[FFmpeg-devel] [PATCH 10/11] avfilter/vf_ssim: use log10 instead of log()/log(10)

[Ronald S. Bultje]

Hi,

On Thu, Oct 29, 2015 at 2:07 PM, Ganesh Ajjanagadde <gajjanag at mit.edu>
wrote:

> On Thu, Oct 29, 2015 at 1:37 PM, Michael Niedermayer
> <michael at niedermayer.cc> wrote:
> > On Thu, Oct 29, 2015 at 12:20:08AM -0400, Ganesh Ajjanagadde wrote:
> >> This is likely more precise and conveys the intent better.
> >>
> >> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
> >> ---
> >>  libavfilter/vf_ssim.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/libavfilter/vf_ssim.c b/libavfilter/vf_ssim.c
> >> index ce1e3db..6b2a8d7 100644
> >> --- a/libavfilter/vf_ssim.c
> >> +++ b/libavfilter/vf_ssim.c
> >> @@ -176,7 +176,7 @@ static float ssim_plane(SSIMDSPContext *dsp,
> >>
> >>  static double ssim_db(double ssim, double weight)
> >>  {
> >> -    return 10 * (log(weight) / log(10) - log(weight - ssim) / log(10));
> >> +    return 10 * (log10(weight) - log10(weight - ssim));
> >
> > LGTM
> >
> > note, this can be simplified further but thats maybe off topic in
> > relation to switching to log10
>
> I did note that you can rewrite as log10(weight/(weight-ssim)), but
> avoided it deliberately as I did not know what people want with
> respect to it. Since you brought it up and think it may be good, I
> will change it.
>
> I personally don't consider it too off topic, and prefer this over
> sending a separate patch for the simplification and dealing with
> another wm4 rant about it.
> Will push all later, once everything is reviewed and ok'ed.


Now, now, let's stay friendly and professional...

Ronald