shithub: opus

Info  •  Files  •  Log  •  Branches

Giving less bits to single-bin bands.

This improves the allocation for 2.5 ms frames.

--- a/libcelt/rate.c

+++ b/libcelt/rate.c

@@ -387,14 +387,18 @@

    ALLOC(thresh, len, int);

    ALLOC(trim_offset, len, int);

-   /* Below this threshold, we're sure not to allocate any PVQ bits */

    for (j=start;j<end;j++)

+   {

+      /* Below this threshold, we're sure not to allocate any PVQ bits */

       thresh[j] = IMAX((C)<<BITRES, (3*(m->eBands[j+1]-m->eBands[j])<<LM<<BITRES)>>4);

-   /* Tilt of the allocation curve */

-   for (j=start;j<end;j++)

+      /* Tilt of the allocation curve */

       trim_offset[j] = C*(m->eBands[j+1]-m->eBands[j])*(alloc_trim-5-LM)*(m->nbEBands-j-1)

             <<(LM+BITRES)>>6;

-

+      /* Giving less resolution to single-coefficient bands because they get

+         more benefit from having one coarse value per coefficient*/

+      if ((m->eBands[j+1]-m->eBands[j])<<LM==1)

+         trim_offset[j] -= C<<BITRES;

+   }

    lo = 1;

    hi = m->nbAllocVectors - 2;

    do