[PLUG] MythTV frontend failure to play video = solved

[JP Vossen <jp@jpsdomain.org>]

This is related to the "Ubuntu 7.10 on Optiplex with i810 video" thread 
because I thought that the MythTV frontend failure to play video was a 
video driver problem.  Looks like it wasn't, though see bottom.


Problem: on a clean install of Gutsy (with Gnome desktop), everything in 
a clean install of the MythTV frontend GUI worked except for actually 
watching LiveTV and recordings.  (Optiplex GX 260)


Solution short version:  ID10T error.
MythTV: Utilities / Setup; Setup; General; Database Configuration 2/2: 
"Use custom identifier for frontend preferences" is *not* a "friendly" 
name, it's more like a hostname.  So *don't* use something stupid like 
"JP's Office" in that field!!!


Solution long version:
I thought I was being clever with the setting above, but it caused a lot 
of wasted time.  Everything in the GUI worked, except for playing LiveTV 
and recordings.  I could see the program guide, set the recording 
schedule, etc., etc.  But I couldn't watch anything, I'd just get a 
black screen for a few seconds, then bounce back into the GUI.

During other t-shooting for the supposed video problem, I happened to 
run mythfrontend from the command line, which allowed me to see lots of 
log messages.  Like these:

2007-10-07 16:50:08.395 TV: Attempting to change from None to WatchingLiveTV
2007-10-07 16:50:08.407 Using protocol version 31
2007-10-07 16:50:15.753 MythSocket(829c668:15): readStringList: Error, 
timeout (quick).
ASSERT: "i <= nodes" in /usr/include/qt3/qvaluelist.h (373)
2007-10-07 16:50:15.754 decodeLongLong() called with offset >= list size.
2007-10-07 16:50:15.755 DPMS Deactivated
2007-10-07 16:50:15.812 
RingBuf(myth://192.168.xx.90:6543/1006_20071007165008.mpg) Error: 
RingBuffer::safe_read(RemoteFile* ...): read failed
[...]
2007-10-07 16:50:15.812 
RingBuf(myth://192.168.xx.90:6543/1006_20071007165008.mpg) Error: 
RingBuffer::safe_read(RemoteFile* ...): read failed
2007-10-07 16:50:15.812 NVP::OpenFile(): Error, couldn't read file: 
myth://192.168.xx.90:6543/1006_20071007165008.mpg
2007-10-07 16:50:15.814 TV Error: StartPlayer(): NVP is not playing 
after 20000 msec
2007-10-07 16:50:15.970 TV Error: LiveTV not successfully started
2007-10-07 16:50:15.991 DPMS Reactivated.

Those "can't get there from here" messages made me I looked in the 
backend server log /var/log/mythtv/mythbackend.log and see things like 
these:
2007-10-07 16:43:31.648 MainServer::HandleAnnounce Playback
2007-10-07 16:43:31.651 adding: JP's as a client (events: 0)
2007-10-07 16:43:31.654 Bad ANN query
2007-10-07 16:43:38.659 Unknown socket closing
2007-10-07 16:43:40.744 Unknown file transfer socket: 0
2007-10-07 16:43:40.756 MainServer::HandleAnnounce Playback

The "JP's" was the tipoff.  Uh oh, it shouldn't look like that...  But I 
hadn't been looking there because I thought it was a frontend video 
problem.  Doh...

So I turned off the "custom identifier" option in the frontend, shut it 
down, then went into the DB and fixed it.  The correct name should be 
'foster-host', which I noted when I looked for settings.  I didn't feel 
like manually re-setting everything, so I did it all in the DB.

# Show me frontend specific settings
select * from settings where hostname != '(NULL)' order by value;

# Delete any new settings just created by turning off the bad value
delete from settings where hostname = 'foster-host';

# Rename the old, bogus name to the new correct one
update settings set hostname = 'foster-host' where hostname = "JP's Office";

When I fired the frontend back up, everything worked!

Note a sub-symptom was a long delay (due to failures and timeouts) when 
going into the Media Library; Watch Recordings menu, since that tries to 
play thumbnails of the current selection.

Also note that just before I did this, I was also messing with the video 
driver (more on that in its thread later).  So it's possible that I had 
two problems at the same time, the above and a bad video setup.  I doubt 
it, but I mention it for completeness...  What I basically did there was 
to remove the i810 and 915resolution drivers, 'sudo apt-get install 
xserver-xorg-video-intel' and 'sudo dpkg-reconfigure xserver-xorg'.

That has thus far *not* solved the "a few pixels cut off at top of 
screen" problem, but since MythTV frontend now works I don't really care.


Thanks for the tips and hope this is useful for someone,
JP
----------------------------|:::======|-------------------------------
JP Vossen, CISSP            |:::======|        jp{at}jpsdomain{dot}org
My Account, My Opinions     |=========|      http://www.jpsdomain.org/
----------------------------|=========|-------------------------------
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