"21:9" ("twenty-one by nine" or "twenty-one to nine") is a consumer electronics (CE) marketing term to describe the ultrawide aspect ratio of 64:27 (2.370:1 or 21.3:9), designed to show films recorded in CinemaScope and equivalent modern anamorphic formats. The main benefit of this screen aspect ratio is a constant display height when displaying other content with a lesser aspect ratio.
The 64:27 aspect ratio of "21:9" is an extension of the existing video aspect ratios 4:3 (SDTV) and 16:9 (HDTV), as it is the third power of 4:3, where 16:9 of traditional HDTV is 4:3 squared. This allows electronic scalers and optical anamorphic lenses to use an easily implementable 4:3 (1.3:1) scaling factor.
SDTV
HDTV
"21:9"
The term "21:9" was chosen as a marketing term, first used by Philips in January 2009.[1] Due to its common denominator, 21:9 is more relatable to 16:9, the aspect ratio of regular HDTVs, rather than the more accurate 64:27. If it actually were 21:9 (2.3:1), the fraction could also be expressed in the reduced form as 7:3, relating to the 4:3 of standard-definition TVs.
Consumer TVs with this aspect ratio were manufactured mainly from 2010 to 2017. Due to it causing pillarboxing with standard 16:9 content,[2] and the resulting low consumer acceptance, this screen format has rarely been used since then.
It is still prevalent in projection systems, using anamorphic lenses, and supported by a number of consumer electronics devices, including Blu-ray players and video scalers.
It is also used in computer monitors, where the term "21:9" can also represent aspect ratios of 43:18 (2.38:1 or 21.5:9) and 12:5 (2.4:1 or 21.6:9) in addition to 64:27. The wider screen provides advantages in multitasking as well as a more immersive gaming experience,[3][4] and even wider screens with aspect ratios such as 32:9 (allowing for two 16:9 views side-by-side) are available. 21:9 phones also exist.
Constant image height
With content of different aspect ratios, adjustments have to be made when showing such content on a display with a fixed aspect ratio. To avoid loss of content (due to cropping) or distortions (due to stretching), horizontal or vertical bars of a uniform color, usually black to make them less noticeable, are added to adjust the image. With the black bars being unnoticed, this has the effect of a changing image size when switching content aspect ratios.
A 21:9 display is able to present all content up to 'Scope aspect ratios at equal height, with changing vertical bars to the left and right of the image. Note how the large center circle, representing the main image area, remains at a constant size on the 21:9 display, while it changes on the other two depending on the aspect ratio of the content.
Uses
Cinema
The "21:9" digital format's aspect ratio of 64:27 (approx. 2.37:1) is positioned between the classical CinemaScope aspect ratio (1678:715, approx. 2.35:1) and the aspect ratio of modern anamorphic cinematic content (1024:429, approx. 2.39:1), matching both with only a slight deviation. Thus, 21:9 screens allow watching most films with minimal letterboxing or pillarboxing.[5]
Video games
Most modern 3D video games support 21:9 monitors, allowing for a wider field of view (FOV) and increased immersion.[6][7] In certain multiplayer games the increased horizontal FOV can give the player with the ultrawide monitor a competitive advantage, revealing information not available to an average player, while in other games the vertical FOV is decreased instead.
Standardization
HDMI
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, CTA 861-F:[10] In November 2016, CTA (formerly CEA) published CTA-861-G[11] with these additional video timings in 64:27, as well as additional frame rates (48 Hz, 100/120 Hz UHD): CTA-861-I,[12] published in February 2023, provides a successor to the VIC enumeration of video timings, using a Resolution ID (RID) carried in Video Format Descriptors (VFDs). These VFDs support additional 21:9 resolutions of:
All of the above timings are supported at frame rates of 23.97, 24, 25, 29.97, 30, 47.95, 48, 50, 59.94, 60, 100, 119.88, 120, 143.86, 144, 200, 239.76, 240, 300, 359.64, 360, 400, 479.52, and 480 Hz, as of CTA-861-I.
Content and source devices
Blu-ray
Some Blu-ray players, e.g., the Oppo BDP-203/205, or Philips BDP3200/12 and BDP9100/05, did support a 21:9 output mode.[19][20][21] In this mode, the player has the capability to trim the letterbox bars and extract the 21:9 center portion of the movie content of a letterboxed disc, upscale it vertically, and scale and re-arrange the 16:9 menus and subtitles for that 21:9 anamorphic upscale so that no user interface elements are trimmed off with the bars.
Streaming services
Video streaming and download services use a proprietary technical infrastructure, and are not confined to the same strict rules about frame aspect ratios as standardized distribution services (such as broadcast and optical discs). They therefore often encode content as just the active frame, without any aspect ratio adjustment bars (letterbox or pillarbox bars). Movies with a 2.39:1 aspect ratio are a natural match for 21:9 output video timings, as long as the streaming clients support such video modes, and even content with other wide aspect ratios such as 2.00:1 and 2.20:1 are inherently maximizing the use of the output frame on such systems.
Display devices
Flat-panel TV
All Blu-ray Disc content with 1920 horizontal resolution has 1080 vertical resolution, though in the case of widescreen formats wider than 16:9, the image appears on 16:9 displays with letterboxing. Philips' "Cinema 21:9" TV eliminates the black bars by scaling the 1920 horizontal resolution to its full width of 2560 and the 800+ pixels of CinemaScope images (actual pixel counts vary)[26][27] is scaled to 1080 with the black space cropped. The result is an image which fills the screen, but does not provide higher quality due to the use of scaling.[28] Despite the intention being to fill the screen with a non-letterboxed image, the zoom mode can result in some cropping at the edges.[29] Content with the full image at 1920×1080 can be displayed in the center of the screen with
See also
- Display aspect ratio
- Ultrawide formats
External links
References
- Cinematic Viewing Experience retrieved 2019-03-13^
- Cedric Demers, Mehdi Azzabi. What is the Aspect Ratio? Rtings.com, 15 June 2017, retrieved 2019-02-02^
- Adam Simmons. The 21:9 (2560 × 1080) Experience PCMonitors.info, 14 April 2016, retrieved 2019-02-02