<FONT face=Verdana>This paper is focused on the model of waveform interpolation (WI) and its parameters quantization

then a waveform interpolation speech coding algorithm based on two-dimensional nonnegative matrix factorization at 1kb/s is presented. This method makes the dimensions of CW magnitude matrix much lower in columns and rows

so it is convenient for quantizing the coding matrix. In addition

speech coders at very low bit rates can hardly get good performance

for there are no sufficient bits to express these coding parameters. Then two-frame joint

inter-frame backward prediction three-stage vector quantization

discrete cosine transform (DCT) and split matrix quantization techniques are promoted in this paper

in order to reduce the speech coding bit rates as well as to improve the quality of the speech. The results of informal subjective listening test show that the performance of 1kb/s 2DNMF-WI coder is a little worse than that of 2kb/s NMF-WI coder.