Title :
A variable bit rate operation of LD-CELP mainly for VBD applications in DCME
Author :
Shapira, Inbar ; Simchony, Tal ; Sourani, Sasson ; Piasetzky, Joshua
Author_Institution :
ECI Telecom Ltd., Israel
Abstract :
This paper describes the candidate algorithm for Annex J of ITU-T Rec. G.728. The algorithm achieves compression and near transparent transmission of VBD signals such as V.34 @ 19200 bps (and up to 21600 bps under moderate analog impairments conditions) using a 40 kbit/s transmission rate. Additionally the algorithm provides toll speech quality and smooth mode-switching (speech-to-data/data-to-speech) during voice and signaling signals. The main novelty of the algorithm is the application of trellis coded quantization (TCQ) approach to codebook search that results in sufficient quantization gain, lower complexity (than LD-CELP), and maintains the same algorithmic delay of 5 samples (0.625 msec)
Keywords :
code standards; data communication; data compression; delays; linear predictive coding; quantisation (signal); speech codecs; speech coding; speech processing; telecommunication standards; trellis codes; voice communication; 19200 bit/s; 21600 bit/s; 40 kbit/s; Annex J; DCME; ITU-T Recommendation G.728; LD-CELP; TCQ; V.34; VBD applications; VBD signals; algorithm; algorithmic delay; analog impairments conditions; codebook search; data communication; decoder; mode-switching; quantization gain; signaling signals; toll speech quality; transmission rate; transparent transmission; trellis coded quantization; variable bit rate operation; voice signals; Bit rate; Convolution; Convolutional codes; Decoding; Equations; Filters; Linear predictive coding; Speech; Switches; Viterbi algorithm;
Conference_Titel :
Speech Coding For Telecommunications Proceeding, 1997, 1997 IEEE Workshop on
Conference_Location :
Pocono Manor, PA
Print_ISBN :
0-7803-4073-6
DOI :
10.1109/SCFT.1997.623902
