Rate-Distortion Performance of Source Coders in the Low Bit-Rate Region for Highly Correlated Gauss-Markov Source

The discrete-time Gauss-Markov process is commonly used as a model in many source coding applications. A highly correlated Gauss-Markov process models the intensity along the motion trajectories encountered in time varying image coding. We investigate the rate-distortion performance of lossy coding schemes operating on such sources in the practically important low bit-rate region of less than one bit per sample. Additional lossless entropy coding is assumed. Low complexity low bit-rate Code-Excited Linear Predic-tive (CELP) coders are designed, analyzed and simulated. Performance close to the R(D) bound is achieved using this coder. For the highly correlated Gauss-Markov source, the CELP coder performs better than the optimized Entropy Constrained DPCM (ECDPCM) and is expected to perform better than the Entropy Constrained Vector Quantization (ECVQ) and Entropy Constrained Block Transform Quan-tization (ECBTQ). Results include comparisons with these and other previously reported coders.