core/bformatdec.cpp

   1
   2 #include "config.h"
   3
   4 #include "bformatdec.h"
   5
   6 #include <algorithm>
   7 #include <array>
   8 #include <cmath>
   9 #include <utility>
  10
  11 #include "almalloc.h"
  12 #include "alnumbers.h"
  13 #include "filters/splitter.h"
  14 #include "front_stablizer.h"
  15 #include "mixer.h"
  16 #include "opthelpers.h"
  17
  18
  19 BFormatDec::BFormatDec(const size_t inchans, const al::span<const ChannelDec> coeffs,
  20     const al::span<const ChannelDec> coeffslf, const float xover_f0norm,
  21     std::unique_ptr<FrontStablizer> stablizer)
  22     : mStablizer{std::move(stablizer)}, mDualBand{!coeffslf.empty()}, mChannelDec{inchans}
  23 {
  24     if(!mDualBand)
  25     {
  26         for(size_t j{0};j < mChannelDec.size();++j)
  27         {
  28             float *outcoeffs{mChannelDec[j].mGains.Single};
  29             for(const ChannelDec &incoeffs : coeffs)
  30                 *(outcoeffs++) = incoeffs[j];
  31         }
  32     }
  33     else
  34     {
  35         mChannelDec[0].mXOver.init(xover_f0norm);
  36         for(size_t j{1};j < mChannelDec.size();++j)
  37             mChannelDec[j].mXOver = mChannelDec[0].mXOver;
  38
  39         for(size_t j{0};j < mChannelDec.size();++j)
  40         {
  41             float *outcoeffs{mChannelDec[j].mGains.Dual[sHFBand]};
  42             for(const ChannelDec &incoeffs : coeffs)
  43                 *(outcoeffs++) = incoeffs[j];
  44
  45             outcoeffs = mChannelDec[j].mGains.Dual[sLFBand];
  46             for(const ChannelDec &incoeffs : coeffslf)
  47                 *(outcoeffs++) = incoeffs[j];
  48         }
  49     }
  50 }
  51
  52
  53 void BFormatDec::process(const al::span<FloatBufferLine> OutBuffer,
  54     const FloatBufferLine *InSamples, const size_t SamplesToDo)
  55 {
  56     ASSUME(SamplesToDo > 0);
  57
  58     if(mDualBand)
  59     {
  60         const al::span<float> hfSamples{mSamples[sHFBand].data(), SamplesToDo};
  61         const al::span<float> lfSamples{mSamples[sLFBand].data(), SamplesToDo};
  62         for(auto &chandec : mChannelDec)
  63         {
  64             chandec.mXOver.process({InSamples->data(), SamplesToDo}, hfSamples.data(),
  65                 lfSamples.data());
  66             MixSamples(hfSamples, OutBuffer, chandec.mGains.Dual[sHFBand],
  67                 chandec.mGains.Dual[sHFBand], 0, 0);
  68             MixSamples(lfSamples, OutBuffer, chandec.mGains.Dual[sLFBand],
  69                 chandec.mGains.Dual[sLFBand], 0, 0);
  70             ++InSamples;
  71         }
  72     }
  73     else
  74     {
  75         for(auto &chandec : mChannelDec)
  76         {
  77             MixSamples({InSamples->data(), SamplesToDo}, OutBuffer, chandec.mGains.Single,
  78                 chandec.mGains.Single, 0, 0);
  79             ++InSamples;
  80         }
  81     }
  82 }
  83
  84 void BFormatDec::processStablize(const al::span<FloatBufferLine> OutBuffer,
  85     const FloatBufferLine *InSamples, const size_t lidx, const size_t ridx, const size_t cidx,
  86     const size_t SamplesToDo)
  87 {
  88     ASSUME(SamplesToDo > 0);
  89
  90     /* Move the existing direct L/R signal out so it doesn't get processed by
  91      * the stablizer.
  92      */
  93     float *RESTRICT mid{al::assume_aligned<16>(mStablizer->MidDirect.data())};
  94     float *RESTRICT side{al::assume_aligned<16>(mStablizer->Side.data())};
  95     for(size_t i{0};i < SamplesToDo;++i)
  96     {
  97         mid[i] = OutBuffer[lidx][i] + OutBuffer[ridx][i];
  98         side[i] = OutBuffer[lidx][i] - OutBuffer[ridx][i];
  99     }
 100     std::fill_n(OutBuffer[lidx].begin(), SamplesToDo, 0.0f);
 101     std::fill_n(OutBuffer[ridx].begin(), SamplesToDo, 0.0f);
 102
 103     /* Decode the B-Format input to OutBuffer. */
 104     process(OutBuffer, InSamples, SamplesToDo);
 105
 106     /* Include the decoded side signal with the direct side signal. */
 107     for(size_t i{0};i < SamplesToDo;++i)
 108         side[i] += OutBuffer[lidx][i] - OutBuffer[ridx][i];
 109
 110     /* Get the decoded mid signal and band-split it. */
 111     std::transform(OutBuffer[lidx].cbegin(), OutBuffer[lidx].cbegin()+SamplesToDo,
 112         OutBuffer[ridx].cbegin(), mStablizer->Temp.begin(),
 113         [](const float l, const float r) noexcept { return l + r; });
 114
 115     mStablizer->MidFilter.process({mStablizer->Temp.data(), SamplesToDo}, mStablizer->MidHF.data(),
 116         mStablizer->MidLF.data());
 117
 118     /* Apply an all-pass to all channels to match the band-splitter's phase
 119      * shift. This is to keep the phase synchronized between the existing
 120      * signal and the split mid signal.
 121      */
 122     const size_t NumChannels{OutBuffer.size()};
 123     for(size_t i{0u};i < NumChannels;i++)
 124     {
 125         /* Skip the left and right channels, which are going to get overwritten,
 126          * and substitute the direct mid signal and direct+decoded side signal.
 127          */
 128         if(i == lidx)
 129             mStablizer->ChannelFilters[i].processAllPass({mid, SamplesToDo});
 130         else if(i == ridx)
 131             mStablizer->ChannelFilters[i].processAllPass({side, SamplesToDo});
 132         else
 133             mStablizer->ChannelFilters[i].processAllPass({OutBuffer[i].data(), SamplesToDo});
 134     }
 135
 136     /* This pans the separate low- and high-frequency signals between being on
 137      * the center channel and the left+right channels. The low-frequency signal
 138      * is panned 1/3rd toward center and the high-frequency signal is panned
 139      * 1/4th toward center. These values can be tweaked.
 140      */
 141     const float cos_lf{std::cos(1.0f/3.0f * (al::numbers::pi_v<float>*0.5f))};
 142     const float cos_hf{std::cos(1.0f/4.0f * (al::numbers::pi_v<float>*0.5f))};
 143     const float sin_lf{std::sin(1.0f/3.0f * (al::numbers::pi_v<float>*0.5f))};
 144     const float sin_hf{std::sin(1.0f/4.0f * (al::numbers::pi_v<float>*0.5f))};
 145     for(size_t i{0};i < SamplesToDo;i++)
 146     {
 147         /* Add the direct mid signal to the processed mid signal so it can be
 148          * properly combined with the direct+decoded side signal.
 149          */
 150         const float m{mStablizer->MidLF[i]*cos_lf + mStablizer->MidHF[i]*cos_hf + mid[i]};
 151         const float c{mStablizer->MidLF[i]*sin_lf + mStablizer->MidHF[i]*sin_hf};
 152         const float s{side[i]};
 153
 154         /* The generated center channel signal adds to the existing signal,
 155          * while the modified left and right channels replace.
 156          */
 157         OutBuffer[lidx][i] = (m + s) * 0.5f;
 158         OutBuffer[ridx][i] = (m - s) * 0.5f;
 159         OutBuffer[cidx][i] += c * 0.5f;
 160     }
 161 }
 162
 163
 164 std::unique_ptr<BFormatDec> BFormatDec::Create(const size_t inchans,
 165     const al::span<const ChannelDec> coeffs, const al::span<const ChannelDec> coeffslf,
 166     const float xover_f0norm, std::unique_ptr<FrontStablizer> stablizer)
 167 {
 168     return std::make_unique<BFormatDec>(inchans, coeffs, coeffslf, xover_f0norm,
 169         std::move(stablizer));
 170 }