qmf_realtime_class.py 文件源码

def DCT4(samples):
    """
        Method to create DCT4 transformation using DCT3

        Arguments   :

            samples : (1D Array) Input samples to be transformed

        Returns     :

            y       :  (1D Array) Transformed output samples

    """

    # Initialize
    samplesup=np.zeros(2*N, dtype = np.float32)
    # Upsample signal:
    samplesup[1::2]=samples

    y=spfft.dct(samplesup,type=3,norm='ortho')*np.sqrt(2)#/2

    return y[0:N]

#The DST4 transform: