/*
* 2-channel UHJ Decoder
*
* Copyright (c) Chris Robinson <chris.kcat@gmail.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "config.h"
#include <array>
#include <complex>
#include <cstring>
#include <memory>
#include <stddef.h>
#include <string>
#include <utility>
#include <vector>
#include "albit.h"
#include "albyte.h"
#include "alcomplex.h"
#include "almalloc.h"
#include "alspan.h"
#include "vector.h"
#include "opthelpers.h"
#include "phase_shifter.h"
#include "sndfile.h"
#include "win_main_utf8.h"
struct FileDeleter {
void operator()(FILE *file) { fclose(file); }
};
using FilePtr = std::unique_ptr<FILE,FileDeleter>;
struct SndFileDeleter {
void operator()(SNDFILE *sndfile) { sf_close(sndfile); }
};
using SndFilePtr = std::unique_ptr<SNDFILE,SndFileDeleter>;
using ubyte = unsigned char;
using ushort = unsigned short;
using uint = unsigned int;
using complex_d = std::complex<double>;
using byte4 = std::array<al::byte,4>;
constexpr ubyte SUBTYPE_BFORMAT_FLOAT[]{
0x03, 0x00, 0x00, 0x00, 0x21, 0x07, 0xd3, 0x11, 0x86, 0x44, 0xc8, 0xc1,
0xca, 0x00, 0x00, 0x00
};
void fwrite16le(ushort val, FILE *f)
{
ubyte data[2]{ static_cast<ubyte>(val&0xff), static_cast<ubyte>((val>>8)&0xff) };
fwrite(data, 1, 2, f);
}
void fwrite32le(uint val, FILE *f)
{
ubyte data[4]{ static_cast<ubyte>(val&0xff), static_cast<ubyte>((val>>8)&0xff),
static_cast<ubyte>((val>>16)&0xff), static_cast<ubyte>((val>>24)&0xff) };
fwrite(data, 1, 4, f);
}
template<al::endian = al::endian::native>
byte4 f32AsLEBytes(const float &value) = delete;
template<>
byte4 f32AsLEBytes<al::endian::little>(const float &value)
{
byte4 ret{};
std::memcpy(ret.data(), &value, 4);
return ret;
}
template<>
byte4 f32AsLEBytes<al::endian::big>(const float &value)
{
byte4 ret{};
std::memcpy(ret.data(), &value, 4);
std::swap(ret[0], ret[3]);
std::swap(ret[1], ret[2]);
return ret;
}
constexpr uint BufferLineSize{1024};
using FloatBufferLine = std::array<float,BufferLineSize>;
using FloatBufferSpan = al::span<float,BufferLineSize>;
struct UhjDecoder {
constexpr static size_t sFilterDelay{1024};
alignas(16) std::array<float,BufferLineSize+sFilterDelay> mS{};
alignas(16) std::array<float,BufferLineSize+sFilterDelay> mD{};
alignas(16) std::array<float,BufferLineSize+sFilterDelay> mT{};
alignas(16) std::array<float,BufferLineSize+sFilterDelay> mQ{};
/* History for the FIR filter. */
alignas(16) std::array<float,sFilterDelay-1> mDTHistory{};
alignas(16) std::array<float,sFilterDelay-1> mSHistory{};
alignas(16) std::array<float,BufferLineSize + sFilterDelay*2> mTemp{};
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);
DEF_NEWDEL(UhjDecoder)
};
const PhaseShifterT<UhjDecoder::sFilterDelay*2> PShift{};
/* Decoding UHJ is done as:
*
* S = Left + Right
* D = Left - Right
*
* W = 0.981530*S + 0.197484*j(0.828347*D + 0.767835*T)
* X = 0.418504*S - j(0.828347*D + 0.767835*T)
* 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, 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
*
* S = (Left + Right)/2
* D = (Left - Right)/2
*
* However, this is incorrect. It's halving Left and Right even though they
* were already halved during encoding, causing S and D to be half what they
* initially were at the encoding stage. This division is not present in
* Gerzon's original paper for deriving Sigma (S) or Delta (D) from the L and R
* signals. As proof, taking Y for example:
*
* Y = 0.795954*D - 0.676406*T + j(0.186626*S)
*
* * Plug in the encoding parameters, using ? as a placeholder for whether S
* and D should receive an extra 0.5 factor
* Y = 0.795954*(j(-0.3420201*W + 0.5098604*X) + 0.6554516*Y)*? -
* 0.676406*(j(-0.1432*W + 0.6511746*X) - 0.7071068*Y) +
* 0.186626*j(0.9396926*W + 0.1855740*X)*?
*
* * Move common factors in
* Y = (j(-0.3420201*0.795954*?*W + 0.5098604*0.795954*?*X) + 0.6554516*0.795954*?*Y) -
* (j(-0.1432*0.676406*W + 0.6511746*0.676406*X) - 0.7071068*0.676406*Y) +
* j(0.9396926*0.186626*?*W + 0.1855740*0.186626*?*X)
*
* * Clean up extraneous groupings
* Y = j(-0.3420201*0.795954*?*W + 0.5098604*0.795954*?*X) + 0.6554516*0.795954*?*Y -
* j(-0.1432*0.676406*W + 0.6511746*0.676406*X) + 0.7071068*0.676406*Y +
* j*(0.9396926*0.186626*?*W + 0.1855740*0.186626*?*X)
*
* * Move phase shifts together and combine them
* Y = j(-0.3420201*0.795954*?*W + 0.5098604*0.795954*?*X - -0.1432*0.676406*W -
* 0.6511746*0.676406*X + 0.9396926*0.186626*?*W + 0.1855740*0.186626*?*X) +
* 0.6554516*0.795954*?*Y + 0.7071068*0.676406*Y
*
* * Reorder terms
* Y = j(-0.3420201*0.795954*?*W + 0.1432*0.676406*W + 0.9396926*0.186626*?*W +
* 0.5098604*0.795954*?*X + -0.6511746*0.676406*X + 0.1855740*0.186626*?*X) +
* 0.7071068*0.676406*Y + 0.6554516*0.795954*?*Y
*
* * Move common factors out
* Y = j((-0.3420201*0.795954*? + 0.1432*0.676406 + 0.9396926*0.186626*?)*W +
* ( 0.5098604*0.795954*? + -0.6511746*0.676406 + 0.1855740*0.186626*?)*X) +
* (0.7071068*0.676406 + 0.6554516*0.795954*?)*Y
*
* * Result w/ 0.5 factor:
* -0.3420201*0.795954*0.5 + 0.1432*0.676406 + 0.9396926*0.186626*0.5 = 0.04843*W
* 0.5098604*0.795954*0.5 + -0.6511746*0.676406 + 0.1855740*0.186626*0.5 = -0.22023*X
* 0.7071068*0.676406 + 0.6554516*0.795954*0.5 = 0.73915*Y
* -> Y = j(0.04843*W + -0.22023*X) + 0.73915*Y
*
* * Result w/o 0.5 factor:
* -0.3420201*0.795954 + 0.1432*0.676406 + 0.9396926*0.186626 = 0.00000*W
* 0.5098604*0.795954 + -0.6511746*0.676406 + 0.1855740*0.186626 = 0.00000*X
* 0.7071068*0.676406 + 0.6554516*0.795954 = 1.00000*Y
* -> Y = j(0.00000*W + 0.00000*X) + 1.00000*Y
*
* Not halving produces a result matching the original input.
*/
void UhjDecoder::decode(const float *RESTRICT InSamples, const size_t InChannels,
const al::span<FloatBufferLine> OutSamples, const size_t SamplesToDo)
{
ASSUME(SamplesToDo > 0);
float *woutput{OutSamples[0].data()};
float *xoutput{OutSamples[1].data()};
float *youtput{OutSamples[2].data()};
/* Add a delay to the input channels, to align it with the all-passed
* signal.
*/
/* S = Left + Right */
for(size_t i{0};i < SamplesToDo;++i)
mS[sFilterDelay+i] = InSamples[i*InChannels + 0] + InSamples[i*InChannels + 1];
/* D = Left - Right */
for(size_t i{0};i < SamplesToDo;++i)
mD[sFilterDelay+i] = InSamples[i*InChannels + 0] - InSamples[i*InChannels + 1];
if(InChannels > 2)
{
/* T */
for(size_t i{0};i < SamplesToDo;++i)
mT[sFilterDelay+i] = InSamples[i*InChannels + 2];
}
if(InChannels > 3)
{
/* Q */
for(size_t i{0};i < SamplesToDo;++i)
mQ[sFilterDelay+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+sFilterDelay, mT.cbegin(), tmpiter,
[](const float d, const float t) noexcept { return 0.828347f*d + 0.767835f*t; });
std::copy_n(mTemp.cbegin()+SamplesToDo, mDTHistory.size(), mDTHistory.begin());
PShift.process({xoutput, SamplesToDo}, mTemp.data());
for(size_t i{0};i < SamplesToDo;++i)
{
/* W = 0.981530*S + 0.197484*j(0.828347*D + 0.767835*T) */
woutput[i] = 0.981530f*mS[i] + 0.197484f*xoutput[i];
/* X = 0.418504*S - j(0.828347*D + 0.767835*T) */
xoutput[i] = 0.418504f*mS[i] - xoutput[i];
}
/* Precompute j*S and store in youtput. */
tmpiter = std::copy(mSHistory.cbegin(), mSHistory.cend(), mTemp.begin());
std::copy_n(mS.cbegin(), SamplesToDo+sFilterDelay, tmpiter);
std::copy_n(mTemp.cbegin()+SamplesToDo, mSHistory.size(), mSHistory.begin());
PShift.process({youtput, SamplesToDo}, mTemp.data());
for(size_t i{0};i < SamplesToDo;++i)
{
/* Y = 0.795954*D - 0.676406*T + j(0.186626*S) */
youtput[i] = 0.795954f*mD[i] - 0.676406f*mT[i] + 0.186626f*youtput[i];
}
if(OutSamples.size() > 3)
{
float *zoutput{OutSamples[3].data()};
/* Z = 1.023332*Q */
for(size_t i{0};i < SamplesToDo;++i)
zoutput[i] = 1.023332f*mQ[i];
}
std::copy(mS.begin()+SamplesToDo, mS.begin()+SamplesToDo+sFilterDelay, mS.begin());
std::copy(mD.begin()+SamplesToDo, mD.begin()+SamplesToDo+sFilterDelay, mD.begin());
std::copy(mT.begin()+SamplesToDo, mT.begin()+SamplesToDo+sFilterDelay, mT.begin());
std::copy(mQ.begin()+SamplesToDo, mQ.begin()+SamplesToDo+sFilterDelay, mQ.begin());
}
/* 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.
*
* This decoding is done as:
*
* S = Left + Right
* D = Left - Right
*
* W = 0.981530*S + j*0.163585*D
* X = 0.418504*S - j*0.828347*D
* Y = 0.762956*D + j*0.384230*S
*
* where j is a +90 degree phase shift.
*
* NOTE: As above, S and D should not be halved. The only consequence of
* halving here is merely a -6dB reduction in output, but it's still incorrect.
*/
void UhjDecoder::decode2(const float *RESTRICT InSamples,
const al::span<FloatBufferLine,3> OutSamples, const size_t SamplesToDo)
{
ASSUME(SamplesToDo > 0);
float *woutput{OutSamples[0].data()};
float *xoutput{OutSamples[1].data()};
float *youtput{OutSamples[2].data()};
/* S = Left + Right */
for(size_t i{0};i < SamplesToDo;++i)
mS[sFilterDelay+i] = InSamples[i*2 + 0] + InSamples[i*2 + 1];
/* D = Left - Right */
for(size_t i{0};i < SamplesToDo;++i)
mD[sFilterDelay+i] = InSamples[i*2 + 0] - InSamples[i*2 + 1];
/* Precompute j*D and store in xoutput. */
auto tmpiter = std::copy(mDTHistory.cbegin(), mDTHistory.cend(), mTemp.begin());
std::copy_n(mD.cbegin(), SamplesToDo+sFilterDelay, tmpiter);
std::copy_n(mTemp.cbegin()+SamplesToDo, mDTHistory.size(), mDTHistory.begin());
PShift.process({xoutput, SamplesToDo}, mTemp.data());
for(size_t i{0};i < SamplesToDo;++i)
{
/* W = 0.981530*S + j*0.163585*D */
woutput[i] = 0.981530f*mS[i] + 0.163585f*xoutput[i];
/* X = 0.418504*S - j*0.828347*D */
xoutput[i] = 0.418504f*mS[i] - 0.828347f*xoutput[i];
}
/* Precompute j*S and store in youtput. */
tmpiter = std::copy(mSHistory.cbegin(), mSHistory.cend(), mTemp.begin());
std::copy_n(mS.cbegin(), SamplesToDo+sFilterDelay, tmpiter);
std::copy_n(mTemp.cbegin()+SamplesToDo, mSHistory.size(), mSHistory.begin());
PShift.process({youtput, SamplesToDo}, mTemp.data());
for(size_t i{0};i < SamplesToDo;++i)
{
/* Y = 0.762956*D + j*0.384230*S */
youtput[i] = 0.762956f*mD[i] + 0.384230f*youtput[i];
}
std::copy(mS.begin()+SamplesToDo, mS.begin()+SamplesToDo+sFilterDelay, mS.begin());
std::copy(mD.begin()+SamplesToDo, mD.begin()+SamplesToDo+sFilterDelay, mD.begin());
}
int main(int argc, char **argv)
{
if(argc < 2 || std::strcmp(argv[1], "-h") == 0 || std::strcmp(argv[1], "--help") == 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)};
if(!infile)
{
fprintf(stderr, "Failed to open %s\n", argv[fidx]);
continue;
}
if(sf_command(infile.get(), SFC_WAVEX_GET_AMBISONIC, NULL, 0) == SF_AMBISONIC_B_FORMAT)
{
fprintf(stderr, "%s is already B-Format\n", argv[fidx]);
continue;
}
uint outchans{};
if(ininfo.channels == 2)
outchans = 3;
else if(ininfo.channels == 3 || ininfo.channels == 4)
outchans = static_cast<uint>(ininfo.channels);
else
{
fprintf(stderr, "%s is not a 2-, 3-, or 4-channel file\n", argv[fidx]);
continue;
}
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('/');
if(lastslash != std::string::npos)
outname.erase(0, lastslash+1);
auto lastdot = outname.find_last_of('.');
if(lastdot != std::string::npos)
outname.resize(lastdot+1);
outname += "amb";
FilePtr outfile{fopen(outname.c_str(), "wb")};
if(!outfile)
{
fprintf(stderr, "Failed to create %s\n", outname.c_str());
continue;
}
fputs("RIFF", outfile.get());
fwrite32le(0xFFFFFFFF, outfile.get()); // 'RIFF' header len; filled in at close
fputs("WAVE", outfile.get());
fputs("fmt ", outfile.get());
fwrite32le(40, outfile.get()); // 'fmt ' header len; 40 bytes for EXTENSIBLE
// 16-bit val, format type id (extensible: 0xFFFE)
fwrite16le(0xFFFE, outfile.get());
// 16-bit val, channel count
fwrite16le(static_cast<ushort>(outchans), outfile.get());
// 32-bit val, frequency
fwrite32le(static_cast<uint>(ininfo.samplerate), outfile.get());
// 32-bit val, bytes per second
fwrite32le(static_cast<uint>(ininfo.samplerate)*sizeof(float)*outchans, outfile.get());
// 16-bit val, frame size
fwrite16le(static_cast<ushort>(sizeof(float)*outchans), outfile.get());
// 16-bit val, bits per sample
fwrite16le(static_cast<ushort>(sizeof(float)*8), outfile.get());
// 16-bit val, extra byte count
fwrite16le(22, outfile.get());
// 16-bit val, valid bits per sample
fwrite16le(static_cast<ushort>(sizeof(float)*8), outfile.get());
// 32-bit val, channel mask
fwrite32le(0, outfile.get());
// 16 byte GUID, sub-type format
fwrite(SUBTYPE_BFORMAT_FLOAT, 1, 16, outfile.get());
fputs("data", outfile.get());
fwrite32le(0xFFFFFFFF, outfile.get()); // 'data' header len; filled in at close
if(ferror(outfile.get()))
{
fprintf(stderr, "Error writing wave file header: %s (%d)\n", strerror(errno), errno);
continue;
}
auto DataStart = ftell(outfile.get());
auto decoder = std::make_unique<UhjDecoder>();
auto inmem = std::make_unique<float[]>(BufferLineSize*static_cast<uint>(ininfo.channels));
auto decmem = al::vector<std::array<float,BufferLineSize>, 16>(outchans);
auto outmem = std::make_unique<byte4[]>(BufferLineSize*outchans);
/* A number of initial samples need to be skipped to cut the lead-in
* from the all-pass filter delay. The same number of samples need to
* be fed through the decoder after reaching the end of the input file
* to ensure none of the original input is lost.
*/
size_t LeadIn{UhjDecoder::sFilterDelay};
sf_count_t LeadOut{UhjDecoder::sFilterDelay};
while(LeadOut > 0)
{
sf_count_t sgot{sf_readf_float(infile.get(), inmem.get(), BufferLineSize)};
sgot = std::max<sf_count_t>(sgot, 0);
if(sgot < BufferLineSize)
{
const sf_count_t remaining{std::min(BufferLineSize - sgot, LeadOut)};
std::fill_n(inmem.get() + sgot*ininfo.channels, remaining*ininfo.channels, 0.0f);
sgot += remaining;
LeadOut -= remaining;
}
auto got = static_cast<size_t>(sgot);
if(ininfo.channels > 2 || use_general)
decoder->decode(inmem.get(), static_cast<uint>(ininfo.channels), decmem, got);
else
decoder->decode2(inmem.get(), decmem, got);
if(LeadIn >= got)
{
LeadIn -= got;
continue;
}
got -= LeadIn;
for(size_t i{0};i < got;++i)
{
/* Attenuate by -3dB for FuMa output levels. */
constexpr float sqrt1_2{0.707106781187f};
for(size_t j{0};j < outchans;++j)
outmem[i*outchans + j] = f32AsLEBytes(decmem[j][LeadIn+i] * sqrt1_2);
}
LeadIn = 0;
size_t wrote{fwrite(outmem.get(), sizeof(byte4)*outchans, got, outfile.get())};
if(wrote < got)
{
fprintf(stderr, "Error writing wave data: %s (%d)\n", strerror(errno), errno);
break;
}
}
auto DataEnd = ftell(outfile.get());
if(DataEnd > DataStart)
{
long dataLen{DataEnd - DataStart};
if(fseek(outfile.get(), 4, SEEK_SET) == 0)
fwrite32le(static_cast<uint>(DataEnd-8), outfile.get()); // 'WAVE' header len
if(fseek(outfile.get(), DataStart-4, SEEK_SET) == 0)
fwrite32le(static_cast<uint>(dataLen), outfile.get()); // 'data' header len
}
fflush(outfile.get());
++num_decoded;
}
if(num_decoded == 0)
fprintf(stderr, "Failed to decode any input files\n");
else if(num_decoded < num_files)
fprintf(stderr, "Decoded %zu of %zu files\n", num_decoded, num_files);
else
printf("Decoded %zu file%s\n", num_decoded, (num_decoded==1)?"":"s");
return 0;
}