Composite Output Problem with Nvidia Geforce 4 Ti

[Computer Nerd Kev]

Hello,
I know I'm a few years too late to attract any Nvidia Geforce 4 fans, however I'll try anyway.

I am trying to use the composite output of my Nvidia Geforce 4 Ti 4200 graphics card to recode onto VHS. This seemed a fairly simple task at the beginning, however I quickly ran into problems when I attempted my first test.

I found that no matter the settings I tried, I was unable to get a distinguishable picture. Amongst the static, I was able to produce some B/W solid, bending lines across the screen which were clearly only produced when the composite cable was plugged in.

I have tried using a CRT TV and got identical results to that shown on the VHS recording despite trying every PAL type available with no change to the picture. I also tried NTSC output (which thinking back was probably stupid as I know little of the effects which could be caused by doing this), this gave me a black screen with some white flecks while there should have been an image.

My setup is simply a cheap adapter which I got of Ebay for the 7 pin mini DIN plug on my graphics card and a cable taking the composite signal to my VCR (plus a RF modulator when testing with the TV).

[Bjs]

If you have not had a proper picture on the tv (bypass vcr hook up) then "ebay" and "cable" is where the problem is ... mini din to composite ... cheap cables generally mean a waste of money ... so many complaints through forums on the subject.

There's also a few reported posts regarding vcr's with this issue ... first bet is to do a direct to tv connection ... if ok move on and solve possible vcr issue.

[jagabo]

If you have not had a proper picture on the tv (bypass vcr hook up) then "ebay" and "cable" is where the problem is

I agree. It may not be the right cable for your card. There is no standard for such cables. Every card has different pinouts.

[Munster1]

Pins 5 to 7 on a Nvidia card s-video socket are non-standard, but pins 1 to 4 should be standard. You might be better off with a 4 pin mini-DIN plug s-video connector.

http://en.wikipedia.org/wiki/S-Video

[Computer Nerd Kev]

Well I did some more searching on the internet and finally found out some more information about my video card. I found some manuals at this FTP site which indicate that my card can output composite signal, however they are for later versions of the Ti 4200 (can't be easy can it) and after looking into a few of the details such as the TV out chip on my card, I think that my version of the Ti 4200 outputs only S-Video signal through the 7 pin Mini DIN plug and the rest of the pins are unused.

I attacked the cable I got off Ebay with a multimeter and the composite plug turned out to be hooked up to pin 3 which is the S-Video Luma signal. One questions which video card that cable was designed for, as the whole idea of the 7 pin plug is that you can connect a normal S-Video cable to it without an adapter.

I guess I will have to use a S-Video convertor for the composite output. In fact I think I'll have to make one myself because the good quality devices cost quite a lot.

Yet another reason to dream of a S-VHS recorder.

[Joe The Dude]

There should be a setting in the nVidia Control Panel that will let you select between S-Video and Composite Video.

[Computer Nerd Kev]

There should be a setting in the nVidia Control Panel that will let you select between S-Video and Composite Video.

There is, problem is that when at that menu on my system, there is nothing in the box named "video output format" and the only settings you can change in the window are PAL/NTSC formats.

At first I ignored this empty box and didn't have a good look at it until I came to the point in one of the manuals which told me of the option.

I found that the only manuals available on the internet for my card, were for later models which could indeed output composite. However reading the 4400 & 4600 manual, I came across this line:

Click Video output format bar to select S-Video or RCA (optional) output, default is auto select.

This indicated that composite output was an optional extra, and if this applies to the 4200 as well, then I'm fairly sure that the bloke who originally put my PC together (it's 2nd hand) rudely denied his PC's future owner of the opportunity to output composite signal from his video card.

Finally, I found from looking at screenshots in the manual that the TV output chips on those video cards in the manual were different from that in mine. Indicating that I have a lesser model.

As for those unused pins, it could be that those extra pins carry CVBS signal, as that chip is apparently capable of that as well.

[jagabo]

I attacked the cable I got off Ebay with a multimeter and the composite plug turned out to be hooked up to pin 3 which is the S-Video Luma signal.

The luma pin of the s-video port includes the grayscale image information and sync pulses. If the graphics card was putting out an s-video signal and only the luma pin was hooked up to the composite input of a TV or capture card you should have gotten a clear grayscale picture.

To get color you can use a simple s-video to composite adapter like this:

http://www.amazon.com/StarTech-com-SVID2COMP-S-Video-Composite-Adapter/dp/tags-on-product/B0000BZ2WC
http://www.amazon.com/StarTech-com-SVID2COMPFM-S-Video-Composite-Adapter/dp/B0009EXWQQ/
http://pinouts.ru/VideoCables/svideo2RCA_pinout.shtml

[Joe The Dude]

You can get the latest driver for your video card here:
[For Windows 2000, or XP 32, or XP MCE]
http://www.nvidia.com/object/winxp_2k_93.71_2.html

Installing that driver should re-enable video output format.

Also, if you don't already have anything like what jagaoo linked to in the post above this one, you should buy one.
I'd recommend the first link he gave:
http://www.amazon.com/StarTech-com-SVID2COMP-S-Video-Composite-Adapter/dp/tags-on-product/B0000BZ2WC

Also, being that you are in Australia, the format of your VCR is most likely PAL Composite/RCA.

[Computer Nerd Kev]

Those simple adapters apparently produce some undesirable picture artifacts from high frequency Luma signals which are displayed as chroma signals.

The ones sold at Jaycar Electronics (an Australian electronics store franchise) cost $150, so I thought it would be a good idea to build one myself based on plans from the (also Australian) Silicon Chip magazine. The first few paragraphs are readable here, at their website and describe the problem with those more basic convertors, of course I have the original magazine. By the way, if you click on one of the pictures at that page, you can then view the rest of the images from the original article by pressing the "Next Image" button.

Mind you, if I should have got B/W picture in my previous tests, perhaps I'd better try one of those cheap adapters first, rather than risk thinking I've built the adapter wrongly. I thought that it must not have had a sync signal, would it be likely that the grounding pins would have to be connected?

Installing that driver should re-enable video output format.

Do you know this, or is it just a guess, because to be honest I'm a bit sheepish about upgrading drivers for things as critical as a video card, especially considering how integrated the Nvidia driver is. I know safe mode is always there, however I feel it quite likely that composite output was an unchosen optional extra in the case of my card.

In Australia we use both PAL B and G, I've tried both as well as every other PAL/NTSC format my card gave me the option of (quite a few).

[jagabo]

Those simple adapters apparently produce some undesirable picture artifacts from high frequency Luma signals which are displayed as chroma signals.

Yes.

The ones sold at Jaycar Electronics (an Australian electronics store franchise) cost $150,

That would be much better. But you're still going to have a crappy low resolution display. It's better to spend the money on a new HDTV. See the sample images in this post:
https://forum.videohelp.com/threads/283861-VGA-to-S-video?p=1756748&viewfull=1#post1756748

Mind you, if I should have got B/W picture in my previous tests, perhaps I'd better try one of those cheap adapters first, rather than risk thinking I've built the adapter wrongly.

Which is one reason I suggested it. Most people don't want to spend a few hundred bucks on a good s-video to composite adapter anyway.

I thought that it must not have had a sync signal, would it be likely that the grounding pins would have to be connected?

Of course the ground pin has to be connected!

[Computer Nerd Kev]

Just to finnish this off, I bought a cheap adapter locally and have been able to get a VHS recording from the signal. Next step, get a PCB for that S-Video to Composite DIY project.

Thanks for the help.

[jagabo]

How did that recording turn out? How bad was the chroma/luma crosstalk? Could you post a short sample of some colorful material?

[Computer Nerd Kev]

Hopefully I've finally got the upload function to work.

The interference isn't actually too bad, in fact I'm glad you encouraged me to do this test because I may not really need that more advanced adapter.

I used a test image from this website which tests high frequency luma signal handling. If I understand the interference problem correctly, this should be the ultimate test.

Here is the original image:



And here is the image sent to the VCR using the S-Video to Composite adapter and captured from the VHS using my video capture card:



Some of the noise appears best (or worst) when shown in video, so here is the video. Mind you some of that interference may be unrelated.
Forum Convert.avi

[jagabo]

Chroma/luma crosstalk doesn't show up much in perfectly vertical bars. Try this image:



If you can find it, there's a video with a similar test pattern but the concentric circles in the middle move around. That's even more difficult for comb filters to handle.

But the chroma/luma crosstalk problem is more a matter of the TV separating the chroma an luma. If the TV (or capture card) has a good 3d comb filter (few do) the false colors will be reduced.

[Computer Nerd Kev]

Wish I could handle image uploads as well as you.

Well I tested with that image you provided and to my eye the patterns where one might expect interference have simply disappeared. This could be the poor quality tape I'm using but all my others have things on them right now.

Normal Video tends to look all right so I'll likely use this adapter unless someone jumps in front of me with a PCB for the other design.

[jagabo]

VHS has very low horizontal resolution -- about 360 lines across the entire frame. And the graphics card is probably using a deflicker filter which blurs the output vertically. So you have a resolution something like 360x300 on tape.

What exactly are the sample image and video? The test pattern enlarged to full screen on the computer, output as s-video by the graphics card, converted to composite by the adapter, recorded onto VHS tape, then played back by the VHS deck, and captured by the computer? What do you see if you connect the composite signal directly to a TV? How does that compare to s-video connected to the TV (if you have a TV with s-video inputs).

[Computer Nerd Kev]

Here is the process I am using:

- Test pattern shown at original 720x480 resolution with a monitor resolution of 800x600 (graphics card driver says this resolution is the same for the S-Video output, what this means I don't know)
- S-Video output from video card
- Cheap S-Video to composite converter
- 2m AV cable to VCR (decent quality)
- Recorded to VHS tape in SP mode, no sound
- Sent through cheap 3m RF cable to video capture card (cringe all you want, but my eyes can't notice quality loss in TV from my Set Top Box)
- Recorded in VirtualDub with YUY2 as input and then compressed with HuffYUV
- Image taken from suitable part of HuffYUV recording using VirtualDub "copy source frame to clipboard"
- Image compressed losslessly in PNG format
- Video converted to MPEG4 at 500Kb/s bitrate using VirtualDub
- Image and video uploaded to this website

I tried viewing the video on a TV and it looked distinctly similar. The final viewable outer ring at the centre was slightly more visable and a trace of the bending lines to the right went down as far as the midle of the"3" next to them, but otherwise I would say it was the same. Colour bleeding was no longer a problem and there was none of that noise, both of which were most likely due to the VHS recording but are unnoticable on normal video footage.

Resolution was chosen for 1:1 aspect ratio without a reduction in resolution forgetting that the video card/VCR were sending video at 4:3. Anyhow, the image provided is almost identical in relevant aspects, to viewing of the tape on my TV.

I don't have a TV with S-Video input for display of the pre-converted video, nor does my video capture card allow it.

Edit:
Here is an image taken the same way as before from a video file recorded to VHS from my PC for a more real-life example.

[jagabo]

- Test pattern shown at original 720x480 resolution with a monitor resolution of 800x600 (graphics card driver says this resolution is the same for the S-Video output, what this means I don't know)

Anything that comes out the s-video port is going to be 480 lines, about ~640x480. So displaying an 800x600 screen means the graphics card is downscaling. You are losing about 20 percent (600 scan lines down to 480 scan lines) of the resolution even before the video comes out the s-video port.

If possible, try setting the resolution to 640x480 (and view the test image cropped down to 640x480). That should give you a better picture.

Also, I believe that graphics card has "theater mode" support -- anything that plays in a media player comes out the s-video port full screen, even if the player is windowed on the Desktop. I don't remember if Nvidia calls it "theater mode" but see if you can enable something similar in the graphics card setup applet or the Nvidia control panel. That allows you to run the Desktop at whatever resolution you want and still get optimal output at the s-video port. I used to use that all the time on my HTPC (now it's dual HDMI at 1080p!).

I tried viewing the video on a TV and it looked distinctly similar. The final viewable outer ring at the centre was slightly more visable and a trace of the bending lines to the right went down as far as the midle of the"3" next to them, but otherwise I would say it was the same. Colour bleeding was no longer a problem and there was none of that noise, both of which were most likely due to the VHS recording but are unnoticable on normal video footage.

The resolution directly at the s-video/composite port should have been much better than the VHS recording. When a similar test pattern is burned to a DVD it will look about like the images in this post (it depends on the TV too, eg, a typical 13" TV won't show as much detail as a good 32"):

https://forum.videohelp.com/threads/313735-Capture-card-for-Laserdisc-and-VHS-Good-card...=1#post1940519

That was done on a PAL system (720x576) but the issues are the same. The SAA7131 image shows the rainbows expected from chroma/luma crosstalk. Only high end TVs have the 3d comb filter needed to eliminate those.

[Computer Nerd Kev]

OK, the driver has a setting for the "full screen device" which works as "theatre mode", however even with this is set and working, there is no way to change the S-Video resolution differently to the monitor resolution.

By setting the monitor resolution to 640x480, I generated the attached images through VHS recording and they are certainly the best yet. First one is 352x288 (my usual VHS capture resolution), second is 640x480.

When a similar test pattern is burned to a DVD it will look about like the images in this post (it depends on the TV too, eg, a typical 13" TV won't show as much detail as a good 32"):

The TV I used before was a 13" CRT and I'm not all that motivated to move a larger one over to my PC.

That image there was what I was expecting when I tried this, not that I'm going to complain.

That was done on a PAL system

Just to clarify, over here in Aus I'm using PAL as well.

[jagabo]

When you use theater mode the resolution you set the second device too doesn't matter. It will be adjusted to standard video resolutions.

Ah, I didn't notice you were using PAL. In that case 640x480 wouldn't be correct. You'd want to set it to 768x576 and use a 576 line test pattern. But you may not be able to specify that resolution. And it's possible that the drivers actually give 1:1 pixel mapping using 800x600 (by cropping) since that's pretty close. You can use the ATI 650 sample image in the post I linked to earlier.

[Computer Nerd Kev]

The graphics card only inicates that it outputs 800x600 or 640x480 video, if I set the monitor to anything in between, it uses 640x480 and the screen pans to where your mouse pointer moves.

Because of this I doubt that it would change this setting for the "theatre mode".

I've included a couple of images taken of that test pattern at the two avalible resolutions, this time using VirtualDub recording video sent from the VCR live without first recording to tape. There is still an absence of any major interferrence.

[jagabo]

The 800x600 shot looks the best so far. The black borders look a little bigger than I would have expected. Do you have overscan compensation enabled in the graphics card's setup?

[Computer Nerd Kev]

The 800x600 shot looks the best so far.

Are you sure you don't mean the 640x480 image above the 800x600 image, or is this conclusion given with consideration of other factors?

The black borders look a little bigger than I would have expected. Do you have overscan compensation enabled in the graphics card's setup?

Overscan or any other screen sizing adjustments are not available for the S-Video output from my graphics card. Playing a VHS tape recorded from TV, the image fills the screen so this can't be my capture card or VCR causing the borders.

[jagabo]

The resolution in the last 640x480 shot looks good -- but a lot of the right and bottom edges of the source image are cropped away. That's why I said the 800x600 shot looks better.