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Diffstat (limited to 'source/application/main/include/Mfcc.hpp')
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diff --git a/source/application/main/include/Mfcc.hpp b/source/application/main/include/Mfcc.hpp deleted file mode 100644 index 86330ca..0000000 --- a/source/application/main/include/Mfcc.hpp +++ /dev/null @@ -1,255 +0,0 @@ -/* - * 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. - */ -#ifndef MFCC_HPP -#define MFCC_HPP - -#include "PlatformMath.hpp" - -#include <vector> -#include <cstdint> -#include <cmath> -#include <limits> -#include <string> - -namespace arm { -namespace app { -namespace audio { - - /* MFCC's consolidated parameters. */ - class MfccParams { - public: - float m_samplingFreq; - uint32_t m_numFbankBins; - float m_melLoFreq; - float m_melHiFreq; - uint32_t m_numMfccFeatures; - uint32_t m_frameLen; - uint32_t m_frameLenPadded; - bool m_useHtkMethod; - - /** @brief Constructor */ - MfccParams(float samplingFreq, uint32_t numFbankBins, - float melLoFreq, float melHiFreq, - uint32_t numMfccFeats, uint32_t frameLen, - bool useHtkMethod); - - MfccParams() = delete; - - ~MfccParams() = default; - - /** @brief Log parameters */ - void Log() const; - }; - - /** - * @brief Class for MFCC feature extraction. - * Based on https://github.com/ARM-software/ML-KWS-for-MCU/blob/master/Deployment/Source/MFCC/mfcc.cpp - * This class is designed to be generic and self-sufficient but - * certain calculation routines can be overridden to accommodate - * use-case specific requirements. - */ - class MFCC { - public: - /** - * @brief Constructor - * @param[in] params MFCC parameters - */ - explicit MFCC(const MfccParams& params); - - MFCC() = delete; - - ~MFCC() = default; - - /** - * @brief Extract MFCC features for one single small frame of - * audio data e.g. 640 samples. - * @param[in] audioData Vector of audio samples to calculate - * features for. - * @return Vector of extracted MFCC features. - **/ - std::vector<float> MfccCompute(const std::vector<int16_t>& audioData); - - /** @brief Initialise. */ - void Init(); - - /** - * @brief Extract MFCC features and quantise for one single small - * frame of audio data e.g. 640 samples. - * @param[in] audioData Vector of audio samples to calculate - * features for. - * @param[in] quantScale Quantisation scale. - * @param[in] quantOffset Quantisation offset. - * @return Vector of extracted quantised MFCC features. - **/ - template<typename T> - std::vector<T> MfccComputeQuant(const std::vector<int16_t>& audioData, - const float quantScale, - const int quantOffset) - { - this->MfccComputePreFeature(audioData); - float minVal = std::numeric_limits<T>::min(); - float maxVal = std::numeric_limits<T>::max(); - - std::vector<T> mfccOut(this->m_params.m_numMfccFeatures); - const size_t numFbankBins = this->m_params.m_numFbankBins; - - /* Take DCT. Uses matrix mul. */ - for (size_t i = 0, j = 0; i < mfccOut.size(); ++i, j += numFbankBins) { - float sum = 0; - for (size_t k = 0; k < numFbankBins; ++k) { - sum += this->m_dctMatrix[j + k] * this->m_melEnergies[k]; - } - /* Quantize to T. */ - sum = std::round((sum / quantScale) + quantOffset); - mfccOut[i] = static_cast<T>(std::min<float>(std::max<float>(sum, minVal), maxVal)); - } - - return mfccOut; - } - - /* Constants */ - static constexpr float ms_logStep = /*logf(6.4)*/ 1.8562979903656 / 27.0; - static constexpr float ms_freqStep = 200.0 / 3; - static constexpr float ms_minLogHz = 1000.0; - static constexpr float ms_minLogMel = ms_minLogHz / ms_freqStep; - - protected: - /** - * @brief Project input frequency to Mel Scale. - * @param[in] freq Input frequency in floating point. - * @param[in] useHTKMethod bool to signal if HTK method is to be - * used for calculation. - * @return Mel transformed frequency in floating point. - **/ - static float MelScale(float freq, - bool useHTKMethod = true); - - /** - * @brief Inverse Mel transform - convert MEL warped frequency - * back to normal frequency. - * @param[in] melFreq Mel frequency in floating point. - * @param[in] useHTKMethod bool to signal if HTK method is to be - * used for calculation. - * @return Real world frequency in floating point. - **/ - static float InverseMelScale(float melFreq, - bool useHTKMethod = true); - - /** - * @brief Populates MEL energies after applying the MEL filter - * bank weights and adding them up to be placed into - * bins, according to the filter bank's first and last - * indices (pre-computed for each filter bank element - * by CreateMelFilterBank function). - * @param[in] fftVec Vector populated with FFT magnitudes. - * @param[in] melFilterBank 2D Vector with filter bank weights. - * @param[in] filterBankFilterFirst Vector containing the first indices of filter bank - * to be used for each bin. - * @param[in] filterBankFilterLast Vector containing the last indices of filter bank - * to be used for each bin. - * @param[out] melEnergies Pre-allocated vector of MEL energies to be - * populated. - * @return true if successful, false otherwise. - */ - virtual bool 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); - - /** - * @brief Converts the Mel energies for logarithmic scale. - * @param[in,out] melEnergies 1D vector of Mel energies. - **/ - virtual void ConvertToLogarithmicScale(std::vector<float>& melEnergies); - - /** - * @brief Create a matrix used to calculate Discrete Cosine - * Transform. - * @param[in] inputLength Input length of the buffer on which - * DCT will be performed. - * @param[in] coefficientCount Total coefficients per input length. - * @return 1D vector with inputLength x coefficientCount elements - * populated with DCT coefficients. - */ - virtual std::vector<float> CreateDCTMatrix( - int32_t inputLength, - int32_t coefficientCount); - - /** - * @brief Given the low and high Mel values, get the normaliser - * for weights to be applied when populating the filter - * bank. - * @param[in] leftMel Low Mel frequency value. - * @param[in] rightMel High Mel frequency value. - * @param[in] useHTKMethod bool to signal if HTK method is to be - * used for calculation. - * @return Value to use for normalizing. - */ - virtual float GetMelFilterBankNormaliser( - const float& leftMel, - const float& rightMel, - bool useHTKMethod); - - private: - MfccParams m_params; - std::vector<float> m_frame; - std::vector<float> m_buffer; - std::vector<float> m_melEnergies; - std::vector<float> m_windowFunc; - std::vector<std::vector<float>> m_melFilterBank; - std::vector<float> m_dctMatrix; - std::vector<uint32_t> m_filterBankFilterFirst; - std::vector<uint32_t> m_filterBankFilterLast; - bool m_filterBankInitialised; - arm::app::math::FftInstance m_fftInstance; - - /** - * @brief Initialises the filter banks and the DCT matrix. **/ - void InitMelFilterBank(); - - /** - * @brief Signals whether the instance of MFCC has had its - * required buffers initialised. - * @return true if initialised, false otherwise. - **/ - bool IsMelFilterBankInited() const; - - /** - * @brief Create mel filter banks for MFCC calculation. - * @return 2D vector of floats. - **/ - std::vector<std::vector<float>> CreateMelFilterBank(); - - /** - * @brief Computes and populates internal memeber buffers used - * in MFCC feature calculation - * @param[in] audioData 1D vector of 16-bit audio data. - */ - void MfccComputePreFeature(const std::vector<int16_t>& audioData); - - /** @brief Computes the magnitude from an interleaved complex array. */ - void ConvertToPowerSpectrum(); - - }; - -} /* namespace audio */ -} /* namespace app */ -} /* namespace arm */ - -#endif /* MFCC_HPP */
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