S-video display quality - WAF problem!

[Steerpike]

Finally, after applying BIOS 0903 to my A8N-VM CSM, the S-Video output quality is what I would call 'Very Good', and I'm proud of my new setup...

However ... the quality is 'Very Good', but it is not as good as the image I get on the same TV straight from my Cable Box, even on the coax (modulated) line. (I have a Motorolla Cable Box feeding into the Coax input on my 32" Sony 'tube' TV; I have my Sage TV Client system feeding into the S-Video input on the same TV. Viewing the same show, I can switch between the two sources and compare.)

The image from the S-Video input of the TV (the Sage source) is somehow 'flat' compared to the signal coming in on the coax. It seems to have the correct whitepoint and blackpoint (thanks to the latest BIOS), and even contrast seems OK, but there is just something indescribable about the image - lacks 'punch' or something.

So after all this effort, I'm still not getting the 'WAF' seal of approval! Of course, the Sage source is going through a capture, encode, playback, decode cycle which the original source is not going through ... and technically perhaps I should be amazed that it is as good as it is ... but my partner is obsessing on the 'flat' nature of the image compared to live TV, and I can't argue technically with her on that - I can see the difference.

Is this something anyone else has noticed, and is there any adjustment that can be suggested? My tuner is a Hauppauge 250, and my sage client is using the NVidia 6150 embedded video display, with PureVideo installed.

[gplasky]

This is inherent in the nature of s-video. Your s-video picture will always be of a lesser quality than your cable picture. Your limitation is the input of your TV. If your TV had a VGA, DVI or HDMI input your picture would be much better. As good as the cable or some people feel it's a little better. You'll never get past this problem using a s-video input. That's limited to a 720 x 560 res on the TV. Some people can use 800 x 600 or 640 x 480. That's going to be the best you can do. If you insist on going with s-video you may get a better picture going with the VGA connection and getting a VGA to s-video transcoder. But there's money involved.

Gerry

[Wheemer]

Svideo is not the limitation... I get better quality from my stb to TV using svideo than I do with coaxial...

The problem is the Capture card reduces the quality a little bit and then the decoder and renderer choice has the biggest impact. Most poeple say that using overlay has the same "punch" that it normally would have.

However I use vmr9 with the nvidia decoder and I'm very impressed. I did have to increase the digital vibrance in the display control panel a little.

[gplasky]

s-video is the limitation when compared to a TV that also has a VGA or DVI or HDMI input. Or component. And it doesn't have to be a HDTV to have these inputs available. But you're right about the capture card. But if your video card can upscale it to a higher resolution and input THAT to the TV, the picture will look better than s-video. And it should also take advantage of higher capture rates.

Gerry

[mlbdude]

Ignoring the compression loss, SVideo from a PC is worse than from a STB since the PC has all the deinterlaicng and scaling to do. If you use something like a hauppauge 350, Hauppauge MVP, or XCard you can get equal quality to a STB DVR.

[Steerpike]

I'm comparing S-Video input to 'antenna' (coax) input on the same TV - an old, classic (but very good) sony tube tv - invented before HD, before VGA inputs, etc. Of course, I would expect the S-Video to be worse than any of the 'newer' input types. But to be worse than the modulated output of the cable box over coax, that's the disappointment. Note, however - it is 'very good' - and if it were not for the fact that I have the ability to do a direct 'a/b comparison', I guarantee it would not be an issue! Maybe there is a way to degrade the coax so I can win WAF ... )

I currently have the 'capture' quality (for the Hauppauge 250) set to something like 'DVD quality'; I think I saw an even higher setting; is it worth trying that?

Digital Vibrance ... I saw that on a configuration screen; let me go find it again and play with it. 'Vibrance' sounds like my problem ...

[amac]

I haven't seen any mention of how you get video into the 250. What is feeding the 250? An svideo or coax line?

[stevech]

I believe that the Svideo out from a graphics card lacks "punch", i.e., lacks high frequencies, as does mine, because the video is sampled several times...
- Sampled going from analog to digital, then to MPEG blocks
- Sampled in going from MPEG to a graphics card's raster buffer
- Sampled again going from the graphic card buffer to NTSC/PAL to S-Video

The last step, I assert, is the worst.
If you have a hardware MPEG to NTSC/PAL decoder, this step would, I'd think, be eliminated.

Some of these sampling steps don't meet the Nyquist rate nor avoid artifacts and aliasing. Such is our lot in life with inexpensive encoders and PC graphics card frame buffers.

Someone will disagree, I suppose.

I don't have serious WAF issues - the time-shifting of shows plus lack of monthly fees overcome the noticeable loss in fidelity. And I have not ventured into HD yet and have no short term plans to do so.

[Steerpike]

Originally Posted by amac

I haven't seen any mention of how you get video into the 250. What is feeding the 250? An svideo or coax line?

Good question; I have an identical Motorola cable box in 'the other room', and am using the composite output from the box to feed the 250 (cable box does not have an s-video output).

[amac]

Originally Posted by Steerpike

Good question; I have an identical Motorola cable box in 'the other room', and am using the composite output from the box to feed the 250 (cable box does not have an s-video output).

Well that could be another source of your problem. These cards work best with a clean signal and I wouldn't describe composite as clean. I use svideo-in with a simiilar older Sony TV and don't notice an appreciable loss. I know for a fact that the composite out on my satellite box is absolutely horrible (so components external to your video encoder can make a real difference).

[Steerpike]

My cable box only has composite and coax out; no s-video. I figured composite would be better than coax, but that's probably like a rock and a hard place! Maybe I should re-visit my cable supplier and get an updated box.

On my Hauppauge 250, they use one input for both composite and S-Video, and a software setting tells the card how to interpret the input. I kinda assumed this would mean that both S-Video and composite were not likely to be that much different on this card anyway, but I could be very wrong!

[Wheemer]

svideo input would be better for sure... what decoder are you using, have you tried the nvidia purevideo one?

[Steerpike]

I'm using the Nvidia Purevideo decoder - I think. How do I know for sure?

I downloaded the trial and installed it, and am still within the trial period.

Thanks!

[Wheemer]

There should be a system tray icon that appears if it's being used.

But I think you will probably never get it to an acceptable WAF until your recording from an svideo source and outputting using svideo or better.