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Use dynamic scaling depending on autocorr length to avoid signed integer overflow. 

Bug: 186706541
Test: atest android.media.cts.DecoderTestAacFormat android.media.cts.DecoderTestXheAac android.media.cts.DecoderTestAacDrc
Change-Id: Ibc035ce2eafe4b0d98377d090adad77bbf5cbb5c
This commit is contained in:
Fraunhofer IIS FDK 2020-05-08 16:39:30 +02:00 committed by Jean-Michel Trivi
parent 5f80d21a8a
commit d8515f231f
1 changed files with 21 additions and 22 deletions
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43
libFDK/src/autocorr2nd.cpp
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@ -1,7 +1,7 @@
/* -----------------------------------------------------------------------------
Software License for The Fraunhofer FDK AAC Codec Library for Android
© Copyright 1995 - 2018 Fraunhofer-Gesellschaft zur Förderung der angewandten
© Copyright 1995 - 2020 Fraunhofer-Gesellschaft zur Förderung der angewandten
Forschung e.V. All rights reserved.
1. INTRODUCTION
@ -102,11 +102,6 @@ amm-info@iis.fraunhofer.de
#include "autocorr2nd.h"
/* If the accumulator does not provide enough overflow bits,
products have to be shifted down in the autocorrelation below. */
#define SHIFT_FACTOR (5)
#define SHIFT >> (SHIFT_FACTOR)
/*!
*
* \brief Calculate second order autocorrelation using 2 accumulators
@ -126,45 +121,49 @@ INT autoCorr2nd_real(
const FIXP_DBL *realBuf = reBuffer;
const int len_scale = fMax(DFRACT_BITS - fNormz((FIXP_DBL)(len / 2)), 1);
/*
r11r,r22r
r01r,r12r
r02r
*/
pReBuf = realBuf - 2;
accu5 = ((fMultDiv2(pReBuf[0], pReBuf[2]) + fMultDiv2(pReBuf[1], pReBuf[3]))
SHIFT);
accu5 =
((fMultDiv2(pReBuf[0], pReBuf[2]) + fMultDiv2(pReBuf[1], pReBuf[3])) >>
len_scale);
pReBuf++;
/* len must be even */
accu1 = fPow2Div2(pReBuf[0]) SHIFT;
accu3 = fMultDiv2(pReBuf[0], pReBuf[1]) SHIFT;
accu1 = fPow2Div2(pReBuf[0]) >> len_scale;
accu3 = fMultDiv2(pReBuf[0], pReBuf[1]) >> len_scale;
pReBuf++;
for (j = (len - 2) >> 1; j != 0; j--, pReBuf += 2) {
accu1 += ((fPow2Div2(pReBuf[0]) + fPow2Div2(pReBuf[1])) SHIFT);
accu1 += ((fPow2Div2(pReBuf[0]) + fPow2Div2(pReBuf[1])) >> len_scale);
accu3 += ((fMultDiv2(pReBuf[0], pReBuf[1]) +
fMultDiv2(pReBuf[1], pReBuf[2])) SHIFT);
accu3 +=
((fMultDiv2(pReBuf[0], pReBuf[1]) + fMultDiv2(pReBuf[1], pReBuf[2])) >>
len_scale);
accu5 += ((fMultDiv2(pReBuf[0], pReBuf[2]) +
fMultDiv2(pReBuf[1], pReBuf[3])) SHIFT);
accu5 +=
((fMultDiv2(pReBuf[0], pReBuf[2]) + fMultDiv2(pReBuf[1], pReBuf[3])) >>
len_scale);
}
accu2 = (fPow2Div2(realBuf[-2]) SHIFT);
accu2 = (fPow2Div2(realBuf[-2]) >> len_scale);
accu2 += accu1;
accu1 += (fPow2Div2(realBuf[len - 2]) SHIFT);
accu1 += (fPow2Div2(realBuf[len - 2]) >> len_scale);
accu4 = (fMultDiv2(realBuf[-1], realBuf[-2]) SHIFT);
accu4 = (fMultDiv2(realBuf[-1], realBuf[-2]) >> len_scale);
accu4 += accu3;
accu3 += (fMultDiv2(realBuf[len - 1], realBuf[len - 2]) SHIFT);
accu3 += (fMultDiv2(realBuf[len - 1], realBuf[len - 2]) >> len_scale);
mScale = CntLeadingZeros(
(accu1 | accu2 | fAbs(accu3) | fAbs(accu4) | fAbs(accu5))) -
1;
autoCorrScaling = mScale - 1 - SHIFT_FACTOR; /* -1 because of fMultDiv2*/
autoCorrScaling = mScale - 1 - len_scale; /* -1 because of fMultDiv2*/
/* Scale to common scale factor */
ac->r11r = accu1 << mScale;
@ -190,7 +189,7 @@ INT autoCorr2nd_cplx(
const FIXP_DBL *imBuffer, /*!< Pointer to imag part of input samples */
const int len /*!< Number of input samples (should be smaller than 128) */
) {
int j, autoCorrScaling, mScale, len_scale;
int j, autoCorrScaling, mScale;
FIXP_DBL accu0, accu1, accu2, accu3, accu4, accu5, accu6, accu7, accu8;
@ -199,7 +198,7 @@ INT autoCorr2nd_cplx(
const FIXP_DBL *realBuf = reBuffer;
const FIXP_DBL *imagBuf = imBuffer;
(len > 64) ? (len_scale = 6) : (len_scale = 5);
const int len_scale = fMax(DFRACT_BITS - fNormz((FIXP_DBL)len), 1);
/*
r00r,
r11r,r22r