Nec Corporation

Makio Nakamura

Akira Hioki

One frame of speech signal data and subframes of speech signal data divided from the frame of speech signal data are encoded by frame and subframe encoding processes while another frame is decoded by frame and subframe decoding processes. The frame and subframe encoding processes and the frame and subframe decoding processes are interleaved to reduce the DSP memory capacity needed for a speech codec.

Speech codec and a method of processing a speech signal with speech codec

A speech encoder synthesizes an excitation sound source in accordance with the linear coupling of at least two predetermined basis vectors. In realizing the codebook search by using signal processing LSIs, the ordination of the first cross correlation R.sub.m between an input speech signal p(n) and plural reproduced signals obtained by using plural basis vectors is computed, and the ordination of the second cross correlation D.sub.mj of the plural reproduced signals qm(n) is computed. These ordinations are arranged to be one ordination Rd.sub.mj. By using the ordination Rd.sub.mj, all possible combinations of the third and fourth cross correlation calculations are carried out to provide a most optimum codebook.

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Tokyo, Japan

Makio Nakamura