the HM-15.0 HEVC encoder was compared with the VP9 1.2.0–5183 encoder and the JM-18.8 H.264/MPEG-4 AVC encoder. Four 4K resolutions sequences were encoded at five different bit rates with the encoders set to use an intra period of one second. In the comparison, the HM-15.0 HEVC encoder had the highest coding efficiency and, on average, for the same subjective quality the bit rate could be reduced by 49.4% compared with the VP9 1.2.0–5183 encoder, and it could be reduced by 52.6% compared with the JM-18.8 H.264/MPEG-4 AVC encoder. In August, 2016, Netflix published the results of a large-scale study comparing the leading open-source HEVC encoder, x265, with the leading open-source AVC encoder, x264 and the reference VP9 encoder, libvpx. Using their advanced Video Multimethod Assessment Fusion (VMAF) video quality measurement tool, Netflix found that x265 delivered identical quality at bit rates ranging from 35.4% to 53.3% lower than x264, and from 17.8% to 21.8% lower than VP9. Features HEVC was designed to substantially improve coding efficiency compared with H.264/MPEG-4 AVC HP, i.e. to reduce bitrate requirements by half with comparable image quality, at the expense of increased computational complexity. HEVC was designed with the goal of allowing video content to have a data compression ratio of up to 1000:1. Depending on the application requirements, HEVC encoders can trade off computational complexity, compression rate, robustness to errors, and encoding delay time. Two of the key features where HEVC was improved compared with H.264/MPEG-4 AVC was support for higher resolution video and improved parallel processing methods. HEVC is targeted at next-generation HDTV displays and content capture systems which feature progressive scanned frame rates and display resolutions from QVGA (320×240) to 4320p (7680×4320), as well as improved picture quality in terms of noise level, color spaces, and dynamic range. Video coding layer The HEVC video coding layer uses the same "hybrid" approach used in all modern video standards, starting from H.261, in that it uses inter-/intra-picture prediction and 2D transform coding. A HEVC encoder first proceeds by splitting a picture into block shaped regions for the first picture, or the first picture of a random access point, which uses intra-picture prediction. Intra-picture prediction is when the prediction of the blocks in the picture is based only on the information in that picture. For all other pictures, inter-picture prediction is used, in which prediction information is used from other pictures. After the prediction methods