[mythtv-users] Nvidia 720x480 troubles

[Jay R. Ashworth]

On Mon, Aug 09, 2004 at 09:47:40PM +0100, Ian Armstrong wrote:
> On Monday 09 Aug 2004 17:44, Greg Estabrooks wrote:
> > > >that 720x480 is the best resolution to capture at with the Hauppauge
> > > > card,
> > >
> > > You need to set your recording profiles to use an aspect ratio of square.
> > > You will also need to set any other program you use (xine, mplayer ) to
> > > use square as well.
> > > You really shouldn't need to do this but nvidia can't seem to ever get
> > > anything quite right.
> >
> >  The problem is that X's DisplayWidthMM and DisplayHeightMM
> > (used in videoout_xv.cpp) are returning values that work out to be an
> > aspect ratio of 1.5(4:3 with 720x480 is not) and videoutbase.cpp doesn't
> > take into account situations where the source image is identical to the
> > current display resolutions. As such it is forcing a resize of the video
> > down to be 640x480 displayed on a 720x480 screen.
> 
> Pixel resolution has nothing to do with the aspect ratio. In PAL, 720x576 
> could be either 4:3 or 16:9. You can't work out the aspect ratio just by 
> looking at the number of pixels in either the width or the height. If 
> DisplaySize for X is set correctly, the image should be scaled to the right 
> size regardless of the actual resolution used. Both Xine & Myth honor 
> DisplaySize, but MPlayer ignores it & needs a command line option to set it. 

And, to expand one layer further: pixels need not be square.

That's why the D-1 standard is 720x486, and yet is also 4:3.  It's also
how consumer camcorders do pseudo-scope widescreen: they record the
same number of effective pixels across, but they're *wider*.

Cheers,
-- jra
-- 
Jay R. Ashworth                                                jra at baylink.com
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