Error in a testbench generated file using validateAudioPlugin

While validating an audio plugin, I get the following error

Generating mex file 'testbench_HeadPhoneSimulator_ver2_mex.mexmaci64'... Cannot allocate this handle object. For code generation, a handle object
    allocated inside a loop cannot be referenced outside of the loop.
More information
Error in ==> testbench_HeadPhoneSimulator_ver2 Line: 58 Column: 9
Warning: Failed to save report information. 
Code generation failed: View Error Report
Error using coder.internal.generateAudioPlugin
Error in validateAudioPlugin

the thing that I don't understand is the fact that the error is in a file that's not written by me, but in a file made by the testbench itself.

I think that the function that provokes the error is the following:

function updateFilters(plugin,n,flag)
    if ~flag
        plugin.Filter_L = dsp.FrequencyDomainFIRFilter('Numerator', plugin.IR_bank(:,1,n).', ...
            'PartitionForReducedLatency', true, 'PartitionLength', 1024);
        plugin.Filter_R = dsp.FrequencyDomainFIRFilter('Numerator', plugin.IR_bank(:,2,n).', ...
            'PartitionForReducedLatency', true, 'PartitionLength', 1024);
    else
        num = zeros(1,1024);
        num(1) = 1;
        plugin.Filter_L = dsp.FrequencyDomainFIRFilter('Numerator', num, ...
            'PartitionForReducedLatency', true, 'PartitionLength', 1024);
        plugin.Filter_R = dsp.FrequencyDomainFIRFilter('Numerator', num, ...
            PartitionForReducedLatency', true, 'PartitionLength', 1024);
    end
end

if needed I will provide the complete code

[jibrahim]

Hi Dario,

Can you please attach your audio plugin class?

[DARIO BENVEGNÙ]

There you go

[jibrahim]

Can you please also attach the enum classes, or strip them off so that the code works without them?

[DARIO BENVEGNÙ]

yeah sorry. I can provide also the impluse response files if you need them

[jibrahim]

Yes, please also attach ImpulseResponseLoader or equivalent code

[DARIO BENVEGNÙ]

this should be enough. thank you.

Answer 1

[jibrahim]

Hi Dario,

Thanks for the reproduction steps. This helps.

The problem is in the method updateFilters. The method recreates the frequency-domain filters every time it is called. This is not supported in this context in codegen (those are the objects validation is complaining are created in a loop).

You probably want to tune these objects instead of recreating them, i.e.

function updateFilters(plugin,n,flag)
        if ~flag
            plugin.Filter_L.Numerator =  plugin.IR_bank(:,1,n).';
            plugin.Filter_R.Numerator = plugin.IR_bank(:,2,n).';
        else
            num = zeros(1,1024);
            num(1) = 1;
            plugin.Filter_L.Numerator =  num;
            plugin.Filter_R.Numerator = num;
        end
end

There is another issue in process, where output was first set to empty, and then its size is changed to the size of input. Code generation does not like this size change. This code fixes the issue:

function output = process(plugin,input) % funzione di elaborazione
    output = input;
    if ~plugin.bypass
        output(:,1) = step(plugin.Filter_L,input(:,1));         
        output(:,2) = step(plugin.Filter_R,input(:,2));
    end
end

With those two changes, you should be able to validate and generate your plugin.

[DARIO BENVEGNÙ]

Thank you Jibrahim, this has solved my issue