Sega Genesis: S-Videom, RGB, and TMSS questions.

Hey everyone. I wanted to know about S-Video and RGB on a Sega Genesis. I currently have a model 3 genesis, which a friend gave me. It's the most crappy model, so I want to upgrade to a better one. I've heard the ones that have "High-Definition Graphics" printed on them in white letters is the best for sound quality. But, I've heard arguments both ways saying that the TMSS and non-TMSS systems are better than the other. What's the truth on this? Some people say you need a 32X if you get a non-TMSS, as there's supposedly a problem with its video encoder.

Now, on to my next question, I currently play old games on my 32" Sony KV32HS510 TV. It has a great picture, so I'll wait to get an RGB monitor whenever it goes out. I was going to mod my new Genesis to output S-Video, but, since I'm playing on that Sony TV, I thought getting an RGB Scart cable and converting it to Component with a box would look better, and be easier. Would it? I found a couple of converters on eBay, but the prices are very different. Here's a cheap little box for about $5:
http://www.ebay.com/itm/NEW-SCART-T...DM500-DREAMBOX-DM100-DM-100-RGB-/320701438095

and here's a more expensive box for $50:
http://www.ebay.com/itm/NEW-SCART-RGB-to-YUV-Component-Video-Converter-Scaler-/221156873851

The more expensive one says that it's a "scaler", would I need that for my Sony TV? Would either of those boxes look good? I'm new to trying to get the best video and sound from these consoles. Thank you.

EDIT: It should say "S-Video" in the title. Sorry.

 

That cheap SCART to component adapter will not work. It is just allows you to input YPbPr component signals from RCA cables to the RGB pins on the SCART connector. There is no signal conversion. Also, not many devices support YPbPr over SCART.

RGB is always better than S-Video. Avoid SCART to Component as it degrades the quality (YPbPr is just an advanced form of S-Video and uses a different color space). Go the SCART to VGA or SCART to HDMI upscaler route instead. As for the TMSS issue, there's a mod board from borti that disables TMSS so some of those early games will play on a console with TMSS. You can even install a game onto it so you can have a built-in game.

Go with a HD Model 1 that has a VA6 motherboard. These have much better video chips. The fix with the 32X only affects composite video and not RGB. RGB is the same on all consoles but make sure you use a high quality RGB SCART cable with boosted C-Sync (aka pure sync or raw sync) to avoid jailbars.

Ozone is also making a everything to HDMI converter that will accept RGB over SCART and VGA and will be much better than those SCART to HDMI converters and for nearly the same price. His also has a VGA output if you can't use HDMI. It should be out in a couple months.

The on-board S-Video isn't too big of an improvement over Composite video so avoid that as well. If you really want S-Video, Helder is making a box that creates Composite video, S-Video, and YPbPr component video from the RGB signals externally and the S-video part is much better quality than the on-board Luma/Chroma signals. You could also make one yourself if you can gather the parts.

As for sound quality, pre-VA7 model ones both HD and Non-HD have great sound quality. Should you get stuck with a model 2 or VA7 model 1, there is a mod board called the Mega AMP which makes the console sound just as good as early HD model 1s.

 

Hi LGMR.

TMSS/Non TMSS are not related with quality. TMMS is a protection and was introduced at the same time as some hardware modifications that Sega introduced in order to reduce production costs on the Megadrive/Genesis.
So you can have a HD graphic model 1 with or without TMSS.

There's an exellent topic on Sega 16:
http://www.sega-16.com/forum/showth...-good-Genesis-1s-and-Genesis-2s-from-bad-ones

Basically, you have to find a version without jailbars if you want to plug it with S-video/Composite. On my experiment, it also depends of your TV. The reason to that is the signal for encoding the color (color subcarrier) for S-video/Composite is derivated from the main clock of the console. So it's not exact and some TV freaks out. Adding a 32x helps for the only reason it has a real Crystal for the Color subcarrier.

You shouldn't have any problem in RGB though (the megadrive and the 32x are linked by RGB chanels).

Same thing with the sound. Avoid anything pre-VA7.

Now for your links:
The first one is just a plain adapter. It doesn't do anything, just link the RCAs to the Scart pins. No convertion, no upscale

The second one: it converts RGB to YPbPr (YUV), but it doesn't upscale. I have one of those linked to my receiver and it doesn't its job.
2 warnings:
- there's no sound going trought this. I modified mine and add a stereo jack in the back.
- sometimes there's a dominante colors (like too much green) but you can ajust the levels with some pots inside.

The only thing you have to know before everything is "Does your Sony TV support 240p video signal?"
I have a KDL46EX500 which works fine with the Megadrive/Genesis with the Svideo, Composite. With the RGB/YUV converter I have sync issue (similar to the jailbars) which I don't have with my receiver.

Hope that's helping.

 

Thank you. I'm pretty sure, but not positive, that my TV will display 240p. It does not have HDMI. It does go up to 1080i and has a DVI port though, so I hope it still goes down to 240p... Going from RGB Scart to Component seems to be my best option until I get an RGB monitor. For the sound, I'll have to go trough the Genesis' headphones port. As for the model, I'll just try to find a HDG version. Thanks again.

 

As long as the DVI port accepts DVI-D, you can use a HDMI to DVI-D cable. Make sure to set the SCART to HDMI converter to 1280x720p should you go the HDMI route.

The reason why I am saying to avoid SCART to Component is because it causes a loss in quality as it has to convert the color space and downgrade the signal. YPbPr (analog component video) is a further separation of S-Video. It contains Luma (Y), Luma-infused Blue (Pb), and Luma-infused Red (Pr). Green is filled in by the TV and not carried by the cable.

Since the console generates the image in the RGB color space, converting to YPbPr then having the TV convert it back to RGB can cause some colors to be slightly off and a slight dip in sharpness. Messing with your TV settings and the converter's settings can make it look the same though. When possible, ALWAYS do RGB to RGB and never put any conversion in between unless it is Analog RGB to Digital RGB.

If your TV has a VGA port or the DVI port accepts DVI-A signals, use a RGB to VGA converter instead of a SCART to Component converter. VGA uses RGB with the only difference being that the signal is 31KHz (SCART normally uses 15KHz) and the lowest resolution supported is 640x480p.

Also, SCART uses RGBS (RGB with C-Sync) whereas VGA uses RGBHV (RGB with H-Sync and V-Sync). This means that there shouldn't be a loss in quality. Those RGB/CGA/EGA to VGA converters will also upscale it to 480p. Should your display support 240p over VGA, a simple sync splitter would allow you to just plug the console into the TV without a converter.

OzOnE is a user on here and he is making a much better scaler that can take pretty much everything except sync-on-red and sync-on-blue and convert it to HDMI, RGB SCART, and VGA. His board is supposed to be released in a couple months if everything goes according to plan. I recommend it over the other scalers on the market as it has the most input and output options.

Modding the TV to have a 15KHz RGB input is also another option but a dangerous one if your TV happens to be a CRT. Take it to a professional for that mod. It can kill you if done improperly.

 

My TV is a CRT, but I've worked inside it before. I had to replace two IC chips on the mainboard, and I also installed two sockets in case they have to be replaced again. I know the precautions to working on a CRT, and I know how to safely discharge it. I never thought of modding it to accept RGB. How would you go about doing that? How does it look? Thanks.

 

It depends on the TV. If you can, find a schematic for your monitor or see where the RGB signals are sent to the tube and try sending the signals there directly. A schematic will give you the info you need for the mod.

If you have a TV with a really good picture (such as a Trinitron), RGB should look perfect. Of course it always looks the best on a PVM or BVM.

When doing this, use C-Sync instead of composite video as sync. It's pure sync so it should provide a better signal than using composite video as sync. You can get C-Sync on the Genesis Model 1 from pin 1 of the AV port. It needs a 220uf cap and a 75 ohm resistor on the C-Sync line. Should you use a console that doesn't have C-Sync on it, you can add a sync stripper to the composite video line or the Luma line to get C-Sync.

This thread may help or you could ask for help there: http://assemblergames.com/l/threads/i-need-some-help-from-you-guys-adding-rgb-inputs-to-crt.58196/

 

Both RGB and YPbPr Component video use full-bandwidth, unmodulated signals. S-Video uses a bandwidth-limited, quadrature-modulated signal to carry the color information.

Or to put it into perspective:

• Composite video carries bandwith-limited luma and chroma in a single signal, so the resolution of both the Brightness and Color are limited, resulting in the well-known slightly fuzzy picture with occasional artifacts due to interference between the Luma and Chroma information.
• S-Video separates the Luma and Chroma signals, so Luma doesn't need to be bandwidth-limited anymore, giving the maximum resolution. Color information is still bandwidth-limited though, so color transitions with no change in brightness are still fuzzy.
• YPbPr Component video and RGB (which is technically also a "component video signal") transmit all the information from the picture as separate signals, none of which needs to be bandwidth-limited. Both can give the maximum resolution for both Brightness and Color, so even color transitions that were fuzzy with S-Video are now as sharp as the video source can make them.

Conversion from RGB to YPbPr or back can be described as a matrix multiplication, which should already be a clue that there is no filtering involved, so no resolution is lost. Y is a weighted sum of R, G and B with factors chosen to approximate the visual "brightness" of the signal. Pb and Pr are the difference between B and Y and R and Y with scale factors chosen to result in a "reasonable" output signal range. The conversion between RGB and YPbPr is lossless except for non-ideal behaviour of the parts used for the conversion circuit (in the analog domain) or rounding (in the digital domain).

 

Ah I see. Thank you for clearing that up. I guess the difference people seem to claim they notice is caused by the converter itself and not the signal conversion. I wonder what converters can do it properly?