[FFmpeg-devel] [PATCH] lavc/aacenc_utils: unroll abs_pow34_v loop

Ganesh Ajjanagadde gajjanag at gmail.com
Tue Mar 22 19:37:16 CET 2016


On Tue, Mar 22, 2016 at 11:30 AM, Rostislav Pehlivanov
<atomnuker at gmail.com> wrote:
> On 22 March 2016 at 18:14, Ganesh Ajjanagadde <gajjanag at gmail.com> wrote:
>>
>>
>> Per doc/optimization.txt, aac is a widely used codec, so even a 0.1%
>> improvement in aac is fair game for optimizations, assuming it is a
>> small code change. Of course, one can debate whether this is small or
>> not. I view it as simple and clean, others may disagree.
>
>
> Nope, I still doubt that that 0.1% is a definite performance improvement.

Then change doc/optimization.txt.

> Sure it might be on your machine but who knows, maybe for someone else
> it'll be a 0.1% decrease in performance or hell, a 1% decrease.

Don't speculate, show evidence. This is something that can be said
about essentially all patches that affect performance. For example,
who knows, a compiler may actually omit worse code on a certain
architecture for something that should be an improvement. This just
highlights the ridiculousness of this line of reasoning.

> Maybe if
> you ran the test when the Moon was overhead the extra decrease in gravity
> could affect a nearby sea or lake and speed up water evaporation,
> saturating the air with more moisture and therefore increasing its ability
> to contain heat causing your CPU to throttle less since it's cooler.

This is very creative and funny, but is not part of serious discussion.

> Still far too small to justify this patch as a non-placebo improvement.
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