DocumentCode :
1157841
Title :
A toll quality 8 kb/s speech codec for the personal communications system (PCS)
Author :
Salami, Redwan ; Laflamme, Claude ; Adoul, Jean-Pierre ; Massaloux, Dominique
Author_Institution :
Dept. of Electr. Eng., Sherbrooke Univ., Que., Canada
Volume :
43
Issue :
3
fYear :
1994
fDate :
8/1/1994 12:00:00 AM
Firstpage :
808
Lastpage :
816
Abstract :
A toll quality speech codec at 8 kb/s suitable for the future personal communications system is presented. The codec is currently under standardization by the ITU-T (successor of CCITT) where the codec terms of reference were mainly determined considering PCS application. The encoding algorithm is based on algebraic code-excited linear prediction (ACELP) and has a speech frame of 10 ms. Efficient pitch and codebook search strategies, along with efficient quantization procedures, have been developed to achieve toll quality encoded speech with a complexity implementable on current fixed-point DSP chips. Formal subjective listening tests, performed by ITU-T SG 12, showed that the codec quality is equivalent to that of G.726 ADPCM at 32 kb/s in error-free conditions and it outperforms G.726 under error conditions. The codec performs adequately under tandeming conditions, and can support a frame erasure rate up to 3% with a degradation in its performance that is still worse than the ITU-T requirements, and this is one subject of study for the next phase. The algorithm has been implemented on a single fixed-point DSP for the ITU-T subjective rest, and required about 29 MIPS. An optimized version, however, requires 24 MIPS without any speech quality degradation
Keywords :
analogue-digital conversion; codecs; linear predictive coding; mobile radio systems; personal communication networks; speech coding; telecommunication standards; vocoders; 8 kbit/s; ACELP; ITU-T subjective test; PCS; algebraic code-excited linear prediction; codebook search strategies; degradation; encoded speech; fixed-point DSP; fixed-point DSP chips; frame erasure rate; personal communications system; pitch; quality; quantization procedures; speech frame; speech quality; subjective listening tests; tandeming conditions; toll quality 8 kb/s speech codec; Degradation; Digital signal processing; Digital signal processing chips; Encoding; Performance evaluation; Personal communication networks; Quantization; Speech codecs; Standardization; Testing;
fLanguage :
English
Journal_Title :
Vehicular Technology, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9545
Type :
jour
DOI :
10.1109/25.312763
Filename :
312763
Link To Document :
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