Dreamcast:Video Output Notes

The Dreamcast natively supports 240p, 480i, and 480p resolutions. All Dreamcast games support 480i, many support 480p, and a few support 240p. The Dreamcast is capable of outputting Composite, S-Video, VGA, RGB, and Component video.

VGA Notes
Not all Dreamcast games are compatible with VGA, but a very large amount are. See the Dreamcast:List of VGA Games and Patches page for more information.

The VGA output of the Dreamcast is 480p, but it is not the "typical" 480p DTV resolution (720 x 480) of televisions. The VGA output of the Dreamcast is 480p VESA resolution (640 x 480) within a 480p DTV signal.

This means that the correct sample rate of the Dreamcast 480p signal is 858 pixels per line, the same sample rate of any 480p DTV signal. If the signal is interpreted as VESA only 800 pixels per line will be sampled, and at this sample rate 43 pixels columns will be lost within the active picture area. Also, if sampled at 800 pixels per line neighboring columns get blurry since the 43 columns are evenly distributed across the screen.

RGB Incompatibilities
A few game discs will output composite and S-Video, but not RGB. Some games can be fixed with an ISO patch, however the very few games which are affected won't run in RGB from their original discs.

Here's some games that are affected:
 * Giga Wing
 * Skies of Arcadia/Eternal Arcadia
 * Street Fighter Alpha/Zero 3
 * Super Street Fighter 2 X
 * Touken Retsuden 4
 * Vampire Chronicle for Matching Service
 * Pop 'n' Music (all 4)

See this thread for fixes.

Progressive Scan (240p & 480p) compatible games
To access the 240p mode in Dreamcast games, a few games (like Bangai-O) ask if you'd like to start the game in a "progressive" mode and some Capcom Dreamcast games (Third Strike) can be forced into a 240p mode by holding Start+L (or Start+Z on the Arcade Stick) when you turn the system on before the Capcom logo appears. These appear to be the only Dreamcast games that support native 240p:


 * Bangai-O
 * Last Hope
 * Street Fighter Alpha 3
 * Black Matrix A/D
 * Marvel vs Capcom: Clash of Super Heroes
 * Street Fighter Zero 3
 * Gunbird 2
 * Neo XYX
 * Street Fighter Zero 3 for Matching Service
 * Gunlord
 * Princess Maker Collection
 * The King of Fighters Dream Match 1999
 * Jo Jo's Bizarre Adventure
 * Street Fighter 3: Third Strike
 * The King of Fighters 99 Evolution
 * Last Blade 2: Final Edition
 * Street Fighter 3: Double Impact
 * Twinkle Star Sprites

Dreamcast is a good platform to use with a downscaler, such as an Extron_Emotia, to force 480p games to 240p.

Forcing Widescreen mode / Aspect Ratio
Some Dreamcast games have been hacked to run in widescreen mode. If you play these games on an HDTV, this is definitely worth checking out this list of widescreen codes.

Also, the aspect ratio of Dreamcast is a bit weird. Check out Fudoh's great post about it and how it can be fixed with the OSSC.

480p Aspect Ratio / Sampling Line Issues
Another problem is that while the DC's signal technically is a 720x480p DTV signal, only the inner 640x480p area is actually used. Any A/D conversion will sample the pillarboxes to the left and right as part of the active image, so you always end up with those aspect ratio problems. The aspect ratio problem is even bigger with DTV sampling (1.18:1 without correction while VESA sampling gives you 1.25:1). You can try using a VGA to component converter to solve the sampling problem, as all component to HDMI converters use DTV sampling rates instead. If you convert from component video to HDMI, it will retain the Dreamcast's picture quality, you'll still end up with the wrong aspect ratio.

You can use a OSSC to apply a DTV sampling AND reduce the active image area to 640 pixels, basically creating a VESA signal from the DTV signal. This solves both problem, but can bring compatibility issues, as not all TVs can accept a 858px wide signal with just a 640 px wide active area. The advantage on the other hand by using a correctly sampled DTV signal without AR correction, is that you get a 1:2 pixel mapping on the horizontal on a Full HD screen. The DC will fill a 1280x1080 area in the middle of the screen, giving you a quite narrow AR, but certainly the best possible picture quality you can get from a DC. By altering the active image area to 640px instead, the signal gets scaled to 1440x1080 instead, so you no longer get an integer scale on the horizontal. Of course you can get proper 4:3 now, but at the expense of some PQ. Some TVs can show 1280x960 from a 640x480p signal, which combines the best PQ with the correct AR, but of course you have to deal with the underscan.