enable lm in multiprocessing decoder & add script for params tuning

decoder.py

@@ -73,7 +73,7 @@ class Scorer(object):
         return len(words)
 
     # execute evaluation
-    def evaluate(self, sentence):
+    def __call__(self, sentence):
         lm = self.language_model_score(sentence)
         word_cnt = self.word_count(sentence)
         score = np.power(lm, self._alpha) \
@@ -84,8 +84,9 @@ class Scorer(object):
 def ctc_beam_search_decoder(probs_seq,
                             beam_size,
                             vocabulary,
+                            blank_id=0,
                             ext_scoring_func=None,
-                            blank_id=0):
+                            nproc=False):
     '''
     Beam search decoder for CTC-trained network, using beam search with width
     beam_size to find many paths to one label, return  beam_size labels in
@@ -107,6 +108,8 @@ def ctc_beam_search_decoder(probs_seq,
     :type external_scoring_function: function
     :param blank_id: id of blank, default 0.
     :type blank_id: int
+    :param nproc: Whether the decoder used in multiprocesses.
+    :type nproc: bool
     :return: Decoding log probability and result string.
     :rtype: list
 
@@ -122,6 +125,12 @@ def ctc_beam_search_decoder(probs_seq,
     if not blank_id < probs_dim:
         raise ValueError("blank_id shouldn't be greater than probs dimension")
 
+    # If the decoder called in the multiprocesses, then use the global scorer
+    # instantiated in ctc_beam_search_decoder_nproc().
+    if nproc is True:
+        global ext_nproc_scorer
+        ext_scoring_func = ext_nproc_scorer
+
     ## initialize
     # the set containing selected prefixes
     prefix_set_prev = {'\t': 1.0}
@@ -193,8 +202,8 @@ def ctc_beam_search_decoder(probs_seq,
 def ctc_beam_search_decoder_nproc(probs_split,
                                   beam_size,
                                   vocabulary,
-                                  ext_scoring_func=None,
                                   blank_id=0,
+                                  ext_scoring_func=None,
                                   num_processes=None):
     '''
     Beam search decoder using multiple processes.
@@ -202,7 +211,6 @@ def ctc_beam_search_decoder_nproc(probs_split,
     :param probs_seq: 3-D list with length batch_size, each element
                       is a 2-D list of  probabilities can be used by
                       ctc_beam_search_decoder.
-
     :type probs_seq: 3-D list
     :param beam_size: Width for beam search.
     :type beam_size: int
@@ -227,10 +235,15 @@ def ctc_beam_search_decoder_nproc(probs_split,
     if not num_processes > 0:
         raise ValueError("Number of processes must be positive!")
 
+    # use global variable to pass the externnal scorer to beam search decoder
+    global ext_nproc_scorer
+    ext_nproc_scorer = ext_scoring_func
+    nproc = True
+
     pool = multiprocessing.Pool(processes=num_processes)
     results = []
     for i, probs_list in enumerate(probs_split):
-        args = (probs_list, beam_size, vocabulary, ext_scoring_func, blank_id)
+        args = (probs_list, beam_size, vocabulary, blank_id, None, nproc)
         results.append(pool.apply_async(ctc_beam_search_decoder, args))
 
     pool.close()

infer.py

@@ -9,6 +9,7 @@ import gzip
 from audio_data_utils import DataGenerator
 from model import deep_speech2
 from decoder import *
+import kenlm
 from error_rate import wer
 
 parser = argparse.ArgumentParser(
@@ -176,7 +177,7 @@ def infer():
                 probs_seq=probs,
                 vocabulary=vocab_list,
                 beam_size=args.beam_size,
-                ext_scoring_func=ext_scorer.evaluate,
+                ext_scoring_func=ext_scorer,
                 blank_id=len(vocab_list))
             print("\nTarget Transcription:\t%s" % target_transcription)
 
@@ -196,9 +197,9 @@ def infer():
             probs_split=probs_split,
             vocabulary=vocab_list,
             beam_size=args.beam_size,
-            #ext_scoring_func=ext_scorer.evaluate,
-            ext_scoring_func=None,
-            blank_id=len(vocab_list))
+            ext_scoring_func=ext_scorer,
+            blank_id=len(vocab_list),
+            num_processes=1)
         for i, beam_search_result in enumerate(beam_search_nproc_results):
             target_transcription = ''.join(
                 [vocab_list[index] for index in infer_data[i][1]])

tune.py

+"""
+   Tune parameters for beam search decoder in Deep Speech 2.
+"""
+
+import paddle.v2 as paddle
+import distutils.util
+import argparse
+import gzip
+from audio_data_utils import DataGenerator
+from model import deep_speech2
+from decoder import *
+from error_rate import wer
+
+parser = argparse.ArgumentParser(
+    description='Parameters tuning script for ctc beam search decoder in  Deep Speech 2.'
+)
+parser.add_argument(
+    "--num_samples",
+    default=100,
+    type=int,
+    help="Number of samples for parameters tuning. (default: %(default)s)")
+parser.add_argument(
+    "--num_conv_layers",
+    default=2,
+    type=int,
+    help="Convolution layer number. (default: %(default)s)")
+parser.add_argument(
+    "--num_rnn_layers",
+    default=3,
+    type=int,
+    help="RNN layer number. (default: %(default)s)")
+parser.add_argument(
+    "--rnn_layer_size",
+    default=512,
+    type=int,
+    help="RNN layer cell number. (default: %(default)s)")
+parser.add_argument(
+    "--use_gpu",
+    default=True,
+    type=distutils.util.strtobool,
+    help="Use gpu or not. (default: %(default)s)")
+parser.add_argument(
+    "--normalizer_manifest_path",
+    default='data/manifest.libri.train-clean-100',
+    type=str,
+    help="Manifest path for normalizer. (default: %(default)s)")
+parser.add_argument(
+    "--decode_manifest_path",
+    default='data/manifest.libri.test-100sample',
+    type=str,
+    help="Manifest path for decoding. (default: %(default)s)")
+parser.add_argument(
+    "--model_filepath",
+    default='./params.tar.gz',
+    type=str,
+    help="Model filepath. (default: %(default)s)")
+parser.add_argument(
+    "--vocab_filepath",
+    default='data/eng_vocab.txt',
+    type=str,
+    help="Vocabulary filepath. (default: %(default)s)")
+parser.add_argument(
+    "--decode_method",
+    default='beam_search_nproc',
+    type=str,
+    help="Method for decoding, beam_search or beam_search_nproc. (default: %(default)s)"
+)
+parser.add_argument(
+    "--beam_size",
+    default=500,
+    type=int,
+    help="Width for beam search decoding. (default: %(default)d)")
+parser.add_argument(
+    "--num_results_per_sample",
+    default=1,
+    type=int,
+    help="Number of outputs per sample in beam search. (default: %(default)d)")
+parser.add_argument(
+    "--language_model_path",
+    default="./data/1Billion.klm",
+    type=str,
+    help="Path for language model. (default: %(default)s)")
+parser.add_argument(
+    "--alpha_from",
+    default=0.0,
+    type=float,
+    help="Where alpha starts from, <= alpha_to. (default: %(default)f)")
+parser.add_argument(
+    "--alpha_stride",
+    default=0.001,
+    type=float,
+    help="Step length for varying alpha. (default: %(default)f)")
+parser.add_argument(
+    "--alpha_to",
+    default=0.01,
+    type=float,
+    help="Where alpha ends with, >= alpha_from. (default: %(default)f)")
+parser.add_argument(
+    "--beta_from",
+    default=0.0,
+    type=float,
+    help="Where beta starts from, <= beta_to. (default: %(default)f)")
+parser.add_argument(
+    "--beta_stride",
+    default=0.01,
+    type=float,
+    help="Step length for varying beta. (default: %(default)f)")
+parser.add_argument(
+    "--beta_to",
+    default=0.0,
+    type=float,
+    help="Where beta ends with, >= beta_from. (default: %(default)f)")
+args = parser.parse_args()
+
+
+def tune():
+    """
+    Tune parameters alpha and beta on one minibatch.
+    """
+
+    if not args.alpha_from <= args.alpha_to:
+        raise ValueError("alpha_from <= alpha_to doesn't satisfy!")
+    if not args.alpha_stride > 0:
+        raise ValueError("alpha_stride shouldn't be negative!")
+
+    if not args.beta_from <= args.beta_to:
+        raise ValueError("beta_from <= beta_to doesn't satisfy!")
+    if not args.beta_stride > 0:
+        raise ValueError("beta_stride shouldn't be negative!")
+
+    # initialize data generator
+    data_generator = DataGenerator(
+        vocab_filepath=args.vocab_filepath,
+        normalizer_manifest_path=args.normalizer_manifest_path,
+        normalizer_num_samples=200,
+        max_duration=20.0,
+        min_duration=0.0,
+        stride_ms=10,
+        window_ms=20)
+
+    # create network config
+    dict_size = data_generator.vocabulary_size()
+    vocab_list = data_generator.vocabulary_list()
+    audio_data = paddle.layer.data(
+        name="audio_spectrogram",
+        height=161,
+        width=2000,
+        type=paddle.data_type.dense_vector(322000))
+    text_data = paddle.layer.data(
+        name="transcript_text",
+        type=paddle.data_type.integer_value_sequence(dict_size))
+    output_probs = deep_speech2(
+        audio_data=audio_data,
+        text_data=text_data,
+        dict_size=dict_size,
+        num_conv_layers=args.num_conv_layers,
+        num_rnn_layers=args.num_rnn_layers,
+        rnn_size=args.rnn_layer_size,
+        is_inference=True)
+
+    # load parameters
+    parameters = paddle.parameters.Parameters.from_tar(
+        gzip.open(args.model_filepath))
+
+    # prepare infer data
+    feeding = data_generator.data_name_feeding()
+    test_batch_reader = data_generator.batch_reader_creator(
+        manifest_path=args.decode_manifest_path,
+        batch_size=args.num_samples,
+        padding_to=2000,
+        flatten=True,
+        sort_by_duration=False,
+        shuffle=False)
+    infer_data = test_batch_reader().next()
+
+    # run inference
+    infer_results = paddle.infer(
+        output_layer=output_probs, parameters=parameters, 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))
+    ]
+
+    cand_alpha = np.arange(args.alpha_from, args.alpha_to + args.alpha_stride,
+                           args.alpha_stride)
+    cand_beta = np.arange(args.beta_from, args.beta_to + args.beta_stride,
+                          args.beta_stride)
+    params_grid = [(alpha, beta) for alpha in cand_alpha for beta in cand_beta]
+    ## tune parameters in loop
+    for (alpha, beta) in params_grid:
+        wer_sum, wer_counter = 0, 0
+        ext_scorer = Scorer(alpha, beta, args.language_model_path)
+        # beam search decode
+        if args.decode_method == "beam_search":
+            for i, probs in enumerate(probs_split):
+                target_transcription = ''.join(
+                    [vocab_list[index] for index in infer_data[i][1]])
+                beam_search_result = ctc_beam_search_decoder(
+                    probs_seq=probs,
+                    vocabulary=vocab_list,
+                    beam_size=args.beam_size,
+                    ext_scoring_func=ext_scorer,
+                    blank_id=len(vocab_list))
+                wer_sum += wer(target_transcription, beam_search_result[0][1])
+                wer_counter += 1
+        # beam search using multiple processes
+        elif args.decode_method == "beam_search_nproc":
+            beam_search_nproc_results = ctc_beam_search_decoder_nproc(
+                probs_split=probs_split,
+                vocabulary=vocab_list,
+                beam_size=args.beam_size,
+                ext_scoring_func=ext_scorer,
+                blank_id=len(vocab_list),
+                num_processes=1)
+            for i, beam_search_result in enumerate(beam_search_nproc_results):
+                target_transcription = ''.join(
+                    [vocab_list[index] for index in infer_data[i][1]])
+                wer_sum += wer(target_transcription, beam_search_result[0][1])
+                wer_counter += 1
+        else:
+            raise ValueError("Decoding method [%s] is not supported." % method)
+
+        print("alpha = %f\tbeta = %f\tWER = %f" %
+              (alpha, beta, wer_sum / wer_counter))
+
+
+def main():
+    paddle.init(use_gpu=args.use_gpu, trainer_count=1)
+    tune()
+
+
+if __name__ == '__main__':
+    main()