THE PICTURE AND sound quality available from DVD video discs is streets ahead of what's available from VHS tapes. That's no doubt why sales of DVD players, widescreen TVs and surround sound systems have rocketed ahead in the last couple of years. DVDs have also generated tremendous interest in setting up home theatres, so enthusiasts can watch movies at home with a presentation almost as good as that in their local cinema.

Fig.1: block diagram of the Component Video To RGB Converter. IC1b is used to produce the G-Y colour difference signal, while IC2a, IC3a & IC4a produce inverted RGB signals which are then buffered and fed to the outputs.

At the same time, the very high picture and sound quality available from the best movie DVDs has raised consumer expectations. And it has motivated enthusiasts to find out how they can achieve the best possible results from their home theatre set-ups.

For example, most people are now aware that the highest picture quality from a DVD can be achieved only by using a player fitted with "component video" outputs, connected in turn to the corresponding inputs of a widescreen TV or video projector. This is because the video is actually recorded on DVDs in digital component format, so component video output signals have undergone less processing than those from S-video or composite video outputs.

As a result, component video signals provide cleaner and sharper pictures than the other signal formats. However, some widescreen TVs (particularly those of European origin) and some projectors don't have component video inputs. Instead, they may be fitted with "RGB" (red, green, blue) video inputs, made either via RCA connectors or a European-style SCART connector – these in addition to the usual composite video and S-video inputs

And that's where problems can arise – RGB inputs are not compatible with component video signals (and most DVD players don't have RGB outputs). This means that you need a converter box to change the signal format if you want to drive your TV's RGB inputs from the component video outputs on your DVD player.