Frame Rate

Frame rate - Wikipedia, the free encyclopedia
There are three main frame rate standards in the TV and movie-making business. ... The 24p frame rate is also a noninterlaced format, and is now widely adopted by ...
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Refresh rate - Wikipedia, the free encyclopedia
... frames per second, but has a 48 or 72 Hz refresh rate. ... If the 120 Hz rate is produced by frame-doubling a 60frame/s 3:2 pulldown signal, ... Frame rate ...
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What is frame rate? - a definition from Whatis.com
Frame rates are used in synchronizing audio and pictures, whether film, ... factors affect the actual frame rate you get on your ... frame rate ...
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Frame Rate Follies
Frame rates are one of the most confusing aspects of dealing with ... Some applications derive the frame rate of a movie by look ...
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Video streaming at high bit rates and frame rates results in much higher quality ... However, it is able to achieve a much higher frame rate. ...
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Digital Video for the Web
The higher the frame rate, the smoother and better quality the movie appears. ... A fairly standard frame rate is 15fps for most videos streamed over the web, ...
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Frame Rate - Video Transfer Inc.
Frame Rate - Contact Video Transfer to learn more about the best frame rate for your video display. ... display frame rate, and these can be different due to ...
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Frame rate, or frame frequency, is the measurement of the frequency (rate) at which an imaging device produces unique consecutive images called Film frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems. Frame rate is most often expressed in frames per second (fps), or simply hertz (Hz).

Flicker fusion frequency The frame rate is related to but not identical to a Physiology called the flicker fusion threshold or flicker fusion rate. Light that is pulsating below this rate is perceived by humans as flickering; light that is pulsating above this rate is perceived by humans as being continuous. The exact rate varies depending upon the person, their level of fatigue, the brightness of the light source, and the area of the retina that is being used to observe the light source. Few people perceive flicker above 75 hertz for CRT monitors.

While many film projects are made at higher frame rates (most notably television material, often filmed at 30 or 60 FPS), nearly all commercial films are principally recorded at 24fps to save on film stock, so the Shutter (photography) in the projection devices is actually arranged to interrupt the light two or three times for every film frame. In this fashion, the common frame rate of 24 fps (frames per second) produces 48 or 72 pulses of light per second on screen, the latter rate being around the flicker fusion rate for most people most of the time.

Older video systems use a more complex approach referred to as Interlace. Broadcasting television systems such as NTSC, PAL, and SECAM produce an image using two passes called fields. Each field contains half of the lines in a complete frame (the odd-numbered lines or the even-numbered lines). Thus, while only using the bandwidth of 25 or 30 complete frames per second, they achieve a flicker fusion frequency of 50 or 60 Hz, at the expense of some vertical judder and additional system complexity. The "frame rate" of interlaced systems is usually defined as the number of complete frames (pairs of fields) transmitted each second (25 or 30 in most broadcast systems). However, since a conventional television camera will scan the scene again for each field, in many circumstances it may be useful to think of the frame rate as being equal to the field rate.

In contrast to televisions, PC monitors always use progressive scan, and therefore internet video formats also do. The "p" versions of HDTV (i.e., 720p or 1080p) also use progressive scan, and many modern DVD players upsample interlaced video into progressive video.

References

Federal Standard 1037C
MIL-STD-188

Frame rates in film and television There are three main frame rate standards in the television and film business.

60i (interlaced; 59.94 to be more precise; 50i= 50 frames in Europe and Australia) is the standard video field rate per second (60 interlaced fields = 29.97 frames) that has been used for television for decades, whether from a broadcast signal, rented DVD, or home camcorder.

30p, or 30-frame progressive, is a noninterlaced format and produces video at 30 frames per second. Progressive (noninterlaced) scanning mimics a film camera's frame-by-frame image capture and gives clarity for high speed subjects and a cinematic-like appearance. Shooting in 30p mode offers video with no interlace artifacts. This frame rate originated in the 1980s in the music video industry.

The 24p frame rate is also a noninterlaced format, and is now widely adopted by those planning on transferring a video signal to film. But film- and video-makers turn to 24p for the "cine"-look even if their productions are not going to be transferred to film, simply because of the "look" of the frame rate.

35 mm movie cameras use a standard exposure rate of 24 frames per second.

25p is a video format which runs twenty-five Progressive scan (hence the "P") frames per second. This framerate is derived from the PAL television standard of 50i (or 50 interlace frames per second). While 25p captures only half the motion that normal 50i PAL registers, it typically yields a higher image quality because it is progressive-scan. It is also better suited to progressive-scan output (e.g. on LCD displays, computer monitors and projectors) because the interlacing is absent.

60p is a Progressive scan format used in high-end HDTV systems, and is almost always what is meant by "1080p" needed, this is not common knowledge - there are MANY 1080p sets that do NOT run at 60fps. While it (1080p60) is not technically part of the ATSC or DVB broadcast standards, it is rapidly gaining ground in the areas of set-top boxes and video recordings.

Computer science Frame rate is also a term used in real-time computer graphics. In a fashion somewhat analogous to the moving-picture definition presented above, a real-time frame is the time it takes to complete a full round of the system's processing tasks. If the frame rate of a real-time system is 60 hertz, the system reevaluates all necessary inputs and updates the necessary outputs 60 times per second under all circumstances.

The designed frame rates of real-time systems vary depending on the equipment. For a real-time system that is steering an oil tanker, a frame rate of 1 Hz may be sufficient, while a rate of even 100 Hz may not be adequate for steering a guided missile. The designer must choose a frame rate appropriate to the application's requirements.

==Frame rates in video games==Frame rates are considered important in video games. The frame rate can make the difference between a game that is playable and one that is not. The first 3D first-person adventure game for a personal computer, 3D Monster Maze, had a frame rate of approximately 6 fps, and was still a success, being playable and addictive. In modern action-oriented games where players must visually track animated objects and react quickly, frame rates of between 30 to 60 fps are considered minimally acceptable by some, though this can vary significantly from game to game. Most modern action games, including popular first person shooters such as Halo 3, run around 30 frames a second, while others, such as Call of Duty 4, run at 60 frames a second. The framerate within most games, particularly PC games, will depend upon what is currently happening in the game in the way of CPU occupying.

A culture of competition has arisen among game enthusiasts with regards to frame rates, with players striving to obtain the highest fps count possible. Indeed, many benchmarks released by the marketing departments of hardware manufacturers and published in hardware reviews focus on the fps measurement. Modern video cards, often featuring NVIDIA or ATI Technologies chipsets, can perform at over 160 fps on graphics intensive games such as F.E.A.R. (computer game) One single GeForce 8800 GTX has been reported to play F.E.A.R. (computer game) at up to 386 fps (at a low resolution). This does not apply to all games: some games apply a limit on the frame rate. For example, in the Grand Theft Auto (series) series, Grand Theft Auto III and Grand Theft Auto: Vice City have a standard 30 fps (Grand Theft Auto: San Andreas runs at 25 fps) and this limit can only be removed at the cost of graphical and gameplay stability. It is also doubtful whether striving for such high frame rates is worthwhile. An average 17" monitor can reach 85 Hz, meaning that any performance reached by the game over 85 fps is discarded. For that reason it is not uncommon to limit the frame rate to the refresh rate of the monitor in a process called vertical synchronization. However, many players feel that not synchronizing every frame produces sufficiently better game execution to justify some "Page tearing" of the images.

It should also be noted that there is a rather large controversy over what is known as the "feel" of the game frame rate. It is argued that games with extremely high frame rates "feel" better and smoother than those that are just getting by. This is especially true in games such as a first-person shooter. There is often a noticeable choppiness perceived in most computer rendered video, despite it being above the flicker fusion frequency (as, after all, one's eyes are not synchronized to the monitor).

This choppiness is not a perceived flicker, but a perceived gap between the object in motion and its afterimage left in the eye from the last frame. A computer samples one point in time, then nothing is sampled until the next frame is rendered, so a visible gap can be seen between the moving object and its afterimage in the eye. Many driving games have this problem, like NASCAR 2005: Chase for the Cup for Xbox, and Gran Turismo 4. The polygon count in a frame may be too much to keep the game running smoothly for a second. The processing power needs to go to the polygon count and usually takes away the power from the framerate.

The reason computer rendered video has a noticeable afterimage separation problem and camera captured video does not is that a camera shutter interrupts the light two or three times for every film frame, thus exposing the film to 2 or 3 samples at different points in time. The light can also enter for the entire time the shutter is open, thus exposing the film to a continuous sample over this time. These multiple samples are naturally interpolated together on the same frame. This leads to a small amount of motion blur between one frame and the next which allows them to smoothly transition.

An example of afterimage separation can be seen when taking a quick 180 degree turn in a game in only 1 second. A still object in the game would render 60 times evenly on that 180 degree arc (at 60 Hz frame rate), and visibly this would separate the object and its afterimage by 3 degrees. A small object and its afterimage 3 degrees apart are quite noticeably separated on screen.

The solution to this problem would be to interpolate the extra frames together in the back-buffer (field multisampling), or simulate the motion blur seen by the human eye in the rendering engine. When vertical sync is enabled, video cards only output a maximum frame rate equal to the refresh rate of the monitor. All extra frames are dropped. When vertical sync is disabled, the video card is free to render frames as fast as it can, but the display of those rendered frames is still limited to the refresh rate of the monitor. For example, a card may render a game at 100 FPS on a monitor running 75 Hz refresh, but no more than 75 FPS can actually be displayed on screen.

Certain elements of a game may be more Graphics processing unit-intensive than others. While a game may achieve a fairly consistent 60 fps, the frame rate may drop below that during intensive scenes. By achieving frame rates in excess of what is displayable, it makes it less likely that frame rates will drop below what is displayable during stressful scenes.

See also

Computer science
Movie projector
Moving image formats
Persistence of vision
List of film formats
Telecine
Film-out
Video compression
24p

External links

All about framerates
Frame Rate Test Video Files
Silent Films: What Was the Right Speed
"Temporal Rate Conversion" - a very detailed guide about the visual interference of TV, Video & PC

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Frame rate - Wikipedia, the free encyclopedia
Frame rate, or frame frequency, is the measurement of the frequency (rate) at which an imaging device produces unique consecutive images called frames.

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frame rate
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What is frame rate? - a definition from Whatis.com
In motion pictures, television, and in computer video displays, the frame rate is the number of frames or images that are projected or displayed per second.

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