A toll quality 8 kb/s speech codec for the personal communications system (PCS)

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 b...

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Vydáno v:IEEE transactions on vehicular technology Ročník 43; číslo 3; s. 808 - 816
Hlavní autoři: Salami, R., Laflamme, C., Adoul, J.-P., Massaloux, D.
Médium: Journal Article
Jazyk:angličtina
Vydáno: IEEE 01.08.1994
Témata:
Degradation
Digital signal processing
Digital signal processing chips
Encoding
Performance evaluation
Personal communication networks
Quantization
Speech codecs
Standardization
Testing
ISSN:0018-9545
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Shrnutí: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.< >
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ISSN:0018-9545
DOI:10.1109/25.312763