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Dividing by a constant is never good

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This commit is contained in:
Jean-Marc Valin 2008-09-19 17:49:21 -04:00
parent d125c264e4
commit 5ea2e7f267
1 changed files with 4 additions and 1 deletions
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5
libcelt/quant_bands.c
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@ -85,6 +85,7 @@ static inline celt_word16_t amp2dB(celt_ener_t amp)
#endif
static const celt_word16_t base_resolution = QCONST16(6.f,8);
static const celt_word16_t base_resolution_1 = QCONST16(0.1666667f,15);
int *quant_prob_alloc(const CELTMode *m)
{
@ -124,11 +125,13 @@ static void quant_coarse_energy_mono(const CELTMode *m, celt_ener_t *eBands, cel
celt_word16_t f; /* Q8 */
celt_word16_t mean = MULT16_16_Q15(Q15ONE-coef,eMeans[i]);
x = amp2dB(eBands[i]);
f = EXTRACT16(celt_div(SHL32(EXTEND32(x-mean-MULT16_16_Q15(coef,oldEBands[i])-prev),8),base_resolution));
#ifdef FIXED_POINT
f = MULT16_16_Q15(x-mean-MULT16_16_Q15(coef,oldEBands[i])-prev,base_resolution_1);
/* Rounding to nearest integer here is really important! */
qi = (f+128)>>8;
#else
f = (x-mean-coef*oldEBands[i]-prev)*base_resolution_1;
/* Rounding to nearest integer here is really important! */
qi = (int)floor(.5+f);
#endif
/* If we don't have enough bits to encode all the energy, just assume something safe.