International Journal of Engineering Sciences & Emerging Technologies, August 2013. ISSN: 2231 – 6604 Volume 6, Issue 1, pp: 1-8 ©IJESET 1 THE EFFECT OF WEIGHT FACTOR ON THE PERFORMANCE OF G.729A SPEECH CODER M. A. Rashed 1 , T. A. El-Garf 1 , I. F. Tarrad 2 , H. A. Almotaafy 1 1 Department of Electrical & Computer Engineering, Higher Technological Institute, 10 th of Ramadan City, Egypt. 2 Department of Electronics & Communications Engineering, Al-Azhar University, Cairo, Egypt. mohammed.adel@windowslive.com talaatelgarf@yahoo.com tarradif@gmail.com Prdr_hosny_aaam@yahoo.com ABSTRACT G.729A (CS-ACELP Annex A) is a high quality low bandwidth codec at 8 kbit/s with low complexity. G.729A is a bit stream interoperable with G.729; i.e., speech coded with G.729A can be decoded with G.729, and vice versa. Several algorithmic changes have been introduced into G.729 which resulted in 50% drop in its complexity. The Aim of this paper is to study the effect of weight factor on the performance of G.729A coder synthesized speech. This coder is implemented in MATLAB with many different values of weight factor. The effect of weight factor on the recovered speech quality has been investigated and studied. Objective analysis on weighted speech has been carried out in order to observe its overall performance. The performance measures prove that at certain values of weight factor, the speech quality is better than at the value listed in the standard. KEYWORDS: Speech Coding, CS-ACELP, G.729, G.729A, Analysis-by-synthesis, Weighted speech, Speech synthesis. I. INTRODUCTION ITU-T has standardized G.729 as the standard speech-coding algorithm for VoIP, DSVD (Digital Simultaneous Voice over Data) and multimedia applications [1-3]. This ITU-T recommendation is based on Conjugate Structure-Adaptive Code Excited Linear Prediction (CS-ACELP) algorithm, operating at a bit-rate of 8 Kbps for discrete speech samples sampled at a rate of 8000 samples per second. Later, it has led to the design of various annexes of standard G.729 with variable bit rate and enhanced speech quality. The G.729A is a low complexity continuous data transmission scheme for DSVD applications [3-5,13]. In this paper, we have focused on the CS-ACELP codec G.729A (8kbps) and the effect of different values of weight factor γ on the speech quality. The rest of the paper is organized as follows. The description of G.729A (Principles of Encoder and Decode) and the algorithmic changes with G729 standard will be presented in Section 2. Proposed Modification in Weight Factor of G.729A will be explained in Section 3. Objective Analysis which used in quality measurements will be presented in Section 4. Section 5 will show the experimental results. The conclusion will be given in the last section.