On Sat, Oct 10, 2015 at 6:10 PM, James Darnley <james.darn...@gmail.com> 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? > > I think this is a case of premature optimization.
The new algorithm is essentially as readable as the old one, is well established and is widely used. FFmpeg accepts commits even for a 10% improvement in an init function (commit 1bc873acd6e15eaca8c2aebfd7dc6472b0429c50) that is rarely called. av_gcd is actually more widely used than the resampler init, so this should be at least as useful. Also, av_gcd is used in the rescale functions, which are very widely used. Maybe in avcodec they are mostly for timestamps, but avfilter uses rescaling heavily. > > On the other hand if people want to replace the current algorithm then > who am I to stop them. I don't care either way. If FFmpeg does not want simple speed improvements like this, then I will return to fixing bugs, security issues, etc. > > > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
