[mythtv-users] XvMC profile group playing MPEG4 videos?

[Steve Smith]

On 19/03/2008, Johnny Russ <jruss at mit.edu> wrote:
> I have an old PIII 1GHz box that I use to playback SD shows and also my
>  kids' videos. In 0.20 I used XvMC to playback my MPEG-2 shows and the
>  default settings (whatever they were) on the internal player worked fine
>  with my MPEG-4 videos. Since updating to 0.21 I haven't been able to get
>  my playback profile setup such that I can playback my MPEG-2 shows and
>  my MPEG-4 videos satisfactorily. With my hardware I can play the videos
>  with ffmpeg, but using this for my TV shows starts to get a little jumpy
>  if anything is going on (e.g. commercial flagging). However, if I use
>  XvMC my TV shows are great with minimal CPU usage, but my MPEG-4 videos
>  have issues (hanging, audio sync, choppy). I thought that XvMC would
>  only be used for MPEG-2 streams
>  (http://www.mythtv.org/wiki/index.php/Playback_profiles)? I set up my
>  playback profile such that XvMC would be used first, then ffmpeg would
>  be used second. I thought this would cause my MPEG-2 shows to use XvMC
>  and then everything else would use ffmpeg. However, with this setup my
>  videos have issues. If I remove the XvMC or change the order of the
>  profile groups then the videos are fine. It seems to me like my MPEG-4
>  videos are using the XvMC profile group instead of falling through to
>  the ffmpeg profile group. Am I mistaken about XvMC will only play MPEG-2
>  content? Since the content all has similar resolutions, I can't make
>  distinctions based on that criteria. Any ideas what is going on? Is
>  there a way to use XvMC for only my TV shows and not for my videos?
>
>  -Johnny
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Johnny,
I had exactly the same issue (p3 933mhz). What was happening was that
when XvMC is
set up MPEG2 works fine, but when it tried to play MPEG4 it the wrong
renderer is used (OpenGL instead of XV-Blit). It's likely that our
systems just aren't powerful enough to use OpenGL. BTW it doesn't try
to use XVMC for MPEG4. I raised a ticket for it but have not got
around to working out a patch although the ticket has been updated to
fix a related issue with Mini-ITX boards (I'm not sure if it fixes our
issue).

However the short cut is simply to re-compile without OpenGL output
support configured, then you can use XVMC just like you did in 20.
(Of course if you're using a prebuilt package you're out of luck either way)


Cheers

Steve