Sega Dreamcast - RetroRGB

Sega Dreamcast

Almost the entire Dreamcast library offers native 480p output with only the proper cable required, no modifications. Most 480i-only games can be patched to run in 480p, but not on the original discs. There’s also an HDMI mod available as well, linked at the bottom of this page. If you’re not familiar with those terms, I highly recommend you read my 240p page before continuing.

Analog Output Options:

The Dremcast can output 240p and 480i via Composite Video, S-Video and basic RGB SCART cables, however VGA and SCART cables with a resolution switch are better options, as you can also output 480p:

VGA:

You can get cheap cables from places like Amazon or Aliexpress, but the quality is hit-or-miss: Some might be totally fine and others might have a lot of interference. Also, the basic VGA cables are ONLY for 480p – You’d need more expensive ones with a switch to support both low and high resolutions:

RetroTINK Dreamcast Basic VGA Adapter
Cheap Amazon Basic DC VGA Cable
Retro-Access Switchable VGA Cable – The 15Khz 240p/480i mode won’t work on VGA CRT monitors, but will work on scalers with a VGA input.

RGB / SCART:

These RGB SCART cables are compatible with all resolutions via a switch and work with all scalers and multiformat monitors, provided they can accept the source signal.

Retro Gaming Cables Dreamcast SCART Cable
Retro-Access Fortraflex Dreamcast SCART Cables
Retro-Access 75 Ohm Coax Dreamcast SCART Cables

Component Video (YPbPr)

Retro Gaming Cables offers a Component Video cable that’s switchable between 15KHz (240p/480i) and 31KHz (480p) modes. They should be compatible with all displays and scalers that can handle those signals. More info in the video below: https://retrorgb.link/rgcdcypbpr

HDRetrovision will (eventually) have their component video solution, which supports all modes and outputs the correct sample rate to HDTV’s. The release has been suspended indefinitely though, for unknown reasons: https://www.hdretrovision.com

HDMI Options:

Cheap HDMI Cables:

Most of the plug-and-play HDMI “cables” I’ve tried for the Dreamcast work very poorly. Most aren’t compatible with any 480i/240p game, some have a very soft output and others barely work at all. Luckily, they don’t seem to add lag, so they don’t completely ruin the experience. In my opinion, these are only good if you need a very cheap solution, or if you just need a temporary solution to hold you off: https://amzn.to/42mszMv

DC Digital

If you’re an absolute Dreamcast superfan, or if it’s the only (or one of the only) consoles you’d like to connect to your flat-panel, you should consider an HDMI mod. They’re extremely complicated to install and costly if you have to pay an installer. BUT, the total price might be cheaper than buying a scaler and quality cables. So for most people with multiple analog video consoles, getting one of the other cables listed on this page and a good upscaler is the most cost-effective, high performance way to connect those consoles to flat-panels.

But if you want a true, digital-to-digital HDMI output from your console, the RetroGEM is an awesome choice: http://retrorgb.link/retrogem

480p Aspect Ratio / Sampling Line Issues

The Dreamcast’s 240p/480i standard definition output is pretty straight forward, however its VGA output, while fine on a CRT monitor has issues with digital solutions. The problem is that the VGA output is a DTV signal. Here’s where things get confusing…

480p DTV signals are what you’d find from a DVD player, cable box or even something like a Playstation 2: A 720x480p “television” resolution. Pretty much every single TV, capture card or analog to digital converter will interpret the Dreamcast’s VGA signal as 640×480 VESA resolution, like you’d find from a PC. The easiest way to spot this, is an aspect ratio that’s too narrow. The aspect ratio itself isn’t the big deal, it’s that the cause of the problem is the wrong samplerate being applied to the signal. The correct sample rate for the DC’s signal, as well as any other 480p DTV signal is 858 pixels per line. If the signal is interpreted as VESA, only 800 pixels per line will be sampled. After deducting invisible areas, front/back porch, sync areas etc, this means that you actually lose 43 pixel columns within the active picture area (picture courtesy of Fudoh): http://pms.hazard-city.de/ossc_sampling.jpg

By applying the wrong sample rate you not only lose 43 pixel columns, but neighboring columns also get fuzzy and blurry and since the 43 columns are evenly distributed across the screen your whole image gets a rather fuzzy look. It’s funny, because there were many times over the years I saw a Dreamcast’s signal and thought it looked a bit soft. Looking back, I wonder if this was what I was always seeing.

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. I guess you could then even go from component video to HDMI and while this retain’s 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 858 px 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 1280×1080 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 1440×1080 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 1280×960 from a 640x480p signal, which combines the best PQ with the correct AR, but of course you have to deal with the underscan.

A huge thank you to Fudoh for helping with this, as I still find it massively confusing.

Progressive Scan (240p & 480p) compatible games:

Not all Dreamcast games are compatible with VGA, but a very large amount are. I found a site that shows which games are compatible and even shows you how to force a VGA mode in most others!:

http://www.epforums.org/showthread.php?56169-Dreamcast-VGA-Compatability-list-amp-Guide

To access the 240p mode in Dreamcast games, a few games ask if you’d like to start the game in a “progressive” mode (Bangai-O) 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. As far as I know, these are 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

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: https://segaretro.org/List_of_Dreamcast_widescreen_codes

Also, the aspect ratio of Dreamcast is a bit weird. I plan on updating this section soon with detailed information. For now, check out Fudoh’s great post about it and how it can be fixed with the OSSC: http://shmups.system11.org/viewtopic.php?p=1201520#p1201520

Some games aren’t RGB-compatible:

I know that probably sounds crazy, but 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 effected won’t run in RGB from their original discs. Here’s some games that are effected, as well as a forum link to fixes:

Effected Games (most): 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’ Musci (all 4).

Links: http://www.bordersdown.net/threads/11538-What-NTSC-Dreamcast-games-are-non-RGB-compatible

Converting 480p to 240p for a “retro” look:

If you run the 480p VGA signal through a downscaler, you can force a 240p mode. I’ve tested this method and in my opinion (when using a display that doesn’t support 480p), a “forced 240p mode” looks better than 480i for many games. Check out my 240p page for more information.

Playing CDr’s:

If the original game is under 800MB and you use good quality (Tayo Uden) discs, you can safely play backups on VA0, VA1 and some VA2 Dreamcast consoles using a software patch. Using cheap media is very bad for your GDROM drive and will absolutely wear your drive much faster than with regular games! Also, games over 800MB (GDROMs can be over 1GB) will either have to be compressed or split to multiple discs. Overall, improper use of CDr’s are not recommended and using an ODE is overall a better choice.

Optical Drive Emulators:

You can replace the Dreamcast’s GDROM drive with an ODE that allows you to launch games from hard drives or flash media. My favorite at the moment is the GDEMU, but here’s a page showing them all: http://retrorgb.com/dreamcastode.html

Hardware Tips and Tricks:

Here’s a video that shows all my favorite tricks for getting the best out of your Dreamcast:

If you’d like info on mods for other systems, head to the Getting RGB From Each System page or check out the main page for more retro-awesomeness.