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Operating Modes

plugindata can run in two distinct modes, each optimized for different workflows:
  1. Plugin Mode - Runs inside a DAW as a VST3/AU/LV2/CLAP plugin
  2. Standalone Mode - Runs as an independent desktop application
Both modes share the same core Pure Data engine but differ in how they handle I/O, MIDI, and system integration.

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Standalone Mode

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Architecture

Standalone mode runs as a native application with full system access. From PluginProcessor.cpp:54-82, the audio bus configuration differs: 
AudioProcessor::BusesProperties PluginProcessor::buildBusesProperties()
{
    AudioProcessor::BusesProperties busesProperties;
    
    if (ProjectInfo::isStandalone) {
        // Standalone: Simple stereo I/O
        busesProperties.addBus(true, "Main Input", 
                              AudioChannelSet::stereo(), true);
        busesProperties.addBus(false, "Main Output", 
                              AudioChannelSet::stereo(), true);
    } else {
        // Plugin: Multiple aux buses
        busesProperties.addBus(true, "Main Input", 
                              AudioChannelSet::stereo(), true);
        
        for (int i = 1; i < numInputBuses; i++)
            busesProperties.addBus(true, "Aux Input " + String(i), 
                                  AudioChannelSet::stereo(), false);
        
        busesProperties.addBus(false, "Main Output", 
                              AudioChannelSet::stereo(), true);
        
        for (int i = 1; i < numOutputBuses; i++)
            busesProperties.addBus(false, "Aux Output" + String(i), 
                                  AudioChannelSet::stereo(), false);
    }
    
    return busesProperties;
}

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Features

Window Management
  • Multiple windows support
  • Native window decorations
  • Maximizable/fullscreen
  • Independent window positioning
File Operations
  • Direct file system access
  • Save/load patches anywhere
  • External file management
  • No DAW session dependency
Audio/MIDI Routing
  • Direct hardware access
  • Selectable audio interfaces
  • Virtual MIDI ports
  • System MIDI devices
  • Internal synthesizer support
From PluginProcessor.cpp:175-179: 
if (ProjectInfo::isStandalone) {
    midiDeviceManager.setInternalSynthPort(
        settingsFile->getProperty<int>("internal_synth"));
} else {
    midiDeviceManager.setInternalSynthPort(0);
}
Multi-Patch Workflow
  • Open multiple patches simultaneously
  • Tab-based interface
  • Split view support
  • Independent patch states
Preferences and Settings
  • Global audio/MIDI settings
  • Theme customization
  • Library management
  • Path configuration

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Audio I/O Configuration

Standalone provides direct control over: Input Configuration
  • Device selection
  • Channel count (up to 32)
  • Sample rate selection
  • Buffer size adjustment
Output Configuration
  • Device selection
  • Channel routing
  • Sample rate matching
  • Latency compensation
Processing
  • Configurable block size (64 samples default)
  • Independent sample rate
  • Direct hardware communication

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Use Cases

Development and Testing
  • Rapid prototyping
  • Algorithm development
  • Quick experimentation
  • Debugging and testing
Live Performance
  • No DAW required
  • Lower latency potential
  • Direct hardware access
  • Simpler signal flow
Sound Design
  • Standalone synthesizers
  • Audio processors
  • Effects chains
  • Experimental instruments
Education
  • Learning Pure Data
  • Teaching DSP concepts
  • No DAW knowledge required
  • Simpler environment

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Plugin Mode

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Architecture

plugindata integrates into DAWs using standard plugin formats:
  • VST3 - Steinberg’s cross-platform format
  • AU - Apple’s Audio Units (macOS)
  • LV2 - Open-source format (Linux)
  • CLAP - Modern open standard

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Integration Features

DAW Synchronization From PluginProcessor.cpp:1055-1128, playhead information is synchronized: 
void PluginProcessor::sendPlayhead()
{
    AudioPlayHead const* playhead = getPlayHead();
    if (!playhead) return;
    
    auto infos = playhead->getPosition();
    
    lockAudioThread();
    setThis();
    
    if (infos.hasValue()) {
        // Playing state
        atoms_playhead[0] = infos->getIsPlaying();
        sendMessage("__playhead", "playing", atoms_playhead);
        
        // Recording state
        atoms_playhead[0] = infos->getIsRecording();
        sendMessage("__playhead", "recording", atoms_playhead);
        
        // Loop points
        atoms_playhead[0] = infos->getIsLooping();
        auto loopPoints = infos->getLoopPoints();
        if (loopPoints.hasValue()) {
            atoms_playhead.emplace_back(loopPoints->ppqStart);
            atoms_playhead.emplace_back(loopPoints->ppqEnd);
        }
        sendMessage("__playhead", "looping", atoms_playhead);
        
        // Tempo
        if (infos->getBpm().hasValue()) {
            atoms_playhead[0] = static_cast<float>(*infos->getBpm());
            sendMessage("__playhead", "bpm", atoms_playhead);
        }
        
        // Position (PPQ, samples, seconds)
        auto ppq = infos->getPpqPosition();
        auto samplesTime = infos->getTimeInSamples();
        auto secondsTime = infos->getTimeInSeconds();
        
        atoms_playhead.resize(3);
        atoms_playhead[0] = ppq.hasValue() ? *ppq : 0.0f;
        atoms_playhead[1] = samplesTime.hasValue() ? *samplesTime : 0.0f;
        atoms_playhead[2] = secondsTime.hasValue() ? *secondsTime : 0.0f;
        sendMessage("__playhead", "position", atoms_playhead);
    }
    
    unlockAudioThread();
}
Pd patches can receive:
  • Playing/recording/looping state
  • Tempo (BPM)
  • Time signature
  • Transport position (PPQ, samples, seconds)
  • Loop points
  • Frame rate
Access via: 
[r __playhead playing]  ← 0 or 1
[r __playhead bpm]      ← Current tempo
[r __playhead position] ← PPQ, samples, seconds (list)
Automation From PluginProcessor.cpp:120-131, parameters are exposed: 
// Volume parameter (built-in)
auto* volumeParameter = new PlugDataParameter(this, "volume", 
                                             0.8f, true, 0, 0.0f, 1.0f);
addParameter(volumeParameter);

// General purpose automation (param1-paramN)
for (int n = 0; n < numParameters; n++) {
    auto* parameter = new PlugDataParameter(this, 
                                           "param" + String(n + 1), 
                                           0.0f, false, n + 1, 0.0f, 1.0f);
    addParameter(parameter);
}
Automation parameters:
  • param1 through param64 (default)
  • Mapped to Pd receivers: [r param1], [r param2], etc.
  • Fully automatable in DAW
  • Saved with DAW project
From PluginProcessor.cpp:1149-1159, parameter updates: 
void PluginProcessor::sendParameters()
{
    ScopedLock lock(audioLock);
    for (auto* param : enabledParameters) {
        if (EXPECT_UNLIKELY(param->wasChanged())) {
            auto title = param->getTitle();
            sendFloat(title.data(), param->getUnscaledValue());
            param->setUnchanged();
        }
    }
}
State Management Plugin state is saved with DAW projects:
  • Patch content (embedded)
  • Parameter values
  • Editor size/position
  • Connection paths (segmented)
  • GUI states
From PluginProcessor.cpp:1224-1308: 
void PluginProcessor::getStateInformation(MemoryBlock& destData)
{
    setThis();
    MemoryOutputStream ostream(destData, false);
    
    ostream.writeInt(patches.size());
    
    // Save each patch
    lockAudioThread();
    for (auto const& patch : patches) {
        auto content = patch->getCanvasContent();
        auto patchFile = patch->getCurrentFile().getFullPathName();
        
        // Store content and location
        ostream.writeString(content);
        ostream.writeString(patchFile);
    }
    unlockAudioThread();
    
    // Save settings
    ostream.writeInt(getLatencySamples() - Instance::getBlockSize());
    ostream.writeInt(oversampling);
    ostream.writeFloat(getValue<float>(tailLength));
    
    // XML format for extensibility
    auto xml = XmlElement("plugdata_save");
    xml.setAttribute("Version", PLUGDATA_VERSION);
    xml.setAttribute("Oversampling", oversampling);
    xml.setAttribute("Width", editor->getWidth());
    xml.setAttribute("Height", editor->getHeight());
    
    PlugDataParameter::saveStateInformation(xml, getParameters());
}
MIDI Routing Plugin mode MIDI handling from PluginProcessor.cpp:1166-1201: 
void PluginProcessor::sendMidiBuffer(int const device, 
                                    MidiBuffer const& buffer)
{
    if (acceptsMidi()) {
        for (auto event : buffer) {
            auto message = event.getMessage();
            auto const channel = message.getChannel() + (device << 4);
            
            if (message.isNoteOn()) {
                sendNoteOn(channel, message.getNoteNumber(), 
                          message.getVelocity());
            } else if (message.isNoteOff()) {
                sendNoteOn(channel, message.getNoteNumber(), 0);
            } else if (message.isController()) {
                sendControlChange(channel, message.getControllerNumber(), 
                                message.getControllerValue());
            } else if (message.isPitchWheel()) {
                sendPitchBend(channel, 
                            message.getPitchWheelValue() - 8192);
            }
            // ... additional MIDI message types
        }
    }
}

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Channel Configuration

Plugin mode supports flexible I/O: Input Buses
  • Main input (stereo, enabled)
  • Aux inputs 1-N (stereo, optional)
  • Up to 32 total input channels
Output Buses
  • Main output (stereo, enabled)
  • Aux outputs 1-N (stereo, optional)
  • Up to 32 total output channels
Pd Access 
[adc~ 1 2]        ← Main input L/R
[adc~ 3 4]        ← Aux input 1 L/R
[adc~ 5 6]        ← Aux input 2 L/R

[dac~ 1 2]        ← Main output L/R
[dac~ 3 4]        ← Aux output 1 L/R  
[dac~ 5 6]        ← Aux output 2 L/R

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Plugin-Specific Features

Presentation Mode From PluginMode.h:13-526, dedicated plugin UI: 
class PluginMode final : public Component
{
public:
    explicit PluginMode(PluginEditor* editor, pd::Patch::Ptr patch)
        : patchPtr(patch)
        , cnv(std::make_unique<Canvas>(editor, patch, this))
    {
        patch->openInPluginMode = true;
        
        // Titlebar with controls
        titleBar.setBounds(0, 0, width, titlebarHeight);
        
        // Scale selector
        scaleComboBox.addItemList(itemList, 1);
        scaleComboBox.onChange = [this] {
            setWidthAndHeight(pluginScales[itemId - 1].floatScale);
        };
    }
    
    void setWidthAndHeight(float scale)
    {
        cnv->zoomScale = scale;
        
        auto newWidth = static_cast<int>(width * scale);
        auto newHeight = static_cast<int>(height * scale) + titlebarHeight;
        
        editor->pluginConstrainer.setSizeLimits(
            newWidth, newHeight, newWidth, newHeight);
        editor->setSize(newWidth, newHeight);
    }
};
Features:
  • Fixed-size UI mode
  • Zoom levels (50%, 75%, 100%, 125%, 150%, 175%, 200%)
  • Fullscreen mode (standalone only)
  • Titlebar with patch name
  • Edit mode toggle
  • Clipped rendering area
Scale settings are saved in meta.json: 
{
  "Zoom": 3,
  "Scale": 1.0
}
Sample Rate Handling From PluginProcessor.cpp:699-759: 
void PluginProcessor::prepareToPlay(double const sampleRate, 
                                   int const samplesPerBlock)
{
    if (approximatelyEqual(sampleRate, 0.0))
        return;
    
    float const oversampleFactor = 1 << oversampling;
    auto maxChannels = std::max(getTotalNumInputChannels(), 
                                getTotalNumOutputChannels());
    
    prepareDSP(getTotalNumInputChannels(), 
              getTotalNumOutputChannels(), 
              sampleRate * oversampleFactor);
    
    // Setup oversampling if enabled
    oversampler = std::make_unique<dsp::Oversampling<float>>(
        std::max(1, maxChannels), oversampling, 
        dsp::Oversampling<float>::filterHalfBandPolyphaseIIR, false);
    
    oversampler->initProcessing(samplesPerBlock);
    
    // Pd uses fixed 64-sample blocks
    auto const pdBlockSize = Instance::getBlockSize(); // 64
    
    // Variable block size handling for plugins
    variableBlockSize = !ProjectInfo::isStandalone || 
                       samplesPerBlock < pdBlockSize || 
                       samplesPerBlock % pdBlockSize != 0;
    
    if (variableBlockSize) {
        inputFifo = std::make_unique<AudioMidiFifo>(
            maxChannels, 
            std::max<int>(pdBlockSize, samplesPerBlock * oversampleFactor) * 3);
        outputFifo = std::make_unique<AudioMidiFifo>(
            maxChannels, 
            std::max<int>(pdBlockSize, samplesPerBlock * oversampleFactor) * 3);
        outputFifo->writeSilence(Instance::getBlockSize());
    }
}
Pd always processes in 64-sample blocks internally. Plugins handle arbitrary block sizes via FIFO buffering. Latency Reporting From PluginProcessor.cpp:192: 
setLatencySamples(pd::Instance::getBlockSize());
Plugins report 64 samples of latency (one Pd block) to the DAW for automatic delay compensation.

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Plugin Limitations

File Access
  • No direct file browser
  • Patches embedded in DAW session
  • External files must be in search path
  • No arbitrary file writing
Window Management
  • Single window per instance
  • Size constrained by plugin mode
  • No multiple patches per instance
  • DAW controls window state
Audio Routing
  • Bus configuration set by DAW
  • Cannot change I/O at runtime
  • No direct hardware access
  • Routing through DAW mixer
Processing
  • Fixed to DAW sample rate
  • DAW controls buffer size
  • Must handle variable block sizes
  • Subject to DAW thread priority

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Oversampling

Both modes support oversampling from PluginProcessor.cpp:655-668: 
void PluginProcessor::setOversampling(int const amount)
{
    if (oversampling == amount)
        return;
    
    oversampling = amount;  // 0=none, 1=2x, 2=4x, 3=8x
    
    auto const blockSize = AudioProcessor::getBlockSize();
    auto const sampleRate = AudioProcessor::getSampleRate();
    
    suspendProcessing(true);
    prepareToPlay(sampleRate, blockSize);
    suspendProcessing(false);
}
Oversampling reduces aliasing in nonlinear processes:
  • None (1x): Standard quality
  • 2x: Good quality, moderate CPU
  • 4x: High quality, higher CPU
  • 8x: Maximum quality, significant CPU
Oversampling uses polyphase IIR filters for efficiency.

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Choosing the Right Mode

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Use Standalone When:

✅ Prototyping new ideas quickly
✅ Learning Pure Data/DSP
✅ Live performance without DAW
✅ Testing with different audio interfaces
✅ Working with multiple patches simultaneously
✅ Need direct file system access
✅ Developing standalone instruments/effects

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Use Plugin When:

✅ Integrating with DAW workflow
✅ Recording automation
✅ Tempo sync required
✅ Multiple instances needed
✅ Mixing with other plugins
✅ Session recall important
✅ Distributing to users with DAWs

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Migration Between Modes

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Standalone to Plugin

  1. Save patch in standalone
  2. Load in DAW as plugin
  3. Configure I/O to match DAW routing
  4. Map automation parameters
  5. Test playhead sync if needed
  6. Set plugin mode for presentation

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Plugin to Standalone

  1. Export patch from DAW session
  2. Open in standalone
  3. Configure audio/MIDI devices
  4. Test I/O channels
  5. Adjust workflow for multi-patch if needed

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Best Practices

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Cross-Compatible Patches

To work well in both modes: Use Relative Paths 
[declare -path abstractions]  ← Search in subdirectory
[declare -lib else]            ← Load library
Dynamic Channel Count 
[adc~ 1 2]    ← Always use channels 1-2 for main I/O
[dac~ 1 2]    ← Works in both modes
Conditional Automation 
[r param1]    ← Works in plugin (automation)
[hsl 128 15]  ← Works in standalone (GUI control)
Portable File Handling
  • Keep external files in same directory as patch
  • Use relative paths with [declare]
  • Test in both modes before distribution

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Performance Optimization

Plugin Mode
  • Minimize processing (shared CPU with DAW)
  • Use efficient algorithms
  • Consider oversampling cost
  • Report accurate latency
Standalone Mode
  • Can use more CPU if needed
  • Direct hardware = lower latency possible
  • Adjust buffer size for latency/stability

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Next Steps

DAW Integration

Learn how plugdata integrates with your DAW

Patching Basics

Master the fundamentals of Pure Data patching

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