HRTF plugin Filter error

Hi

I´m trying to create a dll based on interporlatedHRTF function. Inside audioTestBench enviroment runs perfect, but when I try to compile it , the following error appears:

"Cannot compute constant value for argument #2 for this System object constructor. All arguments to the constructor of this System object must be constants for code generation....."

Seem is related to dsp.FIRFilter constructor, but I don´t know how to solve the situation. Coeficient must change during the process because location of the source must be able to change according to inputs parameter.

classdef HRTF_test < audioPlugin
    properties

        Sx=5;
        Sy=8;
        Rx=5;
        Ry=5;
    end
    
    properties (Access = private)
        
azimuth
elevation
Tdata=load('S005_marl_NYU_DATA.mat');
Tposition=load ('S005_marl_NYU_POS.mat');
leftIR=zeros(1,512)
rightIR=zeros(1,512)
leftfilter 
rightfilter

    end
    
    properties (Constant)
        PluginInterface = audioPluginInterface(...
            audioPluginParameter('Sx',...
            'DisplayName','Position Source X',...
            'Mapping',{'lin',0,10},...
            'Label','meters'),...
            audioPluginParameter('Sy',...
            'DisplayName','Position Source Y',...
            'Mapping',{'lin',0,10},...
            'Label','meters'));
    end

    methods
        function plugin=HRTF_test
             needtocalculateAzimuth(plugin);          
        end
        
        function out = process(plugin, in)
            

            out=[step(plugin.leftfilter,in(:,1)),step(plugin.rightfilter,in(:,2))];

        end
        
        function set.Sx(plugin, val)
           plugin.Sx = val;
           needtocalculateAzimuth(plugin);
           
        end
        
        function set.Sy(plugin,val)
           plugin.Sy=val;
           needtocalculateAzimuth(plugin);
        end
        
        function needtocalculateAzimuth(plugin) % Filter Calculation
           
            if plugin.Sy==5
            plugin.azimuth=0;
            else
            plugin.azimuth=rad2deg(atan((plugin.Sx-plugin.Rx)/(plugin.Sy-plugin.Ry)));
            end
            
            plugin.elevation=0;
            sourcePosition1 = [plugin.Tposition.dposition(:,1),plugin.Tposition.dposition(:,2)];

            desiredPosition = [plugin.azimuth plugin.elevation];

            interpolatedIR  = interpolateHRTF(plugin.Tdata.Tdata,sourcePosition1,desiredPosition);

            plugin.leftIR = squeeze(interpolatedIR(:,1,:))';
            plugin.rightIR = squeeze(interpolatedIR(:,2,:))'; 

            plugin.leftfilter=dsp.FIRFilter('Numerator',plugin.leftIR);
            plugin.rightfilter=dsp.FIRFilter('Numerator',plugin.rightIR);          

        end
        function reset(plugin)
           

        end
    end       

end

[Brian Hemmat]

Hello Pablo,

I can't reproduce your plugin because I don't have access to those mat files.

In general, don't construct the dsp.FIRFilter objects in the loop. Contruct and assign the left filter and right filter in the plugin constructor:

function plugin = HRTF_test
     needtocalculateAzimuth(plugin);
     plugin.leftfilter = dsp.FIRFilter;
     plugin.rightfilter = dsp.FIRFilter;
end

In needtocalculateAzimuth, just update the filter numerators. The numerators property is tunable for exactly this use case.

function needtocalculateAzimuth(plugin) % Filter Calculation
    ...
    plugin.leftfilter.Numerator = leftIR;
    plugin.rightfilter.Numerator = rightIR;
end

For tips on plugin authoring, including implementing composition, see Tips and Tricks for Plugin Authoring.

For examples of plugins (use they to find coding patterns), see Audio Plugin Example Gallery.

HTH,

Brian

[Pablo Panitta]

Hi Brian, thanks a lot for your feedback.

The issue I´m experiencing with this solution is the following :

If I enter to function out with the default position(Sx=5 , Rx=5), the filter is built with default numerator [0.5 0.5]. This is weird because we´re forcing to construct with leftIR & rightIR [1x 512] through "needtocalculateAzimuth" instruction in function plugin. Numerators are correctly calculated [1x512) but for some reason the filter system object doesn´t take them for the initial construction.

Then, when I try to change the position inside the out function loop, off course an error message appears stating the dimension cannot be changed during execution (from [1x2] to [1x512])

If,before enter into function out loop, I change the defalut position to something else, the filter is updated and built with the adequate dimension [1x 512].

I dont´know why this is happening, becuase in both scenarios the same process through needtocalculateAzimuth is follow.

Leave the new lines & .mat files in case you want to try yourself and kindl help me.

Once I solve this issue, I´ll be able to test the .dll compilation.

classdef HRTF_test < audioPlugin
    properties

        Sx=5;
        Sy=8;
        Rx=5;
        Ry=5;
    end
    
    properties (Access = private)
        
azimuth
elevation
Tdata=load('S005_marl_NYU_DATA.mat');
Tposition=load ('S005_marl_NYU_POS.mat');
leftfilter
rightfilter

    end
    
    properties (Constant)
        PluginInterface = audioPluginInterface(...
            audioPluginParameter('Sx',...
            'DisplayName','Position Source X',...
            'Mapping',{'lin',0,10},...
            'Label','meters'),...
            audioPluginParameter('Sy',...
            'DisplayName','Position Source Y',...
            'Mapping',{'lin',0,10},...
            'Label','meters'));
    end

    methods
        function plugin=HRTF_test      
                
                needtocalculateAzimuth(plugin);
                plugin.leftfilter = dsp.FIRFilter;
                plugin.rightfilter = dsp.FIRFilter;

        end
       
        
        function out = process(plugin, in)
            

            out=[step(plugin.leftfilter,in(:,1)),step(plugin.rightfilter,in(:,2))];

        end
        
        function set.Sx(plugin, val)
           plugin.Sx = val;
           needtocalculateAzimuth(plugin);
        end
        
        function set.Sy(plugin,val)
           plugin.Sy=val;
           needtocalculateAzimuth(plugin);
        end
        
        function needtocalculateAzimuth(plugin) % Filter Calculation
           
            if plugin.Sx==5
            plugin.azimuth=0;
            else
            plugin.azimuth=rad2deg(atan((plugin.Sx-plugin.Rx)/(plugin.Sy-plugin.Ry)));
            end
            
            plugin.elevation=0;
            sourcePosition1 = [plugin.Tposition.dposition(:,1),plugin.Tposition.dposition(:,2)];

            desiredPosition = [plugin.azimuth plugin.elevation];

            interpolatedIR  = interpolateHRTF(plugin.Tdata.Tdata,sourcePosition1,desiredPosition);

            leftIR = squeeze(interpolatedIR(:,1,:))';
            rightIR = squeeze(interpolatedIR(:,2,:))'; 

            plugin.leftfilter.Numerator =leftIR;
            plugin.rightfilter.Numerator =rightIR;            

        end
        function reset(plugin)
          reset(plugin.leftfilter);
          reset(plugin.rightfilter);

        end
    end       

end

Thanks

Pablo

Answer 1

[Brian Hemmat]

Hi Pablo,

The following code compiles for me (and should for you). Initialize the Numerator's with the correct size at construction, then call needtocalculateAzimuth to set the values.

classdef HRTF_test < audioPlugin
    properties
        Sx=5;
        Sy=8;
        Rx=5;
        Ry=5;
    end
    
    properties (Access = private)
        azimuth
        elevation
        Tdata = coder.load('S005_marl_NYU_DATA.mat');
        Tposition = coder.load ('S005_marl_NYU_POS.mat');
        leftfilter
        rightfilter
    end
    
    properties (Constant)
        PluginInterface = audioPluginInterface( ...
            audioPluginParameter('Sx', ...
            'DisplayName','Position Source X', ...
            'Mapping',{'lin',0,10}, ...
            'Label','meters'), ...
            audioPluginParameter('Sy', ...
            'DisplayName','Position Source Y', ...
            'Mapping',{'lin',0,10}, ...
            'Label','meters'));
    end
    methods
        function plugin = HRTF_test
            plugin.leftfilter = dsp.FIRFilter('Numerator',zeros(1,512));
            plugin.rightfilter = dsp.FIRFilter('Numerator',zeros(1,512));
            needtocalculateAzimuth(plugin)
        end
        
        function out = process(plugin, in)
            out = [step(plugin.leftfilter,in(:,1)),step(plugin.rightfilter,in(:,2))];
        end
        
        function set.Sx(plugin, val)
            plugin.Sx = val;
            needtocalculateAzimuth(plugin);
        end
        
        function set.Sy(plugin,val)
            plugin.Sy=val;
            needtocalculateAzimuth(plugin);
        end
        
        function needtocalculateAzimuth(plugin) % Filter Calculation
            
            if plugin.Sx == 5
                plugin.azimuth = 0;
            else
                plugin.azimuth = rad2deg(atan((plugin.Sx-plugin.Rx)/(plugin.Sy-plugin.Ry)));
            end
            
            plugin.elevation = 0;
            sourcePosition1 = [plugin.Tposition.dposition(:,1),plugin.Tposition.dposition(:,2)];
            desiredPosition = [plugin.azimuth plugin.elevation];
            interpolatedIR = interpolateHRTF(plugin.Tdata.Tdata,sourcePosition1,desiredPosition);
            leftIR = squeeze(interpolatedIR(:,1,:))';
            rightIR = squeeze(interpolatedIR(:,2,:))';
            plugin.leftfilter.Numerator = leftIR;
            plugin.rightfilter.Numerator = rightIR;
        end
        function reset(plugin)
            reset(plugin.leftfilter)
            reset(plugin.rightfilter)
        end
    end
end

[Pablo Panitta]

Perfect! Thanks Brian!