CCITT Standardizing activities on speech coding
Masahiro Taka, X. Maitre · 2005
CCITT (International Telegraph and Telephone Consultative Committee) Study Group XVIII is in charge of studies on speech processing, such as speech coding techniques. During its last study period (1981-84), a recommendation for 32 kbit/s speech coding was made. Afterwards, Study Group XVIII began standardization studies on wideband speech coding (i.e., 7 kHz audio coding) at 64 kbit/s or less. This paper reports on the progress of these standardization studies. The 32 kbit/s Adaptive Differential PCM (ADPCM) standard is briefly reviewed. Also, the 7 kHz audio coding at 64 kbit/s or less is mainly discussed focussing on its applications, design requirements and coding algorithm.