Title :
A robust low-delay CELP speech coder at 16 kbits/s
Author_Institution :
AT&T Bell Lab., Murray Hill, NJ, USA
Abstract :
A candidate algorithm for the new CCITT 16-kb/s speech coding standard is presented. This algorithm is based on backward-adaptive CELP (code-excited linear prediction) where the predictor and the excitation gain are updated by analyzing previously quantized signals. The only information transmitted is the excitation vector with a size as small as five samples so as to achieve a one-way coding delay of less than 2 ms. With a clear channel, this 16-kb/s coder slightly outperformed the CCITT standard 32 kb/s ADPCM (adaptive differential pulse code modulation) (G.721) in speech quality as measured by the mean opinion score (MOS). With noisy channels, the coder scored slightly higher than G.721 fora bit-error rate of 10/sup -2/ and significantly higher (by a margin of 0.5) for bit-error rate of 10/sup -3/.<>
Keywords :
encoding; filtering and prediction theory; speech analysis and processing; speech synthesis; standards; telecommunication channels; 16 kbit/s; CCITT recommendation G.721; backward-adaptive CELP; bit-error rate; clear channel; code-excited linear prediction; low-delay speech coder; mean opinion score; noisy channels; speech quality; vector excitation coding; Algorithm design and analysis; Bit error rate; Code standards; Delay; Pulse measurements; Pulse modulation; Robustness; Signal analysis; Speech coding; Vectors;
Conference_Titel :
Global Telecommunications Conference and Exhibition 'Communications Technology for the 1990s and Beyond' (GLOBECOM), 1989. IEEE
Conference_Location :
Dallas, TX, USA
DOI :
10.1109/GLOCOM.1989.64152
