A variable frame size - variable prediction order LP based vocoder

Abstract

Speech coding techniques have been vastly exploited in telecommunication applications in recent years. Due to lower sensitivity to channel errors, in such applications, usually fixed rate coding is employed. However, because of the limitation of such algorithms on using fixed bit allocation, they are not capable to reduce the existing redundancy in speech signals very efficiently. This paper presents an efficient variable coding algorithm based on the well known linear prediction method. In the proposed technique, an LP order for analysis and coding of variable length speech frames is designed by analyzing the similarities of waveform within the frame. Employing the advantages of variable frame length and variable order LP system, a very low bit-high quality coding scheme is presented. Experiments show 28% bit rate improvement comparing with a LP based vocoder.