gydecode decodes a channel, channelfile (CHN format), and side information, sideinfofile (SID format), both produced by gyencode, and writes the resulting output data to datfile. That is, gydecode performs VQ-index lookup of the indices in channelfile while updating the VQ codebook as dictated by sideinfofile. gydecode starts decoding using the initial codebook specified by codebook (which should be the same initial codebook originally used by gyencode). codebook_coder (SQ format) gives the scalar quantizer used to decode the side information.
A. Gersho and M. Yano, "Adaptive Vector Quantization by Progressive Codevector Replacement," Proc. ICASSP, pp. 133-136, 1985.