High Efficiency Video Coding (HEVC), also known as H.265 and MPEG-H Part 2, is a video compression standard, one of several potential successors to the widely used AVC (H.264 or MPEG-4 Part 10). In comparison to AVC, HEVC offers about double the data compression ratio at the same level of video quality, or substantially improved video quality at the same bit rate. It supports resolutions up to 8192×4320, including 8K UHD.
In most ways, HEVC is an extension of the concepts in H.264/MPEG-4 AVC. Both work by comparing different parts of a frame of video to find areas that are redundant, both within a single frame as well as subsequent frames. These redundant areas are then replaced with a short description instead of the original pixels. The primary changes for HEVC include the expansion of the pattern comparison and difference-coding areas from 16×16 pixel to sizes up to 64×64, improved variable-block-size segmentation, improved "intra" prediction within the same picture, improved motion vector prediction and motion region merging, improved motion compensation filtering, and an additional filtering step called sample-adaptive offset filtering. Effective use of these improvements requires much more signal processing capability for compressing the video, but has less impact on the amount of computation needed for decompression.
HEVC was developed by the JCT-VC organization, a collaboration between the ISO/IEC MPEG and ITU-T VCEG. The ISO/IEC group refers to it as MPEG-H Part 2 and the ITU-T as H.265. The first version of HEVC was completed in January 2013 and published in June 2013. The second version was completed and approved in 2014 and published in early 2015. Additional 3D-HEVC extensions for 3D video were completed in early 2015. Further extensions remain in development for completion in early 2016, covering video containing rendered graphics, text, or animation as well as (or instead of) camera-captured video scenes.