4K resolution
This resolution is used mainly in digital cinema production, and has a total of 8,847,360 pixels with an aspect ratio 256135 (≈1910). It was standardized as the resolution of the 4K container format defined by Digital Cinema Initiatives in the Digital Cinema System Specification, and is the native resolution of all DCI-compliant 4K digital projectors and monitors. The DCI specification allows several different resolutions for the content inside the container, depending on the desired aspect ratio. The allowed resolutions are defined in SMPTE 428-1: The DCI 4K standard has twice the horizontal and vertical resolution of DCI 2K (), with four times as many pixels overall.
YouTube
YouTube originally offered videos at only one quality level, displayed at a resolution of 320×240 pixels using the Sorenson Spark codec (a variant of H.263), with mono MP3 audio. In June 2007, YouTube added an option to watch videos in 3GP format on mobile phones. In March 2008, a high-quality mode was added, which increased the resolution to 480×360 pixels. In December 2008, 720p HD support was added. At the time of the 720p launch, the YouTube player was changed from a aspect ratio to a widescreen . With this new feature, YouTube began a switchover to H.264/MPEG-4 AVC as its default video compression format. In November 2009, 1080p HD support was added. In July 2010, YouTube announced that it had launched a range of videos in 4K format, which allows a resolution of up to 4096×3072 pixels. In June 2015, support for 8K resolution was added, with the videos playing at 7680×4320 pixels. In November 2016, support for HDR video was added which can be encoded with Hybrid Log-Gamma (HLG) or Perceptual Quantizer (PQ). HDR video can be encoded with the Rec. 2020 color space.