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Moving energy floor to coarse quantization

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By moving the energy floor to the encoder, we can use a different
floor for prediction than for the decay level. Also, the fixed-point
dynamic range has been increased to avoid overflows when a fixed-point
decoder is used on a stream encoded in floating-point.
This commit is contained in:
Jean-Marc Valin 2011-01-24 15:53:17 -05:00
parent 6ec2ca56cf
commit 495114b755
2 changed files with 30 additions and 21 deletions
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10
libcelt/celt.c
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@ -1379,11 +1379,6 @@ int celt_encode_with_ec_float(CELTEncoder * restrict st, const celt_sig * pcm, i
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
{
@ -2186,11 +2181,6 @@ int celt_decode_with_ec_float(CELTDecoder * restrict st, const unsigned char *da
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
{

41
libcelt/quant_bands.c
View file

@ -188,22 +188,28 @@ static int quant_coarse_energy_impl(const CELTMode *m, int start, int end,
int qi, qi0;
celt_word16 q;
celt_word16 x;
celt_word32 f;
celt_word32 f, tmp;
celt_word16 oldE;
celt_word16 decay_bound;
x = eBands[i+c*m->nbEBands];
oldE = MAX16(-QCONST16(9.f,DB_SHIFT), oldEBands[i+c*m->nbEBands]);
#ifdef FIXED_POINT
f = SHL32(EXTEND32(x),15) -MULT16_16(coef,oldEBands[i+c*m->nbEBands])-prev[c];
f = SHL32(EXTEND32(x),7) - PSHR32(MULT16_16(coef,oldE), 8) - prev[c];
/* Rounding to nearest integer here is really important! */
qi = (f+QCONST32(.5,DB_SHIFT+15))>>(DB_SHIFT+15);
qi = (f+QCONST32(.5,DB_SHIFT+7))>>(DB_SHIFT+7);
decay_bound = EXTRACT16(MAX32(-QCONST16(28.f,DB_SHIFT),
SUB32((celt_word32)oldEBands[i+c*m->nbEBands],max_decay)));
#else
f = x-coef*oldEBands[i+c*m->nbEBands]-prev[c];
f = x-coef*oldE-prev[c];
/* Rounding to nearest integer here is really important! */
qi = (int)floor(.5f+f);
decay_bound = MAX16(-QCONST16(28.f,DB_SHIFT), oldEBands[i+c*m->nbEBands]) - max_decay;
#endif
/* Prevent the energy from going down too quickly (e.g. for bands
that have just one bin) */
if (qi < 0 && x < oldEBands[i+c*m->nbEBands]-max_decay)
if (qi < 0 && x < decay_bound)
{
qi += (int)SHR16(oldEBands[i+c*m->nbEBands]-max_decay-x, DB_SHIFT);
qi += (int)SHR16(SUB16(decay_bound,x), DB_SHIFT);
if (qi > 0)
qi = 0;
}
@ -238,12 +244,19 @@ static int quant_coarse_energy_impl(const CELTMode *m, int start, int end,
}
else
qi = -1;
error[i+c*m->nbEBands] = PSHR32(f,15) - SHL16(qi,DB_SHIFT);
error[i+c*m->nbEBands] = PSHR32(f,7) - SHL16(qi,DB_SHIFT);
badness += abs(qi0-qi);
q = SHL16(qi,DB_SHIFT);
oldEBands[i+c*m->nbEBands] = PSHR32(MULT16_16(coef,oldEBands[i+c*m->nbEBands]) + prev[c] + SHL32(EXTEND32(q),15), 15);
prev[c] = prev[c] + SHL32(EXTEND32(q),15) - MULT16_16(beta,q);
//oldEBands[i+c*m->nbEBands] = PSHR32(MULT16_16(coef,oldE) + prev[c] + SHL32(EXTEND32(q),15), 15);
//prev[c] = prev[c] + SHL32(EXTEND32(q),15) - MULT16_16(beta,q);
tmp = PSHR32(MULT16_16(coef,oldE),8) + prev[c] + SHL32(EXTEND32(q),7);
#ifdef FIXED_POINT
tmp = MAX32(-QCONST32(28.f, DB_SHIFT+7), tmp);
#endif
oldEBands[i+c*m->nbEBands] = PSHR32(tmp, 7);
prev[c] = prev[c] + SHL32(EXTEND32(q),7) - PSHR32(MULT16_16(beta,q),8);
} while (++c < C);
}
return badness;
@ -441,6 +454,7 @@ void unquant_coarse_energy(const CELTMode *m, int start, int end, celt_ener *eBa
do {
int qi;
celt_word16 q;
celt_word32 tmp;
tell = ec_dec_tell(dec, 0);
if(budget-tell>=15)
{
@ -462,8 +476,13 @@ void unquant_coarse_energy(const CELTMode *m, int start, int end, celt_ener *eBa
qi = -1;
q = SHL16(qi,DB_SHIFT);
oldEBands[i+c*m->nbEBands] = PSHR32(MULT16_16(coef,oldEBands[i+c*m->nbEBands]) + prev[c] + SHL32(EXTEND32(q),15), 15);
prev[c] = prev[c] + SHL32(EXTEND32(q),15) - MULT16_16(beta,q);
oldEBands[i+c*m->nbEBands] = MAX16(-QCONST16(9.f,DB_SHIFT), oldEBands[i+c*m->nbEBands]);
tmp = PSHR32(MULT16_16(coef,oldEBands[i+c*m->nbEBands]),8) + prev[c] + SHL32(EXTEND32(q),7);
#ifdef FIXED_POINT
tmp = MAX32(-QCONST32(28.f, DB_SHIFT+7), tmp);
#endif
oldEBands[i+c*m->nbEBands] = PSHR32(tmp, 7);
prev[c] = prev[c] + SHL32(EXTEND32(q),7) - PSHR32(MULT16_16(beta,q),8);
} while (++c < C);
}
}