Variable-length codes can be used in entropy coding the outputs of an optimum entropy-constrained quantizer. Transmitting these codes over a synchronous channel, however, requires a buffer connecting the entropy coder to the channel. In a practical application, this buffer is of finite size and hence might overflow or underflow. To alleviate this difficulty, the authors use an adaptive scheme in which the quantizer parameters are changed successively according to the state of the buffer. Rate-distortion performance of optimum entropy-constrained quantizers in conjunction with this adaptive scheme is studied for the class of generalized Gaussian sources. It is demonstrated through simulations that the overflow/underflow problem can be practically eliminated at the cost of a negligible increase in average distortion. Furthermore, it is shown that the efficiency of this system is more pronounced at high rates and for more broad-tailed source densities. Easily computable upper and lower bounds on the average distortion of the adaptive system are developed.
ASJC Scopus subject areas
- Information Systems
- Computer Science Applications
- Library and Information Sciences