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AAC encoder bitrate limitation

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AAC encoder: Make the bit rate limiting functionality more stable for multichannel
     configurations where element bit rate for SBR can differ significantly.

Bug 9428126

Change-Id: I35b134c5b3c160a8f5a16b4314782b731fe49cd8
This commit is contained in:
Jean-Michel Trivi 2013-08-08 17:57:01 -07:00
parent fc4d7b0e73
commit 3c59acf128
1 changed files with 49 additions and 47 deletions
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96
libAACenc/src/aacenc_lib.cpp
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@ -98,7 +98,7 @@ amm-info@iis.fraunhofer.de
/* Encoder library info */
#define AACENCODER_LIB_VL0 3
#define AACENCODER_LIB_VL1 4
#define AACENCODER_LIB_VL2 4
#define AACENCODER_LIB_VL2 5
#define AACENCODER_LIB_TITLE "AAC Encoder"
#define AACENCODER_LIB_BUILD_DATE __DATE__
#define AACENCODER_LIB_BUILD_TIME __TIME__
@ -525,56 +525,58 @@ INT aacEncoder_LimitBitrate(
/* Limit bit rate in respect to available SBR modes if active */
if (sbrActive)
{
SBR_ELEMENT_INFO sbrElInfo[6];
INT sbrBitRate = 0;
int e, tooBig=-1;
int numIterations = 0;
INT initialBitrate, adjustedBitrate;
initialBitrate = adjustedBitrate = bitRate;
FDK_ASSERT(cm.nElements <= (6));
/* Find total bitrate which provides valid configuration for each SBR element. */
do {
int e;
SBR_ELEMENT_INFO sbrElInfo[(6)];
FDK_ASSERT(cm.nElements <= (6));
/* Get bit rate for each SBR element */
aacEncDistributeSbrBits(&cm, sbrElInfo, bitRate);
initialBitrate = adjustedBitrate;
for (e=0; e<cm.nElements; e++)
{
INT sbrElementBitRateIn, sbrBitRateOut;
/* Get bit rate for each SBR element */
aacEncDistributeSbrBits(&cm, sbrElInfo, initialBitrate);
if (cm.elInfo[e].elType != ID_SCE && cm.elInfo[e].elType != ID_CPE) {
continue;
}
sbrElementBitRateIn = sbrElInfo[e].bitRate;
sbrBitRateOut = sbrEncoder_LimitBitRate(sbrElementBitRateIn , cm.elInfo[e].nChannelsInEl, coreSamplingRate, aot);
if (sbrBitRateOut == 0) {
return 0;
}
if (sbrElementBitRateIn < sbrBitRateOut) {
FDK_ASSERT(tooBig != 1);
tooBig = 0;
if (e == 0) {
sbrBitRate = 0;
}
}
if (sbrElementBitRateIn > sbrBitRateOut) {
FDK_ASSERT(tooBig != 0);
tooBig = 1;
if (e == 0) {
sbrBitRate = 5000000;
}
}
if (tooBig != -1)
for (e=0; e<cm.nElements; e++)
{
INT sbrBitRateLimit = (INT)fDivNorm((FIXP_DBL)sbrBitRateOut, cm.elInfo[e].relativeBits);
if (tooBig) {
sbrBitRate = fMin(sbrBitRate, sbrBitRateLimit-16);
FDK_ASSERT( (INT)fMultNorm(cm.elInfo[e].relativeBits, (FIXP_DBL)sbrBitRate) < sbrBitRateOut);
} else {
sbrBitRate = fMax(sbrBitRate, sbrBitRateLimit+16);
FDK_ASSERT( (INT)fMultNorm(cm.elInfo[e].relativeBits, (FIXP_DBL)sbrBitRate) >= sbrBitRateOut);
INT sbrElementBitRateIn, sbrBitRateOut;
if (cm.elInfo[e].elType != ID_SCE && cm.elInfo[e].elType != ID_CPE) {
continue;
}
}
}
if (tooBig != -1) {
bitRate = sbrBitRate;
}
sbrElementBitRateIn = sbrElInfo[e].bitRate;
sbrBitRateOut = sbrEncoder_LimitBitRate(sbrElementBitRateIn , cm.elInfo[e].nChannelsInEl, coreSamplingRate, aot);
if (sbrBitRateOut == 0) {
return 0;
}
/* If bitrates don't match, distribution and limiting needs to be determined again.
Abort element loop and restart with adapted bitrate. */
if (sbrElementBitRateIn != sbrBitRateOut) {
if (sbrElementBitRateIn < sbrBitRateOut) {
adjustedBitrate = fMax(initialBitrate, (INT)fDivNorm((FIXP_DBL)(sbrBitRateOut+8), cm.elInfo[e].relativeBits));
break;
}
if (sbrElementBitRateIn > sbrBitRateOut) {
adjustedBitrate = fMin(initialBitrate, (INT)fDivNorm((FIXP_DBL)(sbrBitRateOut-8), cm.elInfo[e].relativeBits));
break;
}
} /* sbrElementBitRateIn != sbrBitRateOut */
} /* elements */
numIterations++; /* restrict iteration to worst case of num elements */
} while ( (initialBitrate!=adjustedBitrate) && (numIterations<=cm.nElements) );
/* Unequal bitrates mean that no reasonable bitrate configuration found. */
bitRate = (initialBitrate==adjustedBitrate) ? adjustedBitrate : 0;
}
FDK_ASSERT(bitRate > 0);
@ -840,7 +842,7 @@ static AACENC_ERROR aacEncInit(HANDLE_AACENCODER hAacEncoder,
INT sbrError;
SBR_ELEMENT_INFO sbrElInfo[(6)];
CHANNEL_MAPPING channelMapping;
AUDIO_OBJECT_TYPE aot = hAacConfig->audioObjectType;
if ( FDKaacEnc_InitChannelMapping(hAacConfig->channelMode,
@ -1097,7 +1099,7 @@ AACENC_ERROR aacEncOpen(
goto bail;
}
else {
C_ALLOC_SCRATCH_START(pLibInfo, LIB_INFO, FDK_MODULE_LAST);
C_ALLOC_SCRATCH_START(pLibInfo, LIB_INFO, FDK_MODULE_LAST);
FDKinitLibInfo( pLibInfo);
transportEnc_GetLibInfo( pLibInfo );