33. The method of claim 23 , wherein the vector is an input line spectral frequency (LSF) vector including line spectral frequencies (LSFs), and each candidate codevector is an LSF vector including LSFs.
33. The method of claim 23 , wherein the vector is an input line spectral frequency (LSF) vector including line spectral frequencies (LSFs), and each candidate codevector is an LSF vector including LSFs. 35. The method of claim 33 , wherein the illegal space is represented as an illegal criterion for LSF vectors, and the illegal criterion for LSF vectors includes first and second successive LSFs in a pair of LSFs being closer to each other than a minimum separation distance.