[vdr] Ghosting problem and deinterlacing

Niko Mikkila nm at phnet.fi
Tue Dec 27 17:41:41 CET 2005

On Tue, 27 Dec 2005 10:11:35 +0200
Burak BAYER <bbayer at havelsan.com.tr> wrote:

> Niko Mikkila wrote:
> >
> >Softdevice currently lacks advanced deinterlacing algorithms that
> >output progressive video at 50 fps instead of the normal 25 fps.
> >Ghosting could be mostly eliminated with 25 fps algorithms (like
> >lavcdeint in MPlayer), but the fluidity of the video will still suffer.
> >
> >Right now Xine and the vdr-xine plugin is your best bet to get good
> >deinterlaced output. Use the tvtime post-processing plugin with
> >Greedy2Frame, GreedyH or TomsMoComp algorithms (example xine command
> >line is provided in vdr-xine documentation). This will require more
> >processing power than Softdevice with its normal deinterlacing
> >algorithms, but the adaptive algorithms in Xine also look much better.
> >With cheap_mode set to 1, Greedy2Frame works very well at 720x576 on a
> >600 MHz Athlon, but this may require compiling a locally optimized Xine
> >binary.
> >
> >--
> >Niko Mikkilä
> >  
> Thanks for your answer.. Is there any channel changing speed losses on 
> xine-plugin.  How about stability and long time use?? It is important..

Xine is probably slower at changing channels by default since it buffers
a lot. I think the buffer sizes can be tuned in the configuration
though. There should be no problems with stability at least from the
MPEG-2 decoder's part. The Xine UI is a bit unstable at times (perhaps
because of the custom GUI toolkit that seems to have bugs), but you
could try gxine if xine-ui doesn't work for you.

> How about tv-out with graphic card? I see ghosting eliminated with tv a 
> little bit.. Is there any way to improve it with tv-out??

The tv-outs on almost all graphics cards deinterlace the video and
usually scale it unnecessarily too, so I would not recommend them.
There was recently some discussion about them on this list (in November
perhaps, and also in January 2005 IIRC). Older Matrox dualhead cards
could be used through Softdevice and DirectFB, but it's not an easy
setup and it's best suitable for interlaced CRT TV's. Progressive
displays (LCD televisions, monitors) need deinterlacing which is
cheapest to do in software and display through normal VGA or DVI output.

> Last question I cannot work X with resolution 720x576? Can you write 
> your timings here??

I use a normal 1024x768 at 75Hz mode on a 21" CRT monitor and an LCD
projector. That's because the broadcasters here in Finland are
sometimes gracious enough to give us good anamorphic 16:9 video, which
is best displayed by upscaling the image horizontally to 1024x576. For
good deinterlacing results, you should use a refresh rate that is
multiple of 50 Hz (that is, 50 Hz, 100 Hz or 150 Hz). I can only use 75
Hz, which is good enough for me.

> Maybe some good deinterlace algorithms can be port to libpp ..

That would be useful, so hopefully someone does it someday. The hardest
part is already done since there are many good open-source algorithms
made available by the DScaler project.

Niko Mikkilä

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