[mythtv-users] black screen during playback

Kenni Lund kenni at kelu.dk
Sat Jan 26 10:03:51 UTC 2013


2013/1/25 Joey Morris <rjmorris.list at gmail.com>:
> 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.

I had that issue back in MythTV 0.24:
http://www.mythtv.org/pipermail/mythtv-users/2011-July/318731.html

I came to the same conclusion as you - Changing the frontend hostname
and hence getting a clean set of settings, fixed the issue. However,
in my case the issue reoccurred some weeks after I reinstalled the
system and changed the hostname. I did some further digging and I
think I identified a VDPAU filter to be the cause of the issue or at
least to be related to the issue. As far as I remember, my VDPAU
filter were set to "vdpaucolorspace=auto". Once I deleted the string
the issue got fixed (I didn't change the hostname / reset the
settings, I only deleted that string) - and since I haven't seen the
issue since, it seems like the issue somehow was related to that VDPAU
filter.

Best regards
Kenni


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