Dreamcast:Video Output Notes

From ConsoleMods Wiki
Revision as of 02:34, 2 May 2022 by Brickard (talk | contribs)
Jump to navigation Jump to search
Brickard
    • Sega Dreamcast**

The Dreamcast is the 6th generation game console from Sega.

Sega Dreamcast Console.jpg

Resolutions

The Dreamcast natively support 480p, 480i, and 240p resolutions.

All Dreamcast games support 480i, many support 480p, and a few support 240p. An unmodiffied Dreamcast is capable of outputting Composite, VGA, RGB, and Component video.


**Analog Options (can be combined with a converter to get HDMI):**

    • Retro Access** now has both SCART and BNC solutions that work in all resolutions and on all multi-format monitors.

Retro Access Dreamcast SCART Cable (you can choose cable type from the drop-down)

Retro Access Dreamcast BNC Cable (choose length and audio connector from the drop-down)

**Retro Gaming Cables SCART Cable** (compatible with all scalers and monitors _except_ D and A-series BVM's)

    • HDRetrovision** will (eventually) have their component video solution, which supports all modes and outputs the correct sample rate to HDTV's: https://www.hdretrovision.com
    • VGA / SCART Cable By The Foo:** https://ebay.to/2OVIFL3 - These seem to be good quality and the sync combiner works well, however the SCART adapter is often out-of-stock.


**HDMI Options:**
    • DCHDMI**

The DCHDMI is a HDMI solution for the Dreamcast. It requires a complicated internal installation that requires cutting a hole for an HDMI port, but no other video output solution comes close to the quality. It's zero lag and outputs up to 1080p: DCHDMI Direct Purchase Link: https://castlemaniagames.com/products/dchdmi-kit-dreamcast-hdmi-mod-kit?ref=w9\_zngec1o\_ DCHDMI Settings Page: http://www.dansprojects.com/dchdmi\_settings.html


    • HDMI Cables:**

Cheap HDMI Cable #1: https://amzn.to/2yGMiue Cheap HDMI Cable #2: https://amzn.to/2Jpq3gg 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.

Gekko & Akura made by Beharbros: http://www.beharbros.com/ In my opinion, the only "Dreamcast HDMI Plug-and-play" that does a decent job are the Akura and Gekko boxes by the Behar Bros, which are simple analog to digital converters; Using a switchable analog cable and the OSSC will output a better image, but the Gekko is only $55, making it a good contender for people who _only_ need HDMI output from their Dreamcast.

One thing to note is _all_ VGA analog to digital converters won't correct the aspect ratio and sampling issues. More on that below.


**Output Options (videos):**

https://youtu.be/ROjAwpFsoIU

https://youtu.be/iCAhyOD7ytM


**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. 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 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.

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:

<tbody></tbody>

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 an [emotia.html Extron Emotia], 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. Check out [240p.html 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:

https://youtu.be/eOP3ZDUX7Y8


**Summary:**

\- If you'd like the best analog output from your Dreamcast, purchase a video output solution that supports both video modes. You'll be able to play your favorite games in a way that looks best on every display you use it on.

\- Using Dreamcast on a flat-screen can be complicated. The best way at the moment is using the DCHDMI or an OSSC.

\- I like using ODE's to play my DC games, as patching and options are applied much easier.

\- If you'd like digital audio, you can try this TOSLINK mod: https://assemblergames.com/threads/saturn-dreamcast-toslink.57670/


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