Efficient codebook search method of EVRC speech codec

An efficient enhanced variable rate codec (EVRC) codebook search method based on a two-stage search is proposed. At the first stage, a coarse codevector is selected by a fast sequential search, and at the second stage, the pulse replacement procedure is run to enhance the performance of selected codevector. Simulations with various speech data show that the proposed method yields voice quality equivalent to that by the standard method with only 23% codebook search load.