[FFmpeg-devel] On need in AVFrame accessors
Nicolas George
nicolas.george at normalesup.org
Wed Aug 22 14:03:10 CEST 2012
Le sextidi 6 fructidor, an CCXX, Andrey Utkin a écrit :
> The reason to have them was to... ehm, likely, to make faster
> accessing these fields than through av_opt_ptr,
Faster yes, but mostly more reliable: av_opt_ptr is type-pruned and needs to
be checked for failure.
> and ability to make
> accessors non-trivial if needed.
That was not a goal, even though it is a possibility if the need should
arise.
> Thus, no difference/benefit in them comparing with direct
> get/set operation.
The direct get/set operations are forbidden because the position of the
field is not part of the public ABI of the library: for these fields, and
only these, the developers are allowed to move them around in the structure
without bumping the major version. It breaks any dynamically-linked
application that accesses them directly.
Regards,
--
Nicolas George
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