ITU-T G.722.1 annex C: the first ITU-T superwideband audio coder

In May 2005 the ITU-T approved ITU-T G.722.1 Annex C. This Annex extends the G.722.1 codec from 7 kHz audio bandwidth to 14 kHz, 1 octave better than the current ITU-T wideband algorithms. It is a low-complexity audio codec operating at 24, 32, and 48 kb/s. Like the main ITU-T G.722.1 recommendation, its main application is videoconferencing. This article presents the standardization stages from the definition of the foreseen applications and specification of the requirements to the performance evaluation. The adaptation and design of new software tools (included in the ITU-T software tool library, STL), and the utilization of ITU-T P-series recommendations (dealing with transmission characteristics and performance characterization of telephone transmission quality) are also presented.