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Fixes some overflows in the fixed-point pitch code

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The overflows reported were:
- Syy in find_best_pitch() in pitch.c
- xy, xx and yy in remove_doubling() in pitch.c

The fixes are:
- Adaptive scaling in pitch_downsample() which also improves quality
- Adding a missing downshift in find_best_pitch()
- More conservative yshift when calling find_best_pitch()
This commit is contained in:
Jean-Marc Valin 2012-04-06 23:32:11 -04:00
parent cd539dfdcd
commit 178758b81a
2 changed files with 26 additions and 6 deletions
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11
celt/mathops.h
View file

@ -128,6 +128,17 @@ static inline opus_val16 celt_maxabs16(opus_val16 *x, int len)
}
#endif
#ifndef OVERRIDE_CELT_MAXABS32
static inline opus_val32 celt_maxabs32(opus_val32 *x, int len)
{
int i;
opus_val32 maxval = 0;
for (i=0;i<len;i++)
maxval = MAX32(maxval, ABS32(x[i]));
return maxval;
}
#endif
/** Integer log in base2. Defined for zero, but not for negative numbers */
static inline opus_int16 celt_zlog2(opus_val32 x)
{

21
celt/pitch.c
View file

@ -66,7 +66,7 @@ static void find_best_pitch(opus_val32 *xcorr, opus_val16 *y, int len,
best_pitch[0] = 0;
best_pitch[1] = 1;
for (j=0;j<len;j++)
Syy = MAC16_16(Syy, y[j],y[j]);
Syy = ADD32(Syy, SHR32(MULT16_16(y[j],y[j]), yshift));
for (i=0;i<max_pitch;i++)
{
if (xcorr[i]>0)
@ -104,14 +104,23 @@ void pitch_downsample(celt_sig * restrict x[], opus_val16 * restrict x_lp,
opus_val32 ac[5];
opus_val16 tmp=Q15ONE;
opus_val16 lpc[4], mem[4]={0,0,0,0};
#ifdef FIXED_POINT
int shift;
opus_val32 maxabs = celt_maxabs32(x[0], len);
if (C==2)
maxabs = MAX32(maxabs, celt_maxabs32(x[1], len));
shift = IMAX(0,celt_ilog2(maxabs)-11);
if (C==2)
shift++;
#endif
for (i=1;i<len>>1;i++)
x_lp[i] = SHR32(HALF32(HALF32(x[0][(2*i-1)]+x[0][(2*i+1)])+x[0][2*i]), SIG_SHIFT+3);
x_lp[0] = SHR32(HALF32(HALF32(x[0][1])+x[0][0]), SIG_SHIFT+3);
x_lp[i] = SHR32(HALF32(HALF32(x[0][(2*i-1)]+x[0][(2*i+1)])+x[0][2*i]), shift);
x_lp[0] = SHR32(HALF32(HALF32(x[0][1])+x[0][0]), shift);
if (C==2)
{
for (i=1;i<len>>1;i++)
x_lp[i] += SHR32(HALF32(HALF32(x[1][(2*i-1)]+x[1][(2*i+1)])+x[1][2*i]), SIG_SHIFT+3);
x_lp[0] += SHR32(HALF32(HALF32(x[1][1])+x[1][0]), SIG_SHIFT+3);
x_lp[i] += SHR32(HALF32(HALF32(x[1][(2*i-1)]+x[1][(2*i+1)])+x[1][2*i]), shift);
x_lp[0] += SHR32(HALF32(HALF32(x[1][1])+x[1][0]), shift);
}
_celt_autocorr(x_lp, ac, NULL, 0,
@ -231,7 +240,7 @@ void pitch_search(const opus_val16 * restrict x_lp, opus_val16 * restrict y,
}
find_best_pitch(xcorr, y, len>>1, max_pitch>>1, best_pitch
#ifdef FIXED_POINT
, shift, maxcorr
, shift+1, maxcorr
#endif
);