Title :
A low-delay CELP coder for the CCITT 16 kb/s speech coding standard
Author :
Chen, Juin-Hwey ; Cox, Richard V. ; Lin, Yen-Chun ; Jayant, Nikil ; Melchner, Melvin J.
Author_Institution :
AT&T Bell Lab., Murray Hill, NJ, USA
fDate :
6/1/1992 12:00:00 AM
Abstract :
A low-delay code-excited linear prediction (LD-CELP) speech coder which is expected to be standardized in 1992 as a CCITT G Series Recommendation for universal applications of speech coding at 16 kb/s is presented. The coder achieves a one-way coding delay of less than 2 ms by making both the LPC predictor and the excitation gain backward-adaptive and by using a small excitation vector size of five samples. The official CCITT laboratory tests revealed that the speech quality of this 16 kb/s LD-CELP coder is either equivalent to or better than that of the CCITT G.721 standard 32-kb/s ADPCM coder for almost all conditions tested. A description of the LD-CELP algorithm, its implementation on the DSP32C for CCITT testing, and performance results from these tests are presented
Keywords :
codecs; delays; encoding; filtering and prediction theory; speech analysis and processing; speech intelligibility; standards; 16 kbit/s; CCITT G Series Recommendation; DSP32C; LD-CELP algorithm; LPC predictor; backward adaptive excitation gain; code-excited linear prediction; coding delay; excitation vector size; laboratory tests; low delay; speech coder; speech coding standard; speech quality; Bit rate; Code standards; Delay; Linear predictive coding; Performance loss; Phase change materials; Speech analysis; Speech coding; Testing; Vectors;
Journal_Title :
Selected Areas in Communications, IEEE Journal on
