Film frame

In filmmaking, video production, animation, and related fields, a film frame or video frame is one of the many still (or nearly so) images which compose the complete moving picture. The term is derived from the fact that, from the beginning of modern filmmaking toward the end of the 20th century, and in many places still up to the present, the single images have been recorded on a strip of photographic film that quickly increased in length, historically; each image on such a strip looks rather like a framed picture when examined individually. The term may also be used more generally as a noun or verb to refer to the edges of the image as seen in a camera viewfinder or projected on a screen. Thus, the camera operator can be said to keep a car in frame by panning with it as it speeds past. When the moving picture is displayed, each frame is flashed on a screen for a short time (nowadays, usually 1/24, 1/25 or 1/30 of a second) and then immediately replaced by the next one. Persistence of vision blends the frames together, producing the illusion of a moving image. The frame is also sometimes used as a unit of time, so that a momentary event might be said to last six frames, the actual duration of which depends on the frame rate of the system, which varies according to the video or film standard in use. In North America and Japan, 30 frames per second (fps) is the broadcast standard, with 24 frames/s now common in production for high-definition video. In much of the rest of the world, 25 frames/s is standard. In systems historically based on NTSC standards, for reasons originally related to the Chrominance subcarrier in analog NTSC TV systems, the exact frame rate is often the nominal frame rate divided by 1.001Чso, for example, a nominal 30 fps sequence is actually shot at 30/1.001 = 29.97002997... fps. This leads to many synchronization problems which are unknown outside the NTSC world, and also brings about hacks such as drop-frame timecode. In film projection, 24 fps is the norm, except in some special venue systems, such as IMAX, Showscan and Iwerks 70, where 30, 48 or even 60 frame/s have been used. Silent films and 8 mm amateur movies used 16 or 18 frame/s. In a strip of movie film, individual frames are separated by frame lines. Normally, 24 frames are needed for one second of film. In ordinary filming, the frames are photographed automatically, one after the other, in a movie camera. In special effects or animation filming, the frames are often shot one at a time. The size of a film frame varies, depending on the still film format or the motion picture film format. In the smallest 8 mm amateur format for motion pictures film, it is only about 4.8 by 3.5 mm, while an IMAX frame is as large as 69.6 by 48.5 mm. The larger the frame size is in relation to the size of the projection screen, the sharper the image will appear. The size of the film frame of motion picture film also depends on the location of the holes, the size of the holes, the shape of the holes. and the location and type of sound stripe. The most common film format, 35 mm, has a frame size of roughly 22 by 16 mm when used in a still 35 mm camera where the film moves horizontal but the frame size varies when used for motion picture where the film moves vertically (with the exception of VistaVision where the film moves horizontally). Using a 4-perf pulldown, there are exactly 16 frames in one foot of 35 mm film, leading to film frames sometimes being counted in terms of "feet and frames". A system called KeyKode is sometimes used to identify specific physical film frames in a production.