According to one embodiment of the invention, a multistage vector list
quantizer comprises a first stage quantizer to select candidate first stage codewords
from a plurality of first stage codewords, a reference table memory storing a set
of second stage codewords for each first stage codeword, and a second stage codebook
constructor to generate a reduced complexity second stage codebook that is the
union of sets corresponding to the candidate first stage codewords selected by
the first stage quantizer.