"""Contains DeepSpeech2 model.""" from __future__ import absolute_import from __future__ import division from __future__ import print_function import sys import os import time import gzip from decoder import * from lm.lm_scorer import LmScorer import paddle.v2 as paddle from layer import * class DeepSpeech2Model(object): """DeepSpeech2Model class. :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 pretrained_model_path: Pretrained model path. If None, will train from stratch. :type pretrained_model_path: basestring|None """ def __init__(self, vocab_size, num_conv_layers, num_rnn_layers, rnn_layer_size, pretrained_model_path): self._create_network(vocab_size, num_conv_layers, num_rnn_layers, rnn_layer_size) self._create_parameters(pretrained_model_path) self._inferer = None self._loss_inferer = None self._ext_scorer = None def train(self, train_batch_reader, dev_batch_reader, feeding_dict, learning_rate, gradient_clipping, num_passes, output_model_dir, is_local=True, num_iterations_print=100): """Train the model. :param train_batch_reader: Train data reader. :type train_batch_reader: callable :param dev_batch_reader: Validation data reader. :type dev_batch_reader: callable :param feeding_dict: Feeding is a map of field name and tuple index of the data that reader returns. :type feeding_dict: dict|list :param learning_rate: Learning rate for ADAM optimizer. :type learning_rate: float :param gradient_clipping: Gradient clipping threshold. :type gradient_clipping: float :param num_passes: Number of training epochs. :type num_passes: int :param num_iterations_print: Number of training iterations for printing a training loss. :type rnn_iteratons_print: int :param is_local: Set to False if running with pserver with multi-nodes. :type is_local: bool :param output_model_dir: Directory for saving the model (every pass). :type output_model_dir: basestring """ # prepare model output directory if not os.path.exists(output_model_dir): os.mkdir(output_model_dir) # prepare optimizer and trainer optimizer = paddle.optimizer.Adam( learning_rate=learning_rate, gradient_clipping_threshold=gradient_clipping) trainer = paddle.trainer.SGD( cost=self._loss, parameters=self._parameters, update_equation=optimizer, is_local=is_local) # create event handler def event_handler(event): global start_time, cost_sum, cost_counter if isinstance(event, paddle.event.EndIteration): cost_sum += event.cost cost_counter += 1 if (event.batch_id + 1) % num_iterations_print == 0: output_model_path = os.path.join(output_model_dir, "params.latest.tar.gz") with gzip.open(output_model_path, 'w') as f: self._parameters.to_tar(f) print("\nPass: %d, Batch: %d, TrainCost: %f" % (event.pass_id, event.batch_id + 1, cost_sum / cost_counter)) cost_sum, cost_counter = 0.0, 0 else: sys.stdout.write('.') sys.stdout.flush() if isinstance(event, paddle.event.BeginPass): start_time = time.time() cost_sum, cost_counter = 0.0, 0 if isinstance(event, paddle.event.EndPass): result = trainer.test( reader=dev_batch_reader, feeding=feeding_dict) output_model_path = os.path.join( output_model_dir, "params.pass-%d.tar.gz" % event.pass_id) with gzip.open(output_model_path, 'w') as f: self._parameters.to_tar(f) print("\n------- Time: %d sec, Pass: %d, ValidationCost: %s" % (time.time() - start_time, event.pass_id, result.cost)) # run train trainer.train( reader=train_batch_reader, event_handler=event_handler, num_passes=num_passes, feeding=feeding_dict) def infer_loss_batch(self, infer_data): """Model inference. Infer the ctc loss for a batch of speech utterances. :param infer_data: List of utterances to infer, with each utterance a tuple of audio features and transcription text (empty string). :type infer_data: list :return: List of ctc loss. :rtype: List of float """ # define inferer if self._loss_inferer == None: self._loss_inferer = paddle.inference.Inference( output_layer=self._loss, parameters=self._parameters) # run inference return self._loss_inferer.infer(input=infer_data) def infer_batch(self, infer_data, decode_method, beam_alpha, beam_beta, beam_size, cutoff_prob, vocab_list, language_model_path, num_processes): """Model inference. Infer the transcription for a batch of speech utterances. :param infer_data: List of utterances to infer, with each utterance consisting of a tuple of audio features and transcription text (empty string). :type infer_data: list :param decode_method: Decoding method name, 'best_path' or 'beam search'. :param decode_method: string :param beam_alpha: Parameter associated with language model. :type beam_alpha: float :param beam_beta: Parameter associated with word count. :type beam_beta: float :param beam_size: Width for Beam search. :type beam_size: int :param cutoff_prob: Cutoff probability in pruning, default 1.0, no pruning. :type cutoff_prob: float :param vocab_list: List of tokens in the vocabulary, for decoding. :type vocab_list: list :param language_model_path: Filepath for language model. :type language_model_path: basestring|None :param num_processes: Number of processes (CPU) for decoder. :type num_processes: int :return: List of transcription texts. :rtype: List of basestring """ # define inferer if self._inferer == None: self._inferer = paddle.inference.Inference( output_layer=self._log_probs, parameters=self._parameters) # run inference infer_results = self._inferer.infer(input=infer_data) num_steps = len(infer_results) // len(infer_data) probs_split = [ infer_results[i * num_steps:(i + 1) * num_steps] for i in xrange(0, len(infer_data)) ] # run decoder results = [] if decode_method == "best_path": # best path decode for i, probs in enumerate(probs_split): output_transcription = ctc_best_path_decoder( probs_seq=probs, vocabulary=vocab_list) results.append(output_transcription) elif decode_method == "beam_search": # initialize external scorer if self._ext_scorer == None: self._ext_scorer = LmScorer(beam_alpha, beam_beta, language_model_path) self._loaded_lm_path = language_model_path else: self._ext_scorer.reset_params(beam_alpha, beam_beta) assert self._loaded_lm_path == language_model_path # beam search decode beam_search_results = ctc_beam_search_decoder_batch( probs_split=probs_split, vocabulary=vocab_list, beam_size=beam_size, blank_id=len(vocab_list), num_processes=num_processes, ext_scoring_func=self._ext_scorer, cutoff_prob=cutoff_prob) results = [result[0][1] for result in beam_search_results] else: raise ValueError("Decoding method [%s] is not supported." % decode_method) return results def _create_parameters(self, model_path=None): """Load or create model parameters.""" if model_path is None: self._parameters = paddle.parameters.create(self._loss) else: self._parameters = paddle.parameters.Parameters.from_tar( gzip.open(model_path)) def _create_network(self, vocab_size, num_conv_layers, num_rnn_layers, rnn_layer_size): """Create data layers and model network.""" # paddle.data_type.dense_array is used for variable batch input. # The size 161 * 161 is only an placeholder value and the real shape # of input batch data will be induced during training. audio_data = paddle.layer.data( name="audio_spectrogram", type=paddle.data_type.dense_array(161 * 161)) text_data = paddle.layer.data( name="transcript_text", type=paddle.data_type.integer_value_sequence(vocab_size)) self._log_probs, self._loss = deep_speech2( audio_data=audio_data, text_data=text_data, dict_size=vocab_size, num_conv_layers=num_conv_layers, num_rnn_layers=num_rnn_layers, rnn_size=rnn_layer_size)