[mythtv-users] Mythtv Random segfaults SOLVED it was a hardware problem.

[Alan Anderson]

Hi,

I believe others have reported this issue so I thought I would post my 
findings.

I have two backends both running FC4 mythtv-0.18.1-114.

I was seeing the following issues on the MBE.

Transcodeing would sometimes fail.  Most times with a cutlist update error 
other times no error at all.

Commercial flagging appeared to finish, but there was no listing of a 
commflag.  If I ran mythcommflag by hand it would occasionally segfault.

The masterbackend would exit with no errors (I suspect it was segfaulting).
The mythfront end would also segfault while playing back a recording or just 
running through the menu nothing consistant.

All of this was very intermittant.

I ran across a nuv to avi transcode script on the gossamer threads, mencoder 
failed each time on the MBE with a segfault but ran clean on the SBE.

I ended up underclocking the motherboard and so far all these issues have gone 
away.  I have been busy re-flagging the commercials and transcodeing all the 
recordings that have failed over the last month.  It will be days before I 
can verify if things are stable.  But so far everything looks promissing.

The MB is a Abit AN7 N-force chipset, AMD 3200+ DDR400 memory.  Running with 
the default BIOS setting.

So besides being a darn good transcode script this script also makes a pretty 
good mythtv diagnostic.  At least for me it gave a easily re-produceable 
failure that I could work with, and confirmation that the issue was solved 
when it did eventually run clean.

#!/bin/sh
#
#TARGET="source.nuv"
TARGET=$1
#OUTPUT="/data/video/new-file.avi"
OUTPUT=$2

#optimal bitrate is 5.86*width*height

OPTIONS="vbitrate=3000000:mbd=2:keyint=132:vqblur=1.0:cmp=2:subcmp=2:dia=2:mv0:last_pred=3"

rm -f frameno.avi

nice -n 19 mencoder $TARGET -vop denoise3d,lavcdeint \
-ovc lavc -lavcopts vcodec=msmpeg4v2:$OPTIONS:vpass=1 \
-oac mp3lame -lameopts cbr:br=128 \
-o $OUTPUT

nice -n 19 mencoder $TARGET -vop denoise3d,lavcdeint \
-ovc lavc -lavcopts vcodec=msmpeg4v2:$OPTIONS:vpass=2 \
-oac mp3lame -lameopts cbr:br=128 \
-o $OUTPUT


I dropped the FSB from 199MHZ to 166MHZ, and the above script ran clean on the 
MBE.  Later I will need to start cranking it back up till I can find the 
breaking point. 

To the Author of the script thanks.  

Hope this info helps.
Alan Anderson