[mythtv-users] Mac OS X choppy playback at high display resolutions, such as 1080p

Todd Ignasiak todd.ignasiak at gmail.com
Wed Oct 10 21:49:06 UTC 2007


On 10/9/07, MythTV <mythtv at taoyama.com> wrote:
> Todd,
>
> Try this simple patch without the previous patch.
>
> What I think is happening is that in order to keep the line count a
> multiple of 16 the video height is being set to 1088 but the actual
> content is 1080.  When this happens the pixel aspect ratio difference
> becomes 0.013 which causes a transform matrix to be created so
> Quicktime will try to "transform" the image to maintain the aspect
> ratio.  By allowing a 0.015 difference in pixel aspect ratio to be
> ignored it should remove the need for the transform.
>
> After a very quick test it seems to work for me.
>
> Let me know if this fixes the problem for you.

Hi Mino,

I applied that change to my 0.20.2 frontend, and my initial tests all
looked great.  The video was fine, and CPU overhead was relatively
low.
I will record some more 1080i programs this evening, and try to test
on a wide variety of programs (the previous patch worked on some
programs, but not others).

I'll post my results here after doing more testing.

Thanks,
Todd

> Index: videoout_quartz.cpp
> ===================================================================
> --- videoout_quartz.cpp (revision 14063)
> +++ videoout_quartz.cpp (working copy)
> @@ -307,7 +307,7 @@
>                                   .arg(name).arg(sw).arg(sh));
>
>       // scale for non-square pixels
> -    if (fabsf(aspect - (sw * 1.0 / sh)) > 0.01)
> +    if (fabsf(aspect - (sw * 1.0 / sh)) > 0.015)
>       {
>           if (parentData->scaleUpVideo)
>           {


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