Low-delay subband CELP coding for wideband speech

In this paper we propose low-delay techniques for coding 7 kHz speech using subband coding together with code-excited linear predictive coding (CELP). We compare the use of separate as well as joint index codebooks. Specifically, the joint index subband CELP (JISBC) algorithm is found to provide good quality with processing delay in the range of 2.375 ms to 3.375 ms at corresponding bitrates of 16 kbit/s to 8 kbits/s.