Enumeration and trellis-searched coding schemes for speech LSP parameters

Speech coders employing forward adaptive predictive coding (APC) and operating at medium-to-low bit rates necessitate efficient encoding of the linear predictive coding (LPC) coefficients. Line spectrum pair (LSP) parameters are currently one of the most efficient choices of transmission parameters for the LPC coefficients. The authors briefly reviews LSP parameters and presents several low-delay coding schemes for the parameters. The coders are simulated using data generated from both the autocorrelation and covariance LPC analysis methods. The performances of the coders are given for a variety of rates and LPC analysis conditions. The most efficient scheme developed uses a uses a predictive form of trellis-coded quantization (TCQ). Its performance is comparable or superior to that of other low-delay LSP coding schemes. An enumeration scheme that reduces the rate of a given scalar quantization structure without decreasing coder performance is also presented