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Dreamcast Video Display and HDTV Guide

by: lordnikon

This guide will help you get the best video signal quality possible from your Sega Dreamcast.
Note: RGB/SCART Cables have yet to be properly researched for this guide.


A total of 4 different video cable options exist for the Dreamcast:
  • RF Switch
  • Composite
  • S-Video
  • VGA
RF-Switch is the very worst display option. This should be a last resort. Only use this cable if you are connecting to an old SDTV that has no other connection options other than RF Switch.

Composite (Yellow Cable) is the standard video cable that comes with the Dreamcast. This cable gets the job done, and you have to use this if your SDTV's best option is Composite input. However we want to upgrade and improve the video signal by choosing a better cable if possible. This will all depend on whether you are using an SDTV or an HDTV, and what type of connectors your TV has on the back.

S-Video on an SDTV

If you are using an SDTV, and it supports S-Video, then buy the S-Video cable. This is the best Dreamcast video cable you can use on a standard definition TV. Tracking down a quality S-Video cable for the Dreamcast is easy. They are plentiful and all first/third party cables work just as good. A third party Dreamcast S-Video cable should run you about $5-10.

Display lag and HD Signal Processing

SDTV's render in two primary modes: 240p and 480i. The "i" after 480 stands for "Interlaced". Which means it displays two sets of signals alternating on odd/even lines of the TV. Most Dreamcast games will run in 480i on SDTV's (though some render in 240p).

HDTV's have a native fixed pixel resolution. Video is rendered in "progressive scan". Your TV could be 720p, or an even higher resolution at 1080p. While SD displays and older CRT Computer monitors can switch resolutions, HD displays can only render in 1 resolution. Therefore if you connect your Dreamcast to an HD Display, of the many signal processing procedures that take place, it will: 1) convert the signal from interlaced to progressive and 2) scale the image to a higher resolution.

Re-processing the video signal takes time, which creates a subtle delay that can be easier felt than seen depending on the games you play. Not only this, but the process of scaling a smaller image to a larger size degrades picture quality.

Playing on an old CRT monitor

Among the Dreamcast's many unique features, it has ability to output a 640 x 480 VGA signal. This is the highest quality signal output among any console in the Dreamcast's generation. If you don't want to have to worry about additional lag or signal processing, then simply pick up a cheap 17" CRT monitor.

The great thing about the Dreamcast VGA box is that it also has S-Video/Composite out as well, which can be quite convenient if you like to alternate between a CRT and an SDTV.

Choosing a cable for your HDTV

Up until now, we have been talking purely about the video cable affecting picture quality. However now the TV inversly impacts the picture, and we have "display lag" to deal with. So what do we do?

If your HDTV is equipped with a VGA input, buy a Dreamcast VGA box. Even if your TV does not support VGA, there are conversion devices that can re-transcode a VGA signal to component. The difference between using a Dreamcast VGA box and any other cable for the system on an HD display is like night and day. Using a Dreamcast VGA box has the following advantages:
  • Eliminates the need for de-interlacing, thus cutting down the amount of display lag
  • You get the best picture quality possible from the Dreamcast
  • Connecting to the VGA port on HDTV's has been known to bypass time consuming image processing would happen when connecting via Composite/S-Video/Component ports
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