Overscan is usually a function of the TV encoder and not the
display hardware of the graphics chip. At least with the hardware
I have worked on, CRTC timings (what xvidtune sets) are ignored for
both TV and DVI outputs. Overscan functionality (at the hardware
level) looks like a knob on the TV encoder in the cases I've seen.
NVIDIA's binary drivers expose this knob with the "TVOverScan"
config file option or from their control panel. I don't know what
other vendors do, but it's a driver-specific feature. It's conceivable
that it's not possible to adjust the overscan with some TV encoders.
Mark.
On Mon, 20 Nov 2006, Wayne Byarlay wrote:
> Greetings.
>
> Lately I've been trying to track down a problem concerning overscan, with
> respect to Xfree86 and IVTV, the drivers used to operate Hauppauge
> MPEG-encoding video capture cards.
>
> Currently, I am using such a card in a Knoppmyth Linux system, which uses
> Debian Knoppix + MythTV to create a "one-stop-shopping" solution to DVR.
>
> However, there appears to be an issue concerning Overscan, and the X11
> desktop. Normally, one should be able to run "xvidtune", and adjust the X /
> Y height / width and offset. This is necessary, because users of the
> Hauppauge Video Cards are outputting the desktop to a television. By nature,
> televisions overscan quite a bit, and you end up only being able to see
> about 90% of it. The remaining 10% of the desktop is off the edge of the
> television screen.
>
> However, xvidtune
>
> Mythtv itself compensates for this by allowing its own GUI to be re-adjusted
> to compensate the overscan. However, any other Linux app which one may want
> to execute (Such as video game emulators, etc.), don't fit on the screen.
>
> OK, that covers the "Why". Now, for my specific questions to you all:
>
> 1. Is this a known bug in Xfree86 / IVTV?
> 2. If so, is anybody working on fixing it?
> 3. If so, who are they, and may I get into contact with them?
> 4. Would they like assistance?
>
> Perhaps this questions are better for a different mailing list, the -devel
> one; I can check there too...
>
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