[mythtv-users] black screen during playback

Joey Morris rjmorris.list at gmail.com
Fri Jan 25 22:03:32 UTC 2013


Joey Morris <rjmorris at nc.rr.com> wrote on Thu, Aug 23, 2012 at 10:27:30PM -0400:
> Joey Morris <rjmorris at nc.rr.com> wrote on Wed, Aug 22, 2012 at 09:40:15PM -0400:
> > I recently upgraded a combined backend/frontend and two frontends from
> > 0.24 to 0.25.2. Several months ago, while I was on 0.24, one of my
> > frontends suddenly stopped displaying video when using a VDPAU
> > profile, instead giving me just audio with a black screen. It worked
> > fine once I switched to a CPU-only profile. I mentioned it in
> > http://www.gossamer-threads.com/lists/mythtv/users/514994, but I never
> > resolved the problem, so I just stuck with the CPU-only profile.
> > 
> > I hoped the problem would resolve itself in 0.25.2, but it's actually
> > worse. Now I get audio but no video even on the CPU-only profile. I
> > tried VDPAU Normal, one of the OpenGL profiles, and Slim. All produce
> > audio and a black screen. One difference is that the OSD is displayed
> > when using VDPAU Normal but not when using Slim (I don't remember what
> > happened with OpenGL.) The video plays fine in VLC.
> > 
> > I've tried the following with no changes:
> >   - swapped in a different video card
> >   - connected via VGA instead of HDMI
> >   - copied the file to the local drive, added it to the video gallery,
> >     and played it from there
> > 
> > I captured logs with -v playback while using the VDPAU Normal profile
> > and the Slim profile. I would be very grateful if someone could review
> > these to see if anything looks amiss. I'm happy to provide other
> > information or logs if needed.
> > 
> >   VDPAU Normal: http://pastebin.com/KvZE1bZY
> >   Slim: http://pastebin.com/r7hzd5G3
> > 
> > I also captured the log on my working frontend running the VDPAU
> > Normal profile and compared it to the one above. The only difference
> > that seemed like it might be significant is the lack of "Video is
> > d.ddddd frames behind audio" messages on the working machine, so I'm
> > not optimistic that these logs I've posted will reveal the problem.
> > 
> > This is on Mythbuntu 11.04 with an NVidia 210 card.
> 
> Tonight I tried using the onboard graphics instead of the 210 card. My
> CPU is the i3-540, which is a Clarkdale. This time I did get video
> using the Slim (and Normal) profile. I didn't get video using the
> OpenGL Normal profile, however.
> 
> At least I have one usable configuration now, but I'd really rather
> have VDPAU working. Does anyone have any ideas?
> 
> Since both of my 210s work on my other frontend and neither work on
> this one, I don't think the card is to blame. I'm beginning to suspect
> it might be a motherboard problem. But before I start buying new
> hardware, I think I'll first see if I can get VAAPI going on this
> system. Maybe that will be good enough that I can live without VDPAU.
> If not, I'll try a reinstall from scratch.

I'm responding to this rather old email to report that I finally
solved the problem, in case it helps someone searching the archives in
the future.

I tried everything I could think of to isolate the problem:
systematically swapping out every piece of hardware in the system,
reinstalling the OS, upgrading Myth to 0.26, and deleting the playback
profiles so Myth would regenerate the default ones. I still had the
problem of the black screen during video playback using VDPAU. Nothing
in the logs pointed to a problem.

Finally it occurred to me that a common denominator between all these
configurations was the hostname, which Myth uses to pull in settings
from the database. I gave the system a new hostname, and my video with
VDPAU returned! I have no idea which setting in the database was
causing the problem.

The lesson for me in this exercise was that to get a truly clean slate
with a Mythfrontend re-install, you have to use a new hostname.
Otherwise you'll pick up all the settings from your previous install.


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