shithub: opus

Info  •  Files  •  Log  •  Branches

Correct an encoder/decoder mismatch at low volume levels. Relax some low level clamps so that the dynamic range can extend further below the 16bit floor.

--- a/libcelt/bands.c

+++ b/libcelt/bands.c

@@ -152,7 +152,7 @@

       for (i=0;i<end;i++)

       {

          int j;

-         celt_word32 sum = 1e-10f;

+         celt_word32 sum = 1e-27f;

          for (j=M*eBands[i];j<M*eBands[i+1];j++)

             sum += X[j+c*N]*X[j+c*N];

          bank[i+c*m->nbEBands] = celt_sqrt(sum);

@@ -173,7 +173,7 @@

       for (i=0;i<end;i++)

       {

          int j;

-         celt_word16 g = 1.f/(1e-10f+bank[i+c*m->nbEBands]);

+         celt_word16 g = 1.f/(1e-27f+bank[i+c*m->nbEBands]);

          for (j=M*eBands[i];j<M*eBands[i+1];j++)

             X[j+c*N] = freq[j+c*N]*g;

       }

--- a/libcelt/celt.c

+++ b/libcelt/celt.c

@@ -1378,6 +1378,11 @@

    st->prefilter_gain = gain1;

    st->prefilter_tapset = prefilter_tapset;

+   /* Clamp the band energy used for prediction */

+   for (i=0;i<C*st->mode->nbEBands;i++)

+      if (oldBandE[i] < -QCONST16(28.f,DB_SHIFT))

+         oldBandE[i] = -QCONST16(28.f,DB_SHIFT);

+

    /* In case start or end were to change */

    c=0; do

    {

@@ -2152,6 +2157,11 @@

    st->postfilter_gain = postfilter_gain;

    st->postfilter_tapset = postfilter_tapset;

 #endif /* ENABLE_POSTFILTER */

+

+   /* Clamp the band energy used for prediction */

+   for (i=0;i<C*st->mode->nbEBands;i++)

+      if (oldBandE[i] < -QCONST16(28.f,DB_SHIFT))

+         oldBandE[i] = -QCONST16(28.f,DB_SHIFT);

    /* In case start or end were to change */

    c=0; do

--- a/libcelt/quant_bands.c

+++ b/libcelt/quant_bands.c

@@ -527,8 +527,6 @@

          celt_word16 lg = oldEBands[i+c*m->nbEBands]

                         + SHL16((celt_word16)eMeans[i],6);

          eBands[i+c*m->nbEBands] = PSHR32(celt_exp2(SHL16(lg,11-DB_SHIFT)),4);

-         if (oldEBands[i+c*m->nbEBands] < -QCONST16(14.f,DB_SHIFT))

-            oldEBands[i+c*m->nbEBands] = -QCONST16(14.f,DB_SHIFT);

       }

    } while (++c < C);

 }

@@ -542,7 +540,7 @@

    do {

       for (i=0;i<effEnd;i++)

          bandLogE[i+c*m->nbEBands] =

-               celt_log2(MAX32(QCONST32(.001f,14),SHL32(bandE[i+c*m->nbEBands],2)))

+               celt_log2(SHL32(bandE[i+c*m->nbEBands],2))

                - SHL16((celt_word16)eMeans[i],6);

       for (i=effEnd;i<end;i++)

          bandLogE[c*m->nbEBands+i] = -QCONST16(14.f,DB_SHIFT);