[mythtv-users] mpeg2 video stuttering
ojw at weilerfamily.com
ojw at weilerfamily.com
Wed Sep 24 04:26:59 UTC 2008
Quoting "Michael T. Dean" <mtdean at thirdcontact.com>:
> 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: v18.104.22.168
>> MythTV: 0.21.20080304-1
>> NVIDIA: 173.14.12
>> Using HDMI out at 1920x1080
> 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. :)
The prebuffering pause troubleshooting page above seems to
suggest that in 100% of the prebuffering pause problems, I
should see a "NVP: prebuffering pause" in the output of
mythfrontend. I restarted mythfrontend with a -v all, then
played a recorded show. I then searched through the log
output by typing "grep -i prebuffering" and found no matches.
Is it possible that I'm still suffering from prebuffering
pauses? If not, what else could I check?
Looking through the output, I did see many occurances of this:
Xlib: extension "XVideo-MotionCompensation" missing on display ":0.0"
So I suppose if nothing else, I guess I figured out that the
on-motherboard 7100 doesn't support XvMC
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