[mythtv-users] Choppy Video on Playback and LiveTV, not with mplayer

[Stephen Atkins]

Nick wrote:

>On 22/09/05, Lee Koloszyc <teething12 at hotmail.com> wrote:
>  
>
>>Hello all,
>>
>>I am having a problem with mythtv 0.18.1 on Gentoo kernel 2.6.12-r10 on
>>both livetv and playing pre-recorded videos.
>>The play back is supper choppy and pauses about every 2 seconds.
>>Playing the same file directly through mplayer or gmplayer and it runs
>>as smooth as butter.
>>The recording works fine though even while recompiling X in the background.
>>I am running on a somewhat slow system: P3 800, VT6x4 mother board, 512M
>>ram, Radeon 9250 256mb, PVR150, SBLive.
>>I am using the ATI binary drivers 8.16.20.
>>I also had the same problem with an Nvidia FX5200 card in the system,
>>but had to return the card because of less then desirable svideo output.
>>    
>>
>
><snip>
>
>I'd be worried why it's still trying to use an nvidia device when
>you're now using an ATI card. It could likely be related to vsync also
>- try using a different method (along with the correct driver) and so
>if this improves things.
>
>  
>
>>2005-09-22 12:32:11.993 nVidiaVideoSync: Could not open device
>>/dev/nvidia0, No such file or directory
>>2005-09-22 12:32:11.995 DRMVideoSync: VBlank ioctl did not work,
>>unimplemented in this driver?
>>2005-09-22 12:32:12.019 Using realtime priority.
>>2005-09-22 12:32:13.111 OpenGLVideoSync: GLX extensions:
>>GLX_EXT_visual_info GLX_EXT_visual_rating GLX_EXT_import_context
>>GLX_ARB_get_proc_address GLX_ARB_multisample
>>2005-09-22 12:32:13.112 OpenGLVideoSync: GLX Video Sync extension not
>>present.
>>2005-09-22 12:32:13.118 Using audio as timebase
>>2005-09-22 12:32:13.119 Video timing method: RTC
>>2005-09-22 12:32:13.119 Refresh rate: 16579, frame interval: 33366
>>2005-09-22 12:32:13.119 waiting for prebuffer...
>>2005-09-22 12:32:13.253 prebuffer wait timed out..
>>2005-09-22 12:32:13.253 waiting for prebuffer...
>>2005-09-22 12:32:15.607 prebuffering pause
>>    
>>
>
>This buffering could be video or audio related (I'd recommend trying a
>new version of ALSA instead of OSS if the video driver issue doesn't
>help).
>  
>

I've got the same problem with a PVR250 (not mce).  I've noticed in my 
myth logs that my system is trying to load the vidia sync but I don't 
know how to get it to stop trying.  Doing some searching on the net it 
seems the problem could be the OpenGL vsync option when compiling with 
Gentoo emerge.  I'm currently recompiling with a modified use flags of 
+xv -opengl mmx sse.  I'm also using a ati (radeon 7500) and I double 
checked my alsa drivers and they are up to date.  After this I'm not 
sure where to go.  I originally thought it might be IVTV but as it plays 
fine in mplayer I'm sure its a Myth/Xorg config problem.

What exactly is OpenGL vsync?

I'll keep everyone updated.

Stephen