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SubjectRe: BTTV picture mispositioning
I previously noted that the TV picture is mispositioned by a few
hundred pixels when using the bttv drivers included in Linux 2.2 and
late 2.1 kernels to read from a Bt878 video card when display the
results on an 8MB ATI Rage Pro video card using the XFree86 3.3.3.1
Mach64 X server.

I recently discovered that this problem only occurs when the scan line
length is not a power of two.

This is xawtv-2.33, running on Linux/i586 (2.2.2)
v4l: device is BT878(Hauppauge old)

SHIFTED: x11: 1600x1200, 16 bit/pixel, 3200 byte/scanline, DGA, VidMode
SHIFTED: x11: 1280x1024, 16 bit/pixel, 2560 byte/scanline, DGA, VidMode
Centered: x11: 1024x768, 16 bit/pixel, 2048 byte/scanline, DGA, VidMode
SHIFTED: x11: 800x600, 16 bit/pixel, 1600 byte/scanline, DGA, VidMode

This problem seems very similar to the one corrected by the
matrox_hack code, discussed on the video4linux list earlier this week:

On Mon, Feb 01, 1999 at 08:53:07AM -0500, Mark Crichton wrote:
> On Mon, 1 Feb 1999, Gerd Knorr wrote:
> > That matrox_hack() function tries to correct this, but it seems it
> > does'nt work allways correctly.
>
> I removed the matrox_hack
> code from the driver and placed it directly into v4l-conf. I've placed
> that code into the Gnomovision CVS repository (in the tools directory).
> The problem with the matrox_hack in the driver was that it worked well in
> X, but when running fbtv, the picture would be offset by ~400 pixels...
>
> The patch to xawtv's v4l-conf is about 5 lines, and to get xawtv to run
> with it is another 7. If anybody wants, I can make a patch up for them.

I'd be happy to take Mark's patches and try to adopt them to cure my
ATI problem, but I'll need some guidance as to where the fix should
go: in the driver, in v4l-conf, or in xawtv?

-- John Kodis.

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