[mythtv-users] Stuttering video on mythtv 0.26

[Ben Kelly]

I recently upgraded to mythtv 0.26. Everything works fine, except for
> some videos which have very bad stuttering. These videos play fine on
> 0.25. I've also checked mplayer, which plays them very smoothly as
> well. I have an nvidia ION card and I'm using the "vdpau normal"
> profile, but I've been through the others (OpenGL, etc) and the
> problem is always the same on myth 0.26.
>
> I used the video playback test under the Setup Wizard in the frontend.
> SD is ok, but the HD test gets stutter. I've noticed that the log gets
> filled with these on videos experiencing stutter (and this includes
> the HD test):
> "CoreContext mythplayer.cpp:2095 (PrebufferEnoughFrames)"
>
> I've set the nvidia powermizer to max performance, updated to the 304
> nvidia driver, turned off CPU scaling - none of which have made any
> difference.
>
> My setup is:
> - Zotac Mag - Atom 330 CPU
> - ION nvidia graphics
> - Mythbuntu 12.04
> - Mythtv 0.26
>
> I'm at a bit of a loss where to go from here. I'm thinking *something*
> has been changed in the internal player between 0.25 and 0.26 to cause
> this issue, but have no idea what.
>
> For reference, here is the results from qvdpau test:
> **************************
> qvdpautest 0.5.1
> Intel(R) Atom(TM) CPU  330   @ 1.60GHz
> NVIDIA GPU ION (C79) at PCI:3:0:0 (GPU-0)
>
> VDPAU API version : 1
> VDPAU implementation : NVIDIA VDPAU Driver Shared Library  304.43  Sun
> Aug 19 20:44:13 PDT 2012
>
> SURFACE GET BITS: 273.935 M/s
> SURFACE PUT BITS: 311.411 M/s
>
> MPEG DECODING (1920x1080): 60 frames/s
> MPEG DECODING (1280x720): 135 frames/s
> H264 DECODING (1920x1080): 53 frames/s
> H264 DECODING (1280x720): 109 frames/s
> VC1 DECODING (1440x1080): 69 frames/s
>
> MIXER WEAVE (1920x1080): 311 frames/s
> MIXER BOB (1920x1080): 436 fields/s
> MIXER TEMPORAL (1920x1080): 117 fields/s
> MIXER TEMPORAL + IVTC (1920x1080): 75 fields/s
> MIXER TEMPORAL + SKIP_CHROMA (1920x1080): 159 fields/s
> MIXER TEMPORAL_SPATIAL (1920x1080): 34 fields/s
> MIXER TEMPORAL_SPATIAL + IVTC (1920x1080): 27 fields/s
> MIXER TEMPORAL_SPATIAL + SKIP_CHROMA (1920x1080): 38 fields/s
> MIXER TEMPORAL_SPATIAL (720x576 video to 1920x1080 display): 128 fields/s
>
> MULTITHREADED MPEG DECODING (1920x1080): 59 frames/s
> MULTITHREADED MIXER TEMPORAL (1920x1080): 99 fields/
> ****************************
>

More information:

I had originally discounted the network as a cause of the issue, but having
another look at it today, I saw something interesting. A working video
consumes far less network bandwidth than one that is stuttering. So it does
look to be network/streaming related.

The odd thing is that the video that is stuttering is a *smaller* file than
the working video (it's half the size). So why does it take up more
bandwidth when it streams from the BE to the remote FE ? As stated above,
it streamed fine on 0.25, but is now having a problem on 0.26.
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