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PaddleSpeech/paddlespeech/s2t/transform/add_deltas.py

54 lines
1.6 KiB

# 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 numpy as np
def delta(feat, window):
assert window > 0
delta_feat = np.zeros_like(feat)
for i in range(1, window + 1):
delta_feat[:-i] += i * feat[i:]
delta_feat[i:] += -i * feat[:-i]
delta_feat[-i:] += i * feat[-1]
delta_feat[:i] += -i * feat[0]
delta_feat /= 2 * sum(i**2 for i in range(1, window + 1))
return delta_feat
def add_deltas(x, window=2, order=2):
"""
Args:
x (np.ndarray): speech feat, (T, D).
Return:
np.ndarray: (T, (1+order)*D)
"""
feats = [x]
for _ in range(order):
feats.append(delta(feats[-1], window))
return np.concatenate(feats, axis=1)
class AddDeltas():
def __init__(self, window=2, order=2):
self.window = window
self.order = order
def __repr__(self):
return "{name}(window={window}, order={order}".format(
name=self.__class__.__name__, window=self.window, order=self.order)
def __call__(self, x):
return add_deltas(x, window=self.window, order=self.order)