525/60 refers to a
NTSC analog TV signal. Although
NTSC only has 486 horizontal lines in its
Active Area, a
NTSC video signal also includes extra vertical sync lines, which are basically just filler timed to allow the electron guns in a
CRT television time to reposition themselves at the top of the screen. There are 39 vertical sync lines, resulting in a total of 525 lines (486 + 39).
60 is a reference to
NTSC's
Fieldrate of approximately 60
Fields per second, resulting in 29.97 (30 / 1.001) Interlaced
frames per second.
Related Guides
Digital Video Fundamentals - Resolution and Aspect Ratio
