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Adds spreading to the surround masking computation

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This avoids a single low-energy band from changing the masking results.
This commit is contained in:
Jean-Marc Valin 2013-05-06 16:02:31 -04:00
parent a4dccd3f65
commit d2c484b5e7
1 changed files with 11 additions and 1 deletions
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12
celt/celt_encoder.c
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@ -1411,13 +1411,23 @@ int celt_encode_with_ec(CELTEncoder * OPUS_RESTRICT st, const opus_val16 * pcm,
st->energy_save[i]=bandLogE[i]-offset;
st->energy_save=NULL;
}
/* This computes how much masking takes place between surround channels */
if (st->energy_mask&&!st->lfe)
{
opus_val32 mask_avg=0;
opus_val16 offset = shortBlocks?HALF16(SHL16(LM, DB_SHIFT)):0;
for (c=0;c<C;c++)
{
opus_val16 followE, followMask;
followE = followMask = -QCONST16(14.f, DB_SHIFT);
for(i=0;i<st->end;i++)
mask_avg += bandLogE[nbEBands*c+i]-offset-st->energy_mask[nbEBands*c+i];
{
/* We use a simple follower to approximate the masking spreading function. */
followE = MAX16(followE-QCONST16(1.f, DB_SHIFT), bandLogE[nbEBands*c+i]-offset);
followMask = MAX16(followMask-QCONST16(1.f, DB_SHIFT), st->energy_mask[nbEBands*c+i]);
mask_avg += followE-followMask;
}
}
surround_masking = DIV32_16(mask_avg,C*st->end) + QCONST16(.0f, DB_SHIFT);
surround_masking = MIN16(MAX16(surround_masking,-QCONST16(1.5f, DB_SHIFT)), 0);
}