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

[Ganesh Ajjanagadde]

On Thu, Oct 15, 2015 at 6:57 AM, Hendrik Leppkes <h.leppkes at gmail.com> wrote:
> On Thu, Oct 15, 2015 at 12:53 PM, Ganesh Ajjanagadde <gajjanag at mit.edu> wrote:
>> On Thu, Oct 15, 2015 at 6:50 AM, Hendrik Leppkes <h.leppkes at gmail.com> wrote:
>>> On Thu, Oct 15, 2015 at 12:41 PM, Ganesh Ajjanagadde <gajjanag at mit.edu> wrote:
>>>> On Thu, Oct 15, 2015 at 6:37 AM, Hendrik Leppkes <h.leppkes at gmail.com> wrote:
>>>>> On Thu, Oct 15, 2015 at 12:34 PM, Ganesh Ajjanagadde <gajjanag at mit.edu> wrote:
>>>>>> On Wed, Oct 14, 2015 at 6:50 AM, Hendrik Leppkes <h.leppkes at gmail.com> wrote:
>>>>>>> On Wed, Oct 14, 2015 at 12:37 PM, Ganesh Ajjanagadde <gajjanag at mit.edu> wrote:
>>>>>>>> On Wed, Oct 14, 2015 at 5:01 AM, Matt Oliver <protogonoi at gmail.com> wrote:
>>>>>>>>> On 14 October 2015 at 09:46, Ganesh Ajjanagadde <gajjanag at mit.edu> wrote:
>>>>>>>>>
>>>>>>>>>> On Tue, Oct 13, 2015 at 9:12 AM, Ganesh Ajjanagadde <gajjanag at mit.edu>
>>>>>>>>>> wrote:
>>>>>>>>>> > On Tue, Oct 13, 2015 at 4:02 AM, Clément Bœsch <u at pkh.me> wrote:
>>>>>>>>>> >> On Tue, Oct 13, 2015 at 09:25:03AM +0200, Paul B Mahol wrote:
>>>>>>>>>> >> [...]
>>>>>>>>>> >>> What about fmax/FFMAX?
>>>>>>>>>> >>
>>>>>>>>>> >> Feel free to try that out (it looks OT regarding the patch), but fmax()
>>>>>>>>>> >> looks glibc specific
>>>>>>>>>>
>>>>>>>>>> Seems they are actually ISO:
>>>>>>>>>> http://en.cppreference.com/w/c/numeric/math/fmax
>>>>>>>>>>
>>>>>>>>>> Can someone check availability on all of our platforms of interest
>>>>>>>>>> (e.g Microsoft)?
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> fmax and fmin are only available on msvc using 2013 or newer. Currently the
>>>>>>>>> only msvc version without fmax/fmin that FFmpeg supports is 2012 which uses
>>>>>>>>> the C99 to C89 converter.
>>>>>>>>
>>>>>>>> And does that converter handle fmin, fmax, fmaxf, etc?
>>>>>>>> Does it need patches?
>>>>>>>> Bottom line: are they safe to use at the moment?
>>>>>>>>
>>>>>>>
>>>>>>> No, they are not.
>>>>>>>
>>>>>>> One thing I don't understand - why are we bothering with something
>>>>>>> that at best comes out as "same speed" from tests performed? (low
>>>>>>> number of runs are irrelevant as they are not statistically
>>>>>>> significant).
>>>>>>
>>>>>> Because if you actually bothered to run my random numbers benchmark
>>>>>> instead of posting with no basis claiming "statistical
>>>>>> insignificance", or for that matter matter bothered to actually check
>>>>>> the libc link, or even looked at Clement's asm test - you would
>>>>>> finally understand.
>>>>>>
>>>>>> Also, what needs to be done to get fmax, fmin, etc into the converter?
>>>>>>
>>>>>
>>>>> The converter doesn't provide any functions, just alters the syntax if
>>>>> needed. Functions not available cannot be fixed that way, sorry.
>>>>
>>>> Thanks for clarifying. I am still confused: how do we have llabs then?
>>>> Per MSDN, this was not present in MSVC 2012, and was added in MSVC
>>>> 2013 (looks like a similar case to fabs, fabsf).
>>>>
>>>
>>> Docs appear to be wrong in that particular case. It happens sometimes
>>> that functions are available but didn't get added to the docs.
>>
>> But with respect to fmin, fmax, etc - they were not available in 2012,
>> and the docs are right? Are you sure, and have you tested?
>>
>
> Yes those are definitely not available.

Thanks for the check. So you mentioned we can't add fmin/fmax with the
c99-89 converter. I noticed we have a libavutil/libm.h: couldn't a
"portable" fmin/fmax etc go there?

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