A command-line VST3, AU and LADSPA host meant to ease debugging of audio plugins and instruments by making it possible to run them in non-realtime outside of a conventional DAW.

It processes audio and MIDI from input files using the desired plugin, writing the result to an output file. Plugins with multiple input buses (such as sidechains) are supported.


The general usage of plugalyzer follows the pattern plugalyzer [command] [options...]. Available commands and their options are described below.

Process audio files

The process command processes the given audio and/or MIDI files using the given plugin in non-realtime, writing the processed audio to an output file.

Option Description Required
--plugin=<path> Path to, or identifier of the plugin to use. Yes
--input=<path> Path to an audio input file.To supply multiple input files, provide the --input argument multiple times. Yes, unless --midiInput is set
--midiInput=<path> Path to a MIDI input file. No
--output=<path> Path to write the processed audio to. Yes
--overwrite Overwrite the output file if it exists.If this option is not set, processing is aborted if the output file exists. No
--sampleRate=<number> The sample rate to use for processing.Only allowed if no audio input is provided.Defaults to 44100. No
--blockSize=<number> The amount of samples to send to the audio plugin at once for processing.Defaults to 1024. No
--outChannels=<number> The amount of channels to use for the plugin’s output bus. Defaults to the amount of channels of the first input file. No
--param=<name>:<value> Sets the plugin parameter with the given name or index to the given value.Both name and value can be quoted using single or double quotes.To set multiple parameters, supply the --param argument multiple times.Use the listParameters command to list all available parameters. No

Example usage for a plugin with a main and a sidechain input bus:

plugalyzer process                    \
  --plugin=/path/to/my/plugin.vst3    \
  --input=main_input.wav              \
  --input=sidechain_input.wav         \
  --output=out.wav                    \
  --param="Wet/Dry Mix":0.2           \

Bus layouts

The bus layout requested from the plugin is based on the audio input files. Each audio input file is provided to the plugin on a separate bus, each bus having the same amount of channels as the respective input file.

Plugalyzer only supports a single output bus. The amount of channels can be specified using the --outChannels option. If --outChannels is not set, it defaults to the amount of channels of the first audio input file. If no audio input is provided (e.g. when testing MIDI instruments), the plugin’s default output bus layout is used.

Processing limitations

  • Plugalyzer does not support showing plugin GUIs of any kind. Since processing is not done in real-time, this wouldn’t be too useful, either way.
  • Only a single output bus is supported.

List plugin parameters

The listParameters command lists all available plugin parameters and their value range.

Option Description Required
--plugin=<path> Path to, or identifier of the plugin to use. Yes
--blockSize=<number> The processing block size to initialize the plugin with. This is only needed when a plugin doesn’t support initialization with the default block size.Defaults to 1024. No
--sampleRate=<number> The sample rate to initialize the plugin with. This is only needed when a plugin doesn’t support initialization with the default sample rate.Defaults to 44100. No

Example usage:

plugalyzer listParameters --plugin=/path/to/my/plugin.vst3

Example output:

Loaded plugin "Black Box Analog Design HG-2".

Plugin parameters: 
0: Power
   Values:  Off, On
   Default: On
1: Saturation Frequency
   Values:  Low, Flat, High
   Default: Flat
2: Saturation In
   Values:  Off, On
   Default: Off
3: Saturation
   Values:  0 % to 100 %
   Default: 50 %



  • Plugin parameters with a set of discrete values (i.e. not a floating-point range) that aren’t correctly marked as such will not list all valid values. This issue arises, for example, when a JUCE plugin uses the deprecated juce::AudioProcessorValueTreeState::Parameter class where juce::AudioParameterChoice would be a better fit.


There are currently no pre-built binaries available for download, primarily because I do not have machines with all major operating systems available. To compile this project yourself, clone it and build it via CMake. I recommend JetBrain’s CLion for its excellent CMake support.


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