How do I start a `juce::AudioProcessor` from my application?

General JUCE discussion
1

This is how I start my Android JUCE application:

class NP2Application  : public juce::JUCEApplication
{
public:
    //==============================================================================
    NP2Application() {}

    const juce::String getApplicationName() override       { return ProjectInfo::projectName; }
    const juce::String getApplicationVersion() override    { return ProjectInfo::versionString; }
    bool moreThanOneInstanceAllowed() override             { return true; }

    //==============================================================================
    void initialise (const juce::String& commandLine) override
    {
        //This stars by itself
        whiteNoiseComponent = std::make_unique<WhiteNoiseComponent>();
        //This does not starts by itself
        testpluginAudioProcessor = std::make_unique<TestpluginAudioProcessor>();

    }

WhiteNoiseComponent is a class WhiteNoiseComponent : public juce::AudioAppComponent and it starts by itself and generates white noise.

This is my TestAudioPluginProcessor:

class TestpluginAudioProcessor  : public juce::AudioProcessor
{
public:
    //==============================================================================
    TestpluginAudioProcessor();
    ~TestpluginAudioProcessor() override;

    //==============================================================================
    void prepareToPlay (double sampleRate, int samplesPerBlock) override;
    void releaseResources() override;

#ifndef JucePlugin_PreferredChannelConfigurations
    bool isBusesLayoutSupported (const BusesLayout& layouts) const override;
#endif

    void processBlock (juce::AudioBuffer<float>&, juce::MidiBuffer&) override;

    //==============================================================================
    juce::AudioProcessorEditor* createEditor() override;
    bool hasEditor() const override;

    //==============================================================================
    const juce::String getName() const override;

    bool acceptsMidi() const override;
    bool producesMidi() const override;
    bool isMidiEffect() const override;
    double getTailLengthSeconds() const override;

    //==============================================================================
    int getNumPrograms() override;
    int getCurrentProgram() override;
    void setCurrentProgram (int index) override;
    const juce::String getProgramName (int index) override;
    void changeProgramName (int index, const juce::String& newName) override;

    //==============================================================================
    void getStateInformation (juce::MemoryBlock& destData) override;
    void setStateInformation (const void* data, int sizeInBytes) override;

private:
    //==============================================================================
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (TestpluginAudioProcessor)
};

it simply won’t start. Even though it does nothing:

void TestpluginAudioProcessor::processBlock (juce::AudioBuffer<float>& buffer, juce::MidiBuffer& midiMessages)
{
    juce::ScopedNoDenormals noDenormals;
    auto totalNumInputChannels  = getTotalNumInputChannels();
    auto totalNumOutputChannels = getTotalNumOutputChannels();

    for (auto i = totalNumInputChannels; i < totalNumOutputChannels; ++i)
        buffer.clear (i, 0, buffer.getNumSamples());

    for (int channel = 0; channel < totalNumInputChannels; ++channel)
    {
        auto* channelData = buffer.getWritePointer (channel);
        // ..do something to the data...
    }
    ALOGV(TAG, "block process");
}

I do not see block process on the output, which means it’s not processing anything.

How do I start a juce::AudioProcessor from my application?

2

Have you looked at the tutorials? Tutorials | JUCE

Here’s one that shows how to pass audio through a chain of AudioProcessors: JUCE: Tutorial: Cascading plug-in effects