1. A method for decoding a video stream, the method comprising: identifying a current probability distribution; decoding a modified probability distribution from an encoded video stream using the current probability distribution; generating a decoded current portion of a video stream by decoding the current portion from the encoded video stream using the modified probability distribution; identifying a forward update probability distribution for the current portion; and generating, by a processor in response to instructions stored on a non-transitory computer readable medium, an adapted probability distribution based on the current probability distribution and the forward update probability distribution.