[FFmpeg-devel] [PATCH] Move cbrt tables to a separate cbrt_data(_fixed).c files.

Reimar Döffinger Reimar.Doeffinger at gmx.de
Sun Mar 13 18:09:50 CET 2016


On Sun, Mar 13, 2016 at 05:53:10PM +0100, Reimar Döffinger wrote:
> On Sun, Mar 13, 2016 at 05:50:17PM +0100, Hendrik Leppkes wrote:
> > On Sun, Mar 13, 2016 at 5:24 PM, Ganesh Ajjanagadde <gajjanag at gmail.com> wrote:
> > >> @@ -75,9 +66,8 @@ static av_cold void AAC_RENAME(cbrt_tableinit)(void)
> > >>          }
> > >>
> > >>          for (i = 0; i < 1<<13; i++)
> > >> -            cbrt_tab[i] = CBRT(cbrt_tab_dbl[i]);
> > >> +            AAC_RENAME(ff_cbrt_tab)[i] = CBRT(cbrt_tab_dbl[i]);
> > >>      }
> > >>  }
> > >
> > > Note that cbrt_tab_dbl is really intended to be shared by both the
> > > fixed/floating table inits. This was another thing my patch achieved:
> > > only doing the more expensive double table init once across
> > > float/fixed, and then doing the cheap conversion to uint32_t via
> > > av_float2int or lrint(x*8192). Please change; it could go into a
> > > separate patch if you prefer.
> > >
> > 
> > Having both float and fixed decoders used at the same time seems like
> > a rather unlikely use-case, so if such an optimization takes rather
> > high complexity, its probably not worth going, IMHO.
> 
> Nah, it should be done separately because it needs some
> code reshuffling that easily gets confusing, but I don't
> think it will be hard.

Wasn't (though I haven't tested properly), see attached,
still don't think it is a good idea though.
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