[Ffmpeg-devel] [PATCH] updated LGPL AC-3 decoder

[Aurelien Jacobs]

On Sat, 10 Feb 2007 16:30:41 +0100
Michael Niedermayer <michaelni at gmx.at> wrote:

> On Sat, Feb 10, 2007 at 01:02:20AM -0500, Justin Ruggles wrote:
> [...]
> > #include "avcodec.h"
> > #include "ac3.h"
> > #include "ac3tab.h"
> > 
> > static inline int calc_lowcomp1(int a, int b0, int b1)
> > {
> >     if ((b0 + 256) == b1) {
> >         a = 384 ;
> >     } else if (b0 > b1) {
> >         a = a - 64;
> >         if (a < 0) a=0;
> >     }
> >     return a;
> > }
> 
> calc_lowcomp1(int a, int b0, int b1, int C){
>     if ((b0 + 256) == b1) {
>         a= C;
>     } else if (b0 > b1) {
>         a= FFMAX(a - 64, 0);
>     }
>     return a;

I had already spoted lots of potential FFMIN/FFMAX usage before seeing
Michael's reply. So here are a few more that I spoted:

> > [...]
> >         end1=bndend;
> >         if (end1 > 22) end1=22;

end1 = FFMIN(bndend, 22);

> >         for (bin = begin; bin < end1; bin++) {
> >             if (!(is_lfe && bin == 6))
> >                 lowcomp = calc_lowcomp(lowcomp, bndpsd[bin], bndpsd[bin+1], bin) ;
> > 
> >             fastleak -= s->fdecay ;
> >             v = bndpsd[bin] - fgain;
> >             if (fastleak < v) fastleak = v;
> 
> FFMAX

fastleak = FFMAX(fastleak - s->fdecay, bndpsd[bin] - fgain);

> >             slowleak -= s->sdecay ;
> >             v = bndpsd[bin] - s->sgain;
> >             if (slowleak < v) slowleak = v;
> 
> FFMAX

slowleak = FFMAX(slowleak - s->sdecay, bndpsd[bin] - s->sgain);

> >             v=fastleak - lowcomp;
> >             if (slowleak > v) v=slowleak;
> 
> v= FFMAX(fastleak - lowcomp, slowleak)
> 
> [...]
> 
>     /* compute masking curve */
> 
>     for (bin = bndstrt; bin < bndend; bin++) {
>         v1 = excite[bin];
>         tmp = s->dbknee - bndpsd[bin];
>         if (tmp > 0) {
>             v1 += tmp >> 2;
>         }
>         v=hth[bin >> s->halfratecod][s->fscod];
>         if (v1 > v) v=v1;
>         mask[bin] = v;

mask[bin] = FFMAX(hth[bin >> s->halfratecod][s->fscod], v1);

> [...]
>         v=mask[j];
>         v -= snroffset ;
>         v -= s->floor ;
>         if (v < 0) v = 0;
>         v &= 0x1fe0 ;
>         v += s->floor ;

v = (FFMAX(mask[j] - snroffset - s->floor, 0) & 0x1fe0) + s->floor;

>         end1=bndtab[j] + bndsz[j];
>         if (end1 > end) end1=end;

end1 = FFMIN(bndtab[j] + bndsz[j], end);

Aurel