Opensource ML embedded evaluation kit
Change-Id: I12e807f19f5cacad7cef82572b6dd48252fd61fd
diff --git a/source/use_case/ad/src/AdMelSpectrogram.cc b/source/use_case/ad/src/AdMelSpectrogram.cc
new file mode 100644
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+++ b/source/use_case/ad/src/AdMelSpectrogram.cc
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+/*
+ * Copyright (c) 2021 Arm Limited. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * 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.
+ */
+#include "AdMelSpectrogram.hpp"
+
+#include "PlatformMath.hpp"
+
+namespace arm {
+namespace app {
+namespace audio {
+
+ bool AdMelSpectrogram::ApplyMelFilterBank(
+ std::vector<float>& fftVec,
+ std::vector<std::vector<float>>& melFilterBank,
+ std::vector<int32_t>& filterBankFilterFirst,
+ std::vector<int32_t>& filterBankFilterLast,
+ std::vector<float>& melEnergies)
+ {
+ const size_t numBanks = melEnergies.size();
+
+ if (numBanks != filterBankFilterFirst.size() ||
+ numBanks != filterBankFilterLast.size()) {
+ printf_err("unexpected filter bank lengths\n");
+ return false;
+ }
+
+ for (size_t bin = 0; bin < numBanks; ++bin) {
+ auto filterBankIter = melFilterBank[bin].begin();
+ float melEnergy = 1e-10; /* Avoid log of zero at later stages. */
+ const int32_t firstIndex = filterBankFilterFirst[bin];
+ const int32_t lastIndex = filterBankFilterLast[bin];
+
+ for (int32_t i = firstIndex; i <= lastIndex; ++i) {
+ melEnergy += (*filterBankIter++ * fftVec[i]);
+ }
+
+ melEnergies[bin] = melEnergy;
+ }
+
+ return true;
+ }
+
+ void AdMelSpectrogram::ConvertToLogarithmicScale(
+ std::vector<float>& melEnergies)
+ {
+ /* Container for natural logarithms of mel energies */
+ std::vector <float> vecLogEnergies(melEnergies.size(), 0.f);
+
+ /* Because we are taking natural logs, we need to multiply by log10(e).
+ * Also, for wav2letter model, we scale our log10 values by 10 */
+ constexpr float multiplier = 10.0 * /* default scalar */
+ 0.4342944819032518; /* log10f(std::exp(1.0))*/
+
+ /* Take log of the whole vector */
+ math::MathUtils::VecLogarithmF32(melEnergies, vecLogEnergies);
+
+ /* Scale the log values. */
+ for (auto iterM = melEnergies.begin(), iterL = vecLogEnergies.begin();
+ iterM != melEnergies.end(); ++iterM, ++iterL) {
+
+ *iterM = *iterL * multiplier;
+ }
+ }
+
+ float AdMelSpectrogram::GetMelFilterBankNormaliser(
+ const float& leftMel,
+ const float& rightMel,
+ const bool useHTKMethod)
+ {
+ /* Slaney normalization for mel weights. */
+ return (2.0f / (AdMelSpectrogram::InverseMelScale(rightMel, useHTKMethod) -
+ AdMelSpectrogram::InverseMelScale(leftMel, useHTKMethod)));
+ }
+
+} /* namespace audio */
+} /* namespace app */
+} /* namespace arm */