How can I create a multi-channel audio plugin in Matlab?

I have created a simple VST3 Dither plugin in Matlab (generateAudioPlugin). it creates noise and adds it to the input signal.

But, this plugin only works in stereo. i want it to be channel agnostic, so it adapts to my DAW. mono, stereo, 6-ch and so on...

classdef DitherPlugin < audioPlugin
    properties
        ditherOn = true;
        bitDepth = '24-bit';
        ditherType = 'Triangular';
    end
    
    properties (Constant)
        lsbValue16bit = 1/2^15
        lsbValue24bit = 1/2^23
        
        PluginInterface = audioPluginInterface( ...
            audioPluginParameter('ditherOn', ...
            'DisplayName', 'TPDF Dither On/Off', ...
            'Mapping', {'enum', 'Off', 'On'}), ...
            audioPluginParameter('bitDepth', ...
            'DisplayName', 'Bit Depth', ...
            'Mapping', {'enum', '16-bit', '24-bit'}, ...
            'Style', 'dropdown'), ...
            audioPluginParameter('ditherType', ...
            'DisplayName', 'Dither Type', ...
            'Mapping', {'enum', 'Triangular', 'Noise Shaped Dither'}, ...
            'Style', 'dropdown'))
    end
    
    methods
        function set.bitDepth(plugin, depth)
            validDepths = {'16-bit', '24-bit'};
            if any(strcmp(depth, validDepths))
                plugin.bitDepth = depth;
            else
                error('Invalid Bit Depth. Valid options are: %s.', strjoin(validDepths, ', '));
            end
        end
        
        function set.ditherType(plugin, type)
            validTypes = {'Triangular', 'Noise Shaped Dither'};
            if any(strcmp(type, validTypes))
                plugin.ditherType = type;
            else
                error('Invalid type. Valid options are: %s.', strjoin(validTypes, ', '));
            end
        end
        
        function set.ditherOn(plugin, value)
            if islogical(value)
                plugin.ditherOn = value;
            else
                error('Invalid value for ditherOn. Value must be true or false.');
            end
        end
        
        function out = process(plugin, in)
            if plugin.ditherOn
                switch plugin.bitDepth
                    case '16-bit'
                        lsbValue = DitherPlugin.lsbValue16bit;
                    case '24-bit'
                        lsbValue = DitherPlugin.lsbValue24bit;
                    otherwise
                        error('Unknown bit depth setting: %s', plugin.bitDepth);
                end
                
                % Create and apply dither based on the selected dither type
                switch plugin.ditherType
                    case 'Triangular'
                        % Create flat dither noise
                        %implementation...
                        
                    case 'Noise Shaped Dither'
                        % implementation
                        %ditherNoise = ...
                        
                    otherwise
                        error('Unknown dither type setting: %s', plugin.ditherType);
                end
                
                %quantize
                out = round((in + ditherNoise) / lsbValue) * lsbValue;
            else
                % If dither is not enabled, pass the signal through unaffected
                out = in;
            end
        end
    end
end

Answer 1

[jibrahim]

Hi Hasan,

The audio plugin interface allows you to specify the desired numbers of input and output channels. I beleive the default is stereo.

For example, for a plugin with 6 input and output channels:

classdef myPlugin < audioPlugin

        properties (Constant)
        PluginInterface = audioPluginInterface( ...            
            'InputChannels',6, ...
            'OutputChannels',6);
        end

        methods 
            function y= process(~,x)
                y = x;
            end
        end
end

Note that the number of channels is not dynamic, so you would have to specify the maximum number of channels you need.

generateAudioPlugin myPlugin  % generate the plugin
 
p = loadAudioPlugin('myPlugin.dll');
out = process(p,randn(256,6)); % Six input channels. You can just use zeros for channels you are not interested in