Added Ambisonics implementation

applications/SpatialAudio/ita_decodeAmbisonics.m

+function [ loudspeakerSignals ] = ita_decodeAmbisonics( Bformat, LoudspeakerPos, varargin )
+%ITA_DECODEAMBISONICS Summary of this function goes here
+%   Detailed explanation goes here
+
+opts.decoding='remax' % Decoding strategy (remax,inphase,plane)
+
+opts = ita_parse_arguments(opts,varargin);
+
+
+% Initializing further parameters
+nmax=numel(Bformat);
+
+% Weighting for Inphase/ReMax
+g_re=ones(nmax,1); %init weighting factors for ReMax
+g_in=g_re; %init weighting factors for InPhase
+
+
+% ReMax Decoding
+if(sum(strcmp(lower(opts.decoding),{'remax' 'both'})))
+    %             Calculates the B-Format channel weights for ReMax-Decoding
+    %             see J.Daniel Thesis p.312 A.67/A.68
+    weightsReMax=zeros(nmax,1); % init weights
+    % g_m=P_m(r_E) with n=0 for P
+    % r_E is largest root of P_(order+1)
+    syms x;
+    f=1/2^(TheOrder+1)/factorial(TheOrder+1)*diff(((x^2-1)^(TheOrder+1)),(TheOrder+1));%Legendre Polynom n=0 m=order+1
+    maxroot=max(eval(solve(f))); %find maximum root(Nullstelle)
+    for k=1:nmax
+        leggie=legendre(ita_sph_linear2degreeorder(k),abs(maxroot)); % g_m=P_m(r_E)
+        weightsReMax(k)=leggie(1);% pick n=0
+    end
+    g_re=weightsReMax;
+end
+
+% Inphase Decoding
+if(sum(strcmp(lower(opts.decoding),{'inphase' 'both'})))
+    %             Calculates the B-format channel weights for InPhase-Decoding
+    TheOrder = obj.ambGetOrder; % amb order from sim room
+    nmax = (TheOrder+1)^2; % number of channels
+    weightsInPhase=zeros(nmax,1);
+    N=numel(obj.monitorRoom.getSourcePosition)/3;% get number of loudspeaker
+    %Dissertation J.Daniel p.314, 'preserve Energy' in 0. order
+    %g_0=sqrt[N*(2*M+1)/(M+1)^2]
+    weightsInPhase(1)=sqrt(N*(2*TheOrder+1)/(TheOrder+1)^2);
+    
+    for k=2:nmax
+        m=ita_sph_linear2degreeorder(k);
+        % Dissertation J.Daniel p.314
+        % g_m=M!*(M+1)!/[(M+m+1)!*(M-n)!]
+        weightsInPhase(k)=factorial(TheOrder)*factorial(TheOrder+1)/factorial(m+TheOrder+1)/factorial(TheOrder-m);
+    end
+    g_in=weightsInPhase;
+end
+
+weights=g_in.*g_re; %merge weighting factors
+for k=1:numel(weights)
+        Bformat(:,k)=weights(k).*Bformat(:,k); %Apply weighting factors
+end
+% SH and inversion
+Y = ita_sph_base(LS,TheOrder,'williams',false); % generate basefunctions
+Yinv=pinv(Y); % calculate Pseudoinverse
+
+
+if isa(Bformat,'itaAudio')
+    for k=1:LS.nPoints
+        OutputSignals(k)=sum(Bformat*Yinv(:,k)');
+    end
+    OutputSignals=ita_merge(OutputSignals(:));
+else
+    OutputSignals=Bformat*Yinv;
+end
+
+
+
+end

applications/SpatialAudio/ita_encodeAmbisonics.m

+function [ Bformat ] = ita_encodeAmbisonics( sourcePos, varargin )
+%ITA_ENCODEAMBISONICS Summary of this function goes here
+%   Detailed explanation goes here
+if nargin<1
+    error('Source position is needed as itaCoordiantes!');
+end
+
+if ~isa(sourcePos,'itaCoordinates')
+    error('First input data has to be an itaCoordinates!')
+elseif isempty(sourcePos.cart)
+    error('First input data has to be an itaCoordinates WITH inputdata!')
+end
+
+opts.order=1;           %Ambisonics truncation order
+opts.audioSource='';    %Signal of the source (itaAudio or filename)
+
+opts = ita_parse_arguments(opts, varargin);
+
+% Encode Source
+Bformat = ita_sph_base(sourcePos, opts.order, 'Williams', false);
+
+if ~isempty(opts.audioSource)
+    if isa(opts.audioSource,'char')
+        audioIn = ita_read(opts.audioSource);
+    elseif isa(opts.audioSource,'itaAudio')
+        audioIn = opts.audioSource;
+    elseif ~isa(audioIn,'itaAudio')
+        error('Audio input must eihter be itaAudio or valid filename (see ita_read)');
+    end
+    audioOut=audioIn*Bformat(1);
+    for k=2:numel(Bformat)
+        audioOut=ita_merge(audioOut,audioIn*Bformat(k));
+    end
+    Bformat=audioOut;
+end
+end
+