HOA_Mixer.h

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/*

HOA_Mixer.h -- Higher Order Ambisonic mixing 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 mixing encoded ambisonic encoded audio streams.  All incoming streams should have
the same order; the order used is derived from the first stream added.

*/ 

#ifndef HOA_MIXER_H
#define HOA_MIXER_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_Mixer : public FrameStream, public HOA_AmbisonicFramestream {

protected:

    unsigned mNumInputs;                   // the number of ambisonic-encoded inputs
    sample mInvNumInputs;                  // the inverse of the number of inputs (used for normalization)
    unsigned mMaxInputs;                    // the maximum no. of inputs this mixer will accept.
    unsigned mNumFrames;                   // blocksize
    sample *mInPtr;                        // pointer to input buffers (sound sources to be encoded)
    sample **mOutPtr;                      // pointer to Ambisonic encoded output buffers 

    FrameStream ** mInputs;                 // list of inputs, arbitrary # of channels
    unsigned _num_inputs;                   // number of active inputs
        
    Buffer *mInBuffer;                      // buffer for the input framestream
    
public:
    
    // Constructors & destructor:
    
    // default constructor
    HOA_Mixer(unsigned maxInputs = 64);
    
    // initialize with one input, derive the Mixer ambisonic order from this input
    HOA_Mixer(FrameStream &input, unsigned maxInputs = 64);
    
    // destructor
    ~HOA_Mixer();

    // initializing method called by constructors
    void initialize(unsigned maxInputs);
    
    // methods for adding/removing another input to the mixer
    bool addInput(FrameStream &input);
    
    unsigned getNumInputs(void) { return mNumInputs; };     // number of active inputs

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

}

#endif

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