[mythtv] #1058 - what now?

Daniel Kristjansson danielk at cuymedia.net
Fri Jan 27 16:59:27 UTC 2006

On Fri, 2006-01-27 at 16:32 +0000, Ivor Hewitt wrote:
> On Friday 27 January 2006 16:28, Buzz wrote:
> > Would it be possible to scale the video down to the 'maximum XvImage size'
> > (or somewhere under it)?
> No. Well not that there's any point. :)
> Xv is what's providing the performance for scaling the video to your screen 
> res.... if you scale the video before passing it to Xv then you're doing the 
> scaling in software and there's not advantage to using Xv (ok, well apart 
> from the colourspace conversion).

Probably the best solution is to buy a new graphics card, and until
then transcode to something like 1440x1080. While it would be possible
to scale the video to 960x1080 pretty quickly, we would need to encode
onto another set of surfaces any copy the data onto the XVideo service,
ugly stuff; plus it wouldn't look as good as something transcoded to

I've though of implementing OpenGL output, but it doesn't look like that
would help you much either. MythTV can do X11 output, but it is slow...

BTW you might need to encode to something slightly smaller such as
1440x1072, because we decode directly onto the XVideo surface, and
MPEG2 doesn't support a 1080 height, for 1080i MPEG2 actually uses
1088 lines.. I don't know exactly how ffmpeg copes with that. MPEG4
can support multiples of 8, but I don't think we use that feature
in the transcoder.

-- Daniel

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