[FFmpeg-devel] [PATCH 11/15] lavc/on2avc: replace pow(10, x) by exp10(x)

[Ronald S. Bultje]

Hi,

On Sat, Dec 26, 2015 at 8:23 PM, Ganesh Ajjanagadde <gajjanag at mit.edu>
wrote:

> On Sat, Dec 26, 2015 at 4:20 PM, Ganesh Ajjanagadde <gajjanag at mit.edu>
> wrote:
> > On Sat, Dec 26, 2015 at 4:08 PM, James Almer <jamrial at gmail.com> wrote:
> >> On 12/23/2015 3:47 PM, Ganesh Ajjanagadde wrote:
> >>> exp10, introduced recently, is superior for the purpose.
> >>>
> >>> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
> >>> ---
> >>>  libavcodec/on2avc.c | 5 +++--
> >>>  1 file changed, 3 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/libavcodec/on2avc.c b/libavcodec/on2avc.c
> >>> index 04c8e41..0409b3e 100644
> >>> --- a/libavcodec/on2avc.c
> >>> +++ b/libavcodec/on2avc.c
> >>> @@ -22,6 +22,7 @@
> >>>
> >>>  #include "libavutil/channel_layout.h"
> >>>  #include "libavutil/float_dsp.h"
> >>> +#include "libavutil/libm.h"
> >>>  #include "avcodec.h"
> >>>  #include "bytestream.h"
> >>>  #include "fft.h"
> >>> @@ -934,9 +935,9 @@ static av_cold int
> on2avc_decode_init(AVCodecContext *avctx)
> >>>                 "Stereo mode support is not good, patch is welcome\n");
> >>>
> >>>      for (i = 0; i < 20; i++)
> >>> -        c->scale_tab[i] = ceil(pow(10.0, i * 0.1) * 16) / 32;
> >>> +        c->scale_tab[i] = ceil(exp10(i * 0.1) * 16) / 32;
> >>>      for (; i < 128; i++)
> >>> -        c->scale_tab[i] = ceil(pow(10.0, i * 0.1) * 0.5);
> >>> +        c->scale_tab[i] = ceil(exp10(i * 0.1) * 0.5);
> >>>
> >>>      if (avctx->sample_rate < 32000 || avctx->channels == 1)
> >>>          memcpy(c->long_win, ff_on2avc_window_long_24000,
> >>
> >> This apparently broke ICC
> >>
> >>
> http://fate.ffmpeg.org/report.cgi?time=20151226215846&slot=x86_64-linux-gnu-icc-2011.4.191
> >>
> http://fate.ffmpeg.org/report.cgi?time=20151226235348&slot=x86_64-linux-gnu-icc-2011_sp1.13.367
> >>
> http://fate.ffmpeg.org/report.cgi?time=20151226203729&slot=x86_64-archlinux-icc-2013
> >
> > Thanks for the report. A couple of questions:
> > 1. Is there an easy way to acquire icc so that I can reproduce?
> > GCC/Clang are perfectly fine with it.
> > 2. Do you know what the ICC platforms use for exp2?
> >
> > In the absence of remarks and my own inability to fix this, I will
> > revert tonight.
> > BTW, please let me know the general policy for this kind of breakage:
> > i.e, how quickly do such regressions need to be fixed.
>
> Different fix pushed that also speeds up things.


You shouldn't push things without review...

Ronald