[mythtv-users] judder problems with nvidia 358.16

[Marius Schrecker]

On Friday, March 4, 2016 15:01 CET, Will Dormann <wdormann at gmail.com> wrote:
 On 3/4/16 5:10 AM, Marius Schrecker wrote:
> incorrect rtc permissions, although I don't see this fixing the
> incorrect refresh rates being consistently chosen.


I'm no expert on this stuff, but these look suspicious:

Mar 3 20:13:32 mythbox mythfrontend.real: mythfrontend[22207]: E
CoreContext vsync.cpp:275 (TryInit) VSYNC: DRMVideoSync: VBlank ioctl
did not work, unimplemented in this driver?
Mar 3 20:13:32 mythbox mythfrontend.real: mythfrontend[22207]: E
CoreContext vsync.cpp:356 (TryInit) VSYNC: RTCVideoSync: Could not open
/dev/rtc: #012#011#011#011eno: Permission denied (13)
Mar 3 20:13:32 mythbox mythfrontend.real: mythfrontend[22207]: E
CoreContext mythplayer.cpp:2395 (VideoStart) Player(0): Video sync
method can't support double framerate (refresh rate too low for 2x deint)
Mar 3 20:13:32 mythbox mythfrontend.real: mythfrontend[22207]: I
CoreContext mythplayer.cpp:1789 (InitAVSync) Player(0): Display Refresh
Rate: 23.971 Video Frame Rate: 25.000



The equivalent on my system:

Nov 18 21:52:35 <HOSTNAME> mythfrontend.real: mythfrontend[2375]: I
CoreContext mythrender_opengl.cpp:76 (Create) OpenGL: Sync to VBlank is
enabled (good!)




I think the former could cause tearing. But I'd think that the nvidia
driver stuff could handle that stuff. I'm using the nvidia 304.131
driver, FWIW. However according to
<https://www.mythtv.org/wiki/Frame_display_timing>, "Contrary to what
Mythfrontend may say, VDPAU does not use vsync/vblank timing. RTC should
be used instead. " So that may be not relevant. My system config has
persisted through many years of MythTV, though, so that could even be an
artifact of a prior pre-VDPAU configuration.

As for the 23.97fps vs 25fps stuff, that surely seems like trouble. It
almost would seem that you're trying to play PAL video on an NTSC TV?


-WD
Thanks Will,

The TV should handle most stuff that I throw at it, as the output of xrandr shows. Certainly there are both 25Hz and 50Hz modes so 25Hz material should present nop problem.  Interestingly, though not documented here, if I throw some 24p material at it, it tries to render it at 50Hz and I end up with the same problem.  

Mar  3 20:13:32 mythbox mythfrontend.real: mythfrontend[22207]: E
CoreContext vsync.cpp:275 (TryInit) VSYNC: DRMVideoSync: VBlank ioctl
did not work, unimplemented in this driver?

worries me. If I have to downgrade the nvidia driver, I will surely have to do the same with the kernel, but you also say that:

"Contrary to what
Mythfrontend may say, VDPAU does not use vsync/vblank timing. RTC should
be used instead."

I remember seeing some rtc permissions problems in one of the logs, so that might be a place to start:

https://www.mythtv.org/wiki/MythTV-HOWTO#ss5.4
rlimits
The rlimits method is the preferred method and is included in Linux 2.6.12 and above and requires PAM version 0.79 or above. Assuming anyone running mythfrontend is in the audio group and rlimits are supported, all you need to do is place this in your /etc/security/limits.conf
* - rtprio 0
* - nice 0
@audio - rtprio 50
@audio - nice 0

 
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