Justin Schoeman wrote:
>
> Gunther Mayer wrote:
> >
> > Hi,
> >
> > the 1st line of the tv picture is constantly dashed here, e.g.
> > - - - -- - -- -- - - -- -- ----------------------
> >
> > This is a cosmetic problem but nevertheless annoying !
> > I think this problem existed since the early days of bttv.
> >
> > Do others see this artefact, too?
> > Any clueful hints on causes for this?
> >
> > Regards, Gunther
> >
> > P.S.
> > Further data/Kind-of-Workaround:
> > When switching to "grabdisplay" in the default size 384x288
> > the line is fine (and the pictures increases sligtly in size,
> > both horizontal and vertical) !
> >
> > This does not help as soon as vsize>288, so this could be
> > a subtle scaling problem in the BTTV-Risc code or similar?
> >
> > Side note: With "grabdisplay" unfortunately the last line is wrong:-(
> > | ------------------- |
> >
> > The artefacts combination depends on the tv channel selected:
> > RTL (CH60) in the only channel without artefacts, here!
>
> I am pretty sure the operation of bttv is correct. The problem comes
> in, because bttv will capture the ENTIRE video image (including the
> half-line scans). Many broadcasters transmit some information (looks
> like a timestamp to me) in the first half of the first visible display
> line, and this is probably what you are seeing. Analog TVs cut off the
> top, bottom, and borders of the visible image, so you don't usually see
> this.
This doesn't explain why "grabdisplay" is different from "overlay".
If you are right about ill-use of the first line (and the last line, too),
of course these lines should (optionally) not be shown in xawtv ! Ralf ?
Regards, Gunther
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