ref: 47bf175f292d83479ada061e3f9529d63b0a3c69
parent: 68b02b10252dec071b6824d262abeb7c635774dc
author: Jean-Marc Valin <[email protected]>
date: Thu Feb 28 19:07:00 EST 2008
fixed-point: a few more bits converted from the energy quantisation. Almost done
--- a/libcelt/quant_bands.c
+++ b/libcelt/quant_bands.c
@@ -53,7 +53,7 @@
static inline celt_ener_t dB2Amp(celt_ener_t dB)
{celt_ener_t amp;
- amp = PSHR32(celt_exp2(dB/6.0207*8),2)-QCONST16(.3f, 14);
+ amp = PSHR32(celt_exp2(MULT16_16_Q14(21771,dB)),2)-QCONST16(.3f, 14);
if (amp < 0)
amp = 0;
return amp;
@@ -81,6 +81,7 @@
}
#endif
+static const celt_word16_t base_resolution = QCONST16(6.f,8);
#ifdef FIXED_POINT
#define Q8 256.f
@@ -105,13 +106,11 @@
{int qi;
celt_word16_t q; /* dB */
- celt_word16_t res; /* dB */
celt_word16_t x; /* dB */
celt_word16_t f; /* Q8 */
celt_word16_t mean = (1-coef)*eMeans[i];
x = amp2dB(eBands[i]);
- res = DB_SCALING*6;
- f = QCONST16(1.f,8)*(x-mean-coef*oldEBands[i]-prev*1.f)/res;
+ f = DIV32_16(SHL32(EXTEND32(x-mean-coef*oldEBands[i]-prev),8),base_resolution);
#ifdef FIXED_POINT
/* Rounding to nearest integer here is really important! */
qi = (f+128)>>8;
@@ -125,7 +124,7 @@
qi = -1;
else
ec_laplace_encode(enc, qi, 6000-i*200);
- q = qi*res;
+ q = qi*base_resolution;
error[i] = f - SHL16(qi,8);
/*printf("%d ", qi);*/@@ -180,15 +179,13 @@
{int qi;
celt_word16_t q;
- celt_word16_t res;
celt_word16_t mean = (1-coef)*eMeans[i];
- res = DB_SCALING*6.;
/* If we didn't have enough bits to encode all the energy, just assume something safe. */
if (ec_dec_tell(dec, 0) - bits > budget)
qi = -1;
else
qi = ec_laplace_decode(dec, 6000-i*200);
- q = qi*res;
+ q = qi*base_resolution;
/*printf("%d ", qi);*/ /*printf("%f %f ", pred+prev+q, x);*/