Proper interlaced S-Video output on X1550

[themisfit610]

Hey folks,

So my trusty old P3 1 GHz HTPC died the other day

I had a spare Dell box lying around, a nice quiet Sempron 3000+ system with a gig of ram and XP.

I picked up an X1550 from newegg for $30 (!), and dropped it in. No major issues.

However, on the old HTPC, which had a Radeon 9000 AGP, I could enable "Video mode" in the driver somewhere. I'm not sure what Catalyst revision I was running, but it was probably roughly a year old.

The X1550, with the latest Catalyst drivers as of last week, does not have this mode.

The difference is significant. I'm driving a 37" Toshiba NTSC TV over S-Video, and with "video mode" enabled, the image became significantly sharper, at the expense of a "jittery" look on the desktop, which wasn't visible in movies.

I'm pretty sure "video mode" referred to outputting a true interlaced signal, instead of some silly progressive signal that was then interpreted as interlaced by the TV or something along those lines.

Regardless, the image quality now isn't BAD per se, but I know the 9000 had a MUCH sharper image when I enabled "video mode". It was a seriously night and day difference.

Does anyone know more about the mysterious "video mode"? Is it only supported by a specific family of cards, or was it only in certain driver revisions? I'm willing to downgrade all I need to, as the system in question does not game or do anything more intensive than playing SD resolution H.264, which is not GPU accelerated.

I find it hard to believe that an X1550 can't match a 9000's TV-Out quality.

Thanks!

~MiSfit

 

[Peter]

There is no progressive signalling on SVideo.

The native (and only!) resolution in the SVideo signal is 480i, with barely enough horizontal bandwidth for 360 pixels or so.

Your 1366x768 (?) panel will be MUCH happier connected to VGA, DVI or HDMI - simply because you'll get the native panel resolution then.

 

[themisfit610]

I understand all that.

My TV isn't HD, it's a standard NTSC CRT.

I also understand that S-Video doesn't have enough bandwidth for progressive scanning.

However, I know there is something happening differently in this case. I'm guessing the TV-Out chip on the X1550 is encoding a progressive image, (since the 1550 can do component out with the appropriate cable), and then throwing away half the lines to create a pseudo interlaced image, in order to facilitate delivery over S-Video.

Any other ideas?

~MiSfit