Dreamcast:Video Output Notes: Difference between revisions

Revision as of 19:52, 29 March 2024

The Dreamcast natively supports 240p, 480i, and 480p resolutions.^[1] 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.^[2]

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.^[3] 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
Pop 'n' Music (all 4)
Skies of Arcadia/Eternal Arcadia
Street Fighter Alpha/Zero 3
Super Street Fighter 2 X
Touken Retsuden 4
Vampire Chronicle for Matching Service
Vigilante 8 2nd Offense

See this thread for more information.

Progressive Scan 240p 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
Black Matrix A/D
Gunbird 2
Gunlord
Jo Jo's Bizarre Adventure
Last Blade 2: Final Edition
Last Hope
Marvel vs Capcom: Clash of Super Heroes
Neo XYX
Princess Maker Collection
Street Fighter Alpha 3
Street Fighter Zero 3
Street Fighter Zero 3 for Matching Service
Street Fighter 3: Double Impact
Street Fighter 3: Third Strike
The King of Fighters Dream Match 1999
The King of Fighters 99 Evolution
Twinkle Star Sprites

The Dreamcast is also 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.

References

↑ (5/12/2022) Sega Dreamcast. https://www.retrorgb.com/dreamcast.html
↑ The 480p VESA is a standard resolution of PC monitors native to the era the Dreamcast was manufactured.
↑ http://pms.hazard-city.de/ossc_sampling.jpg

[1] (5/12/2022) Sega Dreamcast. https://www.retrorgb.com/dreamcast.html

[2] The 480p VESA is a standard resolution of PC monitors native to the era the Dreamcast was manufactured.

[3] ttp://pms.hazard-city.de/ossc_sampling.jpg

[1]

[2]

[3]

@@ Line 1: / Line 1: @@
-[[Category:RetroRGB Migration]]
+[[Category:Dreamcast]]
-**Sega Dreamcast**
+The Dreamcast natively supports 240p, 480i, and 480p resolutions.<ref>(5/12/2022) Sega Dreamcast. https://www.retrorgb.com/dreamcast.html</ref> 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.
-The Dreamcast (like most other 6th generation game consoles) outputted most games in 480i, with some supporting 240p and 480p.  If you're not familiar with those terms, I highly recommend you read my [240p.html 240p page] before continuing.
+== VGA Notes ==
-[[File:Sega%20Dreamcast%20Console.jpg]]
+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.
-All 480p Dreamcast games look great through VGA and if you have a display that supports a 480p input, then that's by far the best output method in most cases.  If you use an RGB cable, the few 240p games that are available will look great, but all other games will only output in 480i.  As a result, an RGB cable is only a good option if you're using a display that only supports 240p and 480i.
+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.<ref>The 480p VESA is a standard resolution of PC monitors native to the era the Dreamcast was manufactured.</ref>
+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.<ref>http://pms.hazard-city.de/ossc_sampling.jpg</ref> 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.
-=== **Output Options (analog options above, HDMI options below):** ===
+== RGB Incompatibilities ==
-==== **Analog Options (can be combined with a converter to get HDMI):** ====
+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.
-**Retro Access** now has both SCART and BNC solutions that work in all resolutions and on all multi-format monitors.  This is your best choice if you have an all-SCART (or all BNC) setup and are using a 480p-compatible RGB monitor.
+Here's some games that are affected:
+* Giga Wing
+* Pop 'n' Music (all 4)
+* Skies of Arcadia/Eternal Arcadia
+* Street Fighter Alpha/Zero 3
+* Super Street Fighter 2 X
+* Touken Retsuden 4
+* Vampire Chronicle for Matching Service
+* Vigilante 8 2nd Offense
+[https://bordersdown.net/forum/gaming/get-answers-games-and-tech/4715-what-ntsc-dreamcast-games-are-non-rgb-compatible See this thread for more information].
-[https://retro-access.com/products/dreamcast-15khz-31khz-480i-480p-scart-cable?variant=17095604207667?aff=3 Retro Access Dreamcast SCART Cable] (you can choose cable type from the drop-down)
+== Progressive Scan 240p compatible games ==
-[https://retro-access.com/products/dreamcast-15khz-31khz-480i-480p-bnc-cable?variant=17095693828147?aff=3 Retro Access Dreamcast BNC Cable] (choose length and audio connector from the drop-down)
+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:
-[https://www.retrogamingcables.co.uk/SEGA-DREAMCAST-RGB-SCART-CABLE-WITH-480P-MODE?tracking=5543fb4c077bb **Retro Gaming Cables SCART Cable**] (compatible with all scalers and monitors _except_ D and A-series BVM's)
+* Bangai-O
+* Black Matrix A/D
+* Gunbird 2
+* Gunlord
+* Jo Jo's Bizarre Adventure
+* Last Blade 2: Final Edition
+* Last Hope
+* Marvel vs Capcom: Clash of Super Heroes
+* Neo XYX
+* Princess Maker Collection
+* Street Fighter Alpha 3
+* Street Fighter Zero 3
+* Street Fighter Zero 3 for Matching Service
+* Street Fighter 3: Double Impact
+* Street Fighter 3: Third Strike
+* The King of Fighters Dream Match 1999
+* The King of Fighters 99 Evolution
+* Twinkle Star Sprites
-**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 https://www.hdretrovision.com]
+The Dreamcast is also a good platform to use with a downscaler, such as an [[AV:Extron_Emotia|Extron Emotia]], to force 480p games to 240p.
-**Boxes made by Beharbros:**  [http://www.beharbros.com/ http://www.beharbros.com/] My current favorite solution from the Behar Bros is the Kuro Plus:  [https://www.beharbros.com/kuroplus https://www.beharbros.com/kuroplus] In my opinion, the Kuro Plus is the perfect solution for people who have two monitors:  An RGB monitor and a VGA monitor.  This one box can do both for a very reasonable price!  It's very similar to the Toro, but without a scanline generator.  For more info, check out the toro's review:  [http://www.retrorgb.com/toro.html http://www.retrorgb.com/toro.html]
+== Forcing Widescreen mode / Aspect Ratio ==
-**VGA / SCART Cable By The Foo:**  [https://ebay.to/2OVIFL3 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.
+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 this list of widescreen codes].
+Also, the aspect ratio of Dreamcast is a bit weird. Check out [http://shmups.system11.org/viewtopic.php?p=1201520#p1201520 Fudoh's great post about it] and how it can be fixed with the OSSC.
-===== **HDMI Options:** =====
+== 480p Aspect Ratio / Sampling Line Issues ==
-**DCHDMI**
+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.
-The DCHDMI is the _ultimate_ 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_ https://castlemaniagames.com/products/dchdmi-kit-dreamcast-hdmi-mod-kit?ref=w9\_zngec1o\_] DCHDMI Settings Page:  [http://www.dansprojects.com/dchdmi_settings.html http://www.dansprojects.com/dchdmi\_settings.html]
+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.
+== References ==
-**Cheap HDMI Cables:**
-Cheap HDMI Cable #1: [https://amzn.to/2yGMiue https://amzn.to/2yGMiue] Cheap HDMI Cable #2: [https://amzn.to/2Jpq3gg 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.
-**Decent HDMI Cables:**
-Gekko & Akura made by Beharbros:  [http://www.beharbros.com/ 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 [http://retrorgb.com/ossc.html 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** ===
-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...
-p 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 640x480 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 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 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 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:
-<table border="1" cellspacing="0" cellpadding="3" align="center"><tbody><tr><td align="left" valign="top"><p align="center">Bangai-O</p></td><td align="left" valign="top"><p align="center">Last Hope</p></td><td align="left" valign="top"><p align="center">Street Fighter Alpha 3</p></td></tr><tr><td align="left" valign="top"><p align="center">Black Matrix A/D</p></td><td align="left" valign="top"><p align="center">Marvel vs Capcom: Clash of Super Heroes</p></td><td align="left" valign="top"><p align="center">Street Fighter Zero 3</p></td></tr><tr><td align="left" valign="top"><p align="center">Gunbird 2</p></td><td align="left" valign="top"><p align="center">Neo XYX</p></td><td align="left" valign="top"><p align="center">Street Fighter Zero 3 for Matching Service</p></td></tr><tr><td align="left" valign="top"><p align="center">Gunlord</p></td><td align="left" valign="top"><p align="center">Princess Maker Collection</p></td><td align="left" valign="top"><p align="center">The King of Fighters Dream Match 1999</p></td></tr><tr><td align="left" valign="top"><p align="center">Jo Jo's Bizarre Adventure</p></td><td align="left" valign="top"><p align="center">Street Fighter 3: Third Strike</p></td><td align="left" valign="top"><p align="center">The King of Fighters 99 Evolution</p></td></tr><tr><td align="left" valign="top"><p align="center">Last Blade 2: Final Edition</p></td><td align="left" valign="top"><p align="center">Street Fighter 3: Double Impact</p></td><td align="left" valign="top"><p align="center">Twinkle Star Sprites</p></td></tr></tbody></table>
-=== **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 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 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 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://www.retrorgb.com/dreamcastode.html 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 [http://retrorgb.com/ossc.html 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/ 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.

Dreamcast:Video Output Notes: Difference between revisions

Revision as of 19:52, 29 March 2024

Contents

VGA Notes

RGB Incompatibilities

Progressive Scan 240p compatible games

Forcing Widescreen mode / Aspect Ratio

480p Aspect Ratio / Sampling Line Issues

References

Navigation menu

Dreamcast:Video Output Notes: Difference between revisions

Revision as of 19:52, 29 March 2024

VGA Notes

RGB Incompatibilities

Progressive Scan 240p compatible games

Forcing Widescreen mode / Aspect Ratio

480p Aspect Ratio / Sampling Line Issues

References

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