[FFmpeg-devel] [PATCH 2/3] avcodec/aacsbr: Add comment about possibly optimization in sbr_dequant()

[Michael Niedermayer]

On Thu, Nov 19, 2015 at 09:03:03AM -0500, Ganesh Ajjanagadde wrote:
> On Thu, Nov 19, 2015 at 8:17 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
> > From: Michael Niedermayer <michael at niedermayer.cc>
> >
> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > ---
> >  libavcodec/aacsbr.c |    1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/libavcodec/aacsbr.c b/libavcodec/aacsbr.c
> > index d1e3a91..e014646 100644
> > --- a/libavcodec/aacsbr.c
> > +++ b/libavcodec/aacsbr.c
> > @@ -73,6 +73,7 @@ static void sbr_dequant(SpectralBandReplication *sbr, int id_aac)
> >  {
> >      int k, e;
> >      int ch;
> > +    //TODO: Replace exp2f(0.5*x) by a LUT, the inputs are all integer and have a small range
> 
> Entirely possible I missed something, but exp2 gives 2^x, so if inputs
> are integers, can't one simply do the necessary bit shifts and cast
> implicitly to float?
> I think what you meant was all inputs are half-integers or integers.

i meant all arguments to function f(x) are integers, f(x) = exp2(0.5*x)

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Let us carefully observe those good qualities wherein our enemies excel us
and endeavor to excel them, by avoiding what is faulty, and imitating what
is excellent in them. -- Plutarch
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