A high quality MBE-LPC-FE speech coder at 2.4 kbps and 1.2 kbps

摘要

This paper presents a high quality speech coder based on the multi-band excitation (MBE) model operating at 2.4 kb/s and 1.2 kb/s. The features of this coder mainly focus on two aspects. One is an accurate and reliable pitch estimation and voiced/unvoiced decision algorithm. The other is the efficient quantization of the variable dimension spectral amplitude vector. Besides representing the spectral envelope information using an all-pole model, we also encode error vectors of the spectral amplitude vector at several important positions. Informal listening tests indicate that the speech quality of this coder at 2.4 kb/s is comparable and even superior to the INMARSAT-M IMBE 4.15 kb/s coder. The coder has been implemented in real-time on a single TMS320C31 floating point DSP.