MATLAB: Audio Plugin – cascade

audio pluginMATLAB

Hi!

I'm trying to create an audio plugin (AU, VST) that apply filters (LPF, HPF, etc).

I need to cascade 2 butterworth filters but i noticed that any cascade functions are compatible with code generator.

Anyone can help to get a way of cascade this 2 filters?

thanks a lot

Best Answer

Hi Nuno,

I recommend you first try crossoverFilter. It implements a Linkwitz-Riley and supports up to 4 crossovers. You can control the order of the filters with the CrossoverSlopes property.

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MATLAB: How to stop sound function from Audio toolbox

Calling "clear sound" will stop the playback.

>> [audio,fs] = audioread('Counting-16-44p1-mono-15secs.wav');
>> sound(audio,fs)
>> clear sound

MATLAB: How to use Audio Plugin Example System Objects in a custom Plugin

Hi Adrian,

Take a look at the plugin below and see if this answers your needs. What this plugin does is essentially internally use a var-slope BP filter and a param EQ.

classdef ExampleEQ < audioPlugin
    %#codegen
    properties
        % Cutoff frequency in Hz
        LowCutoff = 20
        HighCutoff = 18e3;
        % Slope in dB/octave
        LowSlope = '12'
        HighSlope = '30'
        CenterFrequency1 = 100
        CenterFrequency2 = 1000
        CenterFrequency3 = 10000
        % Q factors for each band
        QualityFactor1 = 2
        QualityFactor2 = 2
        QualityFactor3 = 2
        % dB gain for each band
        PeakGain1 = 0
        PeakGain2 = 0
        PeakGain3 = 0
    end
    properties (Access = private)
        pVarSlopeBP
        pParamEQ
    end
    properties (Constant)
        % Define the plugin interface
        PluginInterface = audioPluginInterface( ...
            'InputChannels',2,...
            'OutputChannels',2,...
            'PluginName','Example EQ',...
            audioPluginParameter('LowCutoff', ...
            'DisplayName',  'Low Cutoff', ...
            'Label',  'Hz', ...
            'Mapping', { 'log', 20, 20000},...
            'Style', 'rotaryknob', 'Layout', [1 1]),...
            audioPluginParameter('HighCutoff', ...
            'DisplayName',  'High Cutoff', ...
            'Label',  'Hz', ...
            'Mapping', { 'log', 20, 20000},...
            'Style', 'rotaryknob', 'Layout', [1 2]),...
            audioPluginParameter('LowSlope', ...
            'DisplayName',  'Low Slope', ...
            'Label',  'dB/octave', ...
            'Mapping', { 'enum', '0','6','12','18','24','30','36','42','48'},...
            'Layout', [3 1]),...
            audioPluginParameter('HighSlope', ...
            'DisplayName',  'High Slope', ...
            'Label',  'dB/octave', ...
            'Mapping', { 'enum', '0','6','12','18','24','30','36','42','48'},...
            'Layout', [3 2]), ...
            audioPluginParameter('PeakGain1','DisplayName','Low Gain','Label','dB',...
            'Mapping',{'lin',-20,20},'Style','vslider','Layout',[5 1]),...
            audioPluginParameter('CenterFrequency1','DisplayName','Low Frequency','Label','Hz',...
            'Mapping',{'log',20,20e3},'Style','rotaryknob','Layout',[7 1]),...
            audioPluginParameter('QualityFactor1','DisplayName','Low Q',...
            'Mapping',{'log',0.2,700},'Style','rotaryknob','Layout',[9 1]),...
            audioPluginParameter('PeakGain2','DisplayName','Mid Gain','Label','dB',...
            'Mapping',{'lin',-20,20},'Style','vslider','Layout',[5 2]),...
            audioPluginParameter('CenterFrequency2','DisplayName','Mid Frequency','Label','Hz',...
            'Mapping',{'log',20,20e3},'Style','rotaryknob','Layout',[7 2]),...
            audioPluginParameter('QualityFactor2','DisplayName','Mid Q',...
            'Mapping',{'log',0.2,700},'Style','rotaryknob','Layout',[9 2]),...
            audioPluginParameter('PeakGain3','DisplayName','High Gain','Label','dB',...
            'Mapping',{'lin',-20,20},'Style','vslider','Layout',[5 3]),...
            audioPluginParameter('CenterFrequency3','DisplayName','High Frequency','Label','Hz',...
            'Mapping',{'log',20,20e3},'Style','rotaryknob','Layout',[7 3]),...
            audioPluginParameter('QualityFactor3','DisplayName','High Q',...
            'Mapping',{'log',0.2,700},'Style','rotaryknob','Layout',[9 3])...
            );
    end
    %----------------------------------------------------------------------

    % Public methods
    %----------------------------------------------------------------------
    methods
        function plugin = ExampleEQ()
            % Constructor
            % Initialize a multinotch filter
            plugin.pVarSlopeBP = audiopluginexample.VarSlopeBandpassFilter;
            plugin.pParamEQ = audiopluginexample.ParametricEqualizerWithUDP;
            fs = plugin.getSampleRate;
            setSampleRate(plugin.pVarSlopeBP, fs);
            setSampleRate(plugin.pParamEQ, fs);
        end
        %------------------------------------------------------------------


        function set.LowCutoff(plugin,val)
            plugin.pVarSlopeBP.LowCutoff = val;%#ok<MCSUP>












            plugin.LowCutoff = val;
        end
        function set.HighCutoff(plugin,val)
            plugin.pVarSlopeBP.HighCutoff = val;%#ok<MCSUP>
            plugin.HighCutoff = val;
        end
        function set.LowSlope(plugin,val)
            plugin.pVarSlopeBP.LowSlope = val;%#ok<MCSUP>
            plugin.LowSlope = val;
        end
        function set.HighSlope(plugin,val)
            plugin.pVarSlopeBP.HighSlope = val;%#ok<MCSUP>
            plugin.HighSlope = val;
        end
        function set.CenterFrequency1(plugin,val)
            plugin.pParamEQ.CenterFrequency1 = val;%#ok<MCSUP>
            plugin.CenterFrequency1 = val;
        end
        function set.CenterFrequency2(plugin,val)
            plugin.pParamEQ.CenterFrequency2 = val;%#ok<MCSUP>
            plugin.CenterFrequency2 = val;
        end
        function set.CenterFrequency3(plugin,val)
            plugin.pParamEQ.CenterFrequency3 = val;%#ok<MCSUP>
            plugin.CenterFrequency3 = val;
        end
        function set.QualityFactor1(plugin,val)
            plugin.pParamEQ.QualityFactor1 = val;%#ok<MCSUP>
            plugin.QualityFactor1 = val;
        end
        function set.QualityFactor2(plugin,val)
            plugin.pParamEQ.QualityFactor2 = val;%#ok<MCSUP>
            plugin.QualityFactor2 = val;
        end
        function set.QualityFactor3(plugin,val)
            plugin.pParamEQ.QualityFactor3 = val;%#ok<MCSUP>
            plugin.QualityFactor3 = val;
        end
        function set.PeakGain1(plugin,val)
            plugin.pParamEQ.PeakGain1 = val;%#ok<MCSUP>
            plugin.PeakGain1 = val;
        end
        function set.PeakGain2(plugin,val)
            plugin.pParamEQ.PeakGain2 = val;%#ok<MCSUP>
            plugin.PeakGain2 = val;
        end
        function set.PeakGain3(plugin,val)
            plugin.pParamEQ.PeakGain3 = val;%#ok<MCSUP>
            plugin.PeakGain3 = val;
        end
        %------------------------------------------------------------------
        function y = process(plugin,x)
            z = plugin.pVarSlopeBP(x);
            y = plugin.pParamEQ(z);
        end
        %------------------------------------------------------------------
        function reset(plugin)
            fs = plugin.getSampleRate;
            setSampleRate(plugin.pVarSlopeBP, fs);
            reset(plugin.pVarSlopeBP)
            setSampleRate(plugin.pParamEQ, fs);
            reset(plugin.pParamEQ)
        end
    end
end

Best Answer

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