A 16-kbit/s Code Excited Linear Prediction (CELP) coder with a 10-ms frame is proposed for wideband speech. The main features of this coder are line spectrum pairs quantization using inter-frame moving average prediction, a fixed excitation codebook with a two-stage, two-channel conjugate structure, and pre-selection in both adaptive codebook search and fixed codebook search. To solve two problems peculiar to the wideband CELP coding, i.e., computational complexity and computational precision, adaptive codebook pre-selection in the residual domain, a trained sparse codebook, and square root LPC coefficients are introduced. The quality of the coder meets the standard for 56-kbit/s coding specified in ITU-T G.722 in terms of mean opinion scores.
Bibliographic reference. Sasaki, Shigeaki / Kataoka, Akitoshi / Moriya, Takehiro (1995): "Wideband CELP coder at 16-kbit/s with 10-ms frame", In EUROSPEECH-1995, 41-44.