High frame rate
The frame rate for motion picture film cameras was typically 24 frames per second (fps) with multiple flashes on each frame during projection to prevent flicker. Analog television and video employed interlacing where only half of the image (known as a video field) was recorded and played back/refreshed at once but at twice the rate of what would be allowed for progressive video of the same bandwidth, resulting in smoother playback, as opposed to progressive video which is more similar to how celluloid works. The field rate of analog television and video systems was typically 50 or 60 fields per second. Usage of frame rates higher than 24 FPS for feature motion pictures and higher than 30 FPS for other applications are emerging trends in the recent past.
History of frame rates in cinema
In early cinema history, there was no standard frame rate established. Thomas Edison's early films were shot at 40 fps, while the Lumière Brothers used 16 fps. This had to do with a combination of the use of a hand crank rather than a motor, which created variable frame rates because of the inconsistency of the cranking of the film through the camera. After the introduction of synch sound recording, 24 fps became the industry standard frame rate for capture and projection of motion pictures. 24 fps was chosen because it was the minimum frame rate that would produce adequate sound quality. This was done because film was expensive, and using the lowest possible frame rate would use the least amount of film.
A few film formats have experimented with frame rates higher than the 24 fps standard. The original 3-strip Cinerama features of the 1950s ran at 26 fps. The first two Todd-AO 70mm features, Oklahoma! (1955) and Around the World in 80 Days (1956) were shot and projected at 30 fps. Douglas Trumbull's 70mm Showscan film format operated at 60 fps.
The IMAX HD (high definition in this case meaning high definition film stock, as 70mm IMAX is the highest resolution motion picture image in the world) film Momentum, presented at Seville Expo '92, was shot and projected at 48 fps. IMAX HD has also been used in film-based theme park attractions, including Disney's Soarin' Over California.
Digital Cinema Initiatives has published a document outlining recommended practice for high frame rate digital cinema. This document outlines the frame rates and resolutions that can be used in high frame rate digital theatrical presentations with currently available equipment.
Usage in the film industry
Peter Jackson's The Hobbit film series, beginning with The Hobbit: An Unexpected Journey in December 2012, used a shooting and projection frame rate of 48 frames per second, becoming the first feature film with a wide release to do so. Its 2013 sequel, The Hobbit: The Desolation of Smaug and 2014 sequel, The Hobbit: The Battle of the Five Armies, followed suit. All films also have versions which are converted and projected at 24 fps.
In 2016, Ang Lee released Billy Lynn's Long Halftime Walk. Unlike The Hobbit trilogy, which used 48 frames per second, the picture shot and projected selected scenes in 120 frames per second, which is five times faster than the 24 frames per second standard used in Hollywood. 
RocketJump's Video Game High School was the first web series to use HFR, and the first content shot and edited in a mixed frame rate. The series, which follows the lives of high school students in a world where gamers are revered as pro-athletes, adopted HFR in its second season, using the standard 24 frames per second for real world interactions, and 48 frames per second for "in-game" action sequences. Although the content is available on YouTube and Netflix, it can only be viewed in mixed frame rate using a special player on RocketJump's website.
Out of the cinema
Some media players are capable of showing HFR content and almost all computers and smart devices can handle this format as well. In recent years some televisions have the ability to take normal 24 fps videos and "convert" them to HFR content by interpolating the motion of the picture, effectively creating new computer generated frames between each two key frames and running them at higher refresh rate. Some computer programs allow for that as well but with higher precision and better quality as the computing power of the PC has grown.
Motion interpolation may cause some artifacts, as a result of the computer "guessing" the frames wrong.
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