[mythtv-users] How I got great quality TV-out on my nVidia MX4000

Robert Johnston anaerin at gmail.com
Wed Mar 9 19:46:13 UTC 2005


On Wed, 9 Mar 2005 12:34:00 -0700 (MST), John Patrick Poet
<john at blueskytours.com> wrote:
> 
> On Wed, 9 Mar 2005, Jeroen Brosens wrote:
> 
> > > I gave up after trying *every* combination of driver/cable/modeline/X11
> > > video output device/eating shoes and decided to buy a nVidia card after
> > > Staffan Pettersson persuaded me (thank you):
> > > http://www.mail-archive.com/mythtv-dev@mythtv.org/msg04131.html
> > >
> > > The card is due to arrive friday, so I can finally get OpenGL
> > > vsync+XvMC+bobdeint working.
> > >
> > > -- Jeroen
> > >
> >
> > I'd like to add that I'd like to challenge the MythTV dev-people to review
> > the Xv/XvMC code regarding the handling of vsync while using bobdeint.
> >
> > One needs hardware with OpenGL support to have a Vsync to get bobdeint
> > working without going out of sync now and then (horrible jittering occurs)
> > and that isn't good news for users of a barebone with built-in graphics
> > that can't support that, like myself (using an ASUS Pundit).
> >
> > It would wipe out all problems I had to get it working! One lousy bobdeint
> > filter that just works.
> 
> I understand that you are frustrated, but your last sentence is a little
> offensive.
> 
> The OpenGL vsync/bobdeint combo is awsome.  Ever since Doug implemented that
> combination, my video playback has been silky smooth.  I have an nVidia
> graphics card.
> 
> The reason it may not work as well for non-nVidia users, is that Doug uses
> an nVidia card.  Pretty much all the "developers" use an nVidia card.  This
> means that all other video cards are not going to be as well tested or
> optimized.
> 
> If someone wanted to buy Doug an Asus Pundit, he *might* be willing to take
> the time to work on improving bobdeint for non nVidia cards, but he is
> unlikely to buy one for himself just for that purpose.
> 
> Doug would probably be willing to explain how the bobdeint code works, if
> someone without nVidia hardware wanted to work with it.

If this was the Windows world, I'd suggest using DirectX or something
similar to get the VSync (As even the pundit's drivers would be DX
compatible). And if we were using VESA, we could capture the VBlank
interrupt from the VESA bus. However, this is *nix, and I'm not sure
how different drivers work WRT VBlank. Is there something in the MESA
project we could use? I believe they implement VSync on non-GL
cards...


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