A new fast approximate arithmetic coder

The results of a research project conducted at Gandalf, a leader in real time data networking products, to develop a fast arithmetic coder are presented. The speed improvement comes from the development of a hybrid model that generates normalized frequency distributions of the sequence of input symbols. This approach enables the implementation of an arithmetic coder with a reduced number of divide instructions. The new coder obtains significantly improved throughput with minimal loss in compression efficiency. Simulation results showed a doubling in computational speed over standard implementations of the algorithm with minimal reduction in efficiency. The algorithm achieves up to 50% more compression efficiency than the commercially available Stacker LZS compressor.