competition update

language_model/wenet/utils/cmvn.py

@@ -0,0 +1,94 @@
+#!/usr/bin/env python3
+# Copyright (c) 2020 Mobvoi Inc (Binbin Zhang)
+#
+# 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 json
+import math
+
+import numpy as np
+
+
+def _load_json_cmvn(json_cmvn_file):
+    """ Load the json format cmvn stats file and calculate cmvn
+
+    Args:
+        json_cmvn_file: cmvn stats file in json format
+
+    Returns:
+        a numpy array of [means, vars]
+    """
+    with open(json_cmvn_file) as f:
+        cmvn_stats = json.load(f)
+
+    means = cmvn_stats['mean_stat']
+    variance = cmvn_stats['var_stat']
+    count = cmvn_stats['frame_num']
+    for i in range(len(means)):
+        means[i] /= count
+        variance[i] = variance[i] / count - means[i] * means[i]
+        if variance[i] < 1.0e-20:
+            variance[i] = 1.0e-20
+        variance[i] = 1.0 / math.sqrt(variance[i])
+    cmvn = np.array([means, variance])
+    return cmvn
+
+
+def _load_kaldi_cmvn(kaldi_cmvn_file):
+    """ Load the kaldi format cmvn stats file and calculate cmvn
+
+    Args:
+        kaldi_cmvn_file:  kaldi text style global cmvn file, which
+           is generated by:
+           compute-cmvn-stats --binary=false scp:feats.scp global_cmvn
+
+    Returns:
+        a numpy array of [means, vars]
+    """
+    means = []
+    variance = []
+    with open(kaldi_cmvn_file, 'r') as fid:
+        # kaldi binary file start with '\0B'
+        if fid.read(2) == '\0B':
+            logging.error('kaldi cmvn binary file is not supported, please '
+                          'recompute it by: compute-cmvn-stats --binary=false '
+                          ' scp:feats.scp global_cmvn')
+            sys.exit(1)
+        fid.seek(0)
+        arr = fid.read().split()
+        assert (arr[0] == '[')
+        assert (arr[-2] == '0')
+        assert (arr[-1] == ']')
+        feat_dim = int((len(arr) - 2 - 2) / 2)
+        for i in range(1, feat_dim + 1):
+            means.append(float(arr[i]))
+        count = float(arr[feat_dim + 1])
+        for i in range(feat_dim + 2, 2 * feat_dim + 2):
+            variance.append(float(arr[i]))
+
+    for i in range(len(means)):
+        means[i] /= count
+        variance[i] = variance[i] / count - means[i] * means[i]
+        if variance[i] < 1.0e-20:
+            variance[i] = 1.0e-20
+        variance[i] = 1.0 / math.sqrt(variance[i])
+    cmvn = np.array([means, variance])
+    return cmvn
+
+
+def load_cmvn(cmvn_file, is_json):
+    if is_json:
+        cmvn = _load_json_cmvn(cmvn_file)
+    else:
+        cmvn = _load_kaldi_cmvn(cmvn_file)
+    return cmvn[0], cmvn[1]