audiostream_tp.py 文件源码

def fft(self, audio, highpass, lowpass):
    """
    Fast fourier transform conditioning

    Output:
    'output' contains the strength of each frequency in the audio signal
    frequencies are marked by its position in 'output':
    frequency = index * rate / buffesize
    output.size = buffersize/2 
    Method:
    Use numpy's FFT (numpy.fft.fft)
    Find the magnitude of the complex numbers returned (abs value)
    Split the FFT array in half, because we have mirror frequencies
     (they're the complex conjugates)
    Use just the first half to apply the bandpass filter

    Great info here: http://stackoverflow.com/questions/4364823/how-to-get-frequency-from-fft-result
    """
    left,right = numpy.split(numpy.abs(numpy.fft.fft(audio)),2)
    output = left[highpass:lowpass]
    return output