[mythtv-users] Video is behind audio, dropping frames to catch up (VDPAU, HD content)

Joseph Fry joe at thefrys.com
Thu Feb 28 02:18:39 UTC 2013


> I have now tried many things, but I am running out of ideas.
>
> * it happens usually every 2-10 minutes
> * it happens for HD h264 and SD MPEG2, just for HD a little more often
> * it happens with and without VDPAU
> * it happened on old and upgraded hardware (only sound card identical)
> * it happens on 0.26 and earlier versions
> * I have tried all VDPAU profiles
> * I have disabled logging over NFS (> /dev/null)
> * I have enabled realtime prio (but it is not mentioned in the log)
> * I have reniced mythfrontend to -2 and X to -12
> * I have set the GPU to max. frequency all the time, so no switching
> * I have disabled the often crashing mythlcdserver
> * I have tried different kernel and NVidia driver versions
>
> What else can I try? What more info should I provide?
>
> Probably, something needs a little CPU time every now and then and this
> probably causes that little "jump" in playback and the log entry from
> the subject, but I don't know what it is and why MythTV is so sensitive
> on such hardware specs (Core i3, 3.1 GHz)?
>
> Or does it probably have something to do with the fact that this is a
> diskless PXE frontend?
>
>
That would be my guess.  Between VDPAU and your CPU... you have a surplus
of cpu resources, I have much less powerful systems (P4 3GHz) using CPU
decoding that don't exhibit symptoms like that even with HD content.  I
find it difficult to believe that it's anything other than the network.

One other other thing to look at... you are using the myth:// protocol and
not accessing your recordings via an NFS mouint, correct?  While 'local'
access should work, you might find the myth protocol to be more stable.
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