Patent ID: 8116373

Claim:
A computer-implemented method for compression of a video data stream, in which video data of an image is represented by image symbols, the method performed by logic instructions embodied in computer hardware and comprising the steps of: reading image symbols out of an image memory; sorting the image symbols with the aid of a context switch on various encoding branches into image symbol groups which are each assigned to different contexts, wherein the image symbols are sorted by: setting the context switch to a prespecified position at a prespecified time; and activating the context, switch after the pre-specified time, in accordance with the context of the image symbol to be sorted; adaptively assigning particular contexts to particular encoding branches by: evaluating the frequency distribution of image symbols sorted to different contexts; identifying two or more contexts having a matching frequency distribution of image symbols; and grouping the two or more identified contexts together, by assigning the two or more identified contexts together to a common encoding branch, such that sorting determinations for image symbols subsequently received at the context switch are influenced by frequency distributions of previously sorted image symbols; and performing entropy encoding of the image symbol groups and merging a data output by the respective encoding branches into a compressed video data stream.