[FFmpeg-devel] [PATCH] avfilter, swresample, swscale: use fabs, fabsf instead of FFABS

Hendrik Leppkes h.leppkes at gmail.com
Wed Oct 14 12:53:58 CEST 2015

On Wed, Oct 14, 2015 at 12:49 PM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
> Ganesh Ajjanagadde <gajjanag <at> mit.edu> writes:
>> What? My numbers actually show that the new code may be faster -
> No, you are misunderstanding the numbers you posted.
> (Or I misunderstand them but nobody said so yet.)
> Highest runs are most relevant, skips have to be
> avoided (afaik).
> [...]
>> If you continue to post such stuff that has no basis, I might actually
>> get tempted into finding out for which floating point values the new
>> code is significantly faster, craft a relevant audio file, and post it
>> showing a huge performance difference - my random numbers benchmark
>> shows there must exist such values.
> Please do so!
>> > The more important question is if you can see the same
>> > changes in the disassembly of af_astats.o as what
>> > ubitux posted here for a short test function?
>> I do. He uses clang/gcc, so do I.
> Sorry, my understanding fails here (I am not a native speaker):
> You did look at the disassembly of af_astats.o and there is
> inlined code instead of a function call?
>> The reason (irrelevant) is that both
>> of us run Arch.
>> What is "more relevant" is if _you_ can see the changes
>> on some non Linux platform.
> If you could show that it is faster on any platform
> I would already be happy!

A more important check would be that its not significantly slower on
any other platform. Just because one compiler/glibc combination
manages to produce an efficient inlined function doesn't necessarily
mean that some other compiler or libc couldn't produce a full function
call with all the overhead that comes with it, becoming significantly

More information about the ffmpeg-devel mailing list