| /* |
| * 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" |
| |
| #include <cfloat> |
| |
| namespace arm { |
| namespace app { |
| namespace audio { |
| |
| bool AdMelSpectrogram::ApplyMelFilterBank( |
| std::vector<float>& fftVec, |
| std::vector<std::vector<float>>& melFilterBank, |
| std::vector<uint32_t>& filterBankFilterFirst, |
| std::vector<uint32_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(); |
| auto end = melFilterBank[bin].end(); |
| float melEnergy = FLT_MIN; /* Avoid log of zero at later stages. */ |
| const uint32_t firstIndex = filterBankFilterFirst[bin]; |
| const uint32_t lastIndex = std::min<int32_t>(filterBankFilterLast[bin], fftVec.size() - 1); |
| |
| for (uint32_t i = firstIndex; i <= lastIndex && filterBankIter != end; ++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() && iterL != vecLogEnergies.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 */ |