[MPlayer-users] mencoder crashes

[Corey Hickey]

Martin Collins wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> On Wed, 21 May 2003 18:06:23 +0400
> "Vladimir I. Umnov" <samba at ezmail.ru> wrote:
> 
> 
>>At the end of the first pass current cvs
>>mencoder crashes always. Command I use:
>>mencoder dvd://1 -o /dev/null -oac copy \
>>-ovc lavc -ofps 23.976 -noaspect -vop
>>scale=512:320,hqdn3d,crop=720:380:0:50 -sws 2 \-lavcopts
>>vcodec=mpeg4:vlelim=-4:vcelim=9:vmax_b_frames=1:vb_qoffset=0.6:vb_s
>>trategy=1:\
>>vqscale=2:vpass=1:lumi_mask=0.05:dark_mask=0.01:naq:v4mv:vhq 
> 
> 
> If you get a core dump post the gdb backtrace.
> Try removing options one by one, starting with vmax_b_frames then the
> vb_ ones.
> There was a similar sounding problem with b-frames and mpeg4 a while ago.
> It was fixed but maybe it's crept back in.
> 
> Martin
> 

Yes, try to narrow it down to a single option that causes the problem.

Since this is a crash at the end of a pass, it might take a while,
though. You can try using -ss to seek to almost the end of the DVD,
but that might not work right (search the archives if you're curious
why. If you have the disk space, you can dump the whole DVD to your
hard disk with mplayer dvd://1 -dumpstream. Seeking with -ss should
work on that file, except that it'll be inaccurate (I forget why).
You'll have to use trial and error. Or you can try hitting CTRL-C after
a few seconds of stream-dumping, and test against that file. Either way,
test encoding with the same options as above, and see what happens. If
you get the same crash, that's good and you have a much shorter
testing-time. Otherwise, your CPU is in for some toasting. :)

If it seems you have to test the entire encode each time, then I would
recommend this order:
1. Change -ovc lavc to -ovc copy (and get rid of -lavcopts). This'll
tell you if the fault is with mencoder or within lavc.
2. If -ovc copy works, then try removing some lavcopts. To be more
efficient, remove the options that slow down the encoding the most.
You might save yourself several hours this way. Offhand, I think
vhq,v4mv, and vmax_b_frames are the most CPU intensive, so try removing
them all at once.
3. Add or remove options until you find which one causes the problem.

If the fault lies within one of the lavc options, you should probably
report the bug to the ffmeg-devel mailing list (follow mplayer's 
DOCS/bugreports.html).
http://lists.sourceforge.net/lists/listinfo/ffmpeg-devel

Good luck,
Corey