[mythtv-users] MythTV and interlacing

Bradley Kite bradley.kite at gmail.com
Mon Jun 30 08:21:00 UTC 2008

On 30/06/2008, Andy Burns <fedora at adslpipe.co.uk> wrote:
> On 30/06/2008 06:23, Bradley Kite wrote:
>  > I've just built myself a VGA to Scart converter as per:
>  > http://gentoo-wiki.com/HOWTO_Setup_X_for_MythTV - the picture quality
>  > is a lot better, but I'm trying to figure out some deinterlacing
>  > stuff.
> On my previous myth box I did the same, likewise the quality was much
>  better than using TVOUT.
>  > I'm driving X with the following modeline:
>  >
>  > ModeLine "720x576 at 25i" 13.5   720 732 795 864  576 581 586 625
>  > interlace -hsync -vsync
>  >
>  > As I am now using a naturally interlaced display mode, and I'm playing
>  > interlaced content on an interlaced display, I would have thought that
>  > I could turn off MythTV's de-interlacing?
> That was what I expected too, though I always found using de-interlacing
>  provided a better looking picture, for a while this bothered me, as I
>  was trying to achive "less processing is best", eventually I decided
>  that whatever looked best, was best.
>  I've tried it but I still
>  > get the tearing etc. which I thought would have disappeared in such a
>  > scenario.
> I didn't get tearing, is your card allowing vertical retrace
>  synchronisation?


Yes I've configured OpenGL Vsync and myth is using it. Its difficult
to describe the exact effect when I turn interlacing off, but when TV
presenters are talking and they move their hands then their hands
flicker a lot, but the rest of the picture (which isnt moving) remains
sharp and clear.

I will see if I can have another play around tonight and figure out
exactly whats going on.

Actually I think I'm running a slightly different mode-line to the one
I posted - I had to change it a bit because I was missing around 2
inches of the screen around the borders due to overscan so maybe thats
having an affect. Maybe there is a better way to eliminate the


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