ITU-T G.729.1: AN 8-32 Kbit/S Scalable Coder Interoperable with G.729 for Wideband Telephony and Voice Over IP
Stéphane Ragot, Balázs Kövesi, Romain Trilling, David Virette, Nicolas Duc, Dominique Massaloux, Stéphane Proust, Bernd Geiser, Martin Gärtner, Stefan Schandl, Hervé Taddei, Yang Gao, E. Shlomot, Hiroyuki Ehara, Kōji Yoshida, Tommy Vaillancourt, Redwan A. Salami, Mi Suk Lee, Do Young Kim · 2007
This paper describes the scalable coder - G.729.1 - which has been recently standardized by ITU-T for wideband telephony and voice over IP (VoIP) applications. G.729.1 can operate at 12 different bit rates from 32 down to 8 kbit/s with wideband quality starting at 14 kbit/s. This coder is a bitstream interoperable extension of ITU-T G.729 based on three embedded stages: narrowband cascaded CELP coding at 8 and 12 kbit/s, time-domain bandwidth extension (TDBWE) at 14 kbit/s, and split-band MDCT coding with spherical vector quantization (VQ) and pre-echo reduction from 16 to 32 kbit/s. Side information - consisting of signal class, phase, and energy - is transmitted at 12, 14 and 16 kbit/s to improve the resilience and recovery of the decoder in case of frame erasures. The quality, delay, and complexity of G.729.1 are summarized based on ITU-T results.