Put an AVIOContext whose lifetime doesn't extend beyond the function where
it is allocated on the stack instead of allocating and freeing it. This
also avoids the need to free it, which in this case fixes possible
memleaks on error.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>