VST Plugins

This guide shows how to load and manage Virtual Studio Technology (VST2) plugins.

VST plugins are external plugins you can find online both free and paid. They can add effects to the sound like reverb, delay or generate sounds like synthesizers.

Unfortunately VST.NET doesn’t support the latest VST3 standard, so we are limited to VST2 as of now, but you can still find many plugins to use.

Altogether, the framework VST support may not be completed, but seems to work fine in most cases.

Loading a VST Plugin

To load a VST plugin we just need to create a new VstPlugin class instance and pass the plugin .dll file path. This implements the IPlugin interface as explained in the page before.

var vst = new VstPlugin("path/to/plugin.dll"); // Loading the plugin

Optionally we can also configure some plugin behaviours through flags.

// Loading the plugin, removing the minimize button, making the window always stay on top and receive midi events from computer keyboard
var vst = new VstPlugin("path/to/plugin.dll", VstFlags.NoMinimize | VstFlags.AlwaysOnTop | VstFlags.ComputerKeyboard);

Using VST Plugins

To process audio through the loaded plugin, we need to add it to a track (both audio, midi and group tracks will work if it’s not a plugin instrument).

var track = new AudioTrack(); // Creating an audio track
var result = audioTrack.AddPlugin(vst); // Adding the VST plugin to the audio track
if (!result.IsSuccess) // Checking if the plugin was successfully added
{
    // Printing the error message if not successfull
    Console.WriteLine($"Couldn't add plugin: {result.Message}");
}

Now whenever a clip inside that track is played the sound will be processed through the VST plugin.

To remove the plugin from the track:

track.RemovePlugin(vst); // Removing the VST plugin from the audio track

Caution

When a plugin is removed from a track it will be disposed and not available to use anymore.

Note

The framework automatically handles plugins swap preventing to add multiple instruments to the same midi track by replacing the current instrument with the new one.

It also prevents from adding plugin instruments to audio tracks and adding the same plugin instance to different tracks.

VST plugins parameters

• Enabled: represents the state of the plugin. If disabled it won’t process/generate sound.
• Name: name of the VST plugin (comes from the dll name).
• PluginId: an unique generated id in the form 5cafb3a8-dba4-47ce-9e58-03d972526c50.
• PluginType: the type of the VST plugin (either an effect or instrument).
• VstFlags: flags to customize certain aspects of the VST.

VST plugins operations

• AddKeyDownEvent(): calls an event whenever the plugin window has focus and a key is pressed.
• AddKeyUpEvent(): calls an event whenever the plugin window has focus and a key is released.
• RemoveKeyDownEvent(): removes a registered key down event.
• RemoveKeyUpEvent(): removes a registered key up event.
• OpenPluginWindow(): opens the plugin interface.
• ClosePluginWindow(): closes the plugin interface.
• Toggle(): toggles the Enabled property.
• Dispose(): calls DisposeVST.
• DisposeVST(): disposes the VST plugin.
• ReceiveMidiEvent(): method which handles incoming midi events. Can also be used to send testing midi events to the vst.

Note

Probably not all midi event types are handled, but I tried to add the most common ones.

Important Note

If you hear time misplacements when playing midi clips through a VST plugin instrument, try to reduce the latency of the AudioDevice as low as possible. For this reason, using the ASIO audio API is highly recommended if you are going to make use of VST plugins.

Example

In this example we create a midi clip, add it to a created midi track, load a plugin instrument and add it to the midi track, then play the midi clip.

var midiClip = new MidiClip("path/to/midi.mid"); // Create a midi clip
var midiTrack = new MidiTrack(); // Create a midi track
var vstInstrument = new VstPlugin("path/to/plugin.dll"); // Load the VST plugin instrument

midiTrack.AddClip(midiClip); // Add the midi clip to the midi track
midiTrack.AddPlugin(vstInstrument); // Add the VST plugin instrument to the midi track

midiClip.Play(); // Play the midi clip (sound will generate from the VST plugin)

The plugin interface Prev

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