Title :
Standardization activity in ITU of extending 16-kbit/s LD-CELP for personal communication systems
Author :
Hayashi, Shinji ; Ogawa, Mineyoshi
Author_Institution :
NTT Human Interface Labs., Tokyo, Japan
Abstract :
This paper introduces the standardization activity in ITU-T (International Telecommunication Union, Telecommunication Standardization Sector) of extending 16-kbit/s LD-CELP (low-delay code-excited linear-predictive) speech coding for personal communication systems. ITU-T Recommendation G.728 (LD-CELP) provides toll quality at 16 kbit/s with very low algorithmic delay time (0.625 ms). However, its quality significantly falls under conditions when-the received codewords are lost for 10 to 100 ms that tend to occur in radio channels. The extension of LD-CELP consists of the decoder modification proposed by AT&T that conceals the erasure of channel frames. Subjective test results using Japanese speech shows fairly good quality with this concealment for frame-erasure conditions
Keywords :
decoding; delays; linear predictive coding; personal communication networks; speech coding; standardisation; 0.625 ms; 10 to 100 ms; 16 kbit/s; AT&T; ITU; ITU-T Recommendation G.728; International Telecommunication Union; Japanese speech; LD-CELP; Telecommunication Standardization Sector; algorithmic delay time; channel frames erasure concealment; decoder modification; low-delay code-excited linear-predictive speech coding; personal communication systems; radio channels; received codewords; speech coding; standardization; subjective test results; toll quality; Circuits; Decoding; Delay effects; Filters; Multiplexing equipment; Robustness; Signal synthesis; Speech coding; Speech synthesis; Standardization;
Conference_Titel :
Universal Personal Communications. 1995. Record., 1995 Fourth IEEE International Conference on
Conference_Location :
Tokyo
Print_ISBN :
0-7803-2955-4
DOI :
10.1109/ICUPC.1995.497122
