diff options
Diffstat (limited to 'samples/SpeechRecognition/src/MFCC.cpp')
| -rw-r--r-- | samples/SpeechRecognition/src/MFCC.cpp | 397 |
1 files changed, 0 insertions, 397 deletions
diff --git a/samples/SpeechRecognition/src/MFCC.cpp b/samples/SpeechRecognition/src/MFCC.cpp deleted file mode 100644 index 234b14d3be..0000000000 --- a/samples/SpeechRecognition/src/MFCC.cpp +++ /dev/null @@ -1,397 +0,0 @@ -// -// Copyright © 2020 Arm Ltd and Contributors. All rights reserved. -// SPDX-License-Identifier: MIT -// - -#include <cstdio> -#include <float.h> - -#include "MFCC.hpp" -#include "MathUtils.hpp" - - -MfccParams::MfccParams( - const float samplingFreq, - const int numFbankBins, - const float melLoFreq, - const float melHiFreq, - const int numMfccFeats, - const int frameLen, - const bool useHtkMethod, - const int numMfccVectors): - m_samplingFreq(samplingFreq), - m_numFbankBins(numFbankBins), - m_melLoFreq(melLoFreq), - m_melHiFreq(melHiFreq), - m_numMfccFeatures(numMfccFeats), - m_frameLen(frameLen), - m_numMfccVectors(numMfccVectors), - - /* Smallest power of 2 >= frame length. */ - m_frameLenPadded(pow(2, ceil((log(frameLen)/log(2))))), - m_useHtkMethod(useHtkMethod) -{} - -std::string MfccParams::Str() -{ - char strC[1024]; - snprintf(strC, sizeof(strC) - 1, "\n \ - \n\t Sampling frequency: %f\ - \n\t Number of filter banks: %u\ - \n\t Mel frequency limit (low): %f\ - \n\t Mel frequency limit (high): %f\ - \n\t Number of MFCC features: %u\ - \n\t Frame length: %u\ - \n\t Padded frame length: %u\ - \n\t Using HTK for Mel scale: %s\n", - this->m_samplingFreq, this->m_numFbankBins, this->m_melLoFreq, - this->m_melHiFreq, this->m_numMfccFeatures, this->m_frameLen, - this->m_frameLenPadded, this->m_useHtkMethod ? "yes" : "no"); - return std::string{strC}; -} - -MFCC::MFCC(const MfccParams& params): - _m_params(params), - _m_filterBankInitialised(false) -{ - this->_m_buffer = std::vector<float>( - this->_m_params.m_frameLenPadded, 0.0); - this->_m_frame = std::vector<float>( - this->_m_params.m_frameLenPadded, 0.0); - this->_m_melEnergies = std::vector<float>( - this->_m_params.m_numFbankBins, 0.0); - - this->_m_windowFunc = std::vector<float>(this->_m_params.m_frameLen); - const float multiplier = 2 * M_PI / this->_m_params.m_frameLen; - - /* Create window function. */ - for (size_t i = 0; i < this->_m_params.m_frameLen; i++) - { - this->_m_windowFunc[i] = (0.5 - (0.5 * cos(static_cast<float>(i) * multiplier))); - } -} - -void MFCC::Init() -{ - this->_InitMelFilterBank(); -} - -float MFCC::MelScale(const float freq, const bool useHTKMethod) -{ - if (useHTKMethod) - { - return 1127.0f * logf (1.0f + freq / 700.0f); - } - else - { - /* Slaney formula for mel scale. */ - float mel = freq / freqStep; - - if (freq >= minLogHz) - { - mel = minLogMel + logf(freq / minLogHz) / logStep; - } - return mel; - } -} - -float MFCC::InverseMelScale(const float melFreq, const bool useHTKMethod) -{ - if (useHTKMethod) - { - return 700.0f * (expf (melFreq / 1127.0f) - 1.0f); - } - else - { - /* Slaney formula for mel scale. */ - float freq = freqStep * melFreq; - - if (melFreq >= minLogMel) - { - freq = minLogHz * expf(logStep * (melFreq - minLogMel)); - } - return freq; - } -} - - -bool MFCC::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("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 MFCC::ConvertToLogarithmicScale(std::vector<float>& melEnergies) -{ - float maxMelEnergy = -FLT_MAX; - - /* 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 */ - MathUtils::VecLogarithmF32(melEnergies, vecLogEnergies); - - /* Scale the log values and get the max */ - for (auto iterM = melEnergies.begin(), iterL = vecLogEnergies.begin(); - iterM != melEnergies.end(); ++iterM, ++iterL) - { - *iterM = *iterL * multiplier; - - /* Save the max mel energy. */ - if (*iterM > maxMelEnergy) - { - maxMelEnergy = *iterM; - } - } - - /* Clamp the mel energies */ - constexpr float maxDb = 80.0; - const float clampLevelLowdB = maxMelEnergy - maxDb; - for (auto iter = melEnergies.begin(); iter != melEnergies.end(); ++iter) - { - *iter = std::max(*iter, clampLevelLowdB); - } -} - -void MFCC::_ConvertToPowerSpectrum() -{ - const uint32_t halfDim = this->_m_params.m_frameLenPadded / 2; - - /* Handle this special case. */ - float firstEnergy = this->_m_buffer[0] * this->_m_buffer[0]; - float lastEnergy = this->_m_buffer[1] * this->_m_buffer[1]; - - MathUtils::ComplexMagnitudeSquaredF32( - this->_m_buffer.data(), - this->_m_buffer.size(), - this->_m_buffer.data(), - this->_m_buffer.size()/2); - - this->_m_buffer[0] = firstEnergy; - this->_m_buffer[halfDim] = lastEnergy; -} - -std::vector<float> MFCC::CreateDCTMatrix( - const int32_t inputLength, - const int32_t coefficientCount) -{ - std::vector<float> dctMatix(inputLength * coefficientCount); - - /* Orthonormal normalization. */ - const float normalizerK0 = 2 * sqrt(1.0 / static_cast<float>(4*inputLength)); - const float normalizer = 2 * sqrt(1.0 / static_cast<float>(2*inputLength)); - - const float angleIncr = M_PI/inputLength; - float angle = angleIncr; /* we start using it at k = 1 loop */ - - /* First row of DCT will use normalizer K0 */ - for (int32_t n = 0; n < inputLength; ++n) - { - dctMatix[n] = normalizerK0; - } - - /* Second row (index = 1) onwards, we use standard normalizer */ - for (int32_t k = 1, m = inputLength; k < coefficientCount; ++k, m += inputLength) - { - for (int32_t n = 0; n < inputLength; ++n) - { - dctMatix[m+n] = normalizer * - cos((n + 0.5) * angle); - } - angle += angleIncr; - } - return dctMatix; -} - -float MFCC::GetMelFilterBankNormaliser( - const float& leftMel, - const float& rightMel, - const bool useHTKMethod) -{ -/* Slaney normalization for mel weights. */ - return (2.0f / (MFCC::InverseMelScale(rightMel, useHTKMethod) - - MFCC::InverseMelScale(leftMel, useHTKMethod))); -} - -void MFCC::_InitMelFilterBank() -{ - if (!this->_IsMelFilterBankInited()) - { - this->_m_melFilterBank = this->_CreateMelFilterBank(); - this->_m_dctMatrix = this->CreateDCTMatrix( - this->_m_params.m_numFbankBins, - this->_m_params.m_numMfccFeatures); - this->_m_filterBankInitialised = true; - } -} - -bool MFCC::_IsMelFilterBankInited() -{ - return this->_m_filterBankInitialised; -} - -void MFCC::_MfccComputePreFeature(const std::vector<float>& audioData) -{ - this->_InitMelFilterBank(); - - /* TensorFlow way of normalizing .wav data to (-1, 1). */ - constexpr float normaliser = 1.0; - for (size_t i = 0; i < this->_m_params.m_frameLen; i++) - { - this->_m_frame[i] = static_cast<float>(audioData[i]) * normaliser; - } - - /* Apply window function to input frame. */ - for(size_t i = 0; i < this->_m_params.m_frameLen; i++) - { - this->_m_frame[i] *= this->_m_windowFunc[i]; - } - - /* Set remaining frame values to 0. */ - std::fill(this->_m_frame.begin() + this->_m_params.m_frameLen,this->_m_frame.end(), 0); - - /* Compute FFT. */ - MathUtils::FftF32(this->_m_frame, this->_m_buffer); - - /* Convert to power spectrum. */ - this->_ConvertToPowerSpectrum(); - - /* Apply mel filterbanks. */ - if (!this->ApplyMelFilterBank(this->_m_buffer, - this->_m_melFilterBank, - this->_m_filterBankFilterFirst, - this->_m_filterBankFilterLast, - this->_m_melEnergies)) - { - printf("Failed to apply MEL filter banks\n"); - } - - /* Convert to logarithmic scale */ - this->ConvertToLogarithmicScale(this->_m_melEnergies); -} - -std::vector<float> MFCC::MfccCompute(const std::vector<float>& audioData) -{ - this->_MfccComputePreFeature(audioData); - - std::vector<float> mfccOut(this->_m_params.m_numMfccFeatures); - - float * ptrMel = this->_m_melEnergies.data(); - float * ptrDct = this->_m_dctMatrix.data(); - float * ptrMfcc = mfccOut.data(); - - /* Take DCT. Uses matrix mul. */ - for (size_t i = 0, j = 0; i < mfccOut.size(); - ++i, j += this->_m_params.m_numFbankBins) - { - *ptrMfcc++ = MathUtils::DotProductF32( - ptrDct + j, - ptrMel, - this->_m_params.m_numFbankBins); - } - - return mfccOut; -} - -std::vector<std::vector<float>> MFCC::_CreateMelFilterBank() -{ - size_t numFftBins = this->_m_params.m_frameLenPadded / 2; - float fftBinWidth = static_cast<float>(this->_m_params.m_samplingFreq) / this->_m_params.m_frameLenPadded; - - float melLowFreq = MFCC::MelScale(this->_m_params.m_melLoFreq, - this->_m_params.m_useHtkMethod); - float melHighFreq = MFCC::MelScale(this->_m_params.m_melHiFreq, - this->_m_params.m_useHtkMethod); - float melFreqDelta = (melHighFreq - melLowFreq) / (this->_m_params.m_numFbankBins + 1); - - std::vector<float> thisBin = std::vector<float>(numFftBins); - std::vector<std::vector<float>> melFilterBank( - this->_m_params.m_numFbankBins); - this->_m_filterBankFilterFirst = - std::vector<int32_t>(this->_m_params.m_numFbankBins); - this->_m_filterBankFilterLast = - std::vector<int32_t>(this->_m_params.m_numFbankBins); - - for (size_t bin = 0; bin < this->_m_params.m_numFbankBins; bin++) - { - float leftMel = melLowFreq + bin * melFreqDelta; - float centerMel = melLowFreq + (bin + 1) * melFreqDelta; - float rightMel = melLowFreq + (bin + 2) * melFreqDelta; - - int32_t firstIndex = -1; - int32_t lastIndex = -1; - const float normaliser = this->GetMelFilterBankNormaliser(leftMel, rightMel, this->_m_params.m_useHtkMethod); - - for (size_t i = 0; i < numFftBins; i++) - { - float freq = (fftBinWidth * i); /* Center freq of this fft bin. */ - float mel = MFCC::MelScale(freq, this->_m_params.m_useHtkMethod); - thisBin[i] = 0.0; - - if (mel > leftMel && mel < rightMel) - { - float weight; - if (mel <= centerMel) - { - weight = (mel - leftMel) / (centerMel - leftMel); - } - else - { - weight = (rightMel - mel) / (rightMel - centerMel); - } - - thisBin[i] = weight * normaliser; - if (firstIndex == -1) - { - firstIndex = i; - } - lastIndex = i; - } - } - - this->_m_filterBankFilterFirst[bin] = firstIndex; - this->_m_filterBankFilterLast[bin] = lastIndex; - - /* Copy the part we care about. */ - for (int32_t i = firstIndex; i <= lastIndex; i++) - { - melFilterBank[bin].push_back(thisBin[i]); - } - } - - return melFilterBank; -} - |