Convert log-power-spectrum to MFCC using the normalized DCT-II

def dct2(input, K=13):
    """Convert log-power-spectrum to MFCC using the normalized DCT-II"""
    nframes, N = input.shape
    freqstep = numpy.pi / N
    cosmat = dctmat(N,K,freqstep,False)
    return numpy.dot(input, cosmat) * (2.0 / N)