1. A method for encoding an input sequence of symbols, the symbols belonging to a finite alphabet, wherein a context model specifies a predefined probability set, and wherein each symbol of the input sequence of symbols is associated with a probability from the predefined probability set on the basis of the context model, the method comprising: selecting a new probability set, wherein the new probability set is not identical to the predefined probability set; assigning each of the symbols of the input sequence a respective probability from the new probability set based upon a mapping, wherein the mapping maps each of the probabilities of the predefined probability set to a respective one of the probabilities from the new probability set; and entropy encoding the input sequence of symbols, wherein the entropy encoding includes grouping symbols on the basis of their respective assigned probabilities from the new probability set.
5. The method claimed in claim 1 , wherein selecting the new probability set comprises selecting the new probability set from amongst a plurality of predetermined candidate probability sets.