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60 lines
2.1 KiB
60 lines
2.1 KiB
// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "frontend/audio/linear_spectrogram.h"
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#include "kaldi/base/kaldi-math.h"
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#include "kaldi/feat/feature-common.h"
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#include "kaldi/feat/feature-functions.h"
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#include "kaldi/matrix/matrix-functions.h"
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namespace ppspeech {
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using kaldi::BaseFloat;
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using kaldi::int32;
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using kaldi::Matrix;
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using kaldi::SubVector;
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using kaldi::Vector;
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using kaldi::VectorBase;
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using std::vector;
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LinearSpectrogramComputer::LinearSpectrogramComputer(const Options& opts)
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: opts_(opts) {
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kaldi::FeatureWindowFunction feature_window_function(opts.frame_opts);
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int32 window_size = opts.frame_opts.WindowSize();
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frame_length_ = window_size;
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dim_ = window_size / 2 + 1;
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BaseFloat hanning_window_energy = kaldi::VecVec(
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feature_window_function.window, feature_window_function.window);
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int32 sample_rate = opts.frame_opts.samp_freq;
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scale_ = 2.0 / (hanning_window_energy * sample_rate);
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}
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// Compute spectrogram feat
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bool LinearSpectrogramComputer::Compute(Vector<BaseFloat>* window,
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Vector<BaseFloat>* feat) {
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window->Resize(frame_length_, kaldi::kCopyData);
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RealFft(window, true);
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kaldi::ComputePowerSpectrum(window);
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SubVector<BaseFloat> power_spectrum(*window, 0, dim_);
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power_spectrum.Scale(scale_);
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power_spectrum(0) = power_spectrum(0) / 2;
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power_spectrum(dim_ - 1) = power_spectrum(dim_ - 1) / 2;
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power_spectrum.Add(1e-14);
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power_spectrum.ApplyLog();
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feat->CopyFromVec(power_spectrum);
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return true;
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}
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} // namespace ppspeech
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