[mythtv-users] Watching live TV video problem (blank/black screen)

Nick Morrott knowledgejunkie at gmail.com
Sat Jun 23 01:22:30 UTC 2007


On 22/06/07, Brad Patterson <bpatterson at espec.com> wrote:
> I just installed a PVR-150 in my myth box last night, and got it working
> "o.k." with an older video card that I had in the machine previously.
> The video during live TV playback was a little herky jerky, though, so I
> swapped out the old GE Force4 MX440 PCI video card with a brand new
> Nvidia FX5200 256MB PCI video card (from PNY).  After I rebooted my
> machine, I went to watch live TV and all I got was 15 seconds of
> blank/black screen (and no sound) and then I was kicked back to the main
> myth menu.
>
> At this point, I thought that maybe I should redo a fresh install of
> Knoppmyth, so I ran that overnight.  This morning, I finished the
> configuration, and re-attempted to watch live TV.  The live TV worked
> fine (although it was still a little herky jerky), but after about 30
> seconds; the screen went blank and a message popped up saying that there
> was a "video output errror" or something to that effect.  At that point,
> I didn't have time to mess around with it anymore, and had to leave for
> work.

LiveTV failing immediately with no playback at all can indicate a
broken video source (bad capture device/bad channels) or bad playback
device (video driver). LiveTV failing after a while can indicate that
your system is not fast enough to play the video, and it bails out.

I would check that you are using the binary nvidia driver with XvMC
support to offload video decoding from the CPU and than MythTV is
using the XvMC support. Check your backend log (typically
/var/log/mythtv/mythbackend.log) for problems with the 'server' side
of things - recording/channels etc - and as Ma suggests, run
mythfrontend from a terminal with the '-v important,general,playback'
logging options to check for messages relating to video output.

-- 
Nick

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