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

[Hendrik Leppkes]

On Tue, Mar 22, 2016 at 8:02 PM, Ganesh Ajjanagadde <gajjanag at gmail.com> wrote:
> On Tue, Mar 22, 2016 at 11:52 AM, Hendrik Leppkes <h.leppkes at gmail.com> wrote:
>> On Tue, Mar 22, 2016 at 7:37 PM, Ganesh Ajjanagadde <gajjanag at gmail.com> wrote:
>>> 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.
>>
>> This particular doc doesn't give you a blanket argument. Specifically
>> if the maintainer objects on account of complexity, you should honor
>> that - the doc even says as much (ie. only "clean and simple" being
>> justified)
>
> It does not. And of course I honor a maintainer's wishes. If he
> refuses to accept a performance improvement, so be it.
>
> I just want it clear that from my view this is still ridiculous given
> FFmpeg's track record on these sorts of things in the past. I also
> find it ironic that there are objections to this on the lines of "what
> about some (unspecified) platform?", when bccc81dfa was accepted with
> no problems.

A 7% overall improvement is quite a different topic than 0.1%, isn't
it. For 7% on all common platforms, one might risk another outcome on
more obscure cases.

- Hendrik