Coding of speech LSP parameters using TSVQ with interblock noiseless coding

Several methods based on tree-searched vector quantization (TSVQ) are developed for the efficient encoding of speech line spectrum pair (LSP) parameters. The TSVQ effectively exploits the intraframe correlation of the LSP parameters. To make use of the interframe correlation, a differential coding scheme called interblock noiseless coding (IBNC) is used to encode the binary TSVQ codewords. Two possible applications of this coding scheme are studied: coding at very low bit rates (≈5-10 bits/frame) and coding for high-quality speech (i.e., 1-dB² spectral distortion). In the first application, a frame repeat TSVQ scheme is used with IBNC to reduce the average bit rate. For the second application, in order to obtain the desired reproduction fidelity, the components of the TSVQ error vector are encoded using scalar quantizers. It is shown that, with only one frame encoding delay, a spectral distortion of 1 dB² can be obtained at approximately 20 bits/frame