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https://github.com/Boof2015/astra-mobile.git
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Boof2015
92 lines
2.7 KiB
C++
92 lines
2.7 KiB
C++
#pragma once
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#define _USE_MATH_DEFINES
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#include <cmath>
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#ifndef M_PI
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#define M_PI 3.14159265358979323846
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#endif
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#include <vector>
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#include <complex>
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#include <algorithm>
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namespace DSP {
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// Simple FFT implementation (Cooley-Tukey radix-2)
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class FFT {
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public:
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explicit FFT(size_t size);
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void forward(const float* input, float* magnitudes);
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void forward(const float* input, std::complex<float>* output);
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size_t getSize() const { return size_; }
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private:
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size_t size_;
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std::vector<std::complex<float>> twiddles_;
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std::vector<std::complex<float>> buffer_; // Reuse buffer to avoid allocations
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std::vector<std::complex<float>> scratch_; // Scratch buffer if needed
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void bitReverse(std::complex<float>* data);
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};
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// Biquad filter for lowpass/bandpass
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class BiquadFilter {
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public:
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BiquadFilter();
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void setLowpass(float frequency, float sampleRate, float Q = 0.707f);
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void setBandpass(float frequency, float sampleRate, float Q = 2.0f);
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void setHighShelf(float frequency, float sampleRate, float gainDB, float Q = 0.707f);
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float process(float input);
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void reset();
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// Process entire buffer (bidirectional for zero phase)
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void processBuffer(const float* input, float* output, size_t length, bool bidirectional = true);
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private:
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float b0_, b1_, b2_;
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float a1_, a2_;
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float x1_, x2_;
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float y1_, y2_;
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};
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// Linear-phase FIR filter for stable trigger detection
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// Uses Kaiser-windowed bandpass design for consistent zero crossings
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class FIRFilter {
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public:
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FIRFilter();
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// Design Kaiser-windowed bandpass filter centered on frequency
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void designBandpass(float centerFreq, float bandwidth, float sampleRate, float sidelobeAtten = 60.0f);
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// Process single sample
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float process(float input);
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// Get filter delay (for phase compensation)
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size_t getDelay() const { return order_ / 2; }
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// Reset filter state
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void reset();
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private:
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std::vector<float> coeffs_;
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std::vector<float> delay_;
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size_t idx_;
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size_t order_;
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// Kaiser window helpers
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static std::vector<float> kaiserWindow(size_t length, float beta);
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static double besselI0(double x);
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};
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// Pitch detection using autocorrelation
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float detectPitch(const float* data, size_t length, float sampleRate, float minFreq = 40.0f, float maxFreq = 2000.0f);
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// FFT-based pitch detection (more stable than autocorrelation)
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float detectPitchFFT(const float* data, size_t length, float sampleRate, float minFreq = 40.0f, float maxFreq = 2000.0f);
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// Find zero-crossing trigger point with hysteresis/hold-off (sub-sample precision)
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float findTriggerPoint(const float* data, size_t length, int searchStart, int searchEnd);
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// Calculate RMS
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float calculateRMS(const float* data, size_t length);
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} // namespace DSP
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