[mythtv-users] Ati 9100IGP to PAL tv help

Julian Edwards myth at julian-edwards.com
Sun Sep 17 19:55:16 UTC 2006

Graeme Wilford wrote:
> On 14/09/06, Robin Hill <myth at robinhill.me.uk> wrote:
>> On Thu Sep 14, 2006 at 09:15:42AM +0100, Chris Martin wrote:
>>> Interestingly while X is clear using this system (far better than
>>> using s-video out) tv playback via myth is not quite perfect.
>>> Movement is ever so slightly jerky (like the timing's out) and fast
>>> motion is a little blurry.  Especailly bad are panning shots which are
>>> quite clearly not smooth.
>>> This happens either with Robin's modelines or with a couple of others
>>> I've found on the internet.  Turning deinterlacing on helps a tiny bit
>>> but not much.  If anyone has some more modelines for me to try or
>>> suggestions then I'm more than happy to hear them
>> This is a synchronisation problem.  Essentially, the system is mid way
>> through updating the graphics buffer at the point it's pushed out to the
>> screen.  Enabling OpenGL vsync seems to help with this (I've not had it
>> enabled for long so I can't be certain on this - with previous drivers
>> enabling this option totally messed up the display, so I've only just
>> got around to retrying it).
> Definitely. I have the 9100 IGP and after finally getting OpenGL vsync
> working with a 50Hz modeline, vsync is perfect and the bob
> de-interlacer looks great. See here for details:
> http://mezzanines.blogspot.com/2006/08/optimising-for-edtv-progressive-output.html
> Cheers,
> Wilf.
Actually, sync is only half the problem.  The main issue is that the 
interlaced video source lines can't be matched up to the correct 
interlaced output lines when you're using TV-out.

If you search the archives there was a great post from Cory Papenfuss 
about a year ago that explained it perfectly.

In the meantime, the only real way to fix it is to de-interlace if 
you're using TV-out.  I'm using an nvidia 6xxx with the component out, 
opengl vsync and bob de-int and the picture is damn near perfect.


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