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Apply simulated HRIR occlusion in the frequency domain

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This commit is contained in:
Chris Robinson
2020-06-21 19:28:37 -07:00
parent 967ea42359
commit a0eb532100
1 changed files with 59 additions and 50 deletions
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utils/makemhr/makemhr.cpp
+59 -50
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@@ -941,15 +941,19 @@ static void SynthesizeOnsets(HrirDataT *hData)
}
/* Attempt to synthesize any missing HRIRs at the bottom elevations of each
* field. Right now this just blends the lowest elevation HRIRs together. It
* is a simple, if inaccurate model.
* field. Right now this just blends the lowest elevation HRIRs together and
* applies a low-pass filter to simulate body occlusion. It is a simple, if
* inaccurate model.
*/
static void SynthesizeHrirs(HrirDataT *hData)
{
const uint channels{(hData->mChannelType == CT_STEREO) ? 2u : 1u};
auto htemp = std::vector<complex_d>(hData->mFftSize);
const uint m{hData->mFftSize/2u + 1u};
auto filter = std::vector<double>(m);
const double beta{3.5e-6 * hData->mIrRate};
auto proc_field = [channels,m](HrirFdT &field) -> void
auto proc_field = [channels,m,beta,&htemp,&filter](HrirFdT &field) -> void
{
const uint oi{field.mEvStart};
if(oi <= 0) return;
@@ -976,6 +980,30 @@ static void SynthesizeHrirs(HrirDataT *hData)
for(uint ei{1u};ei < field.mEvStart;ei++)
{
const double of{static_cast<double>(ei) / field.mEvStart};
const double b{(1.0 - of) * beta};
double lp[4]{};
/* Calculate a low-pass filter to simulate body occlusion. */
lp[0] = Lerp(1.0, lp[0], b);
lp[1] = Lerp(lp[0], lp[1], b);
lp[2] = Lerp(lp[1], lp[2], b);
lp[3] = Lerp(lp[2], lp[3], b);
htemp[0] = lp[3];
for(size_t i{1u};i < htemp.size();i++)
{
lp[0] = Lerp(0.0, lp[0], b);
lp[1] = Lerp(lp[0], lp[1], b);
lp[2] = Lerp(lp[1], lp[2], b);
lp[3] = Lerp(lp[2], lp[3], b);
htemp[i] = lp[3];
}
/* Get the filter's frequency-domain response and extract the
* frequency magnitudes (phase will be reconstructed later)).
*/
FftForward(static_cast<uint>(htemp.size()), htemp.data());
std::transform(htemp.cbegin(), htemp.cbegin()+m, filter.begin(),
[](const complex_d &c) -> double { return std::abs(c); });
for(uint ai{0u};ai < field.mEvs[ei].mAzCount;ai++)
{
uint a0, a1;
@@ -991,16 +1019,42 @@ static void SynthesizeHrirs(HrirDataT *hData)
*/
const double s1{Lerp(field.mEvs[oi].mAzs[a0].mIrs[ti][i],
field.mEvs[oi].mAzs[a1].mIrs[ti][i], af)};
field.mEvs[ei].mAzs[ai].mIrs[ti][i] = Lerp(
field.mEvs[0].mAzs[0].mIrs[ti][i], s1, of);
const double s{Lerp(field.mEvs[0].mAzs[0].mIrs[ti][i], s1, of)};
field.mEvs[ei].mAzs[ai].mIrs[ti][i] = s * filter[i];
}
}
}
}
const double b{beta};
double lp[4]{};
lp[0] = Lerp(1.0, lp[0], b);
lp[1] = Lerp(lp[0], lp[1], b);
lp[2] = Lerp(lp[1], lp[2], b);
lp[3] = Lerp(lp[2], lp[3], b);
htemp[0] = lp[3];
for(size_t i{1u};i < htemp.size();i++)
{
lp[0] = Lerp(0.0, lp[0], b);
lp[1] = Lerp(lp[0], lp[1], b);
lp[2] = Lerp(lp[1], lp[2], b);
lp[3] = Lerp(lp[2], lp[3], b);
htemp[i] = lp[3];
}
FftForward(static_cast<uint>(htemp.size()), htemp.data());
std::transform(htemp.cbegin(), htemp.cbegin()+m, filter.begin(),
[](const complex_d &c) -> double { return std::abs(c); });
for(uint ti{0u};ti < channels;ti++)
{
for(uint i{0u};i < m;i++)
field.mEvs[0].mAzs[0].mIrs[ti][i] *= filter[i];
}
};
std::for_each(hData->mFds.begin(), hData->mFds.begin()+hData->mFdCount, proc_field);
}
// The following routines assume a full set of HRIRs for all elevations.
/* Perform minimum-phase reconstruction using the magnitude responses of the
* HRIR set. Work is delegated to this struct, which runs asynchronously on one
* or more threads (sharing the same reconstructor object).
@@ -1098,49 +1152,6 @@ static void ReconstructHrirs(const HrirDataT *hData, const uint numThreads)
}
}
/* Attempt to occlude the synthesized HRIRs. Right now this just applies some
* attenuation and high frequency damping. It is a simple, if inaccurate
* model.
*/
static void OccludeHrirs(HrirDataT *hData)
{
const uint channels{(hData->mChannelType == CT_STEREO) ? 2u : 1u};
const uint irSize{hData->mIrPoints};
const double beta{3.5e-6 * hData->mIrRate};
auto proc_field = [channels,irSize,beta](HrirFdT &field) -> void
{
const uint oi{field.mEvStart};
if(oi <= 0) return;
for(uint ei{0u};ei < field.mEvStart;ei++)
{
const double of{static_cast<double>(ei) / field.mEvStart};
const double b{(1.0 - of) * beta};
for(uint ai{0u};ai < field.mEvs[ei].mAzCount;ai++)
{
for(uint ti{0u};ti < channels;ti++)
{
double lp[4]{};
for(uint i{0u};i < irSize;i++)
{
const double s0{field.mEvs[ei].mAzs[ai].mIrs[ti][i]};
/* Apply a low-pass to simulate body occlusion. */
lp[0] = Lerp(s0, lp[0], b);
lp[1] = Lerp(lp[0], lp[1], b);
lp[2] = Lerp(lp[1], lp[2], b);
lp[3] = Lerp(lp[2], lp[3], b);
field.mEvs[ei].mAzs[ai].mIrs[ti][i] = lp[3];
}
}
}
}
};
std::for_each(hData->mFds.begin(), hData->mFds.begin()+hData->mFdCount, proc_field);
}
// The following routines assume a full set of HRIRs for all elevations.
// Normalize the HRIR set and slightly attenuate the result.
static void NormalizeHrirs(HrirDataT *hData)
{
@@ -1472,8 +1483,6 @@ static int ProcessDefinition(const char *inName, const uint outRate, const Chann
ReconstructHrirs(&hData, numThreads);
fprintf(stdout, "Truncating minimum-phase HRIRs...\n");
hData.mIrPoints = truncSize;
fprintf(stdout, "Occluding synthesized HRIRs...\n");
OccludeHrirs(&hData);
fprintf(stdout, "Normalizing final HRIRs...\n");
NormalizeHrirs(&hData);
fprintf(stdout, "Calculating impulse delays...\n");