[mythtv] Ticket #2903 is necessary to achieve perfect playback with an interleaved display mode.

Paul Gardiner lists at glidos.net
Sun Mar 29 13:05:17 UTC 2009

Thomas Hilber wrote:
> On Mon, Mar 23, 2009 at 12:50:40PM +0000, Paul Gardiner wrote:
>> I've just started working on the one remaining problem, which
>> is that there is nothing keeping the interlaces in sync between
>> content and display. Half the time I get perfection, half the time
>> I get terrible combs. I believe this is a well known problem. I can
>> hit "back" a few times when this happens and get it back in sync.
> I'm experimenting with VGA2SCART for various graphics cards since a while.
> In the course of that I solved the issue to keep in sync with current 
> field polarity.
> Since August 2008 patches are available for ATI Radeon cards. Newer 
> versions of my patch called 'vga-sync-fields' are also suitable for 
> Intel i9xx chipsets.
> With D945GCLF or D945GCLF2 you can setup a very cheap but high quality 
> SCART DVB receiver.
> Current field status is monitored continuously by the 'vga-sync-fields' patch.
> VGA output frequency is adjusted dynamically in very small degrees to keep
> in sync with DVB stream.
> The patch will be integral part of easy-vdr distribution soon. It is
> primarily written for VDR running xine. But it should't be a big deal to
> port it to mythtv. 

For Mythtv there's a another solution which is to use a "fieldorder"
deinterlacer, see http://svn.mythtv.org/trac/ticket/6391. It's very
light weight in terms of impact on the code, although, it does involve
doubling the frame rate, so may require a little more grunt from the

Interesting you mention Intel i9xx. I had no idea that they supported
the output of interlaced modes from VGA.


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