NTSC

The NTSC specification describes the analog television system for most of the Americas (and certain other countries - see map). Although not used for modern digital television, it influences still-current standards such DVD. Its two most important characteristics (for our purposes) were its frame rate and color format.

• NTSC-type video consists of approximately 29.97 (30000/1001 to be exact) interlaced frames of video per second. See the Wikipedia link below for the historical reasons for this seemingly-odd frame rate. In the original analog standard, each frame consisted of 525 scan lines, 483 of which were visible. The remainder was used for vertical synchronization and other purposes. Each frame was composed of two fields; each field therefore consisted of 262.5 scan lines. See interlaced fieldbased for more about interlaced video.
• NTSC's color is governed by Rec601 (also known as 'Rec.601,' 'BT.601' and 'SMPTE 170M'), which is an international standard that describes color conversion between the RGB color format (as it is taken at the camera and displayed on the screen) and a particular YUV format, which carries the internal signal. See Colorimetry for more on this and related standards.

External links

wikipedia:NTSC (from which this summary was adapted)
Video Basics (doom9.net) An illustrated guide for beginners.