[mythtv-users] Deinterlacing Methods

Daniel Kristjansson danielk at cuymedia.net
Thu Feb 15 14:27:38 UTC 2007

On Sun, 2007-02-11 at 17:16 +0100, Wim Fokkens wrote:
> For the time being is it possible to use other deinterlacers instead
> of the ones we can chose in the user interface?
You can always introduce new deinterlacers programmatically,
but all the existing deinterlacers are available via the
MythTV UI.

> > It is however prone to "bobbing" as it's name would
> > indicate. The smaller your video resolution, the more
> > pronounced is the bobbing.
> For this reason would it be smart to firs upscale both fields > and
after this do the bob deinterlacing?
Scaling the image ahead of time will have no effect on the
bobbing, the bobbing is due to the sampling in the original
video acquisition system. You could halve the vertical
resolution, this is what the onefield deinterlacer does.

> > The vertical resolution needs to be a multiple of 2 of the
> > video source vertical resolution for the bobbing to 
> > completely disappear.
> I tried this I made a modeline with a resolution of 
> 1840 x 1152 @50Hz and feed this to a 24” Sun VGA monitor.
> But I still could see some bobbing I took 2x 576 with are
> the visible line of pal. Or should I take the total number
> of lines (625)

You need exactly double the lines of the displayed lines
So 1152 would be correct. You should also know that certain
drivers, such as nVidia drivers in the 6xxx series and later,
have a bug in XvMC which introduces additional bobbing and
can not be corrected for. The only solution here is to use
an older driver or use one of the new OpenGL bob deinterlacers.

-- Daniel

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