An extreme low bit rate speech coding algorithm around 300bps

An extreme low bit rate speech coding algorithm around 300bps is proposed in this paper. The algorithm builds mixed excitation segment coding model by taking advantage of the segment coder and the MELP coder. Variable dimension matrix quantization (VDMQ) and Variable dimension vector quantization (VDVQ) scheme are presented for quantizing LSP and excitation parameters. These quantization schemes achieve acceptable performance at very low bit rate. Also, the codebook storage is reduced dramatically. Informal subjective listening test shows that the reconstructed speech has high intelligibility and moderate naturalness, the PESQ score can achieve 2.02.