[vdr] Options for deinterlacing (or not)

Ville Aakko ville.aakko at gmail.com
Tue Jan 20 17:19:49 CET 2009


Hi Scott!

2009/1/19 Scott Waye <scott at waye.co.uk>:
> If X is put into an interlaced mode (1920x1080i @ 50Hz), and I do not do
> any de interlacing in xine, why is this not the same as what my digibox
> does?  I'm guessing it has something to do with xine outputting a
> complete frame when the broadcast sends each field?

What you state above is NOT correct. When you use your digiboxx, your
TV panel does all interlacing and scaling. To do what your digibox
does, you should alwways set the output in the same (interlaced)
resolution as the broadast, NOT in the TV's native resolution. And no
vertical scaling is allowed before deinterlacing! (but horizontal is
allowed)

Someone correct me if I'm wrong

> What I'd hope
> happen (for interlaced material) is that xine receives a field from VDR,
> scales it to the X resolution (halfed vertically of course) and sends it
> to the the graphics card which just passes it on to the TV which draws
> that field.  That doesn't seem to happen so where have I gone wrong?

In changing the resolution. To achieve what you want, you need to set
X to a PAL modeline (720 x 576 interlaced for PAL). However, this is
not as straightforward for a VGA card as for full featured DVB cards
or set tob boxes. Even after setting the right modeline, a few
problems remain:

1) You need  to enable sync on vblanck.

2) There is no way to automatically switch the resolution when/if the
standard changes

3) The timigns are not exact on VGA (HDMI etc.) outputs

The first is not possible on all drivers (i.e. fglrx). For the second
problem there are no ready made solutions (but you can of course
manually change between modes, and perhaps restart some sowftware when
needed). For the third problem, see thread "RGB/PAL over VGA at
variable frame rate" for more discussion and patches.


Someone correct me if I'm wrong.

-- 
Ville Aakko - ville.aakko at gmail.com



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