[FFmpeg-devel] [PATCH] lavu/frame: Optimize frame_copy_video

Jean Delvare jdelvare at suse.de
Tue Dec 15 11:44:55 CET 2015

Hi Hendrik,

On Tue, 15 Dec 2015 11:31:57 +0100, Hendrik Leppkes wrote:
> On Tue, Dec 15, 2015 at 11:20 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
> > On Tue, Dec 15, 2015 at 08:58:01AM +0100, Jean Delvare wrote:
> >> Also I can see 12 occurrences of the same cast for this parameter of
> >> function av_image_copy() in the ffmpeg code already. And over 20 more
> >> similar casts for similar parameters of other functions
> >> (ff_combine_frame, swr_convert, copy_picture_field...) So I'm not
> >> introducing anything new, just proposing one more of the same.
> >
> > yes, I have no real oppinion on this except that C is insane or I am
> > and i dont really mind to apply the patch if thats what people prefer.
> > Any real compiler that follows this litterally and breaks the code is
> > IMHO a compiler one should avoid (quite independant of it being used
> > for FFmpeg or other things) unless one wants to language lawyer around
> > on such things instead of writing usefull code
> The "speed up" from removing a copy of 4 pointers is negligible as
> well however, so maybe it should just be kept like it is.

Originally I proposed this patch for performance reasons and also
because I think it makes the code more readable. But seeing how the
same cast is already present everywhere in the ffmpeg code, I would now
also invoke consistency. There's no rationale for not doing the same
here that is already done everywhere else. If it caused any problem we
would know by now (and I verified that this patch passes the test
suite, FWIW.)

Jean Delvare
SUSE L3 Support

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