VARIABLE-RATE VECTOR QUANTIZATION FOR SPEECH, IMAGE, AND VIDEO COMPRESSION

The performance of a vector quantizer can be improved by using a variable rate code. We apply three variable rate vector quantization systems to speech, image, and video sources and compare them to standard vector quantization and noiseless variable rate coding approaches. The systems range from a simple and flexible tree-based vector quantizer to a high performance, but complex, jointly optimized vector quantizer and noiseless code. The systems provide significant performance improvements for subband speech coding, predictive image coding, and motion compensated video, but provide only marginal improvements for vector quantization of linear predictive coefficients in speech and direct vector quantization of images. We suggest criteria for determining when variable rate vector quantization may provide significant performance improvement over standard approaches.