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-rw-r--r--utils/uhjdecoder.cpp77
1 files changed, 50 insertions, 27 deletions
diff --git a/utils/uhjdecoder.cpp b/utils/uhjdecoder.cpp
index 721481a3..5572b690 100644
--- a/utils/uhjdecoder.cpp
+++ b/utils/uhjdecoder.cpp
@@ -130,8 +130,8 @@ struct UhjDecoder {
alignas(16) std::array<float,BufferLineSize + sFilterSize*2> mTemp{};
- void decode(const float *RESTRICT InSamples, const al::span<FloatBufferLine> OutSamples,
- const size_t SamplesToDo);
+ void decode(const float *RESTRICT InSamples, const size_t InChannels,
+ const al::span<FloatBufferLine> OutSamples, const size_t SamplesToDo);
void decode2(const float *RESTRICT InSamples, const al::span<FloatBufferLine,3> OutSamples,
const size_t SamplesToDo);
@@ -307,7 +307,7 @@ void allpass_process(al::span<float> dst, const float *RESTRICT src)
}
-/* Decoding 3- and 4-channel UHJ is done as:
+/* Decoding UHJ is done as:
*
* S = Left + Right
* D = Left - Right
@@ -317,7 +317,10 @@ void allpass_process(al::span<float> dst, const float *RESTRICT src)
* Y = 0.795954*D - 0.676406*T + j(0.186626*S)
* Z = 1.023332*Q
*
- * where j is a +90 degree phase shift. 3-channel UHJ excludes Q/Z.
+ * where j is a +90 degree phase shift. 3-channel UHJ excludes Q, while 2-
+ * channel excludes Q and T. The B-Format signal reconstructed from 2-channel
+ * UHJ should not be run through a normal B-Format decoder, as it needs
+ * different shelf filters.
*
* NOTE: Some sources specify
*
@@ -377,13 +380,11 @@ void allpass_process(al::span<float> dst, const float *RESTRICT src)
*
* Not halving produces a result matching the original input.
*/
-void UhjDecoder::decode(const float *RESTRICT InSamples,
+void UhjDecoder::decode(const float *RESTRICT InSamples, const size_t InChannels,
const al::span<FloatBufferLine> OutSamples, const size_t SamplesToDo)
{
ASSUME(SamplesToDo > 0);
- const size_t Channels{OutSamples.size()};
-
float *woutput{OutSamples[0].data()};
float *xoutput{OutSamples[1].data()};
float *youtput{OutSamples[2].data()};
@@ -394,27 +395,29 @@ void UhjDecoder::decode(const float *RESTRICT InSamples,
/* S = Left + Right */
for(size_t i{0};i < SamplesToDo;++i)
- mS[sFilterSize+i] = InSamples[i*Channels + 0] + InSamples[i*Channels + 1];
+ mS[sFilterSize+i] = InSamples[i*InChannels + 0] + InSamples[i*InChannels + 1];
/* D = Left - Right */
for(size_t i{0};i < SamplesToDo;++i)
- mD[sFilterSize+i] = InSamples[i*Channels + 0] - InSamples[i*Channels + 1];
-
- /* T */
- for(size_t i{0};i < SamplesToDo;++i)
- mT[sFilterSize+i] = InSamples[i*Channels + 2];
+ mD[sFilterSize+i] = InSamples[i*InChannels + 0] - InSamples[i*InChannels + 1];
- if(Channels > 3)
+ if(InChannels > 2)
+ {
+ /* T */
+ for(size_t i{0};i < SamplesToDo;++i)
+ mT[sFilterSize+i] = InSamples[i*InChannels + 2];
+ }
+ if(InChannels > 3)
{
/* Q */
for(size_t i{0};i < SamplesToDo;++i)
- mQ[sFilterSize+i] = InSamples[i*Channels + 3];
+ mQ[sFilterSize+i] = InSamples[i*InChannels + 3];
}
/* Precompute j(0.828347*D + 0.767835*T) and store in xoutput. */
auto tmpiter = std::copy(mDTHistory.cbegin(), mDTHistory.cend(), mTemp.begin());
std::transform(mD.cbegin(), mD.cbegin()+SamplesToDo+sFilterSize, mT.cbegin(), tmpiter,
- [](const float D, const float T) noexcept { return 0.828347f*D + 0.767835f*T; });
+ [](const float d, const float t) noexcept { return 0.828347f*d + 0.767835f*t; });
std::copy_n(mTemp.cbegin()+SamplesToDo, mDTHistory.size(), mDTHistory.begin());
allpass_process({xoutput, SamplesToDo}, mTemp.data());
@@ -438,7 +441,7 @@ void UhjDecoder::decode(const float *RESTRICT InSamples,
youtput[i] = 0.795954f*mD[i] - 0.676406f*mT[i] + 0.186626f*youtput[i];
}
- if(Channels > 3)
+ if(OutSamples.size() > 3)
{
float *zoutput{OutSamples[3].data()};
/* Z = 1.023332*Q */
@@ -452,12 +455,12 @@ void UhjDecoder::decode(const float *RESTRICT InSamples,
std::copy(mQ.begin()+SamplesToDo, mQ.begin()+SamplesToDo+sFilterSize, mQ.begin());
}
-/* There is a difference with decoding 2-channel UHJ compared to 3-channel, due
- * to 2-channel having lost some of the original signal. The B-Format signal
- * reconstructed from 2-channel UHJ should not be run through a normal B-Format
- * decoder, as it needs different shelf filters.
+/* This is an alternative equation for decoding 2-channel UHJ. Not sure what
+ * the intended benefit is over the above equation as this slightly reduces the
+ * amount of the original left response and has more of the phase-shifted
+ * forward response on the left response.
*
- * 2-channel UHJ decoding is done as:
+ * This decoding is done as:
*
* S = Left + Right
* D = Left - Right
@@ -523,13 +526,32 @@ int main(int argc, char **argv)
{
if(argc < 2 || std::strcmp(argv[1], "-h") == 0 || std::strcmp(argv[1], "--help") == 0)
{
- printf("Usage: %s <filename.wav...>\n", argv[0]);
+ printf("Usage: %s <[options] filename.wav...>\n\n"
+ " Options:\n"
+ " --general Use the general equations for 2-channel UHJ (default).\n"
+ " --alternative Use the alternative equations for 2-channel UHJ.\n"
+ "\n"
+ "Note: When decoding 2-channel UHJ to an .amb file, the result should not use\n"
+ "the normal B-Format shelf filters! Only 3- and 4-channel UHJ can accurately\n"
+ "reconstruct the original B-Format signal.",
+ argv[0]);
return 1;
}
size_t num_files{0}, num_decoded{0};
+ bool use_general{true};
for(int fidx{1};fidx < argc;++fidx)
{
+ if(std::strcmp(argv[fidx], "--general") == 0)
+ {
+ use_general = true;
+ continue;
+ }
+ if(std::strcmp(argv[fidx], "--alternative") == 0)
+ {
+ use_general = false;
+ continue;
+ }
++num_files;
SF_INFO ininfo{};
SndFilePtr infile{sf_open(argv[fidx], SFM_READ, &ininfo)};
@@ -553,7 +575,8 @@ int main(int argc, char **argv)
fprintf(stderr, "%s is not a 2-, 3-, or 4-channel file\n", argv[fidx]);
continue;
}
- printf("Converting %s from %d-channel UHJ...\n", argv[fidx], ininfo.channels);
+ printf("Converting %s from %d-channel UHJ%s...\n", argv[fidx], ininfo.channels,
+ (ininfo.channels == 2) ? use_general ? " (general)" : " (alternative)" : "");
std::string outname{argv[fidx]};
auto lastslash = outname.find_last_of('/');
@@ -634,10 +657,10 @@ int main(int argc, char **argv)
}
auto got = static_cast<size_t>(sgot);
- if(ininfo.channels == 2)
+ if(ininfo.channels > 2 || use_general)
+ decoder->decode(inmem.get(), static_cast<uint>(ininfo.channels), decmem, got);
+ else
decoder->decode2(inmem.get(), decmem, got);
- else if(ininfo.channels == 3 || ininfo.channels == 4)
- decoder->decode(inmem.get(), decmem, got);
for(size_t i{0};i < got;++i)
{
for(size_t j{0};j < outchans;++j)
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-29 04:36:44 +0000