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Have a guard on computing nrg to avoid wrap-around. This is discovered in a release test. During entropy coding of spectrum the value of "nrg" was too large and after shifting it became negative, resulting in decoder error.

Browse Source 
Review URL: http://webrtc-codereview.appspot.com/239016

git-svn-id: http://webrtc.googlecode.com/svn/trunk@862 4adac7df-926f-26a2-2b94-8c16560cd09d
This commit is contained in:
turaj@webrtc.org 2011-11-01 17:29:34 +00:00
parent 29d75b3f7d
commit 9116cf7c9b
1 changed files with 51 additions and 24 deletions
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75
src/modules/audio_coding/codecs/iSAC/main/source/entropy_coding.c
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@ -593,6 +593,7 @@ int WebRtcIsac_DecodeSpecUB12(
if (WebRtcIsac_DecodeGain2(streamdata, &gain2_Q10) < 0)
return -ISAC_RANGE_ERROR_DECODE_SPECTRUM;
/* compute inverse AR power spectrum */
WebRtcIsac_FindInvArSpec(ARCoefQ12, gain2_Q10, invARSpec2_Q16);
@ -669,7 +670,8 @@ int WebRtcIsac_EncodeSpecLb(const WebRtc_Word16 *fr,
WebRtc_Word32 in_sqrt;
WebRtc_Word32 newRes;
WebRtc_Word16 err;
int lft_shft;
WebRtc_UWord32 nrg_u32;
int shift_var;
int k, n, j, i;
@ -704,15 +706,15 @@ int WebRtcIsac_EncodeSpecLb(const WebRtc_Word16 *fr,
/* find AR coefficients */
/* number of bit shifts to 14-bit normalize CorrQ7[0] (leaving room for sign) */
lft_shft = WebRtcSpl_NormW32(CorrQ7[0]) - 18;
shift_var = WebRtcSpl_NormW32(CorrQ7[0]) - 18;
if (lft_shft > 0) {
if (shift_var > 0) {
for (k=0; k<AR_ORDER+1; k++) {
CorrQ7_norm[k] = CorrQ7[k] << lft_shft;
CorrQ7_norm[k] = CorrQ7[k] << shift_var;
}
} else {
for (k=0; k<AR_ORDER+1; k++) {
CorrQ7_norm[k] = CorrQ7[k] >> (-lft_shft);
CorrQ7_norm[k] = CorrQ7[k] >> (-shift_var);
}
}
@ -735,12 +737,19 @@ int WebRtcIsac_EncodeSpecLb(const WebRtc_Word16 *fr,
nrg += ( ARCoefQ12[j] * ((CorrQ7_norm[n-j] * ARCoefQ12[n] + 256) >> 9) + 4 ) >> 3;
}
}
if (lft_shft > 0) {
nrg >>= lft_shft;
nrg_u32 = (WebRtc_UWord32)nrg;
if (shift_var > 0) {
nrg_u32 = nrg_u32 >> shift_var;
} else {
nrg <<= -lft_shft;
nrg_u32 = nrg_u32 << (-shift_var);
}
if (nrg_u32 > 0x7FFFFFFF)
nrg = 0x7FFFFFFF;
else
nrg = (WebRtc_Word32)nrg_u32;
gain2_Q10 = WebRtcSpl_DivResultInQ31(FRAMESAMPLES_QUARTER, nrg); /* also shifts 31 bits to the left! */
/* quantize & code gain2_Q10 */
@ -826,7 +835,8 @@ int WebRtcIsac_EncodeSpecUB16(
WebRtc_Word32 in_sqrt;
WebRtc_Word32 newRes;
WebRtc_Word16 err;
int lft_shft;
WebRtc_UWord32 nrg_u32;
int shift_var;
int k, n, j, i;
/* create dither_float signal */
@ -863,15 +873,15 @@ int WebRtcIsac_EncodeSpecUB16(
/* find AR coefficients
number of bit shifts to 14-bit normalize CorrQ7[0]
(leaving room for sign) */
lft_shft = WebRtcSpl_NormW32(CorrQ7[0]) - 18;
shift_var = WebRtcSpl_NormW32(CorrQ7[0]) - 18;
if (lft_shft > 0) {
if (shift_var > 0) {
for (k=0; k<AR_ORDER+1; k++) {
CorrQ7_norm[k] = CorrQ7[k] << lft_shft;
CorrQ7_norm[k] = CorrQ7[k] << shift_var;
}
} else {
for (k=0; k<AR_ORDER+1; k++) {
CorrQ7_norm[k] = CorrQ7[k] >> (-lft_shft);
CorrQ7_norm[k] = CorrQ7[k] >> (-shift_var);
}
}
@ -896,12 +906,18 @@ int WebRtcIsac_EncodeSpecUB16(
256) >> 9) + 4 ) >> 3;
}
}
if (lft_shft > 0) {
nrg >>= lft_shft;
nrg_u32 = (WebRtc_UWord32)nrg;
if (shift_var > 0) {
nrg_u32 = nrg_u32 >> shift_var;
} else {
nrg <<= -lft_shft;
nrg_u32 = nrg_u32 << (-shift_var);
}
if (nrg_u32 > 0x7FFFFFFF)
nrg = 0x7FFFFFFF;
else
nrg = (WebRtc_Word32)nrg_u32;
gain2_Q10 = WebRtcSpl_DivResultInQ31(FRAMESAMPLES_QUARTER, nrg); /* also shifts 31 bits to the left! */
/* quantize & code gain2_Q10 */
@ -967,8 +983,9 @@ int WebRtcIsac_EncodeSpecUB12(const WebRtc_Word16 *fr,
WebRtc_Word32 in_sqrt;
WebRtc_Word32 newRes;
WebRtc_Word16 err;
int lft_shft;
int shift_var;
int k, n, j, i;
WebRtc_UWord32 nrg_u32;
/* create dither_float signal */
GenerateDitherQ7LbUB(ditherQ7, streamdata->W_upper, FRAMESAMPLES);
@ -1010,15 +1027,15 @@ int WebRtcIsac_EncodeSpecUB12(const WebRtc_Word16 *fr,
/* find AR coefficients */
/* number of bit shifts to 14-bit normalize CorrQ7[0] (leaving room for sign) */
lft_shft = WebRtcSpl_NormW32(CorrQ7[0]) - 18;
shift_var = WebRtcSpl_NormW32(CorrQ7[0]) - 18;
if (lft_shft > 0) {
if (shift_var > 0) {
for (k=0; k<AR_ORDER+1; k++) {
CorrQ7_norm[k] = CorrQ7[k] << lft_shft;
CorrQ7_norm[k] = CorrQ7[k] << shift_var;
}
} else {
for (k=0; k<AR_ORDER+1; k++) {
CorrQ7_norm[k] = CorrQ7[k] >> (-lft_shft);
CorrQ7_norm[k] = CorrQ7[k] >> (-shift_var);
}
}
@ -1028,9 +1045,11 @@ int WebRtcIsac_EncodeSpecUB12(const WebRtc_Word16 *fr,
/* quantize & code RC Coef */
WebRtcIsac_EncodeRc(RCQ15, streamdata);
/* RC -> AR coefficients */
WebRtcSpl_ReflCoefToLpc(RCQ15, AR_ORDER, ARCoefQ12);
/* compute ARCoef' * Corr * ARCoef in Q19 */
nrg = 0;
for (j = 0; j <= AR_ORDER; j++) {
@ -1041,10 +1060,18 @@ int WebRtcIsac_EncodeSpecUB12(const WebRtc_Word16 *fr,
nrg += ( ARCoefQ12[j] * ((CorrQ7_norm[n-j] * ARCoefQ12[n] + 256) >> 9) + 4 ) >> 3;
}
}
if (lft_shft > 0) {
nrg >>= lft_shft;
nrg_u32 = (WebRtc_UWord32)nrg;
if (shift_var > 0) {
nrg_u32 = nrg_u32 >> shift_var;
} else {
nrg <<= -lft_shft;
nrg_u32 = nrg_u32 << (-shift_var);
}
if (nrg_u32 > 0x7FFFFFFF) {
nrg = 0x7FFFFFFF;
} else {
nrg = (WebRtc_Word32)nrg_u32;
}
gain2_Q10 = WebRtcSpl_DivResultInQ31(FRAMESAMPLES_QUARTER, nrg); /* also shifts 31 bits to the left! */