[mythtv-users] jumping frames, out of order, and frontend segfaults

Jason Joines jason at joines.org
Mon May 14 16:30:04 UTC 2007

     I'm using mythtv 0.20-0.2 with a Hauppauge PVR 150 on Kubuntu 6.10 
with an AMD AM2 3000+ cpu and 1 GB ram.

     Recently I noticed the picture seemed jumpy during playback.  I 
eventually realized that what was happening was future frames were being 
shown out of order.  For example, if a person was about to nod there head, 
you would see a flash of where there head was about to me, a moment later 
they would move there head there.

     It's been getting worse and yesterday the frontend crashed for the 
first time.  I got a couple of errors in my system log such as this:

May 13 18:52:08 myth kernel: [1923098.337467] mythfrontend[20651]: 
segfault at 00002aaab4cf9250 rip 00002b419792fb90 rsp 0000000044881a60 
error 4
May 13 20:38:47 myth kernel: [1929491.029774] mythfrontend[21294]: 
segfault at 00002aaaafdd7b00 rip 00002b17cd87b270 rsp 000000004307eed8 
error 6

     There are a lot of errors in the backend log like this:
[mpeg2video @ 0x2b288497cfd0]end mismatch left=584 DEFA9
[mpeg2video @ 0x2b288497cfd0]Warning MVs not available
[mpeg2video @ 0x2b288497cfd0]ac-tex damaged at 43 29
[mpeg2video @ 0x2b288497cfd0]Warning MVs not available
[mpeg2video @ 0x2b288497cfd0]ac-tex damaged at 24 29
[mpeg2video @ 0x2b288497cfd0]invalid cbp at 0 8
[mpeg2video @ 0x2b288497cfd0]Warning MVs not available
[mpeg2video @ 0x2b288497cfd0]00 motion_type at 4 29
[mpeg2video @ 0x2b288497cfd0]ac-tex damaged at 30 21
[mpeg2video @ 0x2b288497cfd0]Warning MVs not available
[mpeg2video @ 0x2b288497cfd0]invalid mb type in I Frame at 44 29
[mpeg2video @ 0x2b288497cfd0]Warning MVs not available
[mpeg2video @ 0x2b288497cfd0]ac-tex damaged at 44 16

     Another symptom has cropped up related to being out of order.  Several 
times I've got near the end of a recording and realized I'd fast forwarded 
past the last scene.  I rewound to a spot I knew was before the scene, say 
27:50 and watched to the end but didn't see it, just a commercial.  Then I 
rewound again and saw a different commercial at the same time index.  This 
has happened several times.
     It has even jumped forward a few times during the rewind.

     A few days ago, I thought the problem might be related to load and 
commercial flagging.  I disabled auto commercial flagging in the frontend 
setup and disabled auto skip of the commercials since they weren't being 
     However, last night it was still flagging commercials.  Thinking 
backend might need to be restarted before the change took affect, I 
restarted it this morning.  However, the it kept showing commercial flags 
in the queue.
     I manually killed the mythcommflag job and the load started dropping 
dramatically.  Then it popped up again and I had to manually kill it 
     How do you disable commercial flagging?  Any other ideas as to what 
could be causing the frame ordering issues?

Jason Joines

More information about the mythtv-users mailing list