[mythtv-users] LG TV starts flickering when using LiveTV

Rajil Saraswat rajil.s at gmail.com
Wed Feb 28 03:21:58 UTC 2018


On 02/26/2018 10:13 PM, Stephen Worthington wrote:
> On Mon, 26 Feb 2018 21:11:31 -0600, you wrote:
>
> I would have thought that it was more likely a particular channel or
> program caused this sort of problem, rather than live TV versus
> recorded TV.  It is usually caused by trying to overclock the TV,
> which is usually caused by the TV giving the video card bad EDID data.
> The fix is usually to manually configure the available X video modes -
> a painful process.  Or to copy and manually edit the EDID data -
> equally painful.  But it may be possible to override the settings in
> mythfrontend for a particular frame size, if you can identify that as
> the problem.
>
> When playing video that works, take a look at what M(enu) > Playback
>> Playback data shows for the video output, particularly the frame size
> and frame rate.  You can also install mediainfo and use it to read out
> the same data from the file.  Pressing I twice while a recording is
> selected will tell you the file name to use with mediainfo.  While
> playing the video or recording or live TV, Alt-Tab to a command prompt
> on the desktop and run xrandr to see what video mode the video card is
> set to output at the moment.  Here is what I get from an NTSC movie
> file:
>
> Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 8192 x 8192
> DVI-I-0 disconnected (normal left inverted right x axis y axis)
> VGA-0 disconnected (normal left inverted right x axis y axis)
> DVI-I-1 connected primary 1920x1080+0+0 (normal left inverted right x
> axis y axis) 1600mm x 900mm
>    1920x1080     60.00 +  59.94*   50.00    23.97    60.05    60.00
> 50.04  
>    1280x1024     60.02  
>    1280x720      60.00    59.94    50.00  
>    1024x768      60.00  
>    800x600       60.32  
>    720x576       50.00    50.08  
>    720x480       59.94    60.05  
>    640x480       59.94    59.93  
> HDMI-0 disconnected (normal left inverted right x axis y axis)
>
> You can see it is playing at just under 60 Hz, correct for
> deinterlaced NTSC movies.
>
> And this is from an HD recording from DVB-T:
>
> Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 8192 x 8192
> DVI-I-0 disconnected (normal left inverted right x axis y axis)
> VGA-0 disconnected (normal left inverted right x axis y axis)
> DVI-I-1 connected primary 1920x1080+0+0 (normal left inverted right x
> axis y axis) 1600mm x 900mm
>    1920x1080     60.00 +  59.94    50.00*   23.97    60.05    60.00
> 50.04  
>    1280x1024     60.02  
>    1280x720      60.00    59.94    50.00  
>    1024x768      60.00  
>    800x600       60.32  
>    720x576       50.00    50.08  
>    720x480       59.94    60.05  
>    640x480       59.94    59.93  
> HDMI-0 disconnected (normal left inverted right x axis y axis)
>
> Our TV is 50 Hz, and the output frequency has been changed to that.
>
> Do these checks on things that work, then try the live TV that does
> not and see what video mode it is using.  You should be able to
> identify a video mode that is causing the problem, and then we can see
> if it is possible get mythfrontend to map that to a different video
> mode, or whether you will need to set up manual X config.
>
> Also, what Nvidia driver version are you using?  I think there can be
> problems with the latest drivers where the mode commands that
> mythfrontend sends do not match what the drivers do any more, as they
> redefined how those commands work a bit to accommodate 4K and other
> new things.  I have an older card (Nvidia 220) and have to use older
> drivers with it (340.104), so I do not get those problems.
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Thanks for the tips. The playback data ('M' button) shows a
Video:1920x1080 at 25.00fps. Unfortunately, this is a remote machine which
I manage through vnc. Alt+Tab doesnt work on VNC, instead is trapped by
the client.  I am looking into workaround for that. One thing I have
noticed is that if I start using mythfrontend -w -geometry 800x600, the
LiveTV works fine. Normally i using evilwm as a window manager with
mythfrontend as fullscreen. The nvidia driver i am using is
nvidia-drivers-387.22.


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