Low Bit Rate Speech Coding Using Differential Pulse Code Modulation

Generally, the voice samples are very much correlated with their past/ future samples and this feature has been exploited in the present research work. Here, various voice samples have been encoded with lower number of bits as compared to the original voice samples without much deterioration in the voice quality. We have developed a code using C-programming language on UNIX platform by applying Differential Pulse Code Modulation (DPCM) algorithm (using 4, 5, & 6-bits/ sample) on the original voice samples in Pulse Code Modulation (PCM) form (i.e., 8-bits/ sample). The results, thus obtained, differ in quality depending upon the correlation between the adjacent samples of the original voice and number of bits/ sample used for encoding.