Discrete cosine transform magnitude and phase coefficients used for vector quantization in a speech transform coder

Conventional real and imaginary parts do not exist for the transform coefficients in discrete cosine transforms as they do for the discrete Fourier transform. It is shown that coefficients behaving like magnitude and phase functions can be computed and used for vector quantization in discrete cosine transform coding of speech. For short block transforms, time trajectories of these functions can also be used for vector quantization, giving further flexibility with respect to bit allocation and providing the possibility of capitalizing on the pitch structure of voiced speech