General help with a Dreamcast, please?

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  • #23167
    misternoob
    Participant

    I’m considering adding a Dreamcast to my collection.
    After reading through forums, I gathered a lot of info but I still find lots of things confusing.

    So, my current scenario is as follows:
    – OSSC 1.6 revision connected to a 1080p LCD screen
    – got my hands on a GDEmu

    What I know (or don’t know, please correct me if I’m wrong)
    – Dreamcast has four basic output options: composite, S-Video, RGB and VGA
    – the VGA output is not RGB
    – we can get 480i RGB output through a SCART cable
    – by the SCART standard, the max resolution of 480i is a hardware limitation (ie. not a Dreamcast limitation, but present in every other equipment)
    – Dreamcast’s VGA mode is 720×480 instead of 640×480, which is what the OSSC expects in the VGA input
    – 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
    – 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

    So, what should be the best approach for me, as I’m gonna start from zero?
    I thought about some scenarios, but what are the pros and cons for each? Are there many games that haven’t been patched for both RGB and VGA outputs? Should I wait for newer products to become available? PS2’s 480i through OSSC’s 2X (bob’s deinterlace) looks a bit weird to me, but I believe it’s the PS2’s fault, how does the DC fares in that case?

    1 – Dreamcast with GDEmu, VGA patched GDI games -> “cheap” DC to VGA cable -> OSSC -> TV
    2 – Dreamcast with GDEmu, RGB patched GDI games -> “Innovation” SCART cable -> OSSC -> TV
    3 – Dreamcast -> Akura -> TV
    4 – Dreamcast -> Toro -> OSSC -> TV

    And, for now, that’s it. Thanks.

    #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.

    #23175
    noodohs
    Participant

    The other benefit of running the Dreamcast into the SCART input of the OSSC is that you end up with the correct aspect ratio without having to fiddle with settings on the OSSC. As long as you set the Toro to VGA mode, you’ll still get 480p for games that support it.

    #23176
    nmalinoski
    Participant

    The other benefit of running the Dreamcast into the SCART input of the OSSC is that you end up with the correct aspect ratio without having to fiddle with settings on the OSSC. As long as you set the Toro to VGA mode, you’ll still get 480p for games that support it.

    Correct; DTV 480p, the setting which determines whether the incoming video is processed as VGA 640×480 or 480p (720×480 being one of these resolutions), is defaulted on for AV1 and AV2 on the OSSC, but off for AV3, so simply using a SCART cable to connect the Toro to the OSSC results in no additional configuration on the OSSC, and, as a bonus, you don’t need to run a separate audio cable (Unless you have a 1.5 or earlier OSSC without an audio mod).

    Also, the Toro needs better labeling, as there are two “VGA mode” switches; one signals to the Dreamcast whether to output in 15kHz RGBS (“RGB”) or 31kHz RGBHV (“VGA”), and the other controls whether the Toro outputs RGBHV or RGBS on its DE-15 port.

    #23188
    misternoob
    Participant

    Thank you so much for all the in-depth information, nmalinoski
    After reading your post, I’ve research a bit more to understand some aspects of what you said

    I’m gonna re-write my first post just because it helps me have a better thought flow.

    = the Dreamcast has “officially” 4 ways to connect to the TV:
    * RF: I had no idea this existed until today, I thought the N64 was the last console to have an official release of an RF modulator
    * RCA composite: 480i only, luma and chroma carried on a single wire (1)
    * s-video: 480i only, carries chroma and luma in two different wires
    * SCART: 480i only, capable of carrying RGBs (meaning the sync is carried in a 4th wire) (2) (3)
    * DB-15: 480p only, capable of carrying RGBHV, very susceptible of visual noise due to poor cable shielding (meaning the sync is carried through 2 wires) (4) (5)

    notes:
    1 – luma is the “how bright” the image is, chroma are the colors
    2 – SCART is capable of carrying up to 1080p if the hardware allows it, but it’s not the case of the Dreamcast
    3 – sync is signal that combines vertical and horizontal lines
    4 – DB-15 is usually called VGA, which is a bit of a misnomer

    = Dreamcast games have 3 resolutions:
    * 240p: can be sent through SCART and DB-15
    * 480i: can be sent through composite, s-video and SCART
    * 480p: can be sent through DB-15

    notes:
    1 – few games can output 240p
    2 – most games can output 480p, but not all
    3 – it’s possible to trick certain games into run in 480p with a VGA Box that can output both through RGB and DB-15
    4 – certain games don’t support RGB output at all, so for all of them a patched image is required
    5 – if running games through GDemu, GDmenu has an in-built option to force 480p output

    ===
    I’m not in a hurry to play on the Dreamcast, I mean, I’ve waited 19 years, what’s another year?
    My only concern about the DCHDMI is the complexity of the installation. My soldering skills aren’t as good as needed for a project like the UltraHDMI, and where I live there’s no modders I can trust to install that kind of thing.
    I’m assuming the Dreamcast port only output analog signals, so an external FPGA solution like the ones for the GameCube can’t be expected, right?

    Also, DCHDMI should have a better image/audio quality as it’s getting data directly from the GPU, and not converting the signal from analog to digital like Akura does.

    How complicated is it to run Dreamcast games from another region?
    The PlayStation 2 had region lock and even with modchips, swap tricks, or whatever, PAL games would be black and white on a NTSC TV, unless a component cable was used.
    I’m assuming the Dreamcast can output both 50Hz and 60Hz without bigger mods, right?
    I think I read that the original Xbox had serious troubles with that kind of thing, and even if the European consoles had an PAL60 option, running NTSC games was a bit troublesome. So I’m still concerned about all the things I don’t know.

    #23190
    nmalinoski
    Participant

    * RF: I had no idea this existed until today, I thought the N64 was the last console to have an official release of an RF modulator

    As far as I can tell, RF modulators work off of composite video, and the last console I recall having native RF output was the NES; from the SNES onward, an external RF modulator was used, which could also be used with the N64 and GameCube (and I’m sure the AV Famicom) by virtue of those consoles using the same AV Multi-out port and pinout. In any case, stay far away from this, because it is by far the worst possible choice for video output.

    * RCA composite: 480i only, luma and chroma carried on a single wire (1)
    * s-video: 480i only, carries chroma and luma in two different wires
    * SCART: 480i only, capable of carrying RGBs (meaning the sync is carried in a 4th wire) (2) (3)

    In general, these three output methods are also capable of transmitting 240p. It’s just that the Dreamcast doesn’t support 240p output over these, correct?

    * DB-15: 480p only, capable of carrying RGBHV, very susceptible of visual noise due to poor cable shielding (meaning the sync is carried through 2 wires) (4) (5)

    RGBHV is typically carried over DE-15/VGA cabling, which is often built with coax, which makes it the best-shielded option for the least amount of money (in terms of cabling in general). More often it’s everything else–SCART, component, S-Video, composite cables–that are commonly found to have been constructed with unshielded cabling, although I’m sure you can find garbage VGA cables as well.

    3 – sync is signal that combines vertical and horizontal lines
    4 – DB-15 is usually called VGA, which is a bit of a misnomer

    Regarding note 3, the combination of vertical and horizontal syncs is called composite sync, or CSync.
    Regarding note 4, it’s typically a misnomer when used in the context of Dreamcast, because that output method uses VGA cabling, probably because it’s the most appropriate for outputting separate sync, but the video signals are not compliant with the VGA spec (not that it really matters to a CRT).

    My only concern about the DCHDMI is the complexity of the installation. My soldering skills aren’t as good as needed for a project like the UltraHDMI, and where I live there’s no modders I can trust to install that kind of thing.

    I can’t speak for the DCHDMI, because it’s not out yet, so I haven’t done an install, but I installed my own UltraHDMI, and it’s really not that difficult of an install if you have the right tools and follow the directions. I don’t claim to be any kind of soldering wizard, but that part of the install went surprisingly quick.

    You’ll need a good soldering station (Hakko FX-888D can be had for ~$100 USD, and it comes with an appropriate tip), SMD tweezers (handy for keeping the flex cable in place while you’re tacking it down), and you’ll definitely want the specific rosin flux pen specifically recommended in the installation manual. The hardest part for me was the case modification; I don’t particularly care for cutting plastic.

    I’m assuming the Dreamcast port only output analog signals, so an external FPGA solution like the ones for the GameCube can’t be expected, right?

    Also, DCHDMI should have a better image/audio quality as it’s getting data directly from the GPU, and not converting the signal from analog to digital like Akura does.

    Correct. The GameCube (or at least the DOL-001 model) is special, in that its Digital AV port directly exposes digital audio and video, which I’m not sure any other pre-HDMI console does. And, yes, the Dreamcast only outputs analogue signals, so that’s what the Akura has to deal with. There is, however, an external FPGA solution for this, and you know it as the OSSC. 😛

    How complicated is it to run Dreamcast games from another region?
    The PlayStation 2 had region lock and even with modchips, swap tricks, or whatever, PAL games would be black and white on a NTSC TV, unless a component cable was used.
    I’m assuming the Dreamcast can output both 50Hz and 60Hz without bigger mods, right?
    I think I read that the original Xbox had serious troubles with that kind of thing, and even if the European consoles had an PAL60 option, running NTSC games was a bit troublesome. So I’m still concerned about all the things I don’t know.

    With a GDEMU, playing games from other regions is as simple as launching it, and I don’t think the Dreamcast needs a dual-frequency oscillator, like the PlayStation and PS2 do, to properly play PAL games on an NTSC console or vice versa. PAL games may tend to run in 50Hz, so, if your display can’t handle 50Hz, then you may wish to stick to NTSC versions when possible. Some PAL games, like ChuChuRocket!, do give you the option on bootup to use 50Hz or 60Hz, which is neat.

    I’m not familiar with that issue with the original Xbox. In my experience, Xbox games will run in whatever video mode the console is currently set to, so PAL games running on an NTSC console will display in NTSC, since it’s basically just a PC. The only problem I’m aware of is that, when set to PAL mode, the only additional video option you get is PAL60 (I forget if this also prevents you from using digital audio); your console needs to specifically have its video region set to NTSC to enable any of 480p, 720p, and 1080i.

    #23191
    noodohs
    Participant

    Some notes on your notes. SCART can also transmit 480p as I mentioned above. That plus the ease of configuration on the OSSC side is the main reason I recommend it.

    Regarding RF output, the NES still had an external box thing, but it also had a modulator internally. Not really sure why it had both, but it did… PCE/TG16 also had internal modulators. But even as recent as the original Xbox had options for getting RF if you really wanted it.

    Regarding region lock, I know that you can play JP games on a US console by way of a boot disc. Not sure about PAL and NTSC, though.

    #23192
    nmalinoski
    Participant

    Some notes on your notes. SCART can also transmit 480p as I mentioned above. That plus the ease of configuration on the OSSC side is the main reason I recommend it.

    SCART is capable of transmitting 480p, yes, but the Dreamcast won’t natively output 480p over SCART, since Dreamcast SCART cables only bridge the pin for SD RGBS, and, even if they did bridge the pins for RGBHV mode, neither the console nor the cables have a sync combiner in order to provide 480p RGBS. Simply, you need something like the BeharBros Toro in order to get 480p RGBS out of the Dreamcast.

    Regarding RF output, the NES still had an external box thing, but it also had a modulator internally. Not really sure why it had both, but it did… PCE/TG16 also had internal modulators. But even as recent as the original Xbox had options for getting RF if you really wanted it.

    That external box thing is an RF switch, which is distinct from the RF modulator. The RF switch takes the RF signal from the modulator and puts it on the coax line going into your TV so you don’t have to remove the coax cable with those annoying F-type screw connectors from your TV in order to use it.

    Regarding region lock, I know that you can play JP games on a US console by way of a boot disc. Not sure about PAL and NTSC, though.

    PAL games will also load with a boot disc, but the console will probably switch to PAL output, which is generally unusable on US-market NTSC televisions. Contemporary 4K TVs in the US likely won’t be able to decode PAL, but they might be able to take a 576i/p and/or 50Hz RGB signal; unfortunately, I’m not sure anyone has bothered to confirm that, and it might be a crapshoot.

    #23193
    noodohs
    Participant

    I guess if we are talking about officially supported signals, then yeah, only 480i over SCART. But is there an official box that has a SCART output anyway?

    #23195
    nmalinoski
    Participant

    But is there an official box that has a SCART output anyway?

    As far as I know, Sega sold a straight SCART cable, not any sort of SCART solution involving a breakout box.

    Also, according to RetroRGB, it sounds like the Dreamcast will output 240p over any cable type, but the main downside is that you won’t be able to use 480p for games that support it if you use anything other than a breakout box or a custom cable that can put the console in RGBHV mode.

    #23221
    misternoob
    Participant

    I really appreciate the feedback, guys.

    – I didn’t know later RF boxes were actually modulating composite signals. That’s interesting to know.
    – While I’ve read that composite and S-Video can output 240p, I thought that the only way to get a progressive output from the Dreamcast was through a VGA box. When I read about it, people were talking about VGA Boxes so that’s why I assumed it only worked that way. I’m probably wrong, so don’t quote me on that.
    – I got a Hakko FX-888D earlier this year cause I decided to learn how to solder properly. And thanks for the tips on what else to get.
    – I’m glad that region lock on the Dreamcast is easy to by-pass.
    – Wasn’t the external RF box on the NES just a switch to select either antenna or console?
    – I have a Sony 1080p and a 4K TV, plus a PS2 with component cables. Both TVs work with the PS2 running 50Hz PAL games (directly connected through component). Same was okay for an early Panasonic flatscreen, an early Phillips LCD and a more recent Samsung LCD. And I’ve tried a PS3 with region free PAL DVD concerts through HDMI on the Sony TVs, they also worked without any change in configurations. So, at least in my experience, modern TVs are less fussy about color regions and just accept both inputs. Just to clarify, I’m on an NTSC area, and all of my older systems are NTSC as well.
    – According to the SegaRetro, there has been only one VGA Box model and it was only released in Japan. From the photos on eBay, there’s only composite, S-Video and DB-15 outputs. And the SCART cable was only released in Europe as a simple cable.

    By the way, Christoff uploaded this video on the DCHDMI output last week, if anyone haven’t seen it yet – https://www.youtube.com/watch?v=GXsah8INPi0. Just showing off how clear Crazy Taxi 2 looks, plus the OSD.

    Well, getting a Dreamcast ready for my HDTV sounds a little less of a daunting task.
    I’ll wait for the DCHDMI, if it proves to be impossible to buy like the UltraHDMI, then I’ll resort to Toro. I don’t have enough shelf space to install the Akura without bending the cable.

    Thanks for all the help.

    #23223
    nmalinoski
    Participant

    – Wasn’t the external RF box on the NES just a switch to select either antenna or console?

    Sort of. That particular piece of hardware is known as an RF Switch. It’s designed to fit inline with your cable or antenna input on your TV, and it has a long cable that connects to the NES’s RF output. By default, the switch lets the input from the other cable pass through, but it disconnects that and switches over to the console’s RF signal when it’s detected on that cable.

    For later consoles that use Nintendo’s AV Multi-Out port, or at least the N64 (because I own one of these) Nintendo released a small module that fits into the AV port, has an RF-out jack, and a channel 3/4 selector switch. This module is paired with the exact same RF switch that was released for use with the NES, and it works the same way.

    – According to the SegaRetro, there has been only one VGA Box model and it was only released in Japan. From the photos on eBay, there’s only composite, S-Video and DB-15 outputs. And the SCART cable was only released in Europe as a simple cable.

    Seems legit, though, even in the absence of the official accessory, there was an abundance of VGA boxes available here in North America, and most games still supported it (in contrast to many HDD-capable games for the PS2, where HDD support that was available in Japan was stripped from otherwise identical North American releases, even though North America did end up getting the HDD).

    #23236
    noodohs
    Participant

    – While I’ve read that composite and S-Video can output 240p, I thought that the only way to get a progressive output from the Dreamcast was through a VGA box. When I read about it, people were talking about VGA Boxes so that’s why I assumed it only worked that way. I’m probably wrong, so don’t quote me on that.

    240p is just a “hack” of sorts for 480i. 480i is basically 240 lines at 60 Hz, but every other set of 240 lines alternates its location so that it appears to our eyes like one 480 line image. 240p just uses the same location for every frame instead of alternating, so you get a 60 Hz progressive image but with scanlines.

    In regards to the Dreamcast, what people are talking about is 480p. Composite and s-video are not capable of sending 480p, so you will need a VGA box to do that. SCART can also carry 480p, as previously discussed. All of these connections are capable of carrying 480i and, by extension, 240p (since it’s just a “hack” of 480i). However, as you mentioned, most Dreamcast games don’t support 240p specifically, so you are generally only getting 480i or 480p, the latter of which requires the box.

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