ih_attr=None,
-                 hidden_activation=None,
+                 weight_hh_attr=None,
-                 activation=None,
+                 bias_ih_attr=None,
-                 dtype="float32",
+                 bias_hh_attr=None,
-                 name="RNNCell"):
+                 name=None):
-        """Initialize simple rnn cell.
+        super().__init__()
-
+        std = 1.0 / math.sqrt(hidden_size)
-        :param hidden_size: Dimension of RNN cells.
+        self.weight_hh = self.create_parameter(
-        :type hidden_size: int
+            (hidden_size, hidden_size),
-        :param param_attr: Parameter properties of hidden layer weights that 
+            weight_hh_attr,
-                      can be learned
+            default_initializer=I.Uniform(-std, std))
-        :type param_attr: ParamAttr
+        self.bias_ih = self.create_parameter(
-        :param bias_attr: Bias properties of hidden layer weights that can be learned
+            (hidden_size, ),
-        :type bias_attr: ParamAttr
+            bias_ih_attr,
-        :param hidden_activation: Activation for hidden cell
+            is_bias=True,
-        :type hidden_activation: Activation
+            default_initializer=I.Uniform(-std, std))
-        :param activation: Activation for output
+        self.bias_hh = self.create_parameter(
-        :type activation: Activation
+            (hidden_size, ),
-        :param name: Name of cell
+            bias_hh_attr,
-        :type name: string
+            is_bias=True,
-        """
+            default_initializer=I.Uniform(-std, std))
+
+        self.hidden_size = hidden_size
+        if activation not in ["tanh", "relu", "brelu"]:
+            raise ValueError(
+                "activation for SimpleRNNCell should be tanh or relu, "
+                "but get {}".format(activation))
+        self.activation = activation
+        self._activation_fn = paddle.tanh \
+            if activation == "tanh" \
+            else F.relu
+        if activation == 'brelu':
+            self._activation_fn = brelu
+
+    def forward(self, inputs, states=None):
+        if states is None:
+            states = self.get_initial_states(inputs, self.state_shape)
+        pre_h = states
+        i2h = inputs
+        if self.bias_ih is not None:
+            i2h += self.bias_ih
+        h2h = paddle.matmul(pre_h, self.weight_hh, transpose_y=True)
+        if self.bias_hh is not None:
+            h2h += self.bias_hh
+        h = self._activation_fn(i2h + h2h)
+        return h, h
+
+    @property
+    def state_shape(self):
+        return (self.hidden_size, )
+
+
+class GRUCellShare(nn.RNNCellBase):
+    r"""
+    Gated Recurrent Unit (GRU) RNN cell. Given the inputs and previous states, 
+    it computes the outputs and updates states.
+    The formula for GRU used is as follows:
+    ..  math::
+        r_{t} & = \sigma(W_{ir}x_{t} + b_{ir} + W_{hr}h_{t-1} + b_{hr})
+        z_{t} & = \sigma(W_{iz}x_{t} + b_{iz} + W_{hz}h_{t-1} + b_{hz})
+        \widetilde{h}_{t} & = \tanh(W_{ic}x_{t} + b_{ic} + r_{t} * (W_{hc}h_{t-1} + b_{hc}))
+        h_{t} & = z_{t} * h_{t-1} + (1 - z_{t}) * \widetilde{h}_{t}
+        y_{t} & = h_{t}
+    
+    where :math:`\sigma` is the sigmoid fucntion, and * is the elemetwise 
+    multiplication operator.
+    """
+
+    def __init__(self,
+                 input_size,
+                 hidden_size,
+                 weight_ih_attr=None,
+                 weight_hh_attr=None,
+                 bias_ih_attr=None,
+                 bias_hh_attr=None,
+                 name=None):
+        super().__init__()
+        std = 1.0 / math.sqrt(hidden_size)
+        self.weight_hh = self.create_parameter(
+            (3 * hidden_size, hidden_size),
+            weight_hh_attr,
+            default_initializer=I.Uniform(-std, std))
+        self.bias_ih = self.create_parameter(
+            (3 * hidden_size, ),
+            bias_ih_attr,
+            is_bias=True,
+            default_initializer=I.Uniform(-std, std))
+        self.bias_hh = self.create_parameter(
+            (3 * hidden_size, ),
+            bias_hh_attr,
+            is_bias=True,
+            default_initializer=I.Uniform(-std, std))
 
         self.hidden_size = hidden_size
-        self.param_attr = param_attr
+        self.input_size = input_size
-        self.bias_attr = bias_attr
+        self._gate_activation = F.sigmoid
-        self.hidden_activation = hidden_activation
+        self._activation = paddle.tanh
-        self.activation = activation or fluid.layers.brelu
+
-        self.name = name
+    def forward(self, inputs, states=None):
-
+        if states is None:
-    def call(self, inputs, states):
+            states = self.get_initial_states(inputs, self.state_shape)
-        new_hidden = fluid.layers.fc(
+
-            input=states,
+        pre_hidden = states
-            size=self.hidden_size,
+        x_gates = inputs
-            act=self.hidden_activation,
+        if self.bias_ih is not None:
-            param_attr=self.param_attr,
+            x_gates = x_gates + self.bias_ih
-            bias_attr=self.bias_attr)
+        h_gates = paddle.matmul(pre_hidden, self.weight_hh, transpose_y=True)
-        new_hidden = fluid.layers.elementwise_add(new_hidden, inputs)
+        if self.bias_hh is not None:
-        new_hidden = self.activation(new_hidden)
+            h_gates = h_gates + self.bias_hh
-
+
-        return new_hidden, new_hidden
+        x_r, x_z, x_c = paddle.split(x_gates, num_or_sections=3, axis=1)
+        h_r, h_z, h_c = paddle.split(h_gates, num_or_sections=3, axis=1)
+
+        r = self._gate_activation(x_r + h_r)
+        z = self._gate_activation(x_z + h_z)
+        c = self._activation(x_c + r * h_c)  # apply reset gate after mm
+        h = (pre_hidden - c) * z + c
+
+        return h, h
 
     @property
     def state_shape(self):
-        return [self.hidden_size]
+        r"""
+        The `state_shape` of GRUCell is a shape `[hidden_size]` (-1 for batch
+        size would be automatically inserted into shape). The shape corresponds
+        to the shape of :math:`h_{t-1}`.
+        """
+        return (self.hidden_size, )
 
 
-def bidirectional_simple_rnn_bn_layer(name, input, size, share_weights):
+class BiRNNWithBN(nn.Layer):
     """Bidirectonal simple rnn layer with sequence-wise batch normalization.
     The batch normalization is only performed on input-state weights.
 
     :param name: Name of the layer parameters.
     :type name: string
-    :param input: Input layer.
-    :type input: Variable
     :param size: Dimension of RNN cells.
     :type size: int
     :param share_weights: Whether to share input-hidden weights between
@@ -137,88 +321,44 @@ def bidirectional_simple_rnn_bn_layer(name, input, size, share_weights):
     :return: Bidirectional simple rnn layer.
     :rtype: Variable
     """
-    forward_cell = RNNCell(
+
-        hidden_size=size,
+    def __init__(self, i_size, h_size, share_weights):
-        activation=fluid.layers.brelu,
+        super().__init__()
-        param_attr=fluid.ParamAttr(name=name + '_forward_rnn_weight'),
+        self.share_weights = share_weights
-        bias_attr=fluid.ParamAttr(name=name + '_forward_rnn_bias'))
+        self.pad_value = paddle.to_tensor(np.array([0.0], dtype=np.float32))
-
+        if self.share_weights:
-    reverse_cell = RNNCell(
+            #input-hidden weights shared between bi-directional rnn.
-        hidden_size=size,
+            self.fw_fc = nn.Linear(i_size, h_size)
-        activation=fluid.layers.brelu,
+            # batch norm is only performed on input-state projection
-        param_attr=fluid.ParamAttr(name=name + '_reverse_rnn_weight'),
+            self.fw_bn = nn.BatchNorm1D(h_size, data_format='NLC')
-        bias_attr=fluid.ParamAttr(name=name + '_reverse_rnn_bias'))
+            self.bw_fc = self.fw_fc
-
+            self.bw_bn = self.fw_bn
-    pad_value = fluid.layers.assign(input=np.array([0.0], dtype=np.float32))
+        else:
-
+            self.fw_fc = nn.Linear(i_size, h_size)
-    if share_weights:
+            self.fw_bn = nn.BatchNorm1D(h_size, data_format='NLC')
-        #input-hidden weights shared between bi-directional rnn.
+            self.bw_fc = nn.Linear(i_size, h_size)
-        input_proj = fluid.layers.fc(
+            self.bw_bn = nn.BatchNorm1D(h_size, data_format='NLC')
-            input=input,
+
-            size=size,
+        self.fw_cell = RNNCell(hidden_size=h_size, activation='relu')
-            act=None,
+        self.bw_cell = RNNCell(
-            param_attr=fluid.ParamAttr(name=name + '_fc_weight'),
+            hidden_size=h_size,
-            bias_attr=False)
+            activation='relu', )
-
+        self.fw_rnn = nn.RNN(
-        # batch norm is only performed on input-state projection
+            self.fw_cell, is_reverse=False, time_major=False)  #[B, T, D]
-        input_proj_bn_forward = fluid.layers.batch_norm(
+        self.bw_rnn = nn.RNN(
-            input=input_proj,
+            self.fw_cell, is_reverse=True, time_major=False)  #[B, T, D]
-            act=None,
+
-            param_attr=fluid.ParamAttr(name=name + '_batch_norm_weight'),
+    def forward(self, x, x_len):
-            bias_attr=fluid.ParamAttr(name=name + '_batch_norm_bias'),
+        # x, shape [B, T, D]
-            moving_mean_name=name + '_batch_norm_moving_mean',
+        fw_x = self.fw_bn(self.fw_fc(x))
-            moving_variance_name=name + '_batch_norm_moving_variance')
+        bw_x = self.bw_bn(self.bw_fc(x))
-        input_proj_bn_reverse = input_proj_bn_forward
+        fw_x, _ = self.fw_rnn(inputs=fw_x, sequence_length=x_len)
-    else:
+        bw_x, _ = self.bw_rnn(inputs=bw_x, sequence_length=x_len)
-        input_proj_forward = fluid.layers.fc(
+        x = paddle.concat([fw_x, bw_x], axis=-1)
-            input=input,
+        return x, x_len
-            size=size,
+
-            act=None,
+
-            param_attr=fluid.ParamAttr(name=name + '_forward_fc_weight'),
+class BiGRUWithBN(nn.Layer):
-            bias_attr=False)
-        input_proj_reverse = fluid.layers.fc(
-            input=input,
-            size=size,
-            act=None,
-            param_attr=fluid.ParamAttr(name=name + '_reverse_fc_weight'),
-            bias_attr=False)
-        #batch norm is only performed on input-state projection
-        input_proj_bn_forward = fluid.layers.batch_norm(
-            input=input_proj_forward,
-            act=None,
-            param_attr=fluid.ParamAttr(
-                name=name + '_forward_batch_norm_weight'),
-            bias_attr=fluid.ParamAttr(name=name + '_forward_batch_norm_bias'),
-            moving_mean_name=name + '_forward_batch_norm_moving_mean',
-            moving_variance_name=name + '_forward_batch_norm_moving_variance')
-        input_proj_bn_reverse = fluid.layers.batch_norm(
-            input=input_proj_reverse,
-            act=None,
-            param_attr=fluid.ParamAttr(
-                name=name + '_reverse_batch_norm_weight'),
-            bias_attr=fluid.ParamAttr(name=name + '_reverse_batch_norm_bias'),
-            moving_mean_name=name + '_reverse_batch_norm_moving_mean',
-            moving_variance_name=name + '_reverse_batch_norm_moving_variance')
-    # forward and backward in time
-    input, length = fluid.layers.sequence_pad(input_proj_bn_forward, pad_value)
-    forward_rnn, _ = fluid.layers.rnn(
-        cell=forward_cell, inputs=input, time_major=False, is_reverse=False)
-    forward_rnn = fluid.layers.sequence_unpad(x=forward_rnn, length=length)
-
-    input, length = fluid.layers.sequence_pad(input_proj_bn_reverse, pad_value)
-    reverse_rnn, _ = fluid.layers.rnn(
-        cell=reverse_cell,
-        inputs=input,
-        sequence_length=length,
-        time_major=False,
-        is_reverse=True)
-    reverse_rnn = fluid.layers.sequence_unpad(x=reverse_rnn, length=length)
-
-    out = fluid.layers.concat(input=[forward_rnn, reverse_rnn], axis=1)
-    return out
-
-
-def bidirectional_gru_bn_layer(name, input, size, act):
     """Bidirectonal gru layer with sequence-wise batch normalization.
     The batch normalization is only performed on input-state weights.
 
@@ -233,108 +373,33 @@ def bidirectional_gru_bn_layer(name, input, size, act):
     :return: Bidirectional GRU layer.
     :rtype: Variable
     """
-    input_proj_forward = fluid.layers.fc(
-        input=input,
-        size=size * 3,
-        act=None,
-        param_attr=fluid.ParamAttr(name=name + '_forward_fc_weight'),
-        bias_attr=False)
-    input_proj_reverse = fluid.layers.fc(
-        input=input,
-        size=size * 3,
-        act=None,
-        param_attr=fluid.ParamAttr(name=name + '_reverse_fc_weight'),
-        bias_attr=False)
-    #batch norm is only performed on input-related prohections
-    input_proj_bn_forward = fluid.layers.batch_norm(
-        input=input_proj_forward,
-        act=None,
-        param_attr=fluid.ParamAttr(name=name + '_forward_batch_norm_weight'),
-        bias_attr=fluid.ParamAttr(name=name + '_forward_batch_norm_bias'),
-        moving_mean_name=name + '_forward_batch_norm_moving_mean',
-        moving_variance_name=name + '_forward_batch_norm_moving_variance')
-    input_proj_bn_reverse = fluid.layers.batch_norm(
-        input=input_proj_reverse,
-        act=None,
-        param_attr=fluid.ParamAttr(name=name + '_reverse_batch_norm_weight'),
-        bias_attr=fluid.ParamAttr(name=name + '_reverse_batch_norm_bias'),
-        moving_mean_name=name + '_reverse_batch_norm_moving_mean',
-        moving_variance_name=name + '_reverse_batch_norm_moving_variance')
-    #forward and backward in time
-    forward_gru = fluid.layers.dynamic_gru(
-        input=input_proj_bn_forward,
-        size=size,
-        gate_activation='sigmoid',
-        candidate_activation=act,
-        param_attr=fluid.ParamAttr(name=name + '_forward_gru_weight'),
-        bias_attr=fluid.ParamAttr(name=name + '_forward_gru_bias'),
-        is_reverse=False)
-    reverse_gru = fluid.layers.dynamic_gru(
-        input=input_proj_bn_reverse,
-        size=size,
-        gate_activation='sigmoid',
-        candidate_activation=act,
-        param_attr=fluid.ParamAttr(name=name + '_reverse_gru_weight'),
-        bias_attr=fluid.ParamAttr(name=name + '_reverse_gru_bias'),
-        is_reverse=True)
-    return fluid.layers.concat(input=[forward_gru, reverse_gru], axis=1)
-
-
-def conv_group(input, num_stacks, seq_len_data, masks):
-    """Convolution group with stacked convolution layers.
 
-    :param input: Input layer.
+    def __init__(self, i_size, h_size, act):
-    :type input: Variable
+        super().__init__()
-    :param num_stacks: Number of stacked convolution layers.
+        hidden_size = h_size * 3
-    :type num_stacks: int
+        self.fw_fc = nn.Linear(i_size, hidden_size)
-    :param seq_len_data:Valid sequence length data layer. 
+        self.fw_bn = nn.BatchNorm1D(hidden_size, data_format='NLC')
-    :type seq_len_data:Variable
+        self.bw_fc = nn.Linear(i_size, hidden_size)
-    :param masks: Masks data layer to reset padding.
+        self.bw_bn = nn.BatchNorm1D(hidden_size, data_format='NLC')
-    :type masks: Variable
+
-    :return: Output layer of the convolution group.
+        self.fw_cell = GRUCellShare(input_size=hidden_size, hidden_size=h_size)
-    :rtype: Variable
+        self.bw_cell = GRUCellShare(input_size=hidden_size, hidden_size=h_size)
-    """
+        self.fw_rnn = nn.RNN(
-    filter_size = (41, 11)
+            self.fw_cell, is_reverse=False, time_major=False)  #[B, T, D]
-    stride = (2, 3)
+        self.bw_rnn = nn.RNN(
-    padding = (20, 5)
+            self.fw_cell, is_reverse=True, time_major=False)  #[B, T, D]
-    conv = conv_bn_layer(
+
-        input=input,
+    def forward(self, x, x_len):
-        filter_size=filter_size,
+        # x, shape [B, T, D]
-        num_channels_in=1,
+        fw_x = self.fw_bn(self.fw_fc(x))
-        num_channels_out=32,
+        bw_x = self.bw_bn(self.bw_fc(x))
-        stride=stride,
+        fw_x, _ = self.fw_rnn(inputs=fw_x, sequence_length=x_len)
-        padding=padding,
+        bw_x, _ = self.bw_rnn(inputs=bw_x, sequence_length=x_len)
-        act="brelu",
+        x = paddle.concat([fw_x, bw_x], axis=-1)
-        masks=masks,
+        return x, x_len
-        name='layer_0', )
+
-
+
-    seq_len_data = (np.array(seq_len_data) - filter_size[1] + 2 * padding[1]
+class RNNStack(nn.Layer):
-                    ) // stride[1] + 1
-
-    output_height = (161 - 1) // 2 + 1
-
-    for i in range(num_stacks - 1):
-        #reshape masks
-        output_height = (output_height - 1) // 2 + 1
-        masks = fluid.layers.slice(
-            masks, axes=[2], starts=[0], ends=[output_height])
-        conv = conv_bn_layer(
-            input=conv,
-            filter_size=(21, 11),
-            num_channels_in=32,
-            num_channels_out=32,
-            stride=(2, 1),
-            padding=(10, 5),
-            act="brelu",
-            masks=masks,
-            name='layer_{}'.format(i + 1), )
-
-    output_num_channels = 32
-    return conv, output_num_channels, output_height, seq_len_data
-
-
-def rnn_group(input, size, num_stacks, num_conv_layers, use_gru,
-              share_rnn_weights):
     """RNN group with stacked bidirectional simple RNN or GRU layers.
 
     :param input: Input layer.
@@ -352,42 +417,42 @@ def rnn_group(input, size, num_stacks, num_conv_layers, use_gru,
     :return: Output layer of the RNN group.
     :rtype: Variable
     """
-    output = input
+
-    for i in range(num_stacks):
+    def __init__(self, i_size, h_size, num_stacks, use_gru, share_rnn_weights):
-        if use_gru:
+        super().__init__()
-            output = bidirectional_gru_bn_layer(
+        self.rnn_stacks = nn.LayerList()
-                name='layer_{}'.format(i + num_conv_layers),
+        for i in range(num_stacks):
-                input=output,
+            if use_gru:
-                size=size,
+                #default:GRU using tanh
-                act="relu")
+                self.rnn_stacks.append(
-        else:
+                    BiGRUWithBN(i_size=i_size, h_size=h_size, act="relu"))
-            name = 'layer_{}'.format(i + num_conv_layers)
+            else:
-            output = bidirectional_simple_rnn_bn_layer(
+                self.rnn_stacks.append(
-                name=name,
+                    BiRNNWithBN(
-                input=output,
+                        i_size=i_size,
-                size=size,
+                        h_size=h_size,
-                share_weights=share_rnn_weights)
+                        share_weights=share_rnn_weights))
-    return output
+            i_size = h_size * 2
-
+
-
+    def forward(self, x, x_len):
-def deep_speech_v2_network(audio_data,
+        """
-                           text_data,
+        x: shape [B, T, D]
-                           seq_len_data,
+        x_len: shpae [B]
-                           masks,
+        """
-                           dict_size,
+        for i, rnn in enumerate(self.rnn_stacks):
-                           num_conv_layers=2,
+            x, x_len = rnn(x, x_len)
-                           num_rnn_layers=3,
+        return x, x_len
-                           rnn_size=256,
+
-                           use_gru=False,
+
-                           share_rnn_weights=True):
+class DeepSpeech2(nn.Layer):
     """The DeepSpeech2 network structure.
 
     :param audio_data: Audio spectrogram data layer.
     :type audio_data: Variable
     :param text_data: Transcription text data layer.
     :type text_data: Variable
-    :param seq_len_data: Valid sequence length data layer.
+    :param audio_len: Valid sequence length data layer.
-    :type seq_len_data: Variable
+    :type audio_len: Variable
     :param masks: Masks data layer to reset padding.
     :type masks: Variable
     :param dict_size: Dictionary size for tokenized transcription.
@@ -408,51 +473,80 @@ def deep_speech_v2_network(audio_data,
              before softmax) and a ctc cost layer.
     :rtype: tuple of LayerOutput    
     """
-    audio_data = fluid.layers.unsqueeze(audio_data, axes=[1])
+
-
+    def __init__(self,
-    # convolution group
+                 feat_size,
-    conv_group_output, conv_group_num_channels, conv_group_height, seq_len_data = conv_group(
+                 dict_size,
-        input=audio_data,
+                 num_conv_layers=2,
-        num_stacks=num_conv_layers,
+                 num_rnn_layers=3,
-        seq_len_data=seq_len_data,
+                 rnn_size=256,
-        masks=masks)
+                 use_gru=False,
-
+                 share_rnn_weights=True):
-    # convert data form convolution feature map to sequence of vectors
+        super().__init__()
-    transpose = fluid.layers.transpose(conv_group_output, perm=[0, 3, 1, 2])
+        self.feat_size = feat_size  # 161 for linear
-    reshape_conv_output = fluid.layers.reshape(
+        self.dict_size = dict_size
-        x=transpose,
+
-        shape=[0, -1, conv_group_height * conv_group_num_channels],
+        self.conv = ConvStack(feat_size, num_conv_layers)
-        inplace=False)
+
-    # remove padding part
+        i_size = self.conv.output_height  # H after conv stack
-    seq_len_data = fluid.layers.reshape(seq_len_data, [-1])
+        self.rnn = RNNStack(
-    sequence = fluid.layers.sequence_unpad(
+            i_size=i_size,
-        x=reshape_conv_output, length=seq_len_data)
+            h_size=rnn_size,
-    #rnn group
+            num_stacks=num_rnn_layers,
-    rnn_group_output = rnn_group(
+            use_gru=use_gru,
-        input=sequence,
+            share_rnn_weights=share_rnn_weights)
-        size=rnn_size,
+        self.fc = nn.Linear(rnn_size * 2, dict_size + 1)
-        num_stacks=num_rnn_layers,
+
-        num_conv_layers=num_conv_layers,
+    def predict(self, audio, audio_len):
-        use_gru=use_gru,
+        # [B, D, T] -> [B, C=1, D, T]
-        share_rnn_weights=share_rnn_weights)
+        audio = audio.unsqueeze(1)
-    fc = fluid.layers.fc(
+
-        input=rnn_group_output,
+        # convolution group
-        size=dict_size + 1,
+        x, audio_len = self.conv(audio, audio_len)
-        act=None,
+
-        param_attr=fluid.ParamAttr(
+        # convert data from convolution feature map to sequence of vectors
-            name='layer_{}'.format(num_conv_layers + num_rnn_layers) +
+        B, C, D, T = paddle.shape(x)
-            '_fc_weight'),
+        x = x.transpose([0, 3, 1, 2])  #[B, T, C, D]
-        bias_attr=fluid.ParamAttr(
+        x = x.reshape([B, T, C * D])  #[B, T, C*D]
-            name='layer_{}'.format(num_conv_layers + num_rnn_layers) +
+
-            '_fc_bias'))
+        # remove padding part
-    # pribability distribution with softmax
+        x, audio_len = self.rnn(x, audio_len)  #[B, T, D]
-    log_probs = fluid.layers.softmax(fc)
+
-    log_probs.persistable = True
+        logits = self.fc(x)  #[B, T, V + 1]
-    if not text_data:
+
-        return log_probs, None
+        #ctcdecoder need probs, not log_probs
-    else:
+        probs = F.softmax(logits)
-        #ctc cost
+
-        ctc_loss = fluid.layers.warpctc(
+        return logits, probs
-            input=fc, label=text_data, blank=dict_size, norm_by_times=True)
+
-        ctc_loss = fluid.layers.reduce_sum(ctc_loss)
+    @paddle.no_grad()
-        return log_probs, ctc_loss
+    def infer(self, audio, audio_len):
+        _, probs = self.predict(audio, audio_len)
+        return probs
+
+    def forward(self, audio, text, audio_len, text_len):
+        """
+        audio: shape [B, D, T]
+        text: shape [B, T]
+        audio_len: shape [B]
+        text_len: shape [B]
+        """
+        logits, _ = self.predict(audio, audio_len)
+        return logits
+
+
+class DeepSpeech2Loss(nn.Layer):
+    def __init__(self, vocab_size):
+        super().__init__()
+        # last token id as blank id
+        self.loss = nn.CTCLoss(blank=vocab_size, reduction='none')
+
+    def forward(self, logits, text, audio_len, text_len):
+        # warp-ctc do softmax on activations
+        # warp-ctc need activation with shape [T, B, V + 1]
+        logits = logits.transpose([1, 0, 2])
+
+        ctc_loss = self.loss(logits, text, audio_len, text_len)
+        ctc_loss /= text_len  # norm_by_times
+        ctc_loss = ctc_loss.sum()
+        return ctc_loss

model_utils/network2.py

@@ -1,555 +0,0 @@
-# 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.
-
-import math
-import collections
-import numpy as np
-import paddle
-from paddle import nn
-from paddle.nn import functional as F
-from paddle.nn import initializer as I
-
-__all__ = ['DeepSpeech2']
-
-
-def brelu(x, t_min=0.0, t_max=24.0, name=None):
-    t_min = paddle.to_tensor(t_min)
-    t_max = paddle.to_tensor(t_max)
-    return x.maximum(t_min).minimum(t_max)
-
-
-def sequence_mask(x_len, max_len=None, dtype='float32'):
-    max_len = max_len or x_len.max()
-    x_len = paddle.unsqueeze(x_len, -1)
-    row_vector = paddle.arange(max_len)
-    mask = row_vector < x_len
-    mask = paddle.cast(mask, dtype)
-    return mask
-
-
-class ConvBn(nn.Layer):
-    """Convolution layer with batch normalization.
-
-    :param kernel_size: The x dimension of a filter kernel. Or input a tuple for
-                        two image dimension.
-    :type kernel_size: int|tuple|list
-    :param num_channels_in: Number of input channels.
-    :type num_channels_in: int
-    :param num_channels_out: Number of output channels.
-    :type num_channels_out: int
-    :param stride: The x dimension of the stride. Or input a tuple for two 
-                image dimension. 
-    :type stride: int|tuple|list
-    :param padding: The x dimension of the padding. Or input a tuple for two
-                    image dimension.
-    :type padding: int|tuple|list
-    :param act: Activation type, relu|brelu
-    :type act: string
-    :param masks: Masks data layer to reset padding.
-    :type masks: Variable
-    :param name: Name of the layer.
-    :param name: string
-    :return: Batch norm layer after convolution layer.
-    :rtype: Variable
-
-    """
-
-    def __init__(self, num_channels_in, num_channels_out, kernel_size, stride,
-                 padding, act):
-
-        super().__init__()
-        self.kernel_size = kernel_size
-        self.stride = stride
-        self.padding = padding
-
-        self.conv = nn.Conv2D(
-            num_channels_in,
-            num_channels_out,
-            kernel_size=kernel_size,
-            stride=stride,
-            padding=padding,
-            weight_attr=None,
-            bias_attr=None,
-            data_format='NCHW')
-
-        self.bn = nn.BatchNorm2D(
-            num_channels_out,
-            weight_attr=None,
-            bias_attr=None,
-            data_format='NCHW')
-        self.act = paddle.relu if act == 'relu' else brelu
-
-    def forward(self, x, x_len):
-        """
-        x(Tensor): audio, shape [B, C, D, T]
-        """
-        x = self.conv(x)
-        x = self.bn(x)
-        x = self.act(x)
-
-        x_len = (x_len - self.kernel_size[1] + 2 * self.padding[1]
-                 ) // self.stride[1] + 1
-
-        # reset padding part to 0
-        masks = sequence_mask(x_len)  #[B, T]
-        masks = masks.unsqueeze(1).unsqueeze(1)  # [B, 1, 1, T]
-        x = x.multiply(masks)
-
-        return x, x_len
-
-
-class ConvStack(nn.Layer):
-    """Convolution group with stacked convolution layers.
-
-    :param feat_size: audio feature dim.
-    :type feat_size: int
-    :param num_stacks: Number of stacked convolution layers.
-    :type num_stacks: int
-    """
-
-    def __init__(self, feat_size, num_stacks):
-        super().__init__()
-        self.feat_size = feat_size  # D
-        self.num_stacks = num_stacks
-
-        self.filter_size = (41, 11)  # [D, T]
-        self.stride = (2, 3)
-        self.padding = (20, 5)
-        self.conv_in = ConvBn(
-            num_channels_in=1,
-            num_channels_out=32,
-            kernel_size=self.filter_size,
-            stride=self.stride,
-            padding=self.padding,
-            act='brelu', )
-
-        out_channel = 32
-        self.conv_stack = nn.LayerList([
-            ConvBn(
-                num_channels_in=32,
-                num_channels_out=out_channel,
-                kernel_size=(21, 11),
-                stride=(2, 1),
-                padding=(10, 5),
-                act='brelu') for i in range(num_stacks - 1)
-        ])
-
-        # conv output feat_dim
-        output_height = (feat_size - 1) // 2 + 1
-        for i in range(self.num_stacks - 1):
-            output_height = (output_height - 1) // 2 + 1
-        self.output_height = out_channel * output_height
-
-    def forward(self, x, x_len):
-        """
-        x: shape [B, C, D, T]
-        x_len : shape [B]
-        """
-        x, x_len = self.conv_in(x, x_len)
-        for i, conv in enumerate(self.conv_stack):
-            x, x_len = conv(x, x_len)
-        return x, x_len
-
-
-class RNNCell(nn.RNNCellBase):
-    r"""
-    Elman RNN (SimpleRNN) cell. Given the inputs and previous states, it 
-    computes the outputs and updates states.
-    The formula used is as follows:
-    .. math::
-        h_{t} & = act(x_{t} + b_{ih} + W_{hh}h_{t-1} + b_{hh})
-        y_{t} & = h_{t}
-    
-    where :math:`act` is for :attr:`activation`.
-    """
-
-    def __init__(self,
-                 hidden_size,
-                 activation="tanh",
-                 weight_ih_attr=None,
-                 weight_hh_attr=None,
-                 bias_ih_attr=None,
-                 bias_hh_attr=None,
-                 name=None):
-        super().__init__()
-        std = 1.0 / math.sqrt(hidden_size)
-        self.weight_hh = self.create_parameter(
-            (hidden_size, hidden_size),
-            weight_hh_attr,
-            default_initializer=I.Uniform(-std, std))
-        self.bias_ih = self.create_parameter(
-            (hidden_size, ),
-            bias_ih_attr,
-            is_bias=True,
-            default_initializer=I.Uniform(-std, std))
-        self.bias_hh = self.create_parameter(
-            (hidden_size, ),
-            bias_hh_attr,
-            is_bias=True,
-            default_initializer=I.Uniform(-std, std))
-
-        self.hidden_size = hidden_size
-        if activation not in ["tanh", "relu", "brelu"]:
-            raise ValueError(
-                "activation for SimpleRNNCell should be tanh or relu, "
-                "but get {}".format(activation))
-        self.activation = activation
-        self._activation_fn = paddle.tanh \
-            if activation == "tanh" \
-            else F.relu
-        if activation == 'brelu':
-            self._activation_fn = brelu
-
-    def forward(self, inputs, states=None):
-        if states is None:
-            states = self.get_initial_states(inputs, self.state_shape)
-        pre_h = states
-        i2h = inputs
-        if self.bias_ih is not None:
-            i2h += self.bias_ih
-        h2h = paddle.matmul(pre_h, self.weight_hh, transpose_y=True)
-        if self.bias_hh is not None:
-            h2h += self.bias_hh
-        h = self._activation_fn(i2h + h2h)
-        return h, h
-
-    @property
-    def state_shape(self):
-        return (self.hidden_size, )
-
-
-class GRUCellShare(nn.RNNCellBase):
-    r"""
-    Gated Recurrent Unit (GRU) RNN cell. Given the inputs and previous states, 
-    it computes the outputs and updates states.
-    The formula for GRU used is as follows:
-    ..  math::
-        r_{t} & = \sigma(W_{ir}x_{t} + b_{ir} + W_{hr}h_{t-1} + b_{hr})
-        z_{t} & = \sigma(W_{iz}x_{t} + b_{iz} + W_{hz}h_{t-1} + b_{hz})
-        \widetilde{h}_{t} & = \tanh(W_{ic}x_{t} + b_{ic} + r_{t} * (W_{hc}h_{t-1} + b_{hc}))
-        h_{t} & = z_{t} * h_{t-1} + (1 - z_{t}) * \widetilde{h}_{t}
-        y_{t} & = h_{t}
-    
-    where :math:`\sigma` is the sigmoid fucntion, and * is the elemetwise 
-    multiplication operator.
-    """
-
-    def __init__(self,
-                 input_size,
-                 hidden_size,
-                 weight_ih_attr=None,
-                 weight_hh_attr=None,
-                 bias_ih_attr=None,
-                 bias_hh_attr=None,
-                 name=None):
-        super().__init__()
-        std = 1.0 / math.sqrt(hidden_size)
-        self.weight_hh = self.create_parameter(
-            (3 * hidden_size, hidden_size),
-            weight_hh_attr,
-            default_initializer=I.Uniform(-std, std))
-        self.bias_ih = self.create_parameter(
-            (3 * hidden_size, ),
-            bias_ih_attr,
-            is_bias=True,
-            default_initializer=I.Uniform(-std, std))
-        self.bias_hh = self.create_parameter(
-            (3 * hidden_size, ),
-            bias_hh_attr,
-            is_bias=True,
-            default_initializer=I.Uniform(-std, std))
-
-        self.hidden_size = hidden_size
-        self.input_size = input_size
-        self._gate_activation = F.sigmoid
-        self._activation = paddle.tanh
-
-    def forward(self, inputs, states=None):
-        if states is None:
-            states = self.get_initial_states(inputs, self.state_shape)
-
-        pre_hidden = states
-        x_gates = inputs
-        if self.bias_ih is not None:
-            x_gates = x_gates + self.bias_ih
-        h_gates = paddle.matmul(pre_hidden, self.weight_hh, transpose_y=True)
-        if self.bias_hh is not None:
-            h_gates = h_gates + self.bias_hh
-
-        x_r, x_z, x_c = paddle.split(x_gates, num_or_sections=3, axis=1)
-        h_r, h_z, h_c = paddle.split(h_gates, num_or_sections=3, axis=1)
-
-        r = self._gate_activation(x_r + h_r)
-        z = self._gate_activation(x_z + h_z)
-        c = self._activation(x_c + r * h_c)  # apply reset gate after mm
-        h = (pre_hidden - c) * z + c
-
-        return h, h
-
-    @property
-    def state_shape(self):
-        r"""
-        The `state_shape` of GRUCell is a shape `[hidden_size]` (-1 for batch
-        size would be automatically inserted into shape). The shape corresponds
-        to the shape of :math:`h_{t-1}`.
-        """
-        return (self.hidden_size, )
-
-
-class BiRNNWithBN(nn.Layer):
-    """Bidirectonal simple rnn layer with sequence-wise batch normalization.
-    The batch normalization is only performed on input-state weights.
-
-    :param name: Name of the layer parameters.
-    :type name: string
-    :param size: Dimension of RNN cells.
-    :type size: int
-    :param share_weights: Whether to share input-hidden weights between
-                          forward and backward directional RNNs.
-    :type share_weights: bool
-    :return: Bidirectional simple rnn layer.
-    :rtype: Variable
-    """
-
-    def __init__(self, i_size, h_size, share_weights):
-        super().__init__()
-        self.share_weights = share_weights
-        self.pad_value = paddle.to_tensor(np.array([0.0], dtype=np.float32))
-        if self.share_weights:
-            #input-hidden weights shared between bi-directional rnn.
-            self.fw_fc = nn.Linear(i_size, h_size)
-            # batch norm is only performed on input-state projection
-            self.fw_bn = nn.BatchNorm1D(h_size, data_format='NLC')
-            self.bw_fc = self.fw_fc
-            self.bw_bn = self.fw_bn
-        else:
-            self.fw_fc = nn.Linear(i_size, h_size)
-            self.fw_bn = nn.BatchNorm1D(h_size, data_format='NLC')
-            self.bw_fc = nn.Linear(i_size, h_size)
-            self.bw_bn = nn.BatchNorm1D(h_size, data_format='NLC')
-
-        self.fw_cell = RNNCell(hidden_size=h_size, activation='relu')
-        self.bw_cell = RNNCell(
-            hidden_size=h_size,
-            activation='relu', )
-        self.fw_rnn = nn.RNN(
-            self.fw_cell, is_reverse=False, time_major=False)  #[B, T, D]
-        self.bw_rnn = nn.RNN(
-            self.fw_cell, is_reverse=True, time_major=False)  #[B, T, D]
-
-    def forward(self, x, x_len):
-        # x, shape [B, T, D]
-        fw_x = self.fw_bn(self.fw_fc(x))
-        bw_x = self.bw_bn(self.bw_fc(x))
-        fw_x, _ = self.fw_rnn(inputs=fw_x, sequence_length=x_len)
-        bw_x, _ = self.bw_rnn(inputs=bw_x, sequence_length=x_len)
-        x = paddle.concat([fw_x, bw_x], axis=-1)
-        return x, x_len
-
-
-class BiGRUWithBN(nn.Layer):
-    """Bidirectonal gru layer with sequence-wise batch normalization.
-    The batch normalization is only performed on input-state weights.
-
-    :param name: Name of the layer.
-    :type name: string
-    :param input: Input layer.
-    :type input: Variable
-    :param size: Dimension of GRU cells.
-    :type size: int
-    :param act: Activation type.
-    :type act: string
-    :return: Bidirectional GRU layer.
-    :rtype: Variable
-    """
-
-    def __init__(self, i_size, h_size, act):
-        super().__init__()
-        hidden_size = h_size * 3
-        self.fw_fc = nn.Linear(i_size, hidden_size)
-        self.fw_bn = nn.BatchNorm1D(hidden_size, data_format='NLC')
-        self.bw_fc = nn.Linear(i_size, hidden_size)
-        self.bw_bn = nn.BatchNorm1D(hidden_size, data_format='NLC')
-
-        self.fw_cell = GRUCellShare(input_size=hidden_size, hidden_size=h_size)
-        self.bw_cell = GRUCellShare(input_size=hidden_size, hidden_size=h_size)
-        self.fw_rnn = nn.RNN(
-            self.fw_cell, is_reverse=False, time_major=False)  #[B, T, D]
-        self.bw_rnn = nn.RNN(
-            self.fw_cell, is_reverse=True, time_major=False)  #[B, T, D]
-
-    def forward(self, x, x_len):
-        # x, shape [B, T, D]
-        fw_x = self.fw_bn(self.fw_fc(x))
-        bw_x = self.bw_bn(self.bw_fc(x))
-        fw_x, _ = self.fw_rnn(inputs=fw_x, sequence_length=x_len)
-        bw_x, _ = self.bw_rnn(inputs=bw_x, sequence_length=x_len)
-        x = paddle.concat([fw_x, bw_x], axis=-1)
-        return x, x_len
-
-
-class RNNStack(nn.Layer):
-    """RNN group with stacked bidirectional simple RNN or GRU layers.
-
-    :param input: Input layer.
-    :type input: Variable
-    :param size: Dimension of RNN cells in each layer.
-    :type size: int
-    :param num_stacks: Number of stacked rnn layers.
-    :type num_stacks: int
-    :param use_gru: Use gru if set True. Use simple rnn if set False.
-    :type use_gru: bool
-    :param share_rnn_weights: Whether to share input-hidden weights between
-                              forward and backward directional RNNs.
-                              It is only available when use_gru=False.
-    :type share_weights: bool
-    :return: Output layer of the RNN group.
-    :rtype: Variable
-    """
-
-    def __init__(self, i_size, h_size, num_stacks, use_gru, share_rnn_weights):
-        super().__init__()
-        self.rnn_stacks = nn.LayerList()
-        for i in range(num_stacks):
-            if use_gru:
-                #default:GRU using tanh
-                self.rnn_stacks.append(
-                    BiGRUWithBN(i_size=i_size, h_size=h_size, act="relu"))
-            else:
-                self.rnn_stacks.append(
-                    BiRNNWithBN(
-                        i_size=i_size,
-                        h_size=h_size,
-                        share_weights=share_rnn_weights))
-            i_size = h_size * 2
-
-    def forward(self, x, x_len):
-        """
-        x: shape [B, T, D]
-        x_len: shpae [B]
-        """
-        for i, rnn in enumerate(self.rnn_stacks):
-            x, x_len = rnn(x, x_len)
-        return x, x_len
-
-
-class DeepSpeech2(nn.Layer):
-    """The DeepSpeech2 network structure.
-
-    :param audio_data: Audio spectrogram data layer.
-    :type audio_data: Variable
-    :param text_data: Transcription text data layer.
-    :type text_data: Variable
-    :param audio_len: Valid sequence length data layer.
-    :type audio_len: Variable
-    :param masks: Masks data layer to reset padding.
-    :type masks: Variable
-    :param dict_size: Dictionary size for tokenized transcription.
-    :type dict_size: int
-    :param num_conv_layers: Number of stacking convolution layers.
-    :type num_conv_layers: int
-    :param num_rnn_layers: Number of stacking RNN layers.
-    :type num_rnn_layers: int
-    :param rnn_size: RNN layer size (dimension of RNN cells).
-    :type rnn_size: int
-    :param use_gru: Use gru if set True. Use simple rnn if set False.
-    :type use_gru: bool
-    :param share_rnn_weights: Whether to share input-hidden weights between
-                              forward and backward direction RNNs.
-                              It is only available when use_gru=False.
-    :type share_weights: bool
-    :return: A tuple of an output unnormalized log probability layer (
-             before softmax) and a ctc cost layer.
-    :rtype: tuple of LayerOutput    
-    """
-
-    def __init__(self,
-                 feat_size,
-                 dict_size,
-                 num_conv_layers=2,
-                 num_rnn_layers=3,
-                 rnn_size=256,
-                 use_gru=False,
-                 share_rnn_weights=True):
-        super().__init__()
-        self.feat_size = feat_size  # 161 for linear
-        self.dict_size = dict_size
-
-        self.conv = ConvStack(feat_size, num_conv_layers)
-
-        i_size = self.conv.output_height  # H after conv stack
-        self.rnn = RNNStack(
-            i_size=i_size,
-            h_size=rnn_size,
-            num_stacks=num_rnn_layers,
-            use_gru=use_gru,
-            share_rnn_weights=share_rnn_weights)
-        self.fc = nn.Linear(rnn_size * 2, dict_size + 1)
-
-    def predict(self, audio, audio_len):
-        # [B, D, T] -> [B, C=1, D, T]
-        audio = audio.unsqueeze(1)
-
-        # convolution group
-        x, audio_len = self.conv(audio, audio_len)
-
-        # convert data from convolution feature map to sequence of vectors
-        B, C, D, T = paddle.shape(x)
-        x = x.transpose([0, 3, 1, 2])  #[B, T, C, D]
-        x = x.reshape([B, T, C * D])  #[B, T, C*D]
-
-        # remove padding part
-        x, audio_len = self.rnn(x, audio_len)  #[B, T, D]
-
-        logits = self.fc(x)  #[B, T, V + 1]
-
-        #ctcdecoder need probs, not log_probs
-        probs = F.softmax(logits)
-
-        return logits, probs
-
-    @paddle.no_grad()
-    def infer(self, audio, audio_len):
-        _, probs = self.predict(audio, audio_len)
-        return probs
-
-    def forward(self, audio, text, audio_len, text_len):
-        """
-        audio: shape [B, D, T]
-        text: shape [B, T]
-        audio_len: shape [B]
-        text_len: shape [B]
-        """
-        logits, probs = self.predict(audio, audio_len)
-        print(logits.shape)
-        print(text.shape)
-        print(audio_len.shape)
-        print(text_len.shape)
-        return logits
-
-
-class DeepSpeechLoss(nn.Layer):
-    def __init__(self, vocab_size):
-        super().__init__()
-        self.loss = nn.CTCLoss(blank=vocab_size, reduction='none')
-
-    def forward(self, logits, text, audio_len, text_len):
-        # warp-ctc do softmax on activations
-        # warp-ctc need activation with shape [T, B, V + 1]
-        logits = logits.transpose([1, 0, 2])
-
-        ctc_loss = self.loss(logits, text, audio_len, text_len)
-        ctc_loss /= text_len  # norm_by_times
-        ctc_loss = ctc_loss.sum()
-        return ctc_loss

model_utils/trainer.py

@@ -0,0 +1,279 @@
+# 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.
+
+import time
+import logging
+from pathlib import Path
+import numpy as np
+import paddle
+from paddle import distributed as dist
+from paddle.io import DataLoader, DistributedBatchSampler
+from tensorboardX import SummaryWriter
+from collections import defaultdict
+
+import parakeet
+from parakeet.utils import checkpoint, mp_tools
+
+__all__ = ["ExperimentBase"]
+
+
+class ExperimentBase(object):
+    """
+    An experiment template in order to structure the training code and take 
+    care of saving, loading, logging, visualization stuffs. It's intended to 
+    be flexible and simple. 
+    
+    So it only handles output directory (create directory for the output, 
+    create a checkpoint directory, dump the config in use and create 
+    visualizer and logger) in a standard way without enforcing any
+    input-output protocols to the model and dataloader. It leaves the main 
+    part for the user to implement their own (setup the model, criterion, 
+    optimizer, define a training step, define a validation function and 
+    customize all the text and visual logs).
+    It does not save too much boilerplate code. The users still have to write 
+    the forward/backward/update mannually, but they are free to add 
+    non-standard behaviors if needed.
+    We have some conventions to follow.
+    1. Experiment should have ``model``, ``optimizer``, ``train_loader`` and 
+    ``valid_loader``, ``config`` and ``args`` attributes.
+    2. The config should have a ``training`` field, which has 
+    ``valid_interval``, ``save_interval`` and ``max_iteration`` keys. It is 
+    used as the trigger to invoke validation, checkpointing and stop of the 
+    experiment.
+    3. There are four methods, namely ``train_batch``, ``valid``, 
+    ``setup_model`` and ``setup_dataloader`` that should be implemented.
+    Feel free to add/overwrite other methods and standalone functions if you 
+    need.
+    
+    Parameters
+    ----------
+    config: yacs.config.CfgNode
+        The configuration used for the experiment.
+    
+    args: argparse.Namespace
+        The parsed command line arguments.
+    Examples
+    --------
+    >>> def main_sp(config, args):
+    >>>     exp = Experiment(config, args)
+    >>>     exp.setup()
+    >>>     exp.run()
+    >>> 
+    >>> config = get_cfg_defaults()
+    >>> parser = default_argument_parser()
+    >>> args = parser.parse_args()
+    >>> if args.config: 
+    >>>     config.merge_from_file(args.config)
+    >>> if args.opts:
+    >>>     config.merge_from_list(args.opts)
+    >>> config.freeze()
+    >>> 
+    >>> if args.nprocs > 1 and args.device == "gpu":
+    >>>     dist.spawn(main_sp, args=(config, args), nprocs=args.nprocs)
+    >>> else:
+    >>>     main_sp(config, args)
+    """
+
+    def __init__(self, config, args):
+        self.config = config
+        self.args = args
+
+    def setup(self):
+        """Setup the experiment.
+        """
+        paddle.set_device(self.args.device)
+        if self.parallel:
+            self.init_parallel()
+
+        self.setup_output_dir()
+        self.dump_config()
+        self.setup_visualizer()
+        self.setup_logger()
+        self.setup_checkpointer()
+
+        self.setup_dataloader()
+        self.setup_model()
+
+        self.iteration = 0
+        self.epoch = 0
+
+    @property
+    def parallel(self):
+        """A flag indicating whether the experiment should run with 
+        multiprocessing.
+        """
+        return self.args.device == "gpu" and self.args.nprocs > 1
+
+    def init_parallel(self):
+        """Init environment for multiprocess training.
+        """
+        dist.init_parallel_env()
+
+    def save(self):
+        """Save checkpoint (model parameters and optimizer states).
+        """
+        checkpoint.save_parameters(self.checkpoint_dir, self.iteration,
+                                   self.model, self.optimizer)
+
+    def load_or_resume(self):
+        """Resume from latest checkpoint at checkpoints in the output 
+        directory or load a specified checkpoint.
+        
+        If ``args.checkpoint_path`` is not None, load the checkpoint, else
+        resume training.
+        """
+        iteration = checkpoint.load_parameters(
+            self.model,
+            self.optimizer,
+            checkpoint_dir=self.checkpoint_dir,
+            checkpoint_path=self.args.checkpoint_path)
+        self.iteration = iteration
+
+    def read_batch(self):
+        """Read a batch from the train_loader.
+        Returns
+        -------
+        List[Tensor]
+            A batch.
+        """
+        try:
+            batch = next(self.iterator)
+        except StopIteration:
+            self.new_epoch()
+            batch = next(self.iterator)
+        return batch
+
+    def new_epoch(self):
+        """Reset the train loader and increment ``epoch``.
+        """
+        self.epoch += 1
+        if self.parallel:
+            self.train_loader.batch_sampler.set_epoch(self.epoch)
+        self.iterator = iter(self.train_loader)
+
+    def train(self):
+        """The training process.
+        
+        It includes forward/backward/update and periodical validation and 
+        saving.
+        """
+        self.new_epoch()
+        while self.iteration < self.config.training.max_iteration:
+            self.iteration += 1
+            self.train_batch()
+
+            if self.iteration % self.config.training.valid_interval == 0:
+                self.valid()
+
+            if self.iteration % self.config.training.save_interval == 0:
+                self.save()
+
+    def run(self):
+        """The routine of the experiment after setup. This method is intended
+        to be used by the user.
+        """
+        self.load_or_resume()
+        try:
+            self.train()
+        except KeyboardInterrupt:
+            self.save()
+            exit(-1)
+
+    @mp_tools.rank_zero_only
+    def setup_output_dir(self):
+        """Create a directory used for output.
+        """
+        # output dir
+        output_dir = Path(self.args.output).expanduser()
+        output_dir.mkdir(parents=True, exist_ok=True)
+
+        self.output_dir = output_dir
+
+    @mp_tools.rank_zero_only
+    def setup_checkpointer(self):
+        """Create a directory used to save checkpoints into.
+        
+        It is "checkpoints" inside the output directory.
+        """
+        # checkpoint dir
+        checkpoint_dir = self.output_dir / "checkpoints"
+        checkpoint_dir.mkdir(exist_ok=True)
+
+        self.checkpoint_dir = checkpoint_dir
+
+    @mp_tools.rank_zero_only
+    def setup_visualizer(self):
+        """Initialize a visualizer to log the experiment.
+        
+        The visual log is saved in the output directory.
+        
+        Notes
+        ------
+        Only the main process has a visualizer with it. Use multiple 
+        visualizers in multiprocess to write to a same log file may cause 
+        unexpected behaviors.
+        """
+        # visualizer
+        visualizer = SummaryWriter(logdir=str(self.output_dir))
+
+        self.visualizer = visualizer
+
+    def setup_logger(self):
+        """Initialize a text logger to log the experiment.
+        
+        Each process has its own text logger. The logging message is write to 
+        the standard output and a text file named ``worker_n.log`` in the 
+        output directory, where ``n`` means the rank of the process. 
+        """
+        logger = logging.getLogger(__name__)
+        logger.setLevel("INFO")
+        logger.addHandler(logging.StreamHandler())
+        log_file = self.output_dir / 'worker_{}.log'.format(dist.get_rank())
+        logger.addHandler(logging.FileHandler(str(log_file)))
+
+        self.logger = logger
+
+    @mp_tools.rank_zero_only
+    def dump_config(self):
+        """Save the configuration used for this experiment. 
+        
+        It is saved in to ``config.yaml`` in the output directory at the 
+        beginning of the experiment.
+        """
+        with open(self.output_dir / "config.yaml", 'wt') as f:
+            print(self.config, file=f)
+
+    def train_batch(self):
+        """The training loop. A subclass should implement this method.
+        """
+        raise NotImplementedError("train_batch should be implemented.")
+
+    @mp_tools.rank_zero_only
+    @paddle.no_grad()
+    def valid(self):
+        """The validation. A subclass should implement this method.
+        """
+        raise NotImplementedError("valid should be implemented.")
+
+    def setup_model(self):
+        """Setup model, criterion and optimizer, etc. A subclass should 
+        implement this method.
+        """
+        raise NotImplementedError("setup_model should be implemented.")
+
+    def setup_dataloader(self):
+        """Setup training dataloader and validation dataloader. A subclass 
+        should implement this method.
+        """
+        raise NotImplementedError("setup_dataloader should be implemented.")

training/__init__.py

@@ -0,0 +1,15 @@
+# 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.
+
+from training.trainer import *

training/trainer.py

@@ -0,0 +1,279 @@
+# 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.
+
+import time
+import logging
+from pathlib import Path
+import numpy as np
+from collections import defaultdict
+
+import paddle
+from paddle import distributed as dist
+from tensorboardX import SummaryWriter
+
+from utils import checkpoint
+from utils import mp_tools
+
+__all__ = ["Trainer"]
+
+
+class Trainer():
+    """
+    An experiment template in order to structure the training code and take 
+    care of saving, loading, logging, visualization stuffs. It's intended to 
+    be flexible and simple. 
+    
+    So it only handles output directory (create directory for the output, 
+    create a checkpoint directory, dump the config in use and create 
+    visualizer and logger) in a standard way without enforcing any
+    input-output protocols to the model and dataloader. It leaves the main 
+    part for the user to implement their own (setup the model, criterion, 
+    optimizer, define a training step, define a validation function and 
+    customize all the text and visual logs).
+    It does not save too much boilerplate code. The users still have to write 
+    the forward/backward/update mannually, but they are free to add 
+    non-standard behaviors if needed.
+    We have some conventions to follow.
+    1. Experiment should have ``model``, ``optimizer``, ``train_loader`` and 
+    ``valid_loader``, ``config`` and ``args`` attributes.
+    2. The config should have a ``training`` field, which has 
+    ``valid_interval``, ``save_interval`` and ``max_iteration`` keys. It is 
+    used as the trigger to invoke validation, checkpointing and stop of the 
+    experiment.
+    3. There are four methods, namely ``train_batch``, ``valid``, 
+    ``setup_model`` and ``setup_dataloader`` that should be implemented.
+    Feel free to add/overwrite other methods and standalone functions if you 
+    need.
+    
+    Parameters
+    ----------
+    config: yacs.config.CfgNode
+        The configuration used for the experiment.
+    
+    args: argparse.Namespace
+        The parsed command line arguments.
+    Examples
+    --------
+    >>> def main_sp(config, args):
+    >>>     exp = Trainer(config, args)
+    >>>     exp.setup()
+    >>>     exp.run()
+    >>> 
+    >>> config = get_cfg_defaults()
+    >>> parser = default_argument_parser()
+    >>> args = parser.parse_args()
+    >>> if args.config: 
+    >>>     config.merge_from_file(args.config)
+    >>> if args.opts:
+    >>>     config.merge_from_list(args.opts)
+    >>> config.freeze()
+    >>> 
+    >>> if args.nprocs > 1 and args.device == "gpu":
+    >>>     dist.spawn(main_sp, args=(config, args), nprocs=args.nprocs)
+    >>> else:
+    >>>     main_sp(config, args)
+    """
+
+    def __init__(self, config, args):
+        self.config = config
+        self.args = args
+
+    def setup(self):
+        """Setup the experiment.
+        """
+        paddle.set_device(self.args.device)
+        if self.parallel:
+            self.init_parallel()
+
+        self.setup_output_dir()
+        self.dump_config()
+        self.setup_visualizer()
+        self.setup_logger()
+        self.setup_checkpointer()
+
+        self.setup_dataloader()
+        self.setup_model()
+
+        self.iteration = 0
+        self.epoch = 0
+
+    @property
+    def parallel(self):
+        """A flag indicating whether the experiment should run with 
+        multiprocessing.
+        """
+        return self.args.device == "gpu" and self.args.nprocs > 1
+
+    def init_parallel(self):
+        """Init environment for multiprocess training.
+        """
+        dist.init_parallel_env()
+
+    def save(self):
+        """Save checkpoint (model parameters and optimizer states).
+        """
+        checkpoint.save_parameters(self.checkpoint_dir, self.iteration,
+                                   self.model, self.optimizer)
+
+    def resume_or_load(self):
+        """Resume from latest checkpoint at checkpoints in the output 
+        directory or load a specified checkpoint.
+        
+        If ``args.checkpoint_path`` is not None, load the checkpoint, else
+        resume training.
+        """
+        iteration = checkpoint.load_parameters(
+            self.model,
+            self.optimizer,
+            checkpoint_dir=self.checkpoint_dir,
+            checkpoint_path=self.args.checkpoint_path)
+        self.iteration = iteration
+
+    def read_batch(self):
+        """Read a batch from the train_loader.
+        Returns
+        -------
+        List[Tensor]
+            A batch.
+        """
+        try:
+            batch = next(self.iterator)
+        except StopIteration:
+            self.new_epoch()
+            batch = next(self.iterator)
+        return batch
+
+    def new_epoch(self):
+        """Reset the train loader and increment ``epoch``.
+        """
+        self.epoch += 1
+        if self.parallel:
+            self.train_loader.batch_sampler.set_epoch(self.epoch)
+        self.iterator = iter(self.train_loader)
+
+    def train(self):
+        """The training process.
+        
+        It includes forward/backward/update and periodical validation and 
+        saving.
+        """
+        self.new_epoch()
+        while self.iteration < self.config.training.max_iteration:
+            self.iteration += 1
+            self.train_batch()
+
+            if self.iteration % self.config.training.valid_interval == 0:
+                self.valid()
+
+            if self.iteration % self.config.training.save_interval == 0:
+                self.save()
+
+    def run(self):
+        """The routine of the experiment after setup. This method is intended
+        to be used by the user.
+        """
+        self.resume_or_load()
+        try:
+            self.train()
+        except KeyboardInterrupt:
+            self.save()
+            exit(-1)
+
+    @mp_tools.rank_zero_only
+    def setup_output_dir(self):
+        """Create a directory used for output.
+        """
+        # output dir
+        output_dir = Path(self.args.output).expanduser()
+        output_dir.mkdir(parents=True, exist_ok=True)
+
+        self.output_dir = output_dir
+
+    @mp_tools.rank_zero_only
+    def setup_checkpointer(self):
+        """Create a directory used to save checkpoints into.
+        
+        It is "checkpoints" inside the output directory.
+        """
+        # checkpoint dir
+        checkpoint_dir = self.output_dir / "checkpoints"
+        checkpoint_dir.mkdir(exist_ok=True)
+
+        self.checkpoint_dir = checkpoint_dir
+
+    @mp_tools.rank_zero_only
+    def setup_visualizer(self):
+        """Initialize a visualizer to log the experiment.
+        
+        The visual log is saved in the output directory.
+        
+        Notes
+        ------
+        Only the main process has a visualizer with it. Use multiple 
+        visualizers in multiprocess to write to a same log file may cause 
+        unexpected behaviors.
+        """
+        # visualizer
+        visualizer = SummaryWriter(logdir=str(self.output_dir))
+
+        self.visualizer = visualizer
+
+    def setup_logger(self):
+        """Initialize a text logger to log the experiment.
+        
+        Each process has its own text logger. The logging message is write to 
+        the standard output and a text file named ``worker_n.log`` in the 
+        output directory, where ``n`` means the rank of the process. 
+        """
+        logger = logging.getLogger(__name__)
+        logger.setLevel("INFO")
+        logger.addHandler(logging.StreamHandler())
+        log_file = self.output_dir / 'worker_{}.log'.format(dist.get_rank())
+        logger.addHandler(logging.FileHandler(str(log_file)))
+
+        self.logger = logger
+
+    @mp_tools.rank_zero_only
+    def dump_config(self):
+        """Save the configuration used for this experiment. 
+        
+        It is saved in to ``config.yaml`` in the output directory at the 
+        beginning of the experiment.
+        """
+        with open(self.output_dir / "config.yaml", 'wt') as f:
+            print(self.config, file=f)
+
+    def train_batch(self):
+        """The training loop. A subclass should implement this method.
+        """
+        raise NotImplementedError("train_batch should be implemented.")
+
+    @mp_tools.rank_zero_only
+    @paddle.no_grad()
+    def valid(self):
+        """The validation. A subclass should implement this method.
+        """
+        raise NotImplementedError("valid should be implemented.")
+
+    def setup_model(self):
+        """Setup model, criterion and optimizer, etc. A subclass should 
+        implement this method.
+        """
+        raise NotImplementedError("setup_model should be implemented.")
+
+    def setup_dataloader(self):
+        """Setup training dataloader and validation dataloader. A subclass 
+        should implement this method.
+        """
+        raise NotImplementedError("setup_dataloader should be implemented.")

utils/checkpoint.py

@@ -0,0 +1,135 @@
+# 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.
+
+import os
+import time
+import numpy as np
+import paddle
+from paddle import distributed as dist
+from paddle.nn import Layer
+from paddle.optimizer import Optimizer
+
+from utils import mp_tools
+
+__all__ = ["load_parameters", "save_parameters"]
+
+
+def _load_latest_checkpoint(checkpoint_dir: str) -> int:
+    """Get the iteration number corresponding to the latest saved checkpoint.
+    Args:
+        checkpoint_dir (str): the directory where checkpoint is saved.
+    Returns:
+        int: the latest iteration number.
+    """
+    checkpoint_record = os.path.join(checkpoint_dir, "checkpoint")
+    if (not os.path.isfile(checkpoint_record)):
+        return 0
+
+    # Fetch the latest checkpoint index.
+    with open(checkpoint_record, "rt") as handle:
+        latest_checkpoint = handle.readlines()[-1].strip()
+        step = latest_checkpoint.split(":")[-1]
+        iteration = int(step.split("-")[-1])
+
+    return iteration
+
+
+def _save_checkpoint(checkpoint_dir: str, iteration: int):
+    """Save the iteration number of the latest model to be checkpointed.
+    Args:
+        checkpoint_dir (str): the directory where checkpoint is saved.
+        iteration (int): the latest iteration number.
+    Returns:
+        None
+    """
+    checkpoint_record = os.path.join(checkpoint_dir, "checkpoint")
+    # Update the latest checkpoint index.
+    with open(checkpoint_record, "a+") as handle:
+        handle.write("model_checkpoint_path:step-{}\n".format(iteration))
+
+
+def load_parameters(model,
+                    optimizer=None,
+                    checkpoint_dir=None,
+                    checkpoint_path=None):
+    """Load a specific model checkpoint from disk. 
+    Args:
+        model (Layer): model to load parameters.
+        optimizer (Optimizer, optional): optimizer to load states if needed.
+            Defaults to None.
+        checkpoint_dir (str, optional): the directory where checkpoint is saved.
+        checkpoint_path (str, optional): if specified, load the checkpoint
+            stored in the checkpoint_path and the argument 'checkpoint_dir' will 
+            be ignored. Defaults to None. 
+    Returns:
+        iteration (int): number of iterations that the loaded checkpoint has 
+            been trained.
+    """
+    if checkpoint_path is not None:
+        iteration = int(os.path.basename(checkpoint_path).split("-")[-1])
+    elif checkpoint_dir is not None:
+        iteration = _load_latest_checkpoint(checkpoint_dir)
+        if iteration == 0:
+            return iteration
+        checkpoint_path = os.path.join(checkpoint_dir,
+                                       "step-{}".format(iteration))
+    else:
+        raise ValueError(
+            "At least one of 'checkpoint_dir' and 'checkpoint_path' should be specified!"
+        )
+
+    rank = dist.get_rank()
+
+    params_path = checkpoint_path + ".pdparams"
+    model_dict = paddle.load(params_path)
+    model.set_state_dict(model_dict)
+    print(
+        "[checkpoint] Rank {}: loaded model from {}".format(rank, params_path))
+
+    optimizer_path = checkpoint_path + ".pdopt"
+    if optimizer and os.path.isfile(optimizer_path):
+        optimizer_dict = paddle.load(optimizer_path)
+        optimizer.set_state_dict(optimizer_dict)
+        print("[checkpoint] Rank {}: loaded optimizer state from {}".format(
+            rank, optimizer_path))
+
+    return iteration
+
+
+@mp_tools.rank_zero_only
+def save_parameters(checkpoint_dir, iteration, model, optimizer=None):
+    """Checkpoint the latest trained model parameters.
+    Args:
+        checkpoint_dir (str): the directory where checkpoint is saved.
+        iteration (int): the latest iteration number.
+        model (Layer): model to be checkpointed.
+        optimizer (Optimizer, optional): optimizer to be checkpointed.
+            Defaults to None.
+    Returns:
+        None
+    """
+    checkpoint_path = os.path.join(checkpoint_dir, "step-{}".format(iteration))
+
+    model_dict = model.state_dict()
+    params_path = checkpoint_path + ".pdparams"
+    paddle.save(model_dict, params_path)
+    print("[checkpoint] Saved model to {}".format(params_path))
+
+    if optimizer:
+        opt_dict = optimizer.state_dict()
+        optimizer_path = checkpoint_path + ".pdopt"
+        paddle.save(opt_dict, optimizer_path)
+        print("[checkpoint] Saved optimzier state to {}".format(optimizer_path))
+
+    _save_checkpoint(checkpoint_dir, iteration)

utils/error_rate.py

@@ -14,9 +14,10 @@
 """This module provides functions to calculate error rate in different level.
 e.g. wer for word-level, cer for char-level.
 """
-
 import numpy as np
 
+__all__ = ['word_errors', 'char_errors', 'wer', 'cer']
+
 
 def _levenshtein_distance(ref, hyp):
     """Levenshtein distance is a string metric for measuring the difference

utils/model_check.py

@@ -38,12 +38,12 @@ def check_version():
     Log error and exit when the installed version of paddlepaddle is
     not satisfied.
     """
-    err = "PaddlePaddle version 1.6 or higher is required, " \
+    err = "PaddlePaddle version 2.0.0 or higher is required, " \
           "or a suitable develop version is satisfied as well. \n" \
           "Please make sure the version is good with your code." \
 
     try:
-        fluid.require_version('1.6.0')
+        fluid.require_version('2.0.0')
     except Exception as e:
         print(err)
         sys.exit(1)

utils/mp_tools.py

@@ -0,0 +1,32 @@
+# 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.
+
+import paddle
+from paddle import distributed as dist
+from functools import wraps
+
+__all__ = ["rank_zero_only"]
+
+
+def rank_zero_only(func):
+    rank = dist.get_rank()
+
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+        if rank != 0:
+            return
+        result = func(*args, **kwargs)
+        return result
+
+    return wrapper