Question

我正在做一个从录音机返回基频的Android项目。我用FFT类来计算频率：

http://introcs.cs.princeton.edu/java/97data/FFT.java

和Complex Array来自：

http://introcs.cs.princeton.edu/java/97data/Complex.java.html

这是我计算频率的代码：

public double calculateFFT(byte[] signal)
        {           
        final int mNumberOfFFTPoints =1024;
        double mMaxFFTSample;

        double temp;
        Complex[] y;
        Complex[] complexSignal = new Complex[mNumberOfFFTPoints];
        double[] absSignal = new double[mNumberOfFFTPoints/2];

        for(int i = 0; i < mNumberOfFFTPoints; i++){
            temp = (double)((signal[2*i] & 0xFF) | (signal[2*i+1] << 8)) / 32768.0F;
            complexSignal[i] = new Complex(temp,0.0);
        }

        y = FFT.fft(complexSignal); 

        mMaxFFTSample = 0.0;
        int mPeakPos = 0;
        for(int i = 0; i < (mNumberOfFFTPoints/2); i++)
        {
            absSignal[i] = Math.sqrt(Math.pow(y[i].re(), 2) + Math.pow(y[i].im(), 2));

            if(absSignal[i] > mMaxFFTSample)
            {
                mMaxFFTSample = absSignal[i];
                mPeakPos = i;
            } 
        }


        return ((1.0 * sampleRate) / (1.0 * mNumberOfFFTPoints)) * mPeakPos;

    }

其中sampleRate = 44100且mNumberOfFFTPoints = 1024。从这段代码中我读了很多值，但是我想要得到唯一的基频，所以只有价值。你能帮我理解这个算法吗？