On the ITU-T G.729.1 silence compression scheme

Silence compression scheme is essential for efficient voice communication systems. It allows a significant reduction of transmission bandwidth during silence period where only parametric descriptions of the background noise are transmitted. A silence compression scheme includes a voice activity detection (VAD), a discontinuous transmission (DTX), a silence insertion descriptor (SID), and a comfort noise generator (CNG) module. In this paper, we describe a silence compression scheme for ITU-T Recommendation G.729.1 which employs a unique scalable SID frame structure. This scalable frame structure consists of a lower band core layer, a lower band enhancement layer, and a higher band layer. The scheme is optimized for ITU-T G.729.1 and is interoperable with ITU-T G.729 Annex B.