[Vxl-users] bug report

[Diego M. <dma...@gm...>]

There seems to be a bug in the destruction of the mpegcodec object
stored in the static array created in the function

vidl_codec_sptr* vidl_codec::all_codecs()

(located in core\vidl\vidl_codec.cxx)

The problem manifest itself as a crash when exiting the program. If a
video was loaded in the execution of the program, the static
five-element array created by vidl_codec_storage is destroyed, which
in turns destroy the vidl_mpegcodec object in it. The destructor of
vidl_mpegcodec calls

buffers_->first_frame_num()

(located in core\vidl\vidl_mpegcodec.cxx)

and crashes somewhere inside it (note: buffers_ is not a null
pointer). It seems to be an issue in some tree structure when looking
for an element in it. I don't know why this happens because at this
point in the program, the mpegcodec object was already closed in
~vidl_codec_storage(), so it should not have any data in it.

I found a workaround by deleting the mpeg codec before exiting the
program, but it is an quite ugly solution. Here it is in case someone
needs it.

int main(...)
{
....

// The mpegcodec is in position 1 of the array in my case, but this
may be different in other systems

vidl_codec_sptr* codecs = vidl_codec::all_codecs(); // static
five-element array of codecs

codecs[1]->close(); // close the problem codec as would have been done
if ~vidl_codec_storage() was called

*((bool*) &codecs[1]) = false; // unprotect the pointer to the codec
object without calling unprotect()

return 0;
}