[mythtv-users] Deinterlace or not

[Chris Martin]

On 10/18/06, wouter lists <wouter.lists at gmail.com> wrote:
> Hi all,
>
> I have connected my mythtv box with a vga2scart cable to my tv. To get
> proper image, i added the following modeline to xorg.conf:
> ModeLine "1024x576" 19.875 1024 1092 1140 1272 576 581 586 625 +hsync
> +vsync interlace composite
> Option      "ForceMinDotClock"   "14MHz"
> This produces a wide screen image.
>
> I'm living a PAL country, so everything is interlaced here. The shows
> I record, are interlaced en my vga card produces an interlaced signal.
> Should I use the 'deinterlace' option in mythtv?
> I tried it with both settings and I don't see any difference in the
> picture. Could it spare some cpu-cycles when not using the deinterlace
> option?
>
> According to the mailing list, using bob deint produces the best
> images. But whenever I try to use bob, I get the following error in my
> log file:
> Video sync method can't support double framerate (refresh rate too low
> for bob deint)
>
> Any idea?
>
> Thanks
>
> Wouter


Hi Wouter,

I use the same set up as you; without deinterlacing I see lots of
combing artifacts on fast motion scenes so I've enable kernel
deinterlacing which is not perfect but helps a lot. If your picture
looks fine without deinterlacing then there probably isn't any reason
to enable it, but just to make sure I'd record something with a lot of
motion in it (sport is good) and compare with and without
deinterlacing.

Bob is the best deinterlacer, but it won't work with that modeline
because you're using a 50Hz interlaced signal and bob requires a 50Hz
progressive signal (for PAL stuff anyway).  If you're using a tv that
can take a 50Hz progressive signal (I think one of those 100HZ tvs
would do) then you could try searching for a suitable modeline.

Failing that (I presume you're using an Ati card) if the binary
drivers support tv out and open gl for your card, try using the tv out
from the card and enabling bob deint that way.

Chris