MLECO-2079 Adding the C++ KWS example
Signed-off-by: Eanna O Cathain <eanna.ocathain@arm.com>
Change-Id: I81899bbfaada32f478c2e2fc6441eabb94d8d0fc
diff --git a/samples/common/src/Audio/AudioCapture.cpp b/samples/common/src/Audio/AudioCapture.cpp
new file mode 100644
index 0000000..920d7a5
--- /dev/null
+++ b/samples/common/src/Audio/AudioCapture.cpp
@@ -0,0 +1,96 @@
+//
+// Copyright © 2021 Arm Ltd and Contributors. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+
+#include "AudioCapture.hpp"
+#include <alsa/asoundlib.h>
+#include <sndfile.h>
+#include <samplerate.h>
+
+namespace audio
+{
+ std::vector<float> AudioCapture::LoadAudioFile(std::string filePath)
+ {
+ SF_INFO inputSoundFileInfo;
+ SNDFILE* infile = nullptr;
+ infile = sf_open(filePath.c_str(), SFM_READ, &inputSoundFileInfo);
+
+ float audioIn[inputSoundFileInfo.channels * inputSoundFileInfo.frames];
+ sf_read_float(infile, audioIn, inputSoundFileInfo.channels * inputSoundFileInfo.frames);
+
+ float sampleRate = 16000.0f;
+ float srcRatio = sampleRate / (float)inputSoundFileInfo.samplerate;
+ int outputFrames = ceilf(inputSoundFileInfo.frames * srcRatio);
+
+ // Convert to mono
+ std::vector<float> monoData(inputSoundFileInfo.frames);
+ for(int i = 0; i < inputSoundFileInfo.frames; i++)
+ {
+ for(int j = 0; j < inputSoundFileInfo.channels; j++)
+ monoData[i] += audioIn[i * inputSoundFileInfo.channels + j];
+ monoData[i] /= inputSoundFileInfo.channels;
+ }
+
+ // Resample
+ SRC_DATA srcData;
+ srcData.data_in = monoData.data();
+ srcData.input_frames = inputSoundFileInfo.frames;
+
+ std::vector<float> dataOut(outputFrames);
+ srcData.data_out = dataOut.data();
+
+ srcData.output_frames = outputFrames;
+ srcData.src_ratio = srcRatio;
+
+ src_simple(&srcData, SRC_SINC_BEST_QUALITY, 1);
+
+ sf_close(infile);
+
+ return dataOut;
+ }
+
+ void AudioCapture::InitSlidingWindow(float* data, size_t dataSize, int minSamples, size_t stride)
+ {
+ this->m_window = SlidingWindow<const float>(data, dataSize, minSamples, stride);
+ }
+
+ bool AudioCapture::HasNext()
+ {
+ return m_window.HasNext();
+ }
+
+ std::vector<float> AudioCapture::Next()
+ {
+ if (this->m_window.HasNext())
+ {
+ int remainingData = this->m_window.RemainingData();
+ const float* windowData = this->m_window.Next();
+
+ size_t windowSize = this->m_window.GetWindowSize();
+
+ if(remainingData < windowSize)
+ {
+ std::vector<float> audioData(windowSize, 0.0f);
+ for(int i = 0; i < remainingData; ++i)
+ {
+ audioData[i] = *windowData;
+ if(i < remainingData - 1)
+ {
+ ++windowData;
+ }
+ }
+ return audioData;
+ }
+ else
+ {
+ std::vector<float> audioData(windowData, windowData + windowSize);
+ return audioData;
+ }
+ }
+ else
+ {
+ throw std::out_of_range("Error, end of audio data reached.");
+ }
+ }
+} //namespace asr
\ No newline at end of file
diff --git a/samples/common/src/Audio/MFCC.cpp b/samples/common/src/Audio/MFCC.cpp
new file mode 100644
index 0000000..911c32b
--- /dev/null
+++ b/samples/common/src/Audio/MFCC.cpp
@@ -0,0 +1,354 @@
+//
+// Copyright © 2020 Arm Ltd and Contributors. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+#include "MFCC.hpp"
+#include "MathUtils.hpp"
+
+#include <cfloat>
+#include <cinttypes>
+#include <cstring>
+
+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 auto multiplier = static_cast<float>(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 * cosf(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 / ms_freqStep;
+
+ if (freq >= ms_minLogHz)
+ {
+ mel = ms_minLogMel + logf(freq / ms_minLogHz) / ms_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 = ms_freqStep * melFreq;
+
+ if (melFreq >= ms_minLogMel)
+ {
+ freq = ms_minLogHz * expf(ms_logStep * (melFreq - ms_minLogMel));
+ }
+ return freq;
+ }
+}
+
+
+bool MFCC::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("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<uint32_t>(filterBankFilterLast[bin], fftVec.size() - 1);
+
+ for (uint32_t i = firstIndex; i <= lastIndex && filterBankIter != end; i++)
+ {
+ float energyRep = sqrt(fftVec[i]);
+ melEnergy += (*filterBankIter++ * energyRep);
+ }
+
+ melEnergies[bin] = melEnergy;
+ }
+
+ return true;
+}
+
+void MFCC::ConvertToLogarithmicScale(std::vector<float>& melEnergies)
+{
+ for (float& melEnergy : melEnergies)
+ {
+ melEnergy = logf(melEnergy);
+ }
+}
+
+void MFCC::ConvertToPowerSpectrum()
+{
+ const uint32_t halfDim = this->m_buffer.size() / 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> dctMatrix(inputLength * coefficientCount);
+
+ const float normalizer = sqrtf(2.0f/inputLength);
+ const float angleIncr = M_PI/inputLength;
+ float angle = 0;
+
+ for (int32_t k = 0, m = 0; k < coefficientCount; k++, m += inputLength)
+ {
+ for (int32_t n = 0; n < inputLength; n++)
+ {
+ dctMatrix[m + n] = normalizer * cosf((n + 0.5f) * angle);
+ }
+ angle += angleIncr;
+ }
+
+ return dctMatrix;
+}
+
+float MFCC::GetMelFilterBankNormaliser(
+ const float& leftMel,
+ const float& rightMel,
+ const bool useHTKMethod)
+{
+ /* By default, no normalisation => return 1 */
+ return 1.f;
+}
+
+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() const
+{
+ return this->m_filterBankInitialised;
+}
+
+void MFCC::MfccComputePreFeature(const std::vector<float>& audioData)
+{
+ this->InitMelFilterBank();
+
+ auto size = std::min(std::min(this->m_frame.size(), audioData.size()),
+ static_cast<size_t>(this->m_params.m_frameLen)) * sizeof(float);
+ std::memcpy(this->m_frame.data(), audioData.data(), size);
+
+ /* 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<uint32_t>(this->m_params.m_numFbankBins);
+ this->m_filterBankFilterLast =
+ std::vector<uint32_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;
+
+ uint32_t firstIndex = 0;
+ uint32_t lastIndex = 0;
+ bool firstIndexFound = false;
+ 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 (!firstIndexFound)
+ {
+ firstIndex = i;
+ firstIndexFound = true;
+ }
+ lastIndex = i;
+ }
+ }
+
+ this->m_filterBankFilterFirst[bin] = firstIndex;
+ this->m_filterBankFilterLast[bin] = lastIndex;
+
+ /* Copy the part we care about. */
+ for (uint32_t i = firstIndex; i <= lastIndex; i++)
+ {
+ melFilterBank[bin].push_back(thisBin[i]);
+ }
+ }
+
+ return melFilterBank;
+}
diff --git a/samples/common/src/Audio/MathUtils.cpp b/samples/common/src/Audio/MathUtils.cpp
new file mode 100644
index 0000000..d91b509
--- /dev/null
+++ b/samples/common/src/Audio/MathUtils.cpp
@@ -0,0 +1,111 @@
+//
+// Copyright © 2021 Arm Ltd and Contributors. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+
+#include "MathUtils.hpp"
+#include <vector>
+#include <cmath>
+#include <cstdio>
+
+void MathUtils::FftF32(std::vector<float>& input,
+ std::vector<float>& fftOutput)
+{
+ const int inputLength = input.size();
+
+ for (int k = 0; k <= inputLength / 2; k++)
+ {
+ float sumReal = 0, sumImag = 0;
+
+ for (int t = 0; t < inputLength; t++)
+ {
+ float angle = 2 * M_PI * t * k / inputLength;
+ sumReal += input[t] * cosf(angle);
+ sumImag += -input[t] * sinf(angle);
+ }
+
+ /* Arrange output to [real0, realN/2, real1, im1, real2, im2, ...] */
+ if (k == 0)
+ {
+ fftOutput[0] = sumReal;
+ }
+ else if (k == inputLength / 2)
+ {
+ fftOutput[1] = sumReal;
+ }
+ else
+ {
+ fftOutput[k*2] = sumReal;
+ fftOutput[k*2 + 1] = sumImag;
+ };
+ }
+}
+
+float MathUtils::DotProductF32(const float* srcPtrA, float* srcPtrB,
+ const int srcLen)
+{
+ float output = 0.f;
+
+ for (int i = 0; i < srcLen; ++i)
+ {
+ output += *srcPtrA++ * *srcPtrB++;
+ }
+ return output;
+}
+
+bool MathUtils::ComplexMagnitudeSquaredF32(const float* ptrSrc,
+ int srcLen,
+ float* ptrDst,
+ int dstLen)
+{
+ if (dstLen < srcLen/2)
+ {
+ printf("dstLen must be greater than srcLen/2");
+ return false;
+ }
+
+ for (int j = 0; j < dstLen; ++j)
+ {
+ const float real = *ptrSrc++;
+ const float im = *ptrSrc++;
+ *ptrDst++ = real*real + im*im;
+ }
+ return true;
+}
+
+void MathUtils::VecLogarithmF32(std::vector <float>& input,
+ std::vector <float>& output)
+{
+ for (auto in = input.begin(), out = output.begin();
+ in != input.end(); ++in, ++out)
+ {
+ *out = logf(*in);
+ }
+}
+
+float MathUtils::MeanF32(const float* ptrSrc, const uint32_t srcLen)
+{
+ if (!srcLen)
+ {
+ return 0.f;
+ }
+
+ float acc = std::accumulate(ptrSrc, ptrSrc + srcLen, 0.0);
+ return acc/srcLen;
+}
+
+float MathUtils::StdDevF32(const float* ptrSrc, uint32_t srcLen, float mean)
+{
+ if (!srcLen)
+ {
+ return 0.f;
+ }
+ auto VarianceFunction = [mean, srcLen](float acc, const float value) {
+ return acc + (((value - mean) * (value - mean))/ srcLen);
+ };
+
+ float acc = std::accumulate(ptrSrc, ptrSrc + srcLen, 0.0,
+ VarianceFunction);
+ return sqrtf(acc);
+}
+