Dsp-based G.729 Voice Encoding

Language is an important means that people use to communicate, the most familiar data form is speech in the correspondence system. Along with the development of the move correspondence and Internet, speech correspondence technique is also renewed constantly. The transmission and saving of the digital speech signal is better than analog signal's on security,anti- interference, and so on. This technique is convenient, and can make signal be easy to keep secret, and the price is cheap, so the digital signal takes the specific weight in communication ,the code technique also develop immediately and continuously.The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). Recommendation G.729 was prepared by ITU-T in November of 1995.This Recommendation contains the description of an algorithm for the coding of speech signals at 8 kbit/s using Conjugate-Structure Algebraic-Code-Excited Linear-Prediction (CS-ACELP). This coder is designed to operate with a digital signal obtained from the analogue input signal, then sampling it at 8000 Hz, followed by conversion to 16-bit linear PCM for the input to the encoder. The output of the decoder should be converted back to an analogue signal by similar means.The text does the detailed introduction to the algorithm structure and the theory of G.729 , introduces the C6711 DSK, and explains the process of coding. By test, the result shows that the words sound clear after the signal was coded, the noise is small, meeting the request of the coder.