[FFmpeg-devel] [PATCH] Change round to rint in atrac3.c

Michel Bardiaux mbardiaux
Mon Oct 15 14:52:13 CEST 2007

M?ns Rullg?rd a ?crit :
> Fred Rothganger <fred at rothganger.org> writes:
>> I am compiling ffmpeg under cygwin with -mno-cygwin, and then linking
>> the resulting static libs under MSVC 2005 edition.  There are three
>> symbols that remain undefined at link time:
>> _snprintf
>> _gettimeofday
>> _round
>> This patch addresses _round.  Don't know what the efficiency impact is
>> of using rint() and cast rather than round().
> It's not only a matter of efficiency, it's also a matter of
> correctness.  Using rint() here is plain wrong for several reasons.
> Firstly, rint() uses the current rounding direction, which we have no
> control over, thus making the exact output unpredictable.  

Mmm, then why all those calls to lrint and lrintf?

> Secondly,
> rint() raises the inexact exception when the argument is not an
> integer.
> Just get a C99-compatible libc and be done with it.

Michel Bardiaux
R&D Director
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