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goertzel : add FFT comparison

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This commit is contained in:
Georgi Gerganov
2021-02-07 20:34:37 +02:00
parent 86cf1712cd
commit 1071a3200b
1 changed files with 105 additions and 2 deletions
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107
examples/goertzel/main.cpp
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@@ -28,7 +28,7 @@ struct FreqData {
};
bool g_isCapturing = true;
int g_nSamplesPerFrame = 1024;
constexpr int g_nSamplesPerFrame = 1024;
std::vector<FreqData> g_freqData;
// ref : https://github.com/Harvie/Programs/blob/master/c/goertzel/goertzel.c
@@ -60,11 +60,97 @@ float goertzel_mag(int numSamples, float TARGET_FREQUENCY, int SAMPLING_RATE, fl
real = (q1 * cosine - q2) / scalingFactor;
imag = (q1 * sine) / scalingFactor;
//magnitude = real*real + imag*imag;
magnitude = sqrtf(real*real + imag*imag);
//phase = atan(imag/real)
return magnitude;
}
// FFT routines taken from https://stackoverflow.com/a/37729648/4039976
int log2(int N) {
int k = N, i = 0;
while(k) {
k >>= 1;
i++;
}
return i - 1;
}
int reverse(int N, int n) {
int j, p = 0;
for(j = 1; j <= log2(N); j++) {
if(n & (1 << (log2(N) - j)))
p |= 1 << (j - 1);
}
return p;
}
void ordina(float * f1, int N) {
float f2[2*GGWave::kMaxSamplesPerFrame];
for (int i = 0; i < N; i++) {
int ir = reverse(N, i);
f2[2*i + 0] = f1[2*ir + 0];
f2[2*i + 1] = f1[2*ir + 1];
}
for (int j = 0; j < N; j++) {
f1[2*j + 0] = f2[2*j + 0];
f1[2*j + 1] = f2[2*j + 1];
}
}
void transform(float * f, int N) {
ordina(f, N); //first: reverse order
float * W;
W = (float *)malloc(N*sizeof(float));
W[2*1 + 0] = cos(-2.*M_PI/N);
W[2*1 + 1] = sin(-2.*M_PI/N);
W[2*0 + 0] = 1;
W[2*0 + 1] = 0;
for (int i = 2; i < N / 2; i++) {
W[2*i + 0] = cos(-2.*i*M_PI/N);
W[2*i + 1] = sin(-2.*i*M_PI/N);
}
int n = 1;
int a = N / 2;
for(int j = 0; j < log2(N); j++) {
for(int i = 0; i < N; i++) {
if(!(i & n)) {
int wi = (i * a) % (n * a);
int fi = i + n;
float a = W[2*wi + 0];
float b = W[2*wi + 1];
float c = f[2*fi + 0];
float d = f[2*fi + 1];
float temp[2] = { f[2*i + 0], f[2*i + 1] };
float Temp[2] = { a*c - b*d, b*c + a*d };
f[2*i + 0] = temp[0] + Temp[0];
f[2*i + 1] = temp[1] + Temp[1];
f[2*fi + 0] = temp[0] - Temp[0];
f[2*fi + 1] = temp[1] - Temp[1];
}
}
n *= 2;
a = a / 2;
}
free(W);
}
void FFT(float * f, int N, float d) {
transform(f, N);
for (int i = 0; i < N; i++) {
f[2*i + 0] *= d;
f[2*i + 1] *= d;
}
}
void FFT(float * src, float * dst, int N, float d) {
for (int i = 0; i < N; ++i) {
dst[2*i + 0] = src[i];
dst[2*i + 1] = 0.0f;
}
FFT(dst, N, d);
}
}
void GGWave_setDefaultCaptureDeviceName(std::string name) {
@@ -228,11 +314,28 @@ bool GGWave_mainLoop() {
}
int n = 0;
float data[g_nSamplesPerFrame];
static float data[g_nSamplesPerFrame];
static float out[2*g_nSamplesPerFrame];
do {
n = cbWaveformInp(data, sizeof(float)*g_nSamplesPerFrame);
if (n <= 0) break;
//FFT(data, out, g_nSamplesPerFrame, 1.0);
//for (int i = 0; i < g_nSamplesPerFrame; ++i) {
// out[i] = (out[2*i + 0]*out[2*i + 0] + out[2*i + 1]*out[2*i + 1]);
//}
//for (int i = 1; i < g_nSamplesPerFrame/2; ++i) {
// out[i] += out[g_nSamplesPerFrame - i];
//}
//for (int i = 0; i < (int) g_freqData.size(); ++i) {
// g_freqData[i].mag[g_freqData[i].head] = out[40 + i];
// if (++g_freqData[i].head == (int) g_freqData[i].mag.size()) {
// g_freqData[i].head = 0;
// }
//}
for (int i = 0; i < (int) g_freqData.size(); ++i) {
g_freqData[i].mag[g_freqData[i].head] = goertzel_mag(g_nSamplesPerFrame, g_freqData[i].freq, GGWave::kBaseSampleRate, data);
if (++g_freqData[i].head == (int) g_freqData[i].mag.size()) {