Ok I've posted this on both ffmpeg and gcc mailing lists and nobody has responded so I'm going to ask here in the hope that someone may have solved this.

Basically whenever I encode with ffmpeg I get this message:

"Compiler did not align stack variables, libavcodec has been misscompiled
and will possible be very slow or may crash, this is not a bug in the
application but in the compiler
so reporting it anywhere but to the compiler maintainers is senseless!"

This is a self compiled CVS version. I've tried some compiled binaries which didnt seem to have this problem (not that I noticed anyway) but the binaries I managed to get hold of didn't have XVID support, so I am forced to roll my own.

Anyone know about this problem and can help. I don't really want to install another version of gcc if I can help it.

well i think if it works ok you can ignore the message.
alot of time the developers like to argue over whose responsibility something is by providing the user with a strange message to complain to the other guy.
one thing is to never use the compile optimization -Os
that is just a terrible thing to do as i think it causes very small stack boundries.
if it actually has problems the way it is you could try one of these
-malign-double
-mno-align-double
-mpreferred-stack-boundary=num
default for the boundry would be 4 for 32 bit and 8 for 64 bit

Yeah it seems to work ok, but it did warn that it may be slower and it does take ages to reencode large files so I'd rather not have it any slower.

But, I did find a binary dated from 2005 that works with xvid and doesn't have the warning so I will stick with that until I find a better way.

Cheers