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The HEVC standard defines thirteen levels. [1] [2] A level is a set of constraints for a bitstream.[1] [2] For levels below level 4 only the Main tier is allowed.[1] [2] A decoder that conforms to a given tier/level is required to be capable of decoding all bitstreams that are encoded for that tier/level and for all lower tiers/levels.
Each compression specification defines various mechanisms by which raw video (in essence, a sequence of full-resolution uncompressed digital images) can be reduced in size, from simple bit compression (like Lempel-Ziv-Welch) to psycho-visual and motion summarization, and how the output is stored as a bit stream. So long as the encoder component ...
Of the nine video test sequences, five were at HD resolution, while four were at WVGA (800×480) resolution. The bit rate reductions for HEVC were determined based on PSNR with HEVC having a bit rate reduction of 35.4% compared with H.264/MPEG-4 AVC HP, 63.7% compared with MPEG-4 ASP, 65.1% compared with H.263 HLP, and 70.8% compared with H.262 ...
1080p (1920 × 1080 progressively displayed pixels; also known as Full HD or FHD, and BT.709) is a set of HDTV high-definition video modes characterized by 1,920 pixels displayed across the screen horizontally and 1,080 pixels down the screen vertically; [1] the p stands for progressive scan, i.e. non-interlaced.
It is also capable of decoding 2160p 4K Ultra-High Definition (UHD) resolution videos at 3840 × 2160 pixels (doubling the 1080p Full High Definition standard in both the vertical and horizontal dimensions) and, depending on the driver and the used codec, higher resolutions of up to 4032 × 4080 pixels.
On September 9, 2012, ATEME demonstrated at the IBC 2012 trade show a HEVC encoder that encoded video with a resolution of 3840x2160p at 60 fps with an average bit rate of 15 Mbit/s. [10] [11] ATEME is planning to release their HEVC encoder in October 2013. [10] [11] [12]
In the Class A test sequences, where the resolution of the video was 2560×1600, when compared to a 64×64 CTU size it was shown that the HEVC bit rate increased by 5.7% when forced to use a 32×32 CTU size and increased by 28.2% when forced to use a 16×16 CTU size. [2]
A codec comparison from 2015 found x265 to be a leading HEVC implementation measured by SSIM metric. [16] In August 2016, Netflix published a comparison of x264, VP9, and x265 using video clips from 500 movies and TV shows using 6 different quality metrics and found that both VP9 and x265 have 40%–50% better quality at 1080p than x264.