Ultra Widescreen (21:9 aspect ratio) skins for Kodi

Kodi's skinning engine (GUI layout engine) can handle CIH (Constant Image Height) skins using resolutions with 21:9 (2.33:1) aspect ratio display output for CHP (Constant Height Projection) / CHD (Constant Height Display) formats. Displays supporting this type of input are today marketed as "Ultra Widescreen" displays when referring to commercial televisions, monitors, or projector designed for home theater purposes. These displays can sometimes also be refereed to as Cinema Widescreen, Cinema Display, Cinema 21:9, or 21.9 Display in marketing material.

Movies and other videos encoded for these "Ultra Widescreen" displays with 21:9 (2.33:1) and similar aspect ratios are commonly known in cinema/movie-theater and motion picture terminology as CinemaScope (2.35:1 / 2.35 Scope), Panavision, Cinerama, Technirama, Anamorphic Widescreen (2.39:1), or simply 2.39 aspect ratio videos, and they can sometimes also be incorrect described (rounded) as 2.40:1 or 2.40 movies, like for some Blu-ray Disc film releases which have 1920×800 resolution.

Skins supporting these aspect ratios CIH for CHP/CID output from Kodi is designed to show films/movies recorded in CinemaScope (2.35:1 / 2.35 Scope) or a anamorphic format of 2.39:1 which is used in modern cinemas today, and a anamorphic vertical stretch 21:9 television or projector which allows for displaying all content at equal height, allowing for a more balanced viewing experience. The main benefit of this screen ratio is the absence of the black bars at the top and bottom of the screen when viewing content in this format, and a constant display height when displaying other content with a lesser aspect ratio.

Overview
The 64:27 aspect ratio is the logical extension of the existing video aspect ratios 4:3 and 16:9, as it is the third power of 4:3, where 16:9 of traditional HDTV is 4:3 squared. This allows electronic scalers to use an easily implementable 4:3 (1.33:1) scaling factor. 21:9 (2.33:1) is the approximated screen aspect ratio of the true value 64:27 (2.370:1) in comparison to the common ratio of 16:9 (1.77:1).

Film formats and 21:9
The term "21:9" was chosen as a marketing term, probably first used by Philips. Due to its common denominator, 21:9 sounds more similar to 16:9, the aspect ratio of regular HDTVs, rather than the correct 64:27 or 21\tfrac{1}{3}:9. If it actually were 21:9, the fraction could be expressed more elegantly in the reduced form as 7:3.

Examples
This first image is an example of a native CinemaScope (2.35:1) video shown in Kodi using an 21:9 aspect ratio skin when displayed on a Ultra Widescreen screen with CIH (Constant Image Height). Skins can of course take many forms, this is just an example.



This second image is an example of a native Widescreen (16.9) video shown in Kodi using an 21:9 aspect ratio skin when displayed on a Ultra Widescreen screen with CIH (Constant Image Height). Again, the skins can of course take many forms, this is just an example.



HDMI output standardization
As of May 2013, video timings in this 64:27 aspect ratio are supported by the technical specification that defines video timings for the HDMI interface, CEA 861-F:
 * 1280×720p, anamorphic widescreen pixel aspect ratio of 4:3
 * 1680×720p, near-square pixel aspect ratio of 64:27
 * 1920×1080p, anamorphic pixel aspect ratio of 4:3
 * 2560×1080p, square pixel aspect ratio
 * 3840×2160p, anamorphic pixel aspect ratio of 4:3

All of the above timings are supported at frame rates of 23.97/24, 25, 29.97/30, 50 and 59.94/60 Hz, as well as 100 and 119.88/120 Hz for the non-UltraHD timings.

An additional resolution of 5120×2160p ("5K") could be added at a later time to provide a non-anamorphic UltraHD signal in 21:9. Variations of the 8K UltraHD resultions could also be considered, at 7680×4320p anamorphic and 10240x4320p non-anamorphic.

Resolution and Aspect Ratio Explained
Videos by the ProjectorPeople.com and Filmmaker IQ which does a good job at explaining resolution and aspect ratio, and maybe more importantly, why we today can buy displays/screens/projectors with different aspect ratios:

Aeon Nox 21:9

 * http://forum.kodi.tv/showthread.php?tid=224427
 * http://forum.kodi.tv/showthread.php?tid=208867



Alaska 21:9

 * http://forum.kodi.tv/showthread.php?tid=188070



ScopeNox 21:9

 * http://forum.kodi.tv/showthread.php?tid=210806



ScopeConfluence
"ScopeConfluence" is a work-in-progress 21:9 aspect ratio skin by Funkd, done as a forked Scope (CinemaScope) version of the Confluence skin.
 * https://github.com/Funkd/ScopeConfluence
 * http://forum.kodi.tv/showthread.php?tid=210806&page=3

Numax - pure.cinema
"Numax - pure.cinema" is a not yet released proof-of-concept 2:35.1 CIH format skin by DoghouseCinema