Audio Units (AU) are a system-level

plug-in Plug-in, plug in or plugin may refer to: * Plug-in (computing) is a software component that adds a specific feature to an existing computer program. ** Audio plug-in, adds audio signal processing features ** Photoshop plugin, a piece of softwar ...

architecture provided by Core Audio in

Apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple trees are cultivated worldwide and are the most widely grown species in the genus '' Malus''. The tree originated in Central Asia, where its wild ances ...

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac (computer), Mac computers. Within the market of ...

and iOS operating systems. Audio Units are a set of application programming interface (API) services provided by the

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

to generate, process, receive, or otherwise manipulate streams of audio in near-real-time with minimal latency. It may be thought of as Apple's architectural equivalent to another popular plug-in format, Steinberg's Virtual Studio Technology (VST). Because of the many similarities between Audio Units and VST, several commercial and free wrapping technologies are available (e.g
Symbiosis
and FXpansionbr>VST-AU Adapter
. Celemony Software and

PreSonus PreSonus Audio Electronics, Inc. (often known and styled as PreSonus) is an American manufacturer of professional audio equipment and software, used to create, record, mix, and master music and other audio. This includes their line of digital aud ...

have also developed the Audio Random Access (ARA) extension, which works for both AU and VST, allowing greater integration between the plug-ins and DAW software.

Use

Audio Units allows sound file audio time stretching and pitch scaling (e.g., timestretch), sample rate conversion, and streaming over a Local Area Network. It also comes with a set of AU plug-ins such as EQ filters, dynamic processors, delay, reverb, and a Soundbank Synthesizer Instrument. AU are used by Apple applications such as GarageBand, Soundtrack Pro, Logic Express, Logic Pro, Logic Pro X, Final Cut Pro, MainStage and most 3rd party audio software developed for

such as Ableton Live, Amadeus Pro, Ardour, Audio Hijack, DaVinci Resolve, Digital Performer, Gig Performer, REAPER, and

Studio One Studio One or Studio 1 may refer to: * Studio One (software), digital audio workstation software, developed by PreSonus * ''Studio One'' (American TV series), a 1948–1958 American television anthology series * ''Studio One'' (Emirati TV progra ...

Competing technologies

* Avid's Avid Audio eXtension (a successor to the RTAS format) * Digidesign's Real Time AudioSuite (now obsolete) * LADSPA and Disposable Soft Synth Interface (DSSI) for

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which i ...

* LV2 (crossplatform successor to LADSPA) *

Microsoft Microsoft Corporation is an American multinational corporation, multinational technology company, technology corporation producing Software, computer software, consumer electronics, personal computers, and related services headquartered at th ...

's DirectX * Steinberg's Virtual Studio Technology

References

Music software plugin architectures macOS APIs {{mac-stub