frame rate

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. Frame rates are used in synchronizing audio and pictures, whether film, television, or video. In motion pictures and television, the frame rates are standardized by the Society of Motion Picture and Television Editors (SMPTE). SMPTE Time Code frame rates of 24, 25 and 30 frames per second are common, each having uses in different portions of the industry. The professional frame rate for motion pictures is 24 frames per second and, for television, 30 frames per second (in the U.S.).

In computer video streams, the frame rate describes playback rates for AVI and QuickTime movies. The video playback rate for an AVI or QuickTime movie directly relates to the perceived smoothness of its playback. The higher the number of frames playing per second, the smoother the video playback appears to the user. Lower rates result in a choppy playback. (As a reference point, film uses 24 frames per second to allow the viewer to perceive smooth playback.) Several factors affect the actual frame rate you get on your computer. For example, your PC processor or graphics hardware may only be capable of playing 10-15 frames per second without acceleration.

In developing motion pictures, television, and video, frame rate information is used as a reference for audio signals. The recorded signal includes information about location in time using a 24-hour clock, and individual frame numbers. This signal is used to synchronize multiple audio and video machines during the recording and editing process. Using a master synchronizing device, the operator can issue location commands from a central machine and have all slaved machine follow the master.

This was last updated in April 2005

Dig Deeper on Network Infrastructure