Multiple description coding communication system

摘要

A multiple description coder 20 pairs two samples and transforms the samples prior to quantizing and entropy encoding to improve coding efficiency while simultaneously achieving satisfactory performance with regard to distortion. For the N-Sample case, the multiple description coder pairs the samples using two different algorithms, and then performs the pairing transformation of the two variable case. One method assigns the lowest energy coefficients with the highest energy coefficients and so on until the middle coefficients are paired with each other. Another method assigns the highest energy coefficient with coefficients having energy below some predetermined value. Image coders and decoders are also included. A method for classifying the coefficients prior to performing the pairing transform is disclosed, which classifies the coefficients according to the amount and location of their energy. <IMAGE>