[mythtv] Re: [mythtv-commits] mythtv commit: r7463 by danielk (ie using 16:10 display)

[Daniel Kristjansson]

On Thu, 2005-10-13 at 13:17 -0400, Glen Dragon wrote:

> have been unable to use the full resolution of the screen. I am forced 
> to cut down the myth display size, othewise I get bad 1080i interlacing 
> tearing.
You need to enable deinterlacing to prevent the tearing.

> Does this commit help me?  I currently don't use Xinerama (to my 
> knowledge), since I only have a single screen in X.  X is configured 
> for the 16:10 resolution (1680x1050).  What options should I change to 
> enable this feature?  I looked quick, and I didn't see it on the GUI, 
> tho I might have missed it.
You didn't miss it. It is only enabled when you are using Xinerama.
When you don't have Xinerama, MythTV can detect the aspect ratio.

The problem you are having has nothing to do with the aspect ratio,
the problem is that to fit a 1920x1080 video onto a 1680x1050 display
you need to resize the frame, or cut off part of the video. In your
case you are resizing the 1080 lines to something like 945 lines.
This is done in hardware when you use XVideo. Your hardware uses
point sampling without knowledge of the interlacing, giving you 
both spatial and temporal aliasing (better sampling would cost more).
If you turn on deinterlacing in MythTV you will remove the temporal
aliasing, which causes low frequency waves in the output.

MythTV could have another letter-boxing mode which chops off the
top 15 and bottom 15 lines and some portion of the left and right
of the video to fit exactly onto 1050 lines of a 16:10 display.
This would eliminate annoying low frequency waves, but you would
still get the less annoying high frequency waves if you didn't
use deinterlacing. However, these high frequency waves can be 
eliminated with hardware deinterlacer/"line doubler" hardware.

-- Daniel