Implementation of silence compression scheme for G.723.1 speech coder using TI TMS320C51 DSP chip

The International Telecommunication Union (ITU) silence compression scheme for dual rate speech coder for multimedia communications transmitting at 5.3 and 6.3 kbit/s (Annex A) was designed for the ITU G.723.1 speech coder. Silence compression techniques are used to reduce the transmitted bit rate during silent intervals of speech. This paper describes the algorithm of voice activity detector (VAD) which detects the presence (and absence) of speech and the algorithm of comfort noise generator (CNG) which provides fill-in background noise when there is an absence of speech so as to improve the perceptual performance for the listener. Then it presents a real-time implementation of this silence compression scheme using TI TMS320C5X DSP.