Editing Frame rate (section)

==Film and video==
===Silent film===
Early [[silent film]]s had stated frame rates anywhere from 16 to 24 frames per second (FPS),<ref>{{cite book |chapter-url=https://books.google.com/books?id=sWdBAQAAQBAJ&pg=PA588 |title=The Oxford Handbook of Film Music Studies |chapter=Audio-visual Palimpsests: Resynchronizing Silent Films with 'Special' Music |last=Brown |first=Julie |editor=David Neumeyer |page=588 |publisher=Oxford University Press |year=2014 |isbn=978-0195328493}}</ref> but since the cameras were hand-cranked, the rate often changed during the scene to fit the mood. Projectionists could also change the frame rate in the theater by adjusting a [[rheostat]] controlling the voltage powering the film-carrying mechanism in the [[projector]].<ref>{{cite book |title=Silent Clowns |url=https://archive.org/details/silentclowns00kerrrich |url-access=limited |last=Kerr |first=Walter |publisher=Knopf |year=1975 |page=[https://archive.org/details/silentclowns00kerrrich/page/36 36] |isbn=978-0394469072}}</ref> Film companies often intended for theaters to show their silent films at a higher frame rate than that at which they were filmed.<ref>{{cite book |title=Seductive cinema: the art of silent film |last=Card |first=James |publisher=Knopf |year=1994 |page=[https://archive.org/details/seductivecinemaa00card/page/53 53] |isbn=978-0394572185 |url-access=registration |url=https://archive.org/details/seductivecinemaa00card/page/53 }}</ref> These frame rates were enough for the sense of motion, but it was perceived as jerky motion. To minimize the perceived flicker, projectors employed dual- and triple-blade [[Movie projector shutter|shutters]], so each frame was displayed two or three times, increasing the flicker rate to 48 or 72&nbsp;hertz and reducing eye strain. [[Thomas Edison]] said that 46 frames per second was the minimum needed for the eye to perceive motion: "Anything less will strain the eye."<ref name=Brownlow>{{cite journal |last=Brownlow |first=Kevin |date=Summer 1980 |title=Silent Films: What Was the Right Speed? |journal=[[Sight & Sound]] |volume=49 |issue=3 |pages=164–167 |url=http://www.cinemaweb.com/silentfilm/bookshelf/18_kb_2.htm |archive-url=https://web.archive.org/web/20110708155615/http://www.cinemaweb.com/silentfilm/bookshelf/18_kb_2.htm |archive-date=8 July 2011 |access-date=2 May 2012}}</ref><ref>{{cite book |last1=Elsaesser |first1=Thomas |last2=Barker |first2=Adam |title=Early cinema: space, frame, narrative |year=1990 |publisher=BFI Publishing |isbn=978-0-85170-244-5 |page=284}}</ref> In the mid to late 1920s, the frame rate for silent film increased to 20–26&nbsp;FPS.<ref name=Brownlow/>

===Sound film===
When [[sound film]] was introduced in 1926, variations in film speed were no longer tolerated, as the human ear is more sensitive than the eye to changes in frequency. Many theaters had shown silent films at 22 to 26&nbsp;FPS, which is why the industry chose 24&nbsp;FPS for sound film as a compromise.<ref name="geek">{{Citation |last=TWiT Netcast Network |title=How 24 FPS Became Standard |date=2017-03-30 |url=https://www.youtube.com/watch?v=UcjYqfMaeHU | archive-url=https://ghostarchive.org/varchive/youtube/20211104/UcjYqfMaeHU| archive-date=2021-11-04 | url-status=live|access-date=2017-03-31}}{{cbignore}}</ref> From 1927 to 1930, as various studios updated equipment, the rate of 24&nbsp;FPS became standard for 35&nbsp;mm sound film.<ref name="Read2000"/> At 24&nbsp;FPS, the film travels through the projector at a rate of {{convert|456|mm|in}} per second. This allowed simple two-blade shutters to give a projected series of images at 48 per second, satisfying Edison's recommendation. Many modern 35&nbsp;mm film projectors use three-blade shutters to give 72 images per second—each frame is flashed on screen three times.<ref name=Brownlow/>

===Animation===
[[Image:Animhorse.gif|thumb|This [[animated cartoon]] of a [[Horse gait|galloping horse]] is displayed at 12 drawings per second, and the fast motion is on the edge of being objectionably jerky.]]

In drawn [[Traditional animation|animation]], moving characters are often shot "on twos", that is to say, one drawing is shown for every two frames of film (which usually runs at 24 frame per second), meaning there are only 12 drawings per second.<ref>{{cite web |last1=Chew |first1=Johnny |title=What Are Ones, Twos, and Threes in Animation? |url=https://www.lifewire.com/what-are-ones-twos-and-threes-4057778 |publisher=[[Lifewire]] |access-date=August 8, 2018}}</ref> Even though the image update rate is low, the fluidity is satisfactory for most subjects. However, when a character is required to perform a quick movement, it is usually necessary to revert to animating "on ones", as "twos" are too slow to convey the motion adequately. A blend of the two techniques keeps the eye fooled without unnecessary production cost.<ref>{{cite book |last1=Whitaker |first1=Harold |last2=Sito |first2=John Halas; updated by Tim |title=Timing for animation |date=2009 |publisher=Elsevier/Focal Press |location=Amsterdam |isbn=978-0240521602 |page=52 |edition=2nd |url=https://books.google.com/books?id=yMgqBgAAQBAJ&pg=PA52 |access-date=August 8, 2018}}</ref>

Animation for most "[[Saturday morning cartoon]]s" was produced as cheaply as possible and was most often shot on "threes" or even "fours", i.e. three or four frames per drawing. This translates to only 8 or 6 drawings per second respectively. [[Anime]] is also usually drawn on threes or twos.<ref>{{cite web |url=https://www.animenewsnetwork.com/encyclopedia/lexicon.php?id=61 |title=Shot on threes (ones, twos, etc.) |website=Anime News Network}}</ref><ref>{{cite web |title=CLIP STUDIO PAINT アニメーション機能の使い方 |url=https://www.youtube.com/watch?v=qQalCLD6ky0&t=833 | archive-url=https://ghostarchive.org/varchive/youtube/20211104/qQalCLD6ky0| archive-date=2021-11-04 | url-status=live|last=CLIP STUDIO |date=12 February 2016 |via=YouTube }}{{cbignore}}</ref>

===Modern video standards===
{{See also|List of broadcast video formats}}
Due to the [[mains frequency]] of electric grids, analog television broadcast was developed with frame rates of 50&nbsp;Hz (most of the world) or 60&nbsp;Hz (Canada, US, Mexico, Philippines, Japan, South Korea). The frequency of the electricity grid was extremely stable and therefore it was logical to use for synchronization.

The introduction of color television technology made it necessary to lower that 60&nbsp;FPS frequency by 0.1% to avoid "[[dot crawl]]", a display artifact appearing on legacy black-and-white displays, showing up on highly-color-saturated surfaces. It was found that by lowering the frame rate by 0.1%, the undesirable effect was minimized.

{{As of|2021}}, video transmission standards in North America, Japan, and South Korea are still based on 60/1.001&nbsp;≈&nbsp;59.94 images per second. Two sizes of images are typically used: 1920×1080 ("1080i/p") and 1280×720 ("720p"). Confusingly, ''interlaced'' formats are customarily stated at 1/2 their image rate, 29.97/25&nbsp;FPS, and ''double'' their image height, but these statements are purely custom; in each format, 60 images per second are produced. A resolution of 1080i produces 59.94 or 50 1920×540 images, each squashed to half-height in the photographic process and stretched back to fill the screen on playback in a television set. The 720p format produces 59.94/50 or 29.97/25 1280×720p images, not squeezed, so that no expansion or squeezing of the image is necessary. This confusion was industry-wide in the early days of digital video software, with much software being written incorrectly, the developers believing that only 29.97 images were expected each second, which was incorrect. While it was true that each picture element was polled and sent only 29.97 times per second, the pixel location immediately below that one was polled 1/60 of a second later, part of a completely separate image for the next 1/60-second frame.

At its native 24&nbsp;FPS rate, film could not be displayed on 60&nbsp;Hz video without the necessary [[Three-two pull down|pulldown]] process, often leading to "[[judder]]": to convert 24 frames per second into 60 frames per second, every odd frame is repeated, playing twice, while every even frame is tripled. This creates uneven motion, appearing stroboscopic. Other conversions have similar uneven frame doubling. Newer video standards support 120, 240, or 300 frames per second, so frames can be evenly sampled for standard frame rates such as 24, 48 and 60 FPS film or 25, 30, 50 or 60 FPS video. Of course these higher frame rates may also be displayed at their native rates.<ref>[http://downloads.bbc.co.uk/rd/pubs/whp/whp-pdf-files/WHP169.pdf High Frame-Rate Television], BBC White Paper WHP 169, September 2008, M. Armstrong, D. Flynn, M. Hammond, PAWAN Jahajpuria S. Jolly, R. Salmon.</ref><ref>{{citation |url=https://www.engadget.com/2014/11/27/avatar-sequels-to-shoot-at-48fps/ |title=James Cameron's 'Avatar' sequels will stick to 48 frames per second |author=Jon Fingas |date=November 27, 2014 |work=[[Engadget]] |access-date=April 15, 2017}}</ref>

===Electronic camera specifications===
In electronic camera specifications frame rate refers to the maximum possible rate frames that can be captured (e.g. if the exposure time were set to near-zero), but in practice, other settings (such as exposure time) may reduce the actual frequency to a lower number than the frame rate.<ref>{{cite web|last = Whaley|first = Sean|date = 21 November 2018|title = What is Frame Rate and Why is it Important to PC Gaming?|url = https://www.hp.com/us-en/shop/tech-takes/what-is-frame-rate|access-date = 5 August 2021}}</ref>