HOA_Encoder.h

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/*

HOA_AmbisonicEncoder.h -- Higher Order Ambisonic encoding class
See the copyright notice and acknowledgment of authors in the file COPYRIGHT
Higher Order Ambisonic classes written by Jorge Castellanos, Graham Wakefield, Florian Hollerweger, 2005

Higher Order Ambisonic class for positioning an arbitrary number of mono sound sources into an Ambisonic encoded soundfield.
Multiple sound sources are fed to the encoder as a multichannel framestream. Their position information is fed to the
encoder as two multichannel framestreams (azimuth and elevation). It is possible to specify either one uniform Ambisonic
order or to define the horizontal and vertical order separately (hybrid order encoding). If no order(s) is/are specified,
first order Ambisonic will be used (B-Format).

*/ 

#ifndef HOA_ENCODER_H
#define HOA_ENCODER_H

#include "CSL_Core.h"
#include "Variable.h"
#include "CPoint.h"
#include "HOA_Utilities.h"
#include "HOA_AmbisonicFramestream.h"

namespace csl {

/*

CONVENTIONS USED IN THIS CODE:
------------------------------

***coordinate system***
Left oriented
Azimuth = 0 on the x/z plane and increasing towards the positive y direction
Elevation = 0 on x/y plane and increasing towards the positive z direction
Internal angle representation: spherical radians

***encoding convention***
following the Furse-Malham set (Ambisonic channel weighting for uniform energy distribution)

***abbreviations used in code and comments***
M   ... Ambisonic order (in uniform order system)
M_h ... horizontal Ambisonic order (in hybrid order systems)
M_v ... horizontal Ambisonic order (in hybrid order systems)
N   ... total number of Ambisonic encoded channels (horizontal and vertical)
N_h ... number of horizontal Ambisonic channels (in hybrid order systems)
N_v ... number of vertical Ambisonic channels (in hybrid order systems)
L   ... number of available loudspeakers

***ordering and naming of Ambisonic channels = spherical harmonics***
These conventions follow the ones used in the thesis by Jerome Daniel.
The 3rd order naming convention (which Daniel doesn't provide) follows the one used in the thesis of David Malham.
Watch out for different conventions in other papers!
index           0   1   2   3   4   5   6   7   8   9   10  11  12  13  14  15
M (order)       0   1   1   1   2   2   2   2   2   3   3   3   3   3   3   3
m (=M)          0   1   1   1   2   2   2   2   2   3   3   3   3   3   3   3
n               0   1   1   0   2   2   1   1   0   3   3   2   2   1   1   0
sigma           '1' 1   -1  '1' 1   -1  1   -1  '1' 1   -1  1   -1  1   -1  '1'
name            W   X   Y   Z   U   V   S   T   R   P   Q   N   O   L   M   K
hor/vert/omni   om  h   h   v   h   h   v   v   v   h   h   v   v   v   v   v

*/

class HOA_Encoder : public FrameStream, public Processor, public HOA_AmbisonicFramestream {

private:

    sample mAzimuth, mElevation;            // the azimuth & elevation of the source to be encoded
    sample *mWeights;                       // encoding weights for each order (per source)
    unsigned mNumFrames;                   // blocksize
    sample *mInPtr;                        // pointer to input buffers (sound sources to be encoded)
    sample **mOutPtr;                      // pointer to Ambisonic encoded output buffers 
    
protected:

    Buffer *mInBuffer;          // buffer for the input framestream (sound sources to be encoded)
    
public:
    
    // Constructors & destructor:
    
    // default constructor
    HOA_Encoder();
        
    // initialize with uniform Ambisonic order and static input sound sources
    HOA_Encoder(FrameStream &input, unsigned int order = 1, double azimuth = 0.f, double elevation = 0.f);
    
    // initialize with hybrid Ambisonic order and static input sound sources
    HOA_Encoder(FrameStream &input, unsigned int horder, unsigned int vorder, double azimuth = 0.f, double elevation = 0.f);
    
    // destructor
    ~HOA_Encoder();
    
    // setters for azimuth & elevation
    void setAzimuth(double azimuth)     { mAzimuth = azimuth; };
    void setElevation(double elevation) { mElevation = elevation; };
    double azimuth()                    { return mAzimuth; };
    double elevation()                  { return mElevation; };

    // initializing method called by constructors
    void initialize(FrameStream &input);

    // Overriding Framestream::next_buffer(). Does the DSP processing for the Ambisonic Encoder.
    virtual status next_buffer(Buffer &inputBuffer, Buffer &outputBuffer);
    
};

}

#endif

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