[FFmpeg-devel] [PATCH] avutil/mathematics: speed up av_gcd by using Stein's binary GCD algorithm

Michael Niedermayer michael at niedermayer.cc
Sun Oct 11 00:26:35 CEST 2015

On Sun, Oct 11, 2015 at 12:10:39AM +0200, James Darnley wrote:
> On 2015-10-10 23:06, Ganesh Ajjanagadde wrote:
> > ...
> Is the greatest common denominator (yes, I had to look that up) actually
> used anywhere that is slow and needs to be fast?
> All the uses of 'av_gcd' found by grep appear be dealing with timing.  I
> see framerate, timebase, scale.  I do see uses in rational.c which
> implies uses through AVRational, how many codecs are using rational
> numbers in their processing?

some of the timebase related code does run per packet and some
audio codecs have rather short duration packets so it could be
that in case of such codecs on embeded hw the timebase related
calculations are not as insignificant as one might expect but
I dont know


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