This annex contains the modifications to Recommendation G.728 LD-CELP speech coding algorithm needed to reduce the coding bit rate down to 12.8 and 9.6 kbit/s. These modifications include the modifications to the shape and gain codebooks.

This edition provides the additional description on the calculation of GSTATE(1) and the additional values for codebook related arrays.

This annex includes electronic material containing low bit rate LD_CELP implementation test vectors.