Regularization of a probability model for entropy coding

A device for entropy coding a sequence of syntax elements, comprising:

• a processor configured to:
• receive the sequence of syntax elements;
• determine a symbol for a syntax element of the sequence;
• entropy code, using arithmetic coding, the symbol using a probability model;
• and
• update the probability model using a time-variant update rate to produce an updated probability model, wherein to update the probability model includes to regularize one or more probability values so no probability of the updated probability model is below a defined minimum resolution, wherein
• the probability model comprises a cumulative distribution function of an M-ary random variable,
• M is a positive integer that represents a cardinality of possible observations for a respective syntax element of the sequence of syntax elements, and
• to regularize the one or more probability values comprises to monitor probability values of the updated probability model to determine if any probability value is below a threshold V, where V is a function of M, wherein when a probability value p_m is determined to be below the threshold V, a uniform cumulative distribution function for the M-ary random variable is applied to adjust the updated probability model.