libspatialaudio/source/AmbisonicCommons.cpp at master · videolan/libspatialaudio · GitHub

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/*############################################################################*/
/*#                                                                          #*/
/*#  Ambisonic C++ Library                                                   #*/
/*#  Copyright © 2007 Aristotel Digenis                                      #*/
/*#                                                                          #*/
/*#  Filename:      AmbisonicCommons.cpp                                     #*/
/*#  Version:       0.1                                                      #*/
/*#  Date:          19/05/2007                                               #*/
/*#  Author(s):     Aristotel Digenis                                        #*/
/*#  Licence:       MIT                                                      #*/
/*#                                                                          #*/
/*############################################################################*/


#include "AmbisonicCommons.h"

namespace spaudio {

    float DegreesToRadians(float fDegrees)
    {
        return fDegrees * (float)M_PI / 180.f;
    }

    float RadiansToDegrees(float fRadians)
    {
        return fRadians * 180.f / (float)M_PI;
    }

    unsigned OrderToComponents(unsigned nOrder, bool b3D)
    {
        if (b3D)
            return (unsigned)powf(nOrder + 1.f, 2.f);
        else
            return nOrder * 2 + 1;
    }

    unsigned OrderToComponentPosition(unsigned nOrder, bool b3D)
    {


        unsigned nIndex = 0;

        if (b3D)
        {
            switch (nOrder)
            {
            case 0:    nIndex = 0;    break;
            case 1:    nIndex = 1;    break;
            case 2:    nIndex = 4;    break;
            case 3:    nIndex = 10; break;
            }
        }
        else
        {
            switch (nOrder)
            {
            case 0:    nIndex = 0;    break;
            case 1:    nIndex = 1;    break;
            case 2:    nIndex = 3;    break;
            case 3:    nIndex = 5;    break;
            }
        }

        return nIndex;
    }

    unsigned OrderToSpeakers(unsigned nOrder, bool b3D)
    {

        if (b3D)
            return (nOrder * 2 + 2) * 2;
        else
            return nOrder * 2 + 2;
    }

    char ComponentToChannelLabel(unsigned nComponent, bool b3D)
    {

        char cLabel = ' ';
        if (b3D)
        {
            switch (nComponent)
            {
            case 0:     cLabel = 'W';   break;
            case 1:     cLabel = 'Y';   break;
            case 2:     cLabel = 'Z';   break;
            case 3:     cLabel = 'X';   break;
            case 4:     cLabel = 'V';   break;
            case 5:     cLabel = 'T';   break;
            case 6:     cLabel = 'R';   break;
            case 7:     cLabel = 'U';   break;
            case 8:     cLabel = 'S';   break;
            case 9:     cLabel = 'Q';   break;
            case 10:    cLabel = 'O';   break;
            case 11:    cLabel = 'M';   break;
            case 12:    cLabel = 'K';   break;
            case 13:    cLabel = 'L';   break;
            case 14:    cLabel = 'N';   break;
            case 15:    cLabel = 'P';   break;
            };
        }
        else
        {
            switch (nComponent)
            {
            case 0:     cLabel = 'W';   break;
            case 1:     cLabel = 'X';   break;
            case 2:     cLabel = 'Y';   break;
            case 3:     cLabel = 'U';   break;
            case 4:     cLabel = 'V';   break;
            case 5:     cLabel = 'P';   break;
            case 6:     cLabel = 'Q';   break;
            };
        }

        return cLabel;
    }

    unsigned ComponentPositionToOrder(unsigned nComponent, bool b3D)
    {
        if (b3D)
            return (unsigned)floorf(sqrtf((float)nComponent));
        else
            return (unsigned)floorf((nComponent + 1.f) * 0.5f);
    }

    unsigned OrderAndDegreeToComponent(int order, int degree, bool b3D)
    {
        if (b3D)
            return order * (order + 1) + degree;
        else
            return degree < 0 ? 2 * order - 1 : 2 * order;
    }

    void ComponentToOrderAndDegree(int nComponent, bool b3D, int& order, int& degree)
    {
        order = ComponentPositionToOrder(nComponent, b3D);

        if (b3D)
            degree = nComponent - order * (order + 1);
        else
            degree = nComponent % 2 == 0 ? order : -order;
    }

    template<typename T>
    T N3dToSn3dFactor(int order)
    {
        return static_cast<T>(1.) / (T)std::sqrt(static_cast<T>(2 * order) + 1.);
    }
    template float N3dToSn3dFactor(int order);
    template double N3dToSn3dFactor(int order);

    template<typename T>
    T Sn3dToN3dFactor(int order)
    {
        return (T)std::sqrt(static_cast<T>(2 * order) + 1.);
    }
    template float Sn3dToN3dFactor(int order);
    template double Sn3dToN3dFactor(int order);

    template<typename T>
    T FuMaToSn3dFactor(int order, int degree)
    {
        auto iComponent = OrderAndDegreeToComponent(order, degree, true);

        if (iComponent == 0)
            return std::sqrt(static_cast<T>(2));
        else if (iComponent < 4)
            return std::sqrt(static_cast<T>(2));
        else if (iComponent == 4 || iComponent == 5 || iComponent == 7 || iComponent == 8)
            return static_cast<T>(std::sqrt(3.) / 2.);
        else if (iComponent == 6)
            return static_cast<T>(1.);
        else if (iComponent == 9 || iComponent == 15)
            return static_cast<T>(std::sqrt(5. / 8.));
        else if (iComponent == 10 || iComponent == 14)
            return static_cast<T>(std::sqrt(5.) / 3.);
        else if (iComponent == 11 || iComponent == 13)
            return static_cast<T>(std::sqrt(32. / 45.));
        else if (iComponent == 12)
            return static_cast<T>(1.);

        return static_cast<T>(0);
    }
    template float FuMaToSn3dFactor(int order, int degree);
    template double FuMaToSn3dFactor(int order, int degree);

} // namespace spaudio