Video Fundamentals
Scanning Speed

The scanning speed is the number of video frames generated per second. The scanning speed and the number of lines per frame depend on the video format. The prefix M in the M-NTSC and M-PAL formats refers to a scanning speed of approximately 30 frames per second and a scanning system of 525 lines per complete frame. All other formats specify a rate of 25 frames per second and 625 lines per frame.