public float DetectPitch(float[] buffer, int inFrames) {
if (prevBuffer == null) {
prevBuffer = new float[inFrames];
}
// double frames since we are combining present and previous buffers
int frames = inFrames * 2;
if (fftBuffer == null) {
fftBuffer = new float[frames * 2]; // times 2 because it is complex input
}
for (int n = 0; n < frames; n++) {
if (n < inFrames) {
fftBuffer[n * 2] = prevBuffer[n] * HammingWindow(n, frames);
fftBuffer[n * 2 + 1] = 0; // need to clear out as fft modifies buffer
} else {
fftBuffer[n * 2] = buffer[n - inFrames] * HammingWindow(n, frames);
fftBuffer[n * 2 + 1] = 0; // need to clear out as fft modifies buffer
}
}
// assuming frames is a power of 2
shifter.smbFft(fftBuffer, frames, -1);
float binSize = sampleRate / frames;
int minBin = (int) (85 / binSize);
int maxBin = (int) (300 / binSize);
float maxIntensity = 0f;
int maxBinIndex = 0;
for (int bin = minBin; bin <= maxBin; bin++) {
float real = fftBuffer[bin * 2];
float imaginary = fftBuffer[bin * 2 + 1];
float intensity = real * real + imaginary * imaginary;
if (intensity > maxIntensity) {
maxIntensity = intensity;
maxBinIndex = bin;
}
}
return binSize * maxBinIndex;
}