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

James Darnley james.darnley at gmail.com
Sun Oct 11 00:10:39 CEST 2015

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?

I think this is a case of premature optimization.

On the other hand if people want to replace the current algorithm then
who am I to stop them.

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