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This both reverts 3fe0db172c that caused

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accuracy-related issues at high bit-rate, and fixed an overflow caused by large
Rxy values.
This commit is contained in:
Jean-Marc Valin 2008-04-20 17:16:18 +10:00
parent 65fb92e824
commit 0bc5f7fcdc
1 changed files with 10 additions and 5 deletions
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15
libcelt/vq.c
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@ -139,10 +139,16 @@ void alg_quant(celt_norm_t *X, celt_mask_t *W, int N, int K, const celt_norm_t *
int pulsesAtOnce=1;
int best_id;
celt_word16_t magnitude;
#ifdef FIXED_POINT
int rshift;
#endif
/* Decide on how many pulses to find at once */
pulsesAtOnce = (pulsesLeft*N_1)>>9; /* pulsesLeft/N */
if (pulsesAtOnce<1)
pulsesAtOnce = 1;
#ifdef FIXED_POINT
rshift = yshift+1+celt_ilog2(K-pulsesLeft+pulsesAtOnce);
#endif
magnitude = SHL16(pulsesAtOnce, yshift);
best_id = 0;
@ -161,9 +167,9 @@ void alg_quant(celt_norm_t *X, celt_mask_t *W, int N, int K, const celt_norm_t *
/* Select sign based on X[j] alone */
s = signx[j]*magnitude;
/* Temporary sums of the new pulse(s) */
Rxy = EXTRACT16(SHR32(xy + MULT16_16(s,X[j]),14));
Rxy = EXTRACT16(SHR32(xy + MULT16_16(s,X[j]),rshift));
/* We're multiplying y[j] by two so we don't have to do it here */
Ryy = EXTRACT16(SHR32(yy + MULT16_16(s,y[j]),14));
Ryy = EXTRACT16(SHR32(yy + MULT16_16(s,y[j]),rshift));
/* Approximate score: we maximise Rxy/sqrt(Ryy) (we're guaranteed that
Rxy is positive because the sign is pre-computed) */
@ -189,8 +195,7 @@ void alg_quant(celt_norm_t *X, celt_mask_t *W, int N, int K, const celt_norm_t *
/* Select sign based on X[j] alone */
s = signx[j]*magnitude;
/* Temporary sums of the new pulse(s) */
/* We only shift by 13 so we don't have to multiply by 2 later */
Rxy = ROUND16(xy + MULT16_16(s,X[j]), 13);
Rxy = ROUND16(xy + MULT16_16(s,X[j]), 14);
/* We're multiplying y[j] by two so we don't have to do it here */
Ryy = ROUND16(yy + MULT16_16(s,y[j]), 14);
Ryp = ROUND16(yp + MULT16_16(s,P[j]), 14);
@ -203,7 +208,7 @@ void alg_quant(celt_norm_t *X, celt_mask_t *W, int N, int K, const celt_norm_t *
/* score = 2*g*Rxy - g*g*Ryy;*/
#ifdef FIXED_POINT
/* No need to multiply Rxy by 2 because we did it earlier */
num = MULT16_16_Q15(SUB16(Rxy,g),g);
num = MULT16_16_Q15(ADD16(SUB16(Rxy,g),Rxy),g);
#else
num = g*(2*Rxy-g);
#endif