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quick fix for SF#1601812 where an error of exactly 0 (very rare) in FLAC__lpc_compute_lp_coefficients() could cause an infinite loop later in FLAC__lpc_quantize_coefficients()

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This commit is contained in:
Josh Coalson
2006-11-27 16:27:41 +00:00
parent d9ac0bd63a
commit 32b9baedb4
3 changed files with 13 additions and 6 deletions
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15
src/libFLAC/lpc.c
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@@ -105,18 +105,19 @@ void FLAC__lpc_compute_autocorrelation(const FLAC__real data[], unsigned data_le
}
}
void FLAC__lpc_compute_lp_coefficients(const FLAC__real autoc[], unsigned max_order, FLAC__real lp_coeff[][FLAC__MAX_LPC_ORDER], FLAC__double error[])
void FLAC__lpc_compute_lp_coefficients(const FLAC__real autoc[], unsigned *max_order, FLAC__real lp_coeff[][FLAC__MAX_LPC_ORDER], FLAC__double error[])
{
unsigned i, j;
FLAC__double r, err, ref[FLAC__MAX_LPC_ORDER], lpc[FLAC__MAX_LPC_ORDER];
FLAC__ASSERT(0 < max_order);
FLAC__ASSERT(max_order <= FLAC__MAX_LPC_ORDER);
FLAC__ASSERT(0 != max_order);
FLAC__ASSERT(0 < *max_order);
FLAC__ASSERT(*max_order <= FLAC__MAX_LPC_ORDER);
FLAC__ASSERT(autoc[0] != 0.0);
err = autoc[0];
for(i = 0; i < max_order; i++) {
for(i = 0; i < *max_order; i++) {
/* Sum up this iteration's reflection coefficient. */
r = -autoc[i+1];
for(j = 0; j < i; j++)
@@ -139,6 +140,12 @@ void FLAC__lpc_compute_lp_coefficients(const FLAC__real autoc[], unsigned max_or
for(j = 0; j <= i; j++)
lp_coeff[i][j] = (FLAC__real)(-lpc[j]); /* negate FIR filter coeff to get predictor coeff */
error[i] = err;
/*@@@@@@ see SF bug #1601812 http://sourceforge.net/tracker/index.php?func=detail&aid=1601812&group_id=13478&atid=113478 */
if(err == 0.0) {
*max_order = i+1;
return;
}
}
}