"True" Genesis S-video?!?

[milky]

"The [Genesis 3] Sony CXA1645 chip is a much better part than the CXA1135 found in the other Genesis units (as well as the Master System + NeoGeo). It has real S-video output, which the 1135 does not have."---So says the Genesis 3 S-video+RGB mod page...

So, uh... what does he mean, "real" s-video output?  And what about the JVC X'eye?  Doesn't THAT have "true" s-video, or must I buy/modify a Genesis 3 to obtain the best possilbe s-video picture available from a Genesis cart??

Please, help me!!!

Steve

[NFG]

The X'eye, if it's the same as the Japanese Wondermega, uses a JVC encoder chip, not the Sony found in the other Genesis units.

The CXA1145 was not built to output Svideo without a lot of external components, where the 1645 was.  It's much easier to get excellent Svideo from the 1645.  You can get svideo from the 1145 but it's a lot of extra work and the results aren't always very good.

[milky]

So, uh, looks like i'm gettin' a Genesis 3 :-P  Unless... how's the S-video on WonderMega/X'eye?  Is it as good as a modified Sony 1645?

[NFG]

Honestly I dunno, I hardly ever use my WonderMega, but it'll be WAY cheaper to use the Gen3.  

[matt]

The X'Eye doesn't have S-Video; it was left out of the US model.  Presumably, modifying it would be possible, but since it's been ages since I owned an X'Eye and I had zero interest in S-Video at that point, I have no idea whether or not it'd work.

[Jason One]

I have one of the later versions of the Genesis 2 which has the CXA1645 chip. I'd like to do the s-video mod on it, but I'm not sure how to do the output, as I've never done a mod like this before.

I'm thinking there are basically two options: use the Genesis's A/V output port on the back, or add a standard s-video output port.

If I sent the Y/C signals to the Genesis's A/V output port, would it be possible to preserve the ability to hook the Genesis up to a 32X? What are the essential signals that must travel from the Genesis to the 32X? I assume:

1. Blue
2. 5 VDC (Is this needed?)
3. Green
5. Sync (Needed?)
7. Red
8. Stereo L
9. Stereo R

This would leave two pins free for Y and C -- #4 (composite video) and #6 (audio mono). Those shouldn't be necessary for the Genesis-to-32X connection, right? Then I would need to make a custom cable to go from the Genesis to a standard s-video plug.

Alternately, if I add a standard s-video output port (4-pin mini-DIN), that would mean cutting into the plastic to make a hole for it in the back, and finding a space for it on the board. I haven't opened up my Genesis 2 yet to investigate, so I don't know whether this is feasible. The advantage to this way is that I could use a standard s-video cable and wouldn't affect the 32X connection at all.

So, what do you guys think would be the best way to do it? This will be my first mod, and I really want to do it right. I'm also a little nervous because this type of Genesis 2 (with the CXA1645) is hard to find, and I'd hate to screw it up; but having a Genesis with s-video output would kick the ultimate ass, so I have to try.

[dumdum]

remember that the 32x mixes its own video signals to the megadrive/genesis, i do not think tapping the genesis chips for svideo will work if you want to use the 32x

[Vertigo]

AFAIK getting RGB out of your MegaDrive is a lot easier than getting SVideo, but I guess SVideo is more accessible to Americans than RGB inputs.

[matt]

I'm thinking there are basically two options: use the Genesis's A/V output port on the back, or add a standard s-video output port.

If I sent the Y/C signals to the Genesis's A/V output port, would it be possible to preserve the ability to hook the Genesis up to a 32X? What are the essential signals that must travel from the Genesis to the 32X? I assume:

The 32x's video input uses all pins except for +5v.  So, there wouldn't be any extra space for an S-Video signal.  You'd be better off just installing an S-Video jack.

As has been mentioned, though, you won't be able to play 32X games in S-Vid properly.  They'll run, but you wouldn't be able to see all the graphics.

[Jason One]

The 32x's video input uses all pins except for +5v.  So, there wouldn't be any extra space for an S-Video signal.  You'd be better off just installing an S-Video jack.

As has been mentioned, though, you won't be able to play 32X games in S-Vid properly.  They'll run, but you wouldn't be able to see all the graphics.

Thanks a lot, matt, that was exactly the info I was looking for about the 32X connection.

I realize that the Genesis's s-video output would not be useful for playing 32X games. (However, the s-video output should work fine for Sega CD, since the Genesis itself outputs the Sega CD video signal -- right?)

[matt]

Yes, it works fine with the Sega CD

It may be possible to work something out with the 32X, but I've never had the inclination to look into it myself.

[milky]

Matt, I urge, even inlcine you to look into 32X svideo ;-)

[Talasonic]

Does any CDX have chips that have s-video capability?

[Talasonic]

What about a pure RGB->s-video converter box?  Does anybody make these?  

Also, does s-video make a HUGE difference?  Because I hooked my gen up to an RGB video data monitor and it was simply insane.  May as well have been a computer monitor.  Is it almost like that with s-video?  Thanks!

[NFG]

Svideo is almost as good as RGB for most applications.  What makes a bigger difference is the quality of your TV.  My old JVC was a beautiful TV and the 25" WG Arcade monitor I had was crap compared to it.  After months of work getting things to play on the RGB monitor I ended up using the Svideo TV instead.  =/

[Splynncryth]

you can poke aroung and find converters for RGB to s-vid, but I can't think of any chips off the top of my head.

[ely]

After months of work getting things to play on the RGB monitor I ended up using the Svideo TV instead.  =/

I'm new here, still not sure about all this RGB gaming stuff.  In the world of regular TV, things like cable and satellite tuners still have S-video as the best available connection, for the most part.  But the general rule, however, is to try both composite and S-video, since the scaler/line doubler/comb filter in your TV may be superior to the one in your tuner box.  Taking the above statement into consideration, can this ever be true with consoles as well?

[Talasonic]

ely--
No, in video game systems, if there is any S-Video, it's generated seperately.  So there is no comb filter anywhere.  It is generated separately, and stays separate, if you use S-Video.  This is obviously much better than composite.  

Analog cable is broadcast in composite, as is analog satellite, probably.  Digital cable, or digital satellite like DirecTV, though, is broadcast in at least S-Video.  So you would definately want to use the S-Video cord on a digital system, because the more conversions, the more messed up the picture will be.  

Laserdisc is the only media format I can think of that is recorded in composite (VHS is recorded in S-Video, even though they almost never have that output unless you have SVHS), so if you have a good comb filter in your TV, using the composite cord might be better for laserdisc (if you have a player with S-Video).  But DVD, other digital sources, video games, (S)VHS VCRs, etc will all look better with S-Video.  

SVHS VCRs can generally be counted on for having the best comb filters, though.  So, if you have an NES, or are forced to use composite on a Genesis or whatever, use an SVHS VCR's comb filter if possible.  Of course, see what looks best.  There are very few TVs that have as good comb filters as the average SVHS VCR, though.

[ely]

Thanks for the reply, I must still be missing something though: if the signal is digital, how is it "broadcast in S-Video"?  Most people now, and certainly almost all people with a HT, do have digital cable/sat rather than analog, and yet the common advice is still to compare Svid to composite, even if using something like an iScan.  And I guess the usual complaint is that using Svid from a source with a less than stellar filter, often e.g. the tuner boxes provided by your local company, is that colors look washed out.  I never did get an SVHS VCR.  Good ol' JVC.  Now they have a DVHS VCR that also supports SVHS, about 600 bucks though.

[Talasonic]

Digital signals are not typically broadcast in S-Video, you're right.  They're actually broadcast in something more like component video.  The decoder chip then outputs S-Video, among other things.  It is exactly the same as how DVD works.  Would you prefer composite over S-Video for a DVD?  DirecTV, for example uses the exact same compression format, MPEG-2.  I'd imagine cable systems also use MPEG-2.  

Of course, if your decoder chip is junk, or if the original signal is poor quality somehow, then it might look better in composite.  But most decoder chips aren't like that.  There are probably cases where a bad source might make composite look better, but that would be a fluke.  

So generally, use the best output available from a digital source.  Even though you might think you slightly prefer the composite output, ask yourself, do I prefer it for the majority of the television programs I watch?  Is it that the picture is actually better, or is it just more blurry, making it more appealing to you?  If it's blurriness you want, just use the sharpness control.  If you really prefer composite, then by all means use it, but I think that would be unusual.  

[NFG]

It should be noted that the digital signals received by these devices can vary significantly in quality.  In order to pack more signals into the available bandwidth space each channel's quality is reduced to squeeze in another.  Some special events like sports or premium movies might be allotted more bandwidth, reducing the space available to the rest on a temporary basis.

This means that S-video is often as good as you need because the signals received by the box suck to start with, and you can't magically recreate quality where there is none.

[ely]

Well I didn't mean to imply that I personally use composite over S-video for my tuner box, or for any consoles for that matter.  For one thing, my HDTV is older and lacking any of the fancy Faroudja magic most new ones have, so the box is probably superior anyway.  But still, the advice is there in places like hometheaterspot and avsforum: try composite and Svid and compare, so I asked here whether that advice was ever given for consoles too.

If you look at the newest HDTVs, you'll often find 4+ composite inputs, only one of which is Svid also, or sometimes the Svid is only on the side or front.  But of course this could be because the manufacturers know most people will use component/VGA/DVI and don't care to waste money on extra Svids, rather than promoting their internal scaler.

Has anyone here ever used one of those iScans?  Although I suppose even the cheapest one is more than double an XRGB2+.

[Talasonic]

Manufacturers only put one s-video input on many TVs because they want to save 3 measly bucks per TV and know that composite is a more common connection, especially on cheaper equipment.  

For an ANALOG cable box, the composite output would probably be the one to pick. Since the source is analog, you are choosing which comb filter to use, the one in the TV or the one in the cable box.  Since boxes are often junk, the one in the TV is probably better.  And the one in any SVHS VCR will amost certainly be better.  

This means that S-video is often as good as you need because the signals received by the box suck to start with, and you can't magically recreate quality where there is none.

-Lawrence

I'm not sure what he is comparing S-Video to.  It's generally going to better than composite UNLESS the signal is composite, like I've said all along.  His point about not being able to create quality when none existed is a good one, though.  That is certainly something to keep in mind.  They do change the bandwidth they give each channel.  DirecTV in particular, though, has been launching a lot of spot-beam satellites so that they don't have to send the locals for San Franscisco to people in New York City.  That has been making a HUGE difference.  Also, they keep improving their real-time compressors.  The other thing is that when they can get a higher quality source, that helps a lot.  Compressing noise, or COMPRESSION ARTIFACTS FROM AN ALREADY COMPRESSED CHANNEL is very nasty.  Spike TV for example is WAY better than TNN used to be.  They are getting a much higher quality feed, and so are able to compress it better.