[XviD-devel] segmentation fault
Henning Moll
newsScott at gmx.de
Sun Oct 3 15:20:37 CEST 2004
Hello!
Unfortunately, i have problems using the xvid codec. The whole thing is
a little bit strange, so i will tell you all details i recognized up to
now:
The codec will fail with an segmentation fault _mostly_ during the
second pass of two-pass-encoding. I checked this with several programms
on different OSes: (mencoder, transcode, gordian knot). All show the
same problem.
Now the interesting thing: On the same data, with same parameters, the
segmentation fault appears on different frames. It's kind of random.
Now you think of an hardware problem, but i don't think it is: I don't
have any similar behaviour with other software. Every other codec is
working with all of the programms mentioned above, but not yours... :-(
To weaken that hardware failure theory, i also recompiled transcode and
xvid without special hardware usage (assembly code, MMX, and so). But
the same effect there (only hours later ..;-)
The chance of such a segmentation fault is not very likely, but it
happens often enough to make encoding with xvid nearly impossible.
On different tries it crashes in different functions, but at the moment
i remember only on symbol name:
transfer_8to16sub_mmx
All the other functions where it happends sound similar.
Hmm, now i need your help. What can i do to track down that problem
more?
Any suggestions?
I don't know much of CPUs and that stuff, but I thought of something
like a hardware random number generator. Is there something like that?
Maybe there exists a model range of my CPU which have a slightly
different implementation. Maybe that slightly difference is enought to
let your code segfault? BTW: i have an AMD XP1800+
Are you agree with my theory, that it can not be a hardware _defekt_,
because other (comparable) programms do not have any problems? If not,
why?
Kind regards
Henning
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