Dr. Duda, Thank you for the suggestion. This work is very interesting. As Derek Buitenhuis mentioned, the challenge for applying this technique to HEVC compression is that it would first need to be adopted by the Joint Collaborative Team on Video Coding (http://www.itu.int/en/ITU-T/studygroups/2013-2016/16/Pages/video/jctvc.aspx) as part of the HEVC standard before it could be supported by HEVC encoders and decoders.
The x265 project welcomes collaboration with academic institutions. I will reach out to you directly to see if there are other ways that we may be able to assist you with your research. Best regards, Tom Vaughan -----Original Message----- From: x265-devel [mailto:[email protected]] On Behalf Of Jaroslaw Duda Sent: Sunday, December 29, 2013 4:50 PM To: [email protected] Subject: [x265] New entropy coding - faster than Huffman, compression rate like arithmetic Hallo, There is a new approach to entropy coding (no patents): Asymmetric Numeral Systems(ANS) - the current implementation has about 50% faster decoding than Huffman (single table use per symbol from a large alphabet), giving rates like arithmetic: https://github.com/Cyan4973/FiniteStateEntropy The idea is somehow similar to arithmetic coding, but instead of two numbers to define the current state (range), it uses only a single natural number (containing lg(state) bits of information) - thanks of this much smaller space of states, we can put entire behavior into a small table. Here is a poster explaining the basic concepts and the difference from arithmetic: https://dl.dropboxusercontent.com/u/12405967/poster.pdf I would like to propose a discussion about the possibility of applying it in video compression, maybe adding to h.265 - it should be about 10 times faster than CABAC, providing similar compression rate. The cost is that we need to store coding tables for a given probability distribution: let say 1-16kB for 256 size alphabet. For different contexts (probability distributions), we can build separate tables and switch between them - the memory cost is "the number of different contexts/distributions" times a few kilobytes. So if the number of different contexts used for given coding parameters is smaller than let say a thousand, ANS can provide huge speedup there. It could also work alongside CABAC - speed up only some part of entropy coding. Best, Jarek Duda -- dr Jarosław Duda Center for Science of Information, Purdue University, USA http://www.soihub.org/people.php?id=484 _______________________________________________ x265-devel mailing list [email protected] https://mailman.videolan.org/listinfo/x265-devel _______________________________________________ x265-devel mailing list [email protected] https://mailman.videolan.org/listinfo/x265-devel
