[mythtv-users] mpeg2 video stuttering

Michael T. Dean mtdean at thirdcontact.com
Wed Sep 24 01:56:53 UTC 2008


On 09/23/2008 07:44 PM, ojw at weilerfamily.com wrote:
> After having ditched the idea that a 1.8Ghz P4 can display
> 1080i content, I invested in a dual core Wolfdale processor
> (45nm) at 2.53Ghz and paired it with a Gigabyte GA-73PVM-2SH
> motherboard (Nvidia 630i based mobo with a GeForce 7100 built
> in).  I'm using two Pinnacle PCTV HD Pro USB capture devices
> and am only tuning ATSC based terrestrial transmissions.  Both
> mythfrontend and mythbackend are running on the same box.
>
> The problem I'm having is that when I try to view either a
> recorded show or something live'ish (from the ringbuffer),
> the view jitters.  What should be obviously smooth scene
> pans turns into jerky stutter steps through the scene.
>
> I was thinking it might be the marginally supported PCTV
> HD Pro USB stick but I found that when I transfer the
> recorded MPEG file to a PC running windows XP (using
> windows media player), the video playback is as smooth
> as silk.  I checked the CPU utilization during playback
> on my mythtv box using top and found that it's usage doesn't
> go over 50%.  I also tried configuring for XvMC which results
> in a good cpu usage drop (down to 30%) but the image still
> stutters about the same amount.
>
> I also tried playing the resulting mpegs in mplayer on the
> mythtv box.  At first, mplayer told me I didn't have enough
> CPU power to play the file so I used the -ao null option to
> negate sound.  After I did that, mplayer didn't complain but
> it stuttered more than during playback in mythtv.
>
> I'm not sure where to go from here and was hoping you all
> could direct me to further diagnostic efforts.  I'd be
> happy to post whatever config information you think would
> help diagnose this.  I'll start with the basics:
>
> Kernel: v2.6.26.3
> MythTV: 0.21.20080304-1
> NVIDIA: 173.14.12
> Using HDMI out at 1920x1080

http://www.mythtv.org/wiki/index.php/Troubleshooting:Prebuffering_pause

And, if it turns out yours is not on there, but you are suffering from
prebuffering pauses, please update the page once you find out the cause.  :)

Mike


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