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Normalize HRIRs using their maximum RMS

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This commit is contained in:
Chris Robinson 2019-03-04 08:00:04 -08:00
parent 90d1e1212b
commit da9ec374d8
1 changed files with 23 additions and 2 deletions
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25
utils/makehrtf.cpp
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@ -2457,6 +2457,7 @@ static void NormalizeHrirs(const HrirDataT *hData)
uint n{hData->mIrPoints}; uint n{hData->mIrPoints};
uint ti, fi, ei, ai, i; uint ti, fi, ei, ai, i;
double maxLevel{0.0}; double maxLevel{0.0};
double maxRms{0.0};
for(fi = 0;fi < hData->mFdCount;fi++) for(fi = 0;fi < hData->mFdCount;fi++)
{ {
@ -2467,13 +2468,33 @@ static void NormalizeHrirs(const HrirDataT *hData)
HrirAzT *azd = &hData->mFds[fi].mEvs[ei].mAzs[ai]; HrirAzT *azd = &hData->mFds[fi].mEvs[ei].mAzs[ai];
for(ti = 0;ti < channels;ti++) for(ti = 0;ti < channels;ti++)
{ {
double rms{0.0};
for(i = 0;i < n;i++) for(i = 0;i < n;i++)
{
maxLevel = std::max(std::abs(azd->mIrs[ti][i]), maxLevel); maxLevel = std::max(std::abs(azd->mIrs[ti][i]), maxLevel);
rms += azd->mIrs[ti][i] * azd->mIrs[ti][i];
}
rms = std::sqrt(rms / n);
maxRms = std::max(rms, maxRms);
} }
} }
} }
} }
maxLevel = 1.01 * maxLevel;
/* Normalize using the maximum RMS of the HRIRs. The RMS measure for the
* non-filtered signal is of an impulse with equal length (to the filter):
*
* rms_impulse = sqrt(sum([ 1^2, 0^2, 0^2, ... ]) / n)
* = sqrt(1 / n)
*
* This helps keep a more consistent volume between the non-filtered signal
* and various data sets.
*/
double factor{std::sqrt(1.0 / n) / maxRms};
/* Also ensure the impulse samples themselves won't clip. */
factor = std::min(factor, 0.99/maxLevel);
for(fi = 0;fi < hData->mFdCount;fi++) for(fi = 0;fi < hData->mFdCount;fi++)
{ {
@ -2486,7 +2507,7 @@ static void NormalizeHrirs(const HrirDataT *hData)
for(ti = 0;ti < channels;ti++) for(ti = 0;ti < channels;ti++)
{ {
for(i = 0;i < n;i++) for(i = 0;i < n;i++)
azd->mIrs[ti][i] /= maxLevel; azd->mIrs[ti][i] *= factor;
} }
} }
} }