ATI Radeon BIOS modification to get RGB TV-Output

M

Miksu85

Newcomer
Hi.

My problem is that my ATI Radeon 8500 supports only S-video output and my TV doesn't support S-video. I've connected my Radeon to TV using S-video->Composite/Scart adapter and I get only black&white image on TV screen. Is there any way to make my TV show color image? I don't really wanna buy new TV for this. I've heard that by modifying Radeons BIOS it might be possible to make Radeon output RGB signal (which my TV would support).
 
Do not know about the Bios.
The card should be outputting composite as well as S-video.

It sounds like your TV does handle S-Video but does not have an S-Video socket.

In S-video you have a seperate luma signal chroma signal.

In composite your chroma signal is modulated into the luma signal.

If the TV is expecting an S-Video signal, but receives a composite signal you will end up with black and white (as your chroma signal is not on a seperate line).
Likewise, if it is expecting composite but receives S-Video it will look in the wrong place , however the Card is likely outputting both simultaneously (chroma signel modulated onto luma as well as output on seperate line), but your scart connector has not linked up the S-video lines so only composite is getting through.

Mine only handles certain signal types on certain sockets, so try swapping sockets around.


CC
 
Thanks for good answer Captain Chichkenpants! I guess the TV is not getting all the signals properly. The TV is pretty old and I don't think it supports S-video (the manual doesn't say anythign about it), but the TV supports RGB mode. In RGB mode the image is scrolling vertically very fast and I can only see shades of red.
I bought this 10 m S-video cable (40 €) which came with scart adapter which has 3 RCA jacks (red,white and yellow) and S-video jack. When I look at Radeon's S-video output socket, it has total 9 pins, while the S-video cable plug has only 5 pins. The S-video socket in scart adapter also has only 5 pins... So could this be the problem?
 
You should get an s-video to composite adapter (cheap, just make sure it has the correct number of pins) and connect the composite plug (RCA) to the yellow connector on on the scart adapter (the white and red are for audio).

Normally TV sets that support RGB input via scart have two scart connectors, one for composite and s-video and one for RGB.
 
S-video != RGB != composite.

SVideo = colors + luma
RGB = single color per cable
composite = all in one

My RadeOn (ATI) had everything needed sold with :)
my ATI SVideo => composite has a lot of connectors (3-3-2; 8 total) and works.

The scart (peritel in France AFAIK), have sound left, sound right, (red & white don't remember which is which), yellow (composite), and can have a SVideo input too.

Black & White image ... could it be PAL/SECAM/NTSC problem ?


If you find a way to make the RadeOn output RGB channels, I'm interested, however you will need a special cable to get the RGB output from a SVideo connector to 3 R/G/B connectors...
 
Black & White image ... could it be PAL/SECAM/NTSC problem ?
Click to expand...

it may be. I get the same problem when using a PAL version not compatible with TV products tuned to Aus standards. There are about 4-5 PAL standards I can choose and PAL-BDH(?) works for me. maybe you could try switching between alternative standards for your country? Are you NTSC or PAL?
 
Bolloxoid wrote:

You should get an s-video to composite adapter (cheap, just make sure it has the correct number of pins) and connect the composite plug (RCA) to the yellow connector on on the scart adapter (the white and red are for audio).
Click to expand...

Be careful about buying an adapter to extract the composite signal from the extended s-video socket. There is not a standard pinout for the extra pins so an adapter for one system may not work for another.

As an example, the adapter that came with my Radeon 9500 Pro works fine with a Kyro 2 but doesn't work with my laptop which has an ATI Rage Mobility chip.
 
Thanks for your replies!

I don't think this problem is releated to NTSC/PAL because my TV supports both (and SECAM too) and I've tried them all and also tried all PAL sub standards like PAL-B, PAL-M... If I need to buy an adapter which has all pins then I guess I'll have to buy a new S-video cable too.

Because my Radeon has only S-Video socket, it doesn't support RGB at all. But hacking the BIOS it would support, however since it doesn't have RGB connectors I wonder if the RGB will be somehow outputted from S-video and from which pins... And I'm not sure if I should try this anyway cause it breaks the warranty and might make the card completely unusable.
 
Here's a link that describes the pins of a 7-pin Radeon TV-out connector. Perhaps the composite signal is still in the same pin even if you have a 8-pin connector. Mobility connectors a known to differ.

http://www.digit-life.com/articles2/radeon-tv-out/

It is probably easier to just buy an RCA cable and connect the s-video-to-composite connector straight to the Radeon and the RCA cable to the scart adapter.

It seems that there are also adapters that create composite signal from a regular 4-pin s-video adapter (mixing chrominance and luminance) instead of just taking the ready composite signal from an extended s-video connector that is usually found in graphics cards.
 
Thanks Bolloxoid!
I've been able to find only adapters which have 4-pin s-video connector. Should this kind of adapter work with my radeon too? or would it be better to use adapter with extended 7-pin s-video connector?
 
I guess a 4-pin connector would work too. I don't know whether it could cause problems with the graphics card detecting the TV though.

If you want to find an extended connector, you should look for them in computer stores. Almost all retail graphics card packages contain one, I would imagine computer stores sell them separately too.
 
I visited all local computer and electronics stores, without no luck. In one electronics store they said that this kind of hardware is not sold separately because it's non-standard and hardware depend. In computer store where I bought my PC (and radeon) they said I should try to find adapter from electronics store, but from electronics store they said I should look from computer stores... anyway, I looked my radeon's manual and I found out that required adapter should be supplied with card. But I didn't get one, probably because radeon was bulked into PC and wasn't retail packaged :(
 
This might sound like a silly question, but did you contact ATI to see if they'll give or sell you an adapter?

(Edit....)

In fact, I just went to ATI's web site, clicked on "Buy...Accessories", selected my country, and "Software / Accessories", selected Radeon 8500, and bingo, on the list is a a Radeon S-Video to Composite Output Adapter, for $5.00 U.S.

Good luck! ;)

(Edit #2...)

If you are not in North America, ATI's site will take you here:

http://www.videocapturecard.com/ati.html

where they have a special page for these adapters:

http://www.s-video.com/svideorca.html
 
I went to computer store where I bought my PC and told them that in radeon's handbook was said that this adapter should be included, as my suprise they game me one for free.

Now that I got color ouput working, the colors are very bad though. All colors are "cycling" strangely and especially red areas are "bleeding" which looks very annoying. Setting "Composite Sharpness" in display settings to "Less" helps a bit, but quality is still bad and colors are flickering :(
 
Magnum PI said:
i owned several TV sets that had only one SCART input, and supported RGB and composite. but they didn't support svideo.

i seems that a SCART input can be composite/RGB or composite/Svideo but can't support both RGB and Svideo.
Click to expand...

You are right, I didn't remember it quite correctly when I posted that. S-video is a later addition to the list of supported formats for scart and the pinout had to be changed so that simultaneous use of RGB was no longer possible. That was solved by adding another scart connector to TV sets supporting S-video.
 
We had a Schneider TV, which started smoking and almost exploded some time ago. It had only one scart socket, but it supported all composite, RGB and S-video... or actually it supported SVHS, but I guess that means same as S-video?
 
Miksu85 said:
or actually it supported SVHS, but I guess that means same as S-video?
Click to expand...


AFAIK S-VHS is a cassette format, while SVideo is an adapter and signal format.
S-Video is sometimes incorrectly reported as S-VHS.
The correct name is S-Video when talking about adapter/signal.
 
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