Reply To: General help with a Dreamcast, please?

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#23174
nmalinoski
Participant

– Dreamcast has four basic output options: composite, S-Video, RGB and VGA
– the VGA output is not RGB
– Dreamcast’s VGA mode is 720×480 instead of 640×480, which is what the OSSC expects in the VGA input

“RGB” and “VGA” here are both RGB; the differences are that “RGB” in this context means 15kHz RGBS, which carries horizontal and vertical syncs together on a 4th line, and is only good for SD video; while “VGA” in this context means 31kHz RGBHV, which carries horizontal and vertical syncs separately 4th and 5th lines, and is needed for 480p (and 576p?).

The “VGA” labeling is confusing, because, while it’s an appropriate and accepted term for the connector, the video format is not VGA, in that the Dreamcast does not output any of the video modes, including 640×480, that the VGA standard calls for; like you said, it instead outputs 720×480.

– by the SCART standard, the max resolution of 480i is a hardware limitation (ie. not a Dreamcast limitation, but present in every other equipment)

Yes and no. SCART generally only carries SD video, and this limitation has been built into several consoles, including the Dreamcast, Xbox, and PS2; however, SCART is very much capable of 480p and greater with compatible equipment. Some SCART devices are capable of transmitting and receiving YPbPr component for ED and HD video; and, in our retro videogame realm, you’re able to transmit 480p RGBS over SCART using a Toro, which can be wired into a 480p-capable monitor (like a PVM or BVM), or into an OSSC for display on contemporary flat panel TVs.

– Some games can’t output in VGA mode, meaning not all VGA boxes can run all Dreamcast games
– Some games can’t output in RGB mode
– Some games can run natively at 240p, but it’s only possible through VGA
– Some games have been modified by fans to output VGA – such as the ones by Japanese_Cake
– There are some advanced VGA boxes by the BeharBros

Mostly correct. Most of the breakout boxes that I’m aware of have some form of compatibility. The BeharBros Toro, for example, can play 480p games no problem, and can trick 480i-only but RGB-compatible games into outputting 480p by flipping the DC-side mode switch to “RGB”, then flipping it back to “VGA” during the Sega licensing screen, but I don’t think it will work with the RGB-incompatible games, as I don’t think is has the capability to output S-Video or composite video (and there’s nothing in the manual that suggests it can).

I think the only breakout boxes that are compatible with every game are the ones that include not only the VGA connector but also the S-Video and composite video outputs. These usually have a video mode switch, so they will work with the 480p-compatible games, can trick the 480i-only games into 480p using the switch trick, and can play the non-RGB-compatible games over S-Video or (gag) composite video.

Straight VGA cables may not have the mode switch, and definitely won’t be able to play the non-RGB-compatible games; not to mention the cheap ones from companies like Tomee are poorly shielded and can introduce visual noise.

I’m not sure if it’s required to use RGBHV to play 240p games.

Of course, all of this is rendered moot by your GDEMU. If you use GDMENU (Which I highly suggest), there is a “Force VGA” option that automatically enables 480p mode for 480i-only games; and, while it won’t magically make non-RGB-compatible games work, due to the nature of the device, you can run patched versions of those games to also run them at 480p.

– Dan/citrus3000psi is currently working on an HDMI FPGA project for the Dreamcast
– Pound’s HDMI cable converts the VGA signal into a 480p digital one
– The guys at HD Retrovision are currently working on a Dreamcast component cable
– RetroGamingCables is working on a SCART Dreamcast cable

Pound’s HDMI cable is convenient but not perfect; and the other solutions are not out yet.

So, what should be the best approach for me, as I’m gonna start from zero?

For you, what you should get depends on a few things. If you want something now, I would recommend a BeharBros Toro and a SCART cable (the SCART and component inputs on the OSSC have low-pass filtering that the DE-15 input does not); or, if you would prefer to bypass your OSSC, the Akura is a good choice for connecting your Dreamcast directly to your TV. If you go this route, do keep in mind that the BeharBros products need to be positioned directly behind the console, and the manufacturer recommends against bending that little cable, so any of these boxes will significantly increase the depth of your console’s footprint.

If you can wait (or even if you can’t; go ahead and buy a Toro for now), I would get a DCHDMI and bypass the OSSC (Or use one of these and enable whatever direct/passthrough mode will be on the DCHDMI to keep using the OSSC). To me, HDMI mods like these are inherently more future-proof, as the world has moved on to HDMI, and the analogue AV equipment needed to provide compatibility is getting rarer and more expensive. I recently installed an UltraHDMI into my N64, and, after using it for even a short timespan, it’s so good that I don’t think I’ll be going back to running it through an RGB decoder and my OSSC; I expect the DCHDMI will provide a similar experience.