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

[Hendrik Leppkes]

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.