MLECO-2079 Adding the C++ KWS example
Signed-off-by: Eanna O Cathain <eanna.ocathain@arm.com>
Change-Id: I81899bbfaada32f478c2e2fc6441eabb94d8d0fc
diff --git a/samples/SpeechRecognition/include/Wav2LetterMFCC.hpp b/samples/SpeechRecognition/include/Wav2LetterMFCC.hpp
new file mode 100644
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+++ b/samples/SpeechRecognition/include/Wav2LetterMFCC.hpp
@@ -0,0 +1,78 @@
+//
+// Copyright © 2020 Arm Ltd and Contributors. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+#pragma once
+
+#include "MFCC.hpp"
+
+/* Class to provide Wav2Letter specific MFCC calculation requirements. */
+class Wav2LetterMFCC : public MFCC
+{
+
+public:
+ explicit Wav2LetterMFCC(const MfccParams& params)
+ : MFCC(params)
+ {}
+
+ Wav2LetterMFCC() = delete;
+ ~Wav2LetterMFCC() = default;
+
+protected:
+
+ /**
+ * @brief Overrides base class implementation of this 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
+ */
+ 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) override;
+
+ /**
+ * @brief Override for the base class implementation convert mel
+ * energies to logarithmic scale. The difference from
+ * default behaviour is that the power is converted to dB
+ * and subsequently clamped.
+ * @param[in,out] melEnergies 1D vector of Mel energies
+ **/
+ void ConvertToLogarithmicScale(std::vector<float>& melEnergies) override;
+
+ /**
+ * @brief Create a matrix used to calculate Discrete Cosine
+ * Transform. Override for the base class' default
+ * implementation as the first and last elements
+ * use a different normaliser.
+ * @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.
+ */
+ std::vector<float> CreateDCTMatrix(int32_t inputLength,
+ int32_t coefficientCount) override;
+
+ /**
+ * @brief Given the low and high Mel values, get the normaliser
+ * for weights to be applied when populating the filter
+ * bank. Override for the base class implementation.
+ * @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 normalising.
+ */
+ float GetMelFilterBankNormaliser(const float& leftMel,
+ const float& rightMel,
+ bool useHTKMethod) override;
+};
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