Bit rate reduction by Markov-Huffman coding of speech parameters

A post-quantization processing method is presented which reduces the bit rate of LPC-coded speech without any effect on the speech quality. A Markov model is applied to the quantization levels of the LPC parameters and the resulting transition probabilities are used co generate Huffman coding tables. The appropriate coding table is selected depending on the quantization level of the parameter in the previous frame. It is demonstrated that Markov-Huffman coding can lead to average savings of more than 20% in bit rate. A suboptimal scheme is also investigated, which can facilitate the implementation of the method on currently available signal processing chips.