Ultra HD Blu-ray is the latest home video disc format and includes support for a number of advanced picture technologies.
First and most obvious, Ultra HD Blu-ray supports playback of content at an Ultra HD resolution. If you don’t know what that means, read this education page first. In short, Ultra HD TVs have a 3,840 x 2,160 resolution, which is exactly four times that of 1,920 x 1,080–aka 1080p–TVs. Films offered in the Ultra HD Blu-ray format will match this resolution at up to 60 frames per second; some of these films will be transferred from 4K (or better) masters; others could be upconverted from 2K masters. Ultra HD Blu-ray players will also be able to upconvert 1080p or 1080i Blu-ray discs, as well as 480i DVDs, to be output at an Ultra HD resolution.
Higher resolution isn’t the only thing that Ultra HD Blu-ray brings to the table, however. The format also allows for much better color. While UHD BD sticks with 4:2:0 chroma sub-sampling (like Blu-ray), it supports a higher 10- or 12-bit color depth and a much wider color gamut (P3 or Rec 2020) than the current Blu-ray (Rec 709) format. For more information on this topic, read The Color’s the Thing That Will Make 4K So Amazing.
Likewise, the UHD BD format supports playback of High Dynamic Range content, which is encoded at a much higher brightness level with more possible range between full black and the brightest white. Ultra HD Blu-ray mandates support for the 10-bit SMPTE 2084 HDR format (aka HDR10), while support for HDR technologies like Dolby Vision is optional. Read High Hopes for High Dynamic Range (HDR) Video for more details on HDR.
Like Blu-ray, UHD BD supports higher-quality audio soundtracks, too–uncompressed Dolby TrueHD and DTS-HD Master Audio, as well as the new 3D object-based formats like Dolby Atmos and DTS:X.
Ultra HD Blu-ray still requires the use of compression to fit everything on the disc, in the form of HEVC/H.265 compression with a maximum bit rate of 100 Mbps (compared with a maximum of 40 Mbps for Blu-ray). A UHD BD disc can hold up to 100 GB of data, compared with 50 GB for a double-layer BD or 25 GB for a single-layer BD.
The Ultra HD Blu-ray format does not include support for 3D at the higher resolution, although the player manufacturers may opt to include support for 1080p Blu-ray 3D.
To pass Ultra HD content from player to TV, you need a UHD TV that has HDMI 2.0 inputs with HDCP 2.2 copy protection. If you want to put an AV receiver in the chain, it also must support HDMI 2.0 with HDCP 2.2 (although some UHD players could add a second audii-only HDMI output to mate with an older, non-HDMI-2.0 receiver). In order to pass HDR content from a UHD disc, the TV and receiver need HDMI 2.0a. Check out What You Need to Know About HDMI 2.0 for more information.
Finally, the Ultra HD Blu-ray specification supports copy and export features. Copy allows you to transfer a bit-for-bit copy of a UHD disc to either the UHD player’s internal hard drive or an authorized attached media drive, while Export allows for the creation of an authorized digital copy, for playback through authorized services like UltraViolet or Vidity.
• 4K Blu-ray Reviewed: Ultra HD Equipment Selection, Setup, and Initial Thoughts, Blu-ray.com