[FFmpeg-devel] [PATCH] avcodec/snowenc: fix discarded const warning

Nicolas George george at nsup.org
Sun Sep 20 20:14:33 CEST 2015

Le jour du Labour, an CCXXIII, Ganesh Ajjanagadde a écrit :
> This fixes a -Wdiscarded-qualifiers in e.g
> http://fate.ffmpeg.org/log.cgi?time=20150919093218&log=compile&slot=x86_64-archlinux-gcc-ddebug.
> It is quite clear from the code that the discard of constness was deliberate,
> so the cast should be fine.

It may have been deliberate, but is it right? Unless I am missing somewhere
like last time, the codec is modifying a memory location that could be
read-only, according to the const flag on the function parameter. It will
probably never happen because of how we manage AVFrame allocation, but it is
not satisfactory.

If codecs are authorized to modify basic properties of the input frame, then
const should be removed on the declaration of the encode_frame() method. If
not, then snowenc should be changed to avoid doing it; that last solution
seems not very complicated at a quick glance, just use a separate variable
for quality.


  Nicolas George
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