SD Analog Video Standards

Standard Definition Analog Video Standards

We'll cover the main analog standards in use today around the world, but we'll mainly focus on two in particular: NTSC and PAL.

NTSC and PAL at a glance:

 
NTSC

(National Television Systems Committee). The current analog television system standard used in the U.S. and several other countries, mostly in the Americas and parts of Asia (including Japan), although variations are used in different countries. It consists of 525 horizontal scan lines, about 480 of which are used for active picture area, the rest reserved for other purposes like sync and closed captioning. It has a 59.94 field refresh rate (usually referred to simply as 60 fields) or 29.97 frames per second (fps).

Due to the nature of its analog composite signal, and its tendency to shift phase (hue) during transmission, it is often jokingly referred to as "Never Twice the Same Color"

Of historical note: Since its origins trace back to the 1930's and black and white tv, when color was introduced in the 1950's, the system was made to be backwards compatible with black and white, encoding the video in a color difference system which converts the video into different luma/chroma components described in more detail in the section Color Spaces. Also, on the introduction of color, for technical considerations, the frame rate had to be changed from 30 frames per second (fps) to 29.97 fps.

PAL

(Phase Alternating Line). The current analog television system used in most of Europe and much of the world. Although the color is handled somewhat differently than NTSC, the luma and chroma components are combined into a single composite signal. Consists of 625 horizontal total scan lines, with 576 active picture lines, the rest are reserved for other purposes like sync and closed captioning.

SECAM

(Système Electronique Couleur Avec Mémoire. French for Sequential Color With Memory). First developed in France beginning in 1956 and widely introduced in 1967. Unlike NTSC and PAL, where both color difference channels are transmitted together, in SECAM the color components are transmitted one at a time and information about the other color component is used from the preceding line. In addition to France and its former colonies, it was also adopted by the Soviet Union, other Eastern European and Middle Eastern countries. Recently, many European countries have switched or are switching to PAL. Countries that still employ SECAM include Russia, parts of Africa and many Middle Eastern countries.