The Anatomy of a Quasi-Static Arithmetic Encoder

The paper proposes a new architecture for arithmetic encoders called Quasi-Static. Unlike the classical implementations, the Quasi-Static Encoder buffers the input stream and uses a static model for encoding the data in the buffer. The big advantage of such approach is the higher encoding speed obtained however with the price of slight degraded compression rates. The Quasi-Static Encoder is tested on three types of data - English text, log files and binary files - and compared with two dynamic arithmetic encoders. For 128kB buffers, the Quasi-Static Encoder is about 3.6 times faster than the dynamic counterparts. The loss in compression rate depends on data type and the considered dynamic implementation. The Quasi-Static Encoder outperforms Dippenstein's implementation on English texts and exe files and is below Sachin Garg implementation that gains between 0.08 and 0.20 bpb in compression rate.