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

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