1. A system for context-based adaptive binary arithmetic encoding and decoding, the system comprising: a calculating device configured to calculate an index value for one of a first bin to be encoded and a second bin to be decoded; a memory device to store context models in cluster, wherein the index value for one of the first bin and the second bin is related to one of the context models; and a binary arithmetic unit configured to serve as one of an encoder for encoding the first bin based on the one context model and a decoder for decoding the second bin based on the one context model.