On Sat, Oct 31, 2015 at 10:15 AM, Ganesh Ajjanagadde <gajja...@mit.edu> wrote: > On Fri, Oct 30, 2015 at 7:29 PM, Michael Niedermayer > <mich...@niedermayer.cc> wrote: >> On Fri, Oct 30, 2015 at 06:53:34PM -0400, Ganesh Ajjanagadde wrote: >>> On Fri, Oct 30, 2015 at 6:35 PM, Michael Niedermayer <michae...@gmx.at> >>> wrote: >>> > From: Michael Niedermayer <mich...@niedermayer.cc> >>> > >>> > This should fix the build failure of avf_showcqt.c >>> > >>> > An alternative solution would be to add a check for fmin/fmax to >>> > fate-source and >>> > then to replace them by FFMIN/FFMAX, i can do that if preferred? >>> > >>> > Untested due to lack of a affected platform >>> >>> I recall some interest on my end to get fmin, fmax etc for different >>> reasons, and it was remarked that commit >>> 4436a8f44dedc83767b3d9da9beb85d1fae2ca30 may be relevant. The summary >>> seems to be that getting it to work on all platforms is not so simple. >> >> :/ >> ill replace the problematic ones by FFMIN/MAX for now so the build >> failure on the affected msvc platforms is fixed >> tieing a build fix to this complexity would be unwise >> >> >>> I am definitely interested in getting it to work in order to replace >>> FFMAX/FFMIN for floating point in especially libavfilter. This will >>> allow better nan signalling at a slight performance cost. >> >> would that performance cost affect all systems or just ones not >> having fmin/fmax ? >> i think affecting all systems would be bad > > A correct fmin and fmax will be slower than FFMIN/FFMAX, simply > because they do NaN handling. How much slower, I have not tested. Also > note that flags may be passed to the compiler to ignore NaN's, > something which can possibly be done locally if desired. However, I > view FFMAX/FFMIN as the cleaner solution if NaN signalling/propagation > is not an issue, so I may not pursue this. >
Common problem with FFMIN/FFMAX (and other macros that evaluates arguments more than once): FFMAX(a, myfunc(b)) will call myfunc twice (OK compiler may optimize it and call myfunc once) and often people don't care about it. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
