core/uhjfilter.h

   1 #ifndef CORE_UHJFILTER_H
   2 #define CORE_UHJFILTER_H
   3
   4 #include <array>
   5
   6 #include "almalloc.h"
   7 #include "bufferline.h"
   8 #include "resampler_limits.h"
   9
  10
  11 struct UhjFilterBase {
  12     /* The filter delay is half it's effective size, so a delay of 128 has a
  13      * FIR length of 256.
  14      */
  15     static constexpr size_t sFilterDelay{128};
  16 };
  17
  18 struct UhjEncoder : public UhjFilterBase {
  19     /* Delays and processing storage for the unfiltered signal. */
  20     alignas(16) std::array<float,BufferLineSize+sFilterDelay> mS{};
  21     alignas(16) std::array<float,BufferLineSize+sFilterDelay> mD{};
  22
  23     /* History for the FIR filter. */
  24     alignas(16) std::array<float,sFilterDelay*2 - 1> mWXHistory{};
  25
  26     alignas(16) std::array<float,BufferLineSize + sFilterDelay*2> mTemp{};
  27
  28     /**
  29      * Encodes a 2-channel UHJ (stereo-compatible) signal from a B-Format input
  30      * signal. The input must use FuMa channel ordering and UHJ scaling (FuMa
  31      * with an additional +3dB boost).
  32      */
  33     void encode(float *LeftOut, float *RightOut, const FloatBufferLine *InSamples,
  34         const size_t SamplesToDo);
  35
  36     DEF_NEWDEL(UhjEncoder)
  37 };
  38
  39
  40 struct UhjDecoder : public UhjFilterBase {
  41     static constexpr size_t sLineSize{BufferLineSize+MaxResamplerPadding+sFilterDelay};
  42     using BufferLine = std::array<float,sLineSize>;
  43
  44     alignas(16) std::array<float,BufferLineSize+MaxResamplerEdge+sFilterDelay> mS{};
  45     alignas(16) std::array<float,BufferLineSize+MaxResamplerEdge+sFilterDelay> mD{};
  46     alignas(16) std::array<float,BufferLineSize+MaxResamplerEdge+sFilterDelay> mT{};
  47
  48     alignas(16) std::array<float,sFilterDelay-1> mDTHistory{};
  49     alignas(16) std::array<float,sFilterDelay-1> mSHistory{};
  50
  51     alignas(16) std::array<float,BufferLineSize+MaxResamplerEdge + sFilterDelay*2> mTemp{};
  52
  53     float mCurrentWidth{-1.0f};
  54
  55     /**
  56      * The width factor for Super Stereo processing. Can be changed in between
  57      * calls to decodeStereo, with valid values being between 0...0.7.
  58      */
  59     float mWidthControl{0.593f};
  60
  61     /**
  62      * Decodes a 3- or 4-channel UHJ signal into a B-Format signal with FuMa
  63      * channel ordering and UHJ scaling. For 3-channel, the 3rd channel may be
  64      * attenuated by 'n', where 0 <= n <= 1. So to decode 2-channel UHJ, supply
  65      * 3 channels with the 3rd channel silent (n=0). The B-Format signal
  66      * reconstructed from 2-channel UHJ should not be run through a normal
  67      * B-Format decoder, as it needs different shelf filters.
  68      */
  69     void decode(const al::span<float*> samples, const size_t samplesToDo,
  70         const size_t forwardSamples);
  71
  72     /**
  73      * Applies Super Stereo processing on a stereo signal to create a B-Format
  74      * signal with FuMa channel ordering and UHJ scaling. The samples span
  75      * should contain 3 channels, the first two being the left and right stereo
  76      * channels, and the third left empty.
  77      */
  78     void decodeStereo(const al::span<float*> samples, const size_t samplesToDo,
  79         const size_t forwardSamples);
  80
  81     using DecoderFunc = void (UhjDecoder::*)(const al::span<float*> samples,
  82         const size_t samplesToDo, const size_t forwardSamples);
  83
  84     DEF_NEWDEL(UhjDecoder)
  85 };
  86
  87 #endif /* CORE_UHJFILTER_H */