[mythtv] [mythtv-commits] Ticket #6391: New deinterlacer for perfect image quality when using an interlaced display mode that matches the source

Mark Kendall mark.kendall at gmail.com
Fri Apr 3 09:05:08 UTC 2009

>  1) You mention aligning the opengl and software versions. Which would
>  change? I ask because the OpenGL one in its current form does a completely
>  different job. It would be no good for my set up. Its purpose doesn't seem
>  to be to sychronise interlaces, but to truly deinterlace.

They are both trying to achieve the same thing - currently they just
use different approaches. I previously found that the OpenGL approach
(one field at a time) was consistently more successful on my old
display but this may have changed with more recent drivers or may just
be an artifact of how OpenGL interacts with the framebuffer. I'd be
very surprised if it doesn't do just as good a job as the software
version on your display.

>  2) You mention testing 576i and 480i via HDMI. Is that with 576i and 480i
>  display modes? Matched source and display mode is the only case this
>  deinterlacer works correctly. I ask because someone commented in myth-
>  users that few TVs will accept SD modes via HDMI. It would be very
>  interesting if that's not the case.

Yes - this is with 576i and 480i display modes over DVI/HDMI. My new
tv takes just about everything I would want to throw at it (which was
the main reason I chose it!). As mentioned on the list, Samsungs seem
not to accept SD interlaced modes (I've got 2, neither of which will
do 576/480i).

>  3) I thought I'd accounted for bottom field first. Any idea what I did
>  wrong?

Well - if you look at your code, it doesn't do anything if tff is 0.

>  4) I made a similar change to avoid flickering OSD, but it didn't work
>  (for the second occurence of the frame newframe == lastframe, I copied
>  both field rather than just the second field). I also noticed that yadif
>  suffers from flickering OSD. My changes were on fixes rather than trunk.
>  Is that significant?

I have made some changes in trunk in recent weeks, so they may account
for the different behaviour. I don't think I've seen a flickering osd
with yadif (though I'll check just to be sure).



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