[mythtv-users] Backend crashing when changing live tv channel

[Craig Huff]

I am running MythTV 0.23 on Mythbuntu 10.04.  Since I had to change
over to using Comcast tuner boxen to deal with digital cable to feed
my pair Hauppauge PVR-500s, I have been getting crashes the first time
I (actually the wife, to be accurate) try to watch live tv through
MythTV.  [Hey, at least I was able to negotiate having all four tuner
boxes dedicated to Myth, and it _should_ just work, right?] ;-)

I didn't have any such trouble when I was using the tuners in the
PVR-500s, and the tuning scripts work just fine when invoked manually
or for scheduled recordings.  From what I can see in the logs, the
problem isn't so much with the channel changing itself, but about a
second after the channel change a memory corruption error occurs.  I
could use help figuring out what's going on and how to fix it.

FWIW, here's a short snippet from mythbackend.log surrounding the time
of one such crash:

2010-11-11 18:47:01.198 TVRec(1): Changing from None to WatchingLiveTV
2010-11-11 18:47:01.210 TVRec(1): HW Tuner: 1->1
2010-11-11 18:47:02.236 ret_pid(0) child(10643) status(0x0)
2010-11-11 18:47:03.237 ret_pid(0) child(10643) status(0x0)
2010-11-11 18:47:04.238 ret_pid(0) child(10643) status(0x0)
2010-11-11 18:47:05.238 ret_pid(0) child(10643) status(0x0)
2010-11-11 18:47:06.239 ret_pid(0) child(10643) status(0x0)
2010-11-11 18:47:07.239 ret_pid(0) child(10643) status(0x0)
247    <--N.B.: Echo from tuner script reporting the channel to which
the Motorola DCT2524 cable box was tuned.
2010-11-11 18:47:07.288 ret_pid(10643) child(10643) status(0x0)
2010-11-11 18:47:07.288 External Tuning program exited with no error
2010-11-11 18:47:08.385 ProgramInfo(): Updated pathname '':'' ->
'1247_20101111184707.mpg'
2010-11-11 18:47:08.461 ProgramInfo(): Updated pathname '':'' ->
'1247_20101111184707.mpg'
2010-11-11 18:47:08.472 AutoExpire: CalcParams(): Max required Free
Space: 2.0 GB w/freq: 15 min
 *********************** WARNING ***********************
 ivtv drivers prior to 0.10.0 can cause lockups when
 reading VBI. Drivers between 0.10.5 and 1.0.3+ do not
 properly capture VBI data on PVR-250 and PVR-350 cards.

2010-11-11 18:47:08.675 TVRec(1): Changing from WatchingLiveTV to None
2010-11-11 18:47:08.677 ProgramInfo(1247_20101111184707.mpg), Error:
Unknown type, recording width was 0
*** glibc detected *** /usr/bin/mythbackend: malloc(): memory
corruption: 0x0883e229 ***
======= Backtrace: =========
/lib/tls/i686/cmov/libc.so.6(+0x6b591)[0x1c96591]
/lib/tls/i686/cmov/libc.so.6(+0x6e395)[0x1c99395]
/lib/tls/i686/cmov/libc.so.6(__libc_malloc+0xec)[0x1c9b02c]
/usr/lib/nvidia-current/libGL.so.1(+0x33e80)[0x16bee80]
======= Memory map: ========
00110000-001b9000 r-xp 00000000 08:02 952332
/usr/lib/libmythavformat-0.23.so.0.23.0
001b9000-001bc000 r--p 000a9000 08:02 952332
/usr/lib/libmythavformat-0.23.so.0.23.0
001bc000-001c2000 rw-p 000ac000 08:02 952332
/usr/lib/libmythavformat-0.23.so.0.23.0


Any help would, as usual, be greatly appreciated.

Craig.