A method and apparatus for identifying frequency bands to compute linear phase shifts between frame prototypes in a speech coder includes partitioning the frequency spectrum of a prototype of a frame by dividing the frequency spectrum into segments, assigning one or more bands to each segment, and establishing, for each segment, a set of bandwidths for the bands. The bandwidths may be fixed and uniformly distributed in any given segment. The bandwidths may be fixed and non-uniformly distributed in any segment. The bandwidths may be variable and non-uniformly distributed in any given segment.

Method and apparatus for identifying frequency bands to compute linear phase shifts between frame prototypes in a speech coder

This paper describes and implements wideband speech codec algorithms on the DSP56156 digital signal processor. Two wideband speech codec algorithms are described. The first algorithm is based on the G722 recommendation provided by the International Telegraph and Telephone Consultative Committee Study Group XVIII for 7 kHz audiocoding at 64 kbits/s. To reduce the bit rate and improve the speech quality, a second algorithm is proposed for 7 kHz audiocoding at 40 kbits/s. The second algorithm is based on the method proposed by the British Telecom Research Laboratory in the GSM Pan-European study on digital cellular land mobile radio. The results obtained for the two wideband codec algorithms are included.

M. El-Sharkawy

Papers

A DSP56156 wideband coder