[mythtv] Video Output patch v13
terry1 at beam.ltd.uk
Thu Apr 21 08:26:23 UTC 2005
Daniel Kristjansson wrote:
> On Wed, 2005-04-20 at 21:43 +0100, Terry Barnaby wrote:
>>Actually, going back to MythTv CVS 2005.04.14, it also uses quite a lot
>>of CPU while displaying the small video in "Watch Recordings", not
>>quite the same level as with the patch (about 90% versis 98%).
>>The picture does stutter, but the colours are correct.
>>It appears that MythTv may be doing software decoding when displaying
>>the small video in "Watch Recordings". It think it may have always
>>done this from my original XvMC VLD implementation, but I am not sure ???
> Yes MythTV uses software decoding for this, there is a "CPU friendly"
> option in mythfrontend setup somewhere to slow down the framerate.
> I believe this is in playbackbox.
> Basically the loop is:
> Get a frame from the NVP
> Allocate a RBGA buffer the same size as the videoframe
> Convert the frame from yuv color space to rgb color space using MMX
> Release the frame back to the NVP
> Scale RGBA buffer it to the preview window size
> Create a QImage from the scaled image
> delete the RGBA buffer
> finally it draws the QImage.
> This is very inefficient, but it should work.
> BTW I'm not seeing this color issue, can you get me a screenshot?
> Is MMX enabled? See the output of:
> cat ../config.mak | grep MMX
> Also, are there any error messages?
> -- Daniel
> mythtv-dev mailing list
> mythtv-dev at mythtv.org
I did some playing around with this, compiling both original CVS and CVS
with your patch with different CPU types.
I believe the issue I had was that the patch version was compiled with cpu=pentium
and hence no MMX as you have suggested
I have recompiled with cpu=pentium4 and now the colour issue has gone.
There is a difference between the patched and unpached versions however,
the unpatched version displays continuous video with occasional tears
probably because the system can not keep up.
The patch version displays the video as solid frames but with a delay between
each frame. This is probably better.
Is there any real reason why MythTv uses this "alternate" software scheme ?
Any idea as to why it does just not use the normal video output system with
a small overlay window in the right place ???
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