What are Audio Plugins?

ByMunyaradzi Mafaro

Audio plugins are software tools used in music production and audio engineering. They allow users to add effects, synthesizers, and other audio processing to their projects. Plugins extend the capabilities of digital audio workstations (DAWs) like Pro Tools, Logic Pro, Ableton Live, FL Studio, and others.

Plugins usually focus on tasks such as compression, equalization (EQ), reverberation, or sound synthesis. Audio engineers and music producers use multiple plugins to shape and sculpt the sounds in their mixes. The right combination of plugins can help achieve professional-quality audio.

How do audio plugins work?

Most audio plugins use digital signal processing (DSP) to analyze and manipulate audio signals. The DSP applies mathematical operations to modify the sound waves when an audio signal is sent into the plugin. For example:

  • A compressor plugin uses algorithms to reduce the dynamic range of the audio
  • An EQ plugin boosts or cuts particular frequency ranges to change the tone
  • A reverb plugin simulates the reflections of sounds in a physical space

The processed audio is then sent out of the plugin and back into the main project. Many plugins have graphical user interfaces with knobs, faders, buttons, and displays for controlling the parameters. Under the hood, adjusting these controls changes variables in the underlying DSP code to alter the sound.

What are the main audio plugin formats?

There are several widely used formats for professional audio plugins. Each has its strengths and compatibilities. The main plugin formats are:

VST (Virtual Studio Technology)

VST is a plugin standard developed by Steinberg, first released in 1996. It is one of the most common cross-platform formats. Key points about VST:

  • Supported by many significant DAWs on Windows and macOS
  • An open standard that allows third-party developers to create VST plugins
  • The latest version is VST3, which adds new capabilities like note expression

Many of the most popular plugin companies, such as Waves, FabFilter, iZotope, Native Instruments, and others, offer their products in the VST format.

AU (Audio Units)

Audio Units is a plugin architecture created by Apple. It is the standard format for audio plugins on macOS. Essential details about AU:

  • Deeply integrated into Apple’s Core audio system
  • Allows plugins to be used in any AU host application
  • Optimized for efficient use of the Mac’s hardware and OS
  • Includes a validation process for improved stability

Most professional audio plugins for Mac are available in the AU format in addition to VST, and some Mac-only plugins are AU-only.

AAX (Avid Audio eXtension)

AAX is a plugin standard created by Avid for their Pro Tools DAW. It replaces the older RTAS and TDM plugin formats. The AAX format has two variants:

  • AAX Native: For native processing using the host computer’s CPU
  • AAX DSP: For processing on dedicated DSP hardware like Pro Tools HDX systems

Pro Tools versions after ten support AAX plugins only. Developers need a special license and SDK from Avid to create AAX plugins.

CLAP (CLever Audio Plugin)

CLAP is a newer open-source plugin API created by u-he, a developer of plugins and synths. The format aims to be a modern alternative to existing standards. Notable features of CLAP:

  • Supports novel features missing from older formats like VST3 and AU
  • Uses a flexible licensing scheme for closed or open-source development
  • Built from the ground up to support precise timing and low latency
  • Small and easy to integrate into existing plugin codebases

Support for CLAP is growing among DAW and plugin developers. Bitwig, u-he, Surge, Vital, and others have already adopted the format.

Other plugin formats and technologies

In addition to the main cross-platform formats, there are other standards and technologies related to audio plugins:

  • LV2: An open-source plugin specification built on top of the LADSPA API
  • ARA (Audio Random Access): An extension that gives plugins access to the DAW’s audio clips
  • MIDI 2.0: The latest MIDI protocol version, which enables new possibilities for controlling plugins

Some DAWs also have proprietary plugin architectures. For example, FL Studio supports FL Native plugins, and Reason has its Rack Extensions format.

How to choose the proper plugin format

For most users, the best plugin format depends on their choice of DAW and platform. Follow these guidelines:

  • On Windows: VST or AAX plugins offer the widest compatibility
  • On macOS: AU or VST provides the most profound integration and best performance
  • With Pro Tools: AAX format is required, either Native or DSP, depending on the setup
  • For cross-platform use: VST is a safe bet for most major DAWs on both Windows and Mac
  • For maximum features: Investigate newer options like VST3 and CLAP to access unique capabilities

The future of audio plugin formats

Plugin formats have evolved dramatically from the early days of digital audio. Developers continue to add features and extend functionality. Critical areas of advancement include:

  • Seamless integration: Better communication between plugins and DAWs for fluid workflows
  • New forms of synthesis: Harnessing the power of AI/ML, cloud computing, and other technologies
  • Expressive controllers: Richer mappings for manipulating plugin parameters in meaningful ways
  • Fidelity improvements: Higher sampling rates, lower latency, and expanded dynamic range

Upcoming versions of the significant plugin standards aim to support these innovations. CLAP is an example of a format built with future possibilities in mind from the start.

Munyaradzi Mafaro is a music enthusiast and he also likes to tackle topics of business, productivity, and the possibilities for growth in the digital world.