Video Normen

What’s up with the different types and terminologies of video cables?  What’s CVBS, what is SVHS, what is SCART?  And which cable do I need for my system? It’s best to start with what all these terms have in common.  They all explain the method of image transfer that is used.  Some are more sophisticated than others and they all have different uses and goals.

But before we get to that, we need to take a step back and see what makes up a video signal.

A standard color video signal comes from 2 or more signals which can be combined.  One signal defines how bright the image is (luminance) and the other one defines the color (chrominance).  An RGB signal will have at least 3 signals, one for each base color - Red, Green and Blue.

Let's have a look at the most common standards :

CVBS (an abbreviation for Color Video Blanking Sync) or composite video merges both luminance and chrominance signals into one cable.  The color signal is a bit hidden so a black and white (or monochrome) display ignores it, showing you just the brightness with a black and white picture as the result.  A color display will take the color signal and combine both signals into a color picture.  As a consequence of putting both signals on a single cable, the resulting image can be a bit blurry as some information gets lost in transport and recombining the signals.

SVHS  (or Super-VHS, named after the old video recording tapes) keeps both these signals separate, leaving more room on the cable (aka bandwidth) for both picture (luminance) and color (chrominance) information.  When combining both signals in your display the resolution will be higher than CVBS and the colors will be crisper.

SCART (or RGB) expands on splitting up the signals and uses different signal cables for each color, plus various technical synchronisation pins.  Again more room on the wire becomes available because each base color - Red, Green or Blue - no longer has to share the same space with the other ones.  Splitting up these color signals also removes the need for a luminance signal as each signal basically is a luminance for its specific color (yes, it can sound complicated).  The SCART-standard is by origin a French design and stands for "Syndicat des Constructeurs d'Appareils Radiorécepteurs et Téléviseurs" (Syndicate of radio- and television receiver constructors).

Which cable do I need ?

It depends on your system, your display and your budget.  The best way to start is to have a look at the back of your display.  If you have a SCART connector, consider using a SCART cable if your system supports it.  Most consoles from the 16-bit generation and up do, with some exceptions.

If there is no SCART plug available or free on your display, CVBS remains an option.  The yellow / red / white plugs (yellow for the video signal, red and white for stereo audio) are pretty much universal on any display on the market.