Portal de Periódicos da CAPES

ADPCM with a multiquantizer for speech coding

1988; Institute of Electrical and Electronics Engineers; Volume: 6; Issue: 2 Linguagem: Inglês

10.1109/49.616

1558-0008

Tomohiko Taniguchi, S. Unagami, K. Iseda, S. Tominaga,

Digital Filter Design and Implementation

A speech coding algorithm with low complexity and a short processing delay is introduced. The proposed algorithm is ADPCM (adaptive digital pulse code modulation) with a multiquantizer (ADPCM-MQ). The input signal is processed in parallel by multiple ADPCM coders with different characteristics. Then the optimum ADPCM coder with minimum error power is dynamically selected for each frame. A 16-kb/s codec based on this algorithm has been implemented using two general-purpose digital signal processors (MB8764) with 8.3 ms of total processing delay. A segmental SNR of 19-21 dB was achieved at 16 kb/s; with postfiltering the segmental SNR was increased to 23-25 dB. Combined with the time domain compression scheme, the algorithm can be easily applied to 8-kb/s coding. It is also extensible to variable-rate coding. >