[FFmpeg-devel] Detecting invalid filter parameters

[Jean Delvare]

Hi FFmpeg developers,

The delogo video filter currently doesn't check the logo area passed as
parameters for validity. If the logo area is partly outside of the
frame or inside but too close to the border, the code will silently
trim the area to make it fit inside the frame, then go on, with
undesirable results.

I would like to add a check for the delogo filter parameters to ensure
that there is enough frame room around the area to execute the
algorithm.

My question is: do I have to do this check in filter_frame() for every
frame, or can I do it once in init() and be done with it? Or is it
supposed to be done in config_props()? I read the documentation about
config_props but I'm afraid it did not really enlightened me as to what
this callback is for. For performance reasons I'd like to avoid
performing the same check repeatedly.

Sorry if this sounds like a newbie question but well I guess that's
what I am. I'm still not sure what is the difference between filter
links and pads (or more generally what pads are)...

Thanks,
-- 
Jean Delvare
SUSE L3 Support