Shigeaki Sasaki

G.711.1 Annex D and G.722 Annex B - New ITU-T superwideband codecs

This paper presents high quality monaural superwideband extensions to G.711.1 and G.722, recently standardized as Recommendations ITU-T G.711.1 Annex D and G.722 Annex B. The superwideband (50-14000 Hz) functionality is achieved using embedded scalable structure that adds extension layers on top of the wideband core codecs. The bit rates are extended to 96/112/128 and 64/80/96 kbit/s for G.711.1 and G.722, respectively. The main technologies include lower and higher band (0–4 kHz and 4–8 kHz) enhancements, 8–14 kHz bandwidth extension and transform coding based on algebraic vector quantization. The codecs performance is illustrated with listening test results extracted from formal ITU-T Characterization tests.

A wideband speech and audio coding candidate for ITU-T G.711WBE standardization

This paper describes an ITU-T G.711 embedded wideband speech coder, submitted as a candidate to the ITU-T G.711 wideband extension standardization qualification phase. The codec generates a bitstream comprised of three layers: a G.711 core layer with noise shaping, a time-domain weighted vector quantized narrowband enhancement layer, and an MDCT-based higher band enhancement layer. Through subjective evaluations, the coder was found to meet all tested requirements and objectives set in terms of reference, with a low computational complexity at 10 WMOPS.