vixtro
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Post by vixtro on Nov 5, 2010 2:18:52 GMT
I recently got a Samsung lE26R41BD S LCD HD TV for my bedroom so I can do some HD gaming with my Xbox 360 away from the frontroom. Initially I was worried about my older consoles (the Sega Saturn especially) looking bad with composite on a 26" HD screen. At first, I was amazed how great the Sega Saturn looked, so crisp and clear! But then I started to notice the screen heavily distorting/glitching whenever the games were loading. At first I couldn't really tell because it seemed random in most games and most of the loading was on a black screen, but when I popped in Sonic 3D, I noticed it distort the screen during the music loading transition whenever hitting a speed shoes or invincibility box. I'm using the official RGB SCART cable I got with the console, when I plug it into the AV SCART slot, I get a crappier composite picture albeit, without any screen distortion at all, just when I use the RGB slot it does this.
So I'm wondering, is this what the Saturn is like on HD TV's? I'm having a hard time thinking it might just be purely the TV's fault because I have (third party) RGB SCART cables for the Dreamcast and original Xbox and they both display fine looking pictures on the TV without any distortion problems.
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Post by Kibbles on Nov 5, 2010 5:33:25 GMT
How bad is this distortion?
I could stand some distortion on Sonic 3D if all my other games looked great ;D
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Post by buckoa51 on Nov 5, 2010 9:12:50 GMT
The problem is that all HDTV's misinterpret the Saturns 240p output resolution as an interlace signal and then apply deinterlacing. This is very bad news because at best the deinterlacing adds input lag and at worst it looks and scales horrible too.
The only way around this is to buy a videoprocessor. The XRGB series is very popular, but keep in mind the XRGB3, lovely though its picture is, is so quirky and incompatible it is next to useless on its own on lots of HDTV's. The DVDO Edge, while it introduces some heavy ringing when scaling 240p signals is a lot more flexible and user friendly. You can find it for around $400 now, or you can go the route of having an XRGB and a DVDO Edge if your as batpoop insane as I am. Using a videoprocessor, you'll need a SCART cable wired EXACTLY to spec, else you'll get nothing but problems believe me.
All depends how fussy you are about picture quality really, if you have the space, go buy a Sony Trinitron CRT from Craigslist for all your retro consoles.
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Post by Kibbles on Nov 5, 2010 15:23:03 GMT
Dealing with the OP's actual issue, I'd reccomend trying a much cheaper RGB to Component converter since he states the issue is not visible with Composite input, it would be reasonable to assume that there is an issue somewhere in the RGB circuitry that is resulting in the effects he is seeing.
I am not 100% sure 'all' HDTVs 'deinterlace' a '240p' signal - although 240p is a misnomer since Saturn's output resolution is all over the place in low res mode.
Even if the 'deinterlace' was set to on...
there is nothing to actually deinterlace so the processor wouldn't be doing anything.
I think a lot of the cheaper HDTVs treat signals in much the same way PC monitors do - the reason they will say '480i' when you check the channel info is just because the manufacturer didn't include a database entry for every possible sub 480i resolution (which is far more numbers than simply 240 with regards to Saturn).
De-interlacing 240p video is physically not something you can do and the processors should detect that from the image alone, never mind the input.
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vixtro
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Post by vixtro on Nov 5, 2010 15:23:53 GMT
I should have done this before but I tested it on the newer TV I have in the frontroom, a Samsung LE32C450 LCD HD TV and on that the picture is fine, no distortion or any vertical lines in the picture (forgot to mention that before).
It simply must be because it's an older HD TV and thus does not fully support older signals, shame, I'll just have to stick to the crappy composite then.
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Post by buckoa51 on Nov 6, 2010 11:09:23 GMT
The 240p/15kHz signal is mistaken for 480i and deinterlacing is applied, when what is really needed is line-doubling (which the XRGB3 does). AFIK there isn't a HDTV on the market that correctly handles 240p/15kHz which is why Saturn, SNES etc look so much nicer on a CRT (well that and the scaling issue of course). The deinterlacer will just deinterlace, it doesn't care if the odd and even fields are actually the same. See retrogaming.hazard-city.de/ 15khz is basically transmitted as an interlace signal where both odd and even are the same, so its interlace progressive, confusing huh! Ok, so if you're not as anal as me about picture quality but you DO want 240p/15khz handled properly, one of these www.hdboxpro.com/eng/public.htm is supposed to do the trick, I've not tried it but I hear good things about them for the money. Picture quality will be 100% better than composite. Also, you might want to open your SCART lead and check that it is properly wired, you can find a diagram here:- members.optusnet.com.au/eviltim/gamescart/gamescart.htm#saturnMany Saturn SCART cables leave off the resistor and the cable works fine with most TV's but not all (plays havoc on my setup). |
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Post by Kibbles on Nov 6, 2010 15:21:12 GMT
15KHz Progressive RGB is 'transmitted' as a progressive RGB signal at '240p' resolution.
The two sets of fields you refer to as progressive only applies when the '480i 30p' standard is used - that is when both fields contain information from the same frame.
240p is... 240p.
It is being line-doubled by your TV, just not as well as it would be by a stand-alone line doubler.
Line doubling is a form of deinterlacing depending on how you cut it, but the word 'deinterlacing' when used in conjunction with a progressive signal really doesn't make any sense - the processor inside your TV line doubles 240p video.
Additionally, deinterlacers *do* care about the fields.
Many modern deinterlacers activley monitor the image for comb toothing and use it to determine whether or not the image should be deinteralced.
You can activley see it happening, if the image stays still for a long time on an interlaced signal and there is a sudden movement, you will see a comb-tooth effect for a split second because the deinterlacing has been tricked by the still image into switching itself off.
The uses of such pratices include:
- 60 and 50 fps signals where you want to retain the fluid motion, actively monitoring the interlacing pattern allows you to deinterlace the edges of objects using a 'bob' and simply leave the rest of the image interlaced to preserve detail.
- TVs that have automatic 30/25/24p modes.
They need to actively search for the comb toothing and intervals of the interlaced frames to determine which 'pull up' method needs to be used.
But the point is that in 240p 15Khz RGB there is only a single set of fields, there is literally nothing to deinterlace, the only thing a processor can do is line-double - and that is the same thing your line doublers are doing.
The reason it looks bad is because the processors inside TVs don't do a great job of it.
Weirdly Evangelion 2.0's UK cinema master had active deinterlacing artefacts present in the video even though it was a 2K digital cinema file.
It looks like it was de-interlaced in real time.
For what it's worth, the upscaler in most crap Hitatchi sets does a better job than VLC's internal deinterlacers. (fancy that huh?)
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vixtro
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Post by vixtro on Nov 6, 2010 15:45:52 GMT
Looking into some third party RGB SCART cables, I noticed they have all their pins on the SCART whereas the official Sega Saturn SCART has quite a few pins missing. I assume the official one only has the minimum pins it actually needs, but would those extra full set of pins on the third party cables make a difference?
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Post by Kibbles on Nov 6, 2010 16:05:18 GMT
They shouldn't make any difference, the pins won't be wired up to anything in the Saturn cable.
Although I should point out they *do* make a difference on scart to scart cables, I think pin 12 has been known to cause 'noise' issues on fully wired cables,
although for the Saturn cable you should be fine!
Does your TV support S-Video on scart?
If your issue is not resolved with another brand of RGB cable you might be able to get a half-way decent picture using an S-Vhs cable (although that is almost entirely dependant on the TV in question)
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Post by buckoa51 on Nov 7, 2010 1:24:42 GMT
"240p is... 240p"
True, but trust me 99% of HDTV's see it as 480i and try to deinterlace it. Fair enough what you said about deinterlacers being smarter than that is actually technically correct, but it's still possible to incorrectly apply deinterlacing techniques to a picture that really only needs line doubling, which is what 99% of HDTV's do. It's all explained on the link I sent you anyway.
Going back to the actual topic, I did some more thinking on this and I would seriously consider cracking open your SCART cable and making sure it's wired up correctly. My Saturn SCART which is missing the resistor gives me a noisy picture, though not when the console is loading, actually all the time.
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vixtro
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Post by vixtro on Nov 7, 2010 18:01:58 GMT
Going back to the actual topic, I did some more thinking on this and I would seriously consider cracking open your SCART cable and making sure it's wired up correctly. My Saturn SCART which is missing the resistor gives me a noisy picture, though not when the console is loading, actually all the time. I could try that, but honestly I wouldn't know what to look for although I could take pictures and post them here? I was thinking about recording the games to show exactly what happens with the distortion, but my capture card will only take composite or s-video. I could use a camera, but it will probably be a bit rubbish. Another thing I noticed is if the cable is a little loose or leaning to one side when plugged in, I sometimes get a complete purple overlay. The best way to describe it is it's like being underwater in the Chemical Plant Zone in Sonic 2, lol. |
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Post by buckoa51 on Nov 8, 2010 9:54:43 GMT
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vixtro
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Post by vixtro on Nov 8, 2010 15:56:25 GMT
That's an awesome page, allot of decent info. I had a look at my Sega Saturn SCART with that and it all seems wired up properly, everything on the diagram connecting to the outside had a pin, but on the inside, the only pin that was shown for the ground was pin 4. I'm assuming that's how it's supposed to be. Going off of my own topic a bit, I couldn't help but notice that the Dreamcast SCART can support composite as well as RGB. I have only have a third party RGB SCART for the Dreamcast that only does RGB, so is it only the official SCART that supports both signals at the same time? |
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Post by buckoa51 on Nov 9, 2010 0:05:53 GMT
Hmm well if your cable is wired up correctly as per that diagram then it's really tricky to know what's going on. If you say it's only getting interference during loading it seems likely its picking up noise from somewhere. Troubleshooting SCART can be a pain at times, it could be something as simple as a missing earth.
As for the Dreamcast it would depend entirely on how the SCART cable was wired as to what it supported. Use VGA on a HDTV with the Dreamcast wherever possible.
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vixtro
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Post by vixtro on Nov 10, 2010 22:09:14 GMT
Hmm well if your cable is wired up correctly as per that diagram then it's really tricky to know what's going on. If you say it's only getting interference during loading it seems likely its picking up noise from somewhere. Troubleshooting SCART can be a pain at times, it could be something as simple as a missing earth. As for the Dreamcast it would depend entirely on how the SCART cable was wired as to what it supported. Use VGA on a HDTV with the Dreamcast wherever possible. I don't think anything is wrong with the cable, like I said, it works fine with my other HD TV (Samsung LE32C450 LCD). I could upload a video on my YouTube if you guys like to show what sort of distortion I'm talking about, it probably won't look great though as my capture card won't take RGB so I'll have to use a camera. |
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