Variable dimension matrix quantization of LSP parameters for very low bit rate vocoder below 300bps

This paper examines the efficient quantization of LSP parameters for very low bit rate vocoder below 300 bps, a new quantization scheme called variable dimension matrix quantization (VDMQ) is presented. In the VDMQ scheme, the extracted LSP parameters matrix with variable dimension is quantized directly without dimension conversion. Based on the distance measure definition between tow LSP matrices with different dimension, the optimal codeword is deduced. Theoretical analysis and experiment results show that the VDMQ scheme performs better than the segment quantization and matrix quantization scheme at very low bit rate. Also, the codebook storage is almost reduced by 90%. The VDMQ scheme provides a new effective approach for efficient LSP parameters quantization at very low bit rate.