Audacity (audio editor)

Audacity is a free and open-source digital audio editor and recording application software, available for Windows, macOS, Linux, and other Unix-like operating systems.

As of December 6, 2022, Audacity is the most popular download at FossHub, with over 114.2 million downloads since March 2015. It was previously served by Google Code and SourceForge, where it was downloaded over 200 million times. It is now part of Muse Group.

It is licensed under GPL-2.0 or later. Executables with VST3 support are licensed GPL-3-only to maintain license compatibility.

History
The project was started in the fall of 1999 by Dominic Mazzoni and Roger Dannenberg at Carnegie Mellon University, initially under the name CMU Visual Audio. On May 28, 2000, Audacity was released as Audacity 0.8 to the public.

Mazzoni eventually left CMU to pursue software development and in particular development of Audacity, with Dannenberg remaining at CMU and continuing development of Nyquist, a scripting language which Audacity uses for some effects.

Over the years, additional volunteer contributors emerged, including James Crook who started the fork DarkAudacity to experiment with a new look and other UX changes. Most of its changes were eventually incorporated into the mainline version and the fork ended.

In April 2021, it was announced that Muse Group (owners of MuseScore and Ultimate Guitar) would acquire the Audacity trademark and continue to develop the application, which remains free and open source.

Features and use
In addition to recording audio from multiple sources, Audacity can be used for post-processing of all types of audio, including effects such as normalization, trimming, and fading in and out. It has been used to record and mix entire albums, such as by Tune-Yards. It is currently used in the Sound Creation unit of the UK OCR National Level 2 ICT course.

Recording
Audacity can record multiple tracks at once, provided the sound card supports it. In addition to a normal mode, recordings can be scheduled ("Timer Record"), or used in a Punch in and roll fashion.

Non-destructive editing
Historically, Audacity is a destructive editor, meaning all changes are directly applied to the waveform. This comes with certain benefits but means that any change made cannot be tweaked later on without undoing all changes in-between. For a long time, non-destructive editing was exclusive to volume envelopes and playback rates, but since version 3, this has been extended to clip trimming and effects.

Importing, exporting and conversions
Audacity natively imports and exports WAV, AIFF, MP3, Ogg Vorbis, and all file formats supported by libsndfile library. Due to patent licensing concerns, the FFmpeg library necessary to import and export proprietary formats such as M4A (AAC) and WMA is not bundled with Audacity but has to be downloaded separately.

In conjunction with batch processing features, Audacity can be used to convert files from one format to another, or to digitize records, tapes or MiniDiscs.

Customizability and extensibility
Audacity supports LADSPA, LV2, VST, VST3, Audio Units, Vamp and Nyquist plugins, which allows it to load most audio effect plugins. It additionally features a console for Nyquist, a Lisp dialect, in which users can script their own plugins and support for external python scripting.

Audacity is somewhat customizable and supports arbitrary arrangements of its toolbars, custom themes and enabling and disabling of several features.

In January 2024, Intel introduced some AI-powered capabilities for Audacity as part of its OpenVINO plugin suite.

Audio analysis
Audacity has several features to allow for spectrum analysis using the Fourier transform algorithm and spectrograms. As with effects, additional analysis plugins can be added, such as ones that check audio books for ACX compatibility.

Limitations
While Audacity has some features found in digital audio workstations, it should not be considered as such yet. In its current form, it is an audio editor and recorder. In particular, MIDI editing, piano rolls, virtual instruments, parameter automation and channel routings are not yet implemented.

Due to the use of wxWidgets, which do not have full iOS or Android support, Audacity cannot run on mobile platforms.

Other features
Audacity can make precise adjustments to speed (tempo) while maintaining pitch, to synchronize audio with video or for precise running time. It also has a large array of digital effects and plug-ins, including: noise reduction based on sampling the noise to be minimized, vocal reduction and isolation for creation of karaoke tracks and isolated vocal tracks, pitch adjustment maintaining speed, and speed adjustment maintaining pitch. Audacity also has support for multi-channel modes with sampling rates up to 96 kHz with 32 bits per sample. It can also detect dropout errors while recording with an overburdened CPU.

Language support
In addition to English, Audacity is available in Afrikaans, Arabic, Basque, Bulgarian, Catalan, Chinese (simplified), Chinese (traditional), Corsican, Czech, Danish, Dutch, Finnish, French, Galician, German, Greek, Hungarian, Irish, Italian, Japanese, Lithuanian, Macedonian, Marathi, Norwegian (Bokmål), Polish, Portuguese (Brazilian), Romanian, Russian, Slovak, Slovenian, Spanish, Swedish, Turkish, Ukrainian, Vietnamese and Welsh.

The documentation, the Audacity Manual, is available only in English. The Audacity Forum offers technical support in English.

Architecture


The diagram illustrates Audacity's layers and modules. Note the three important classes within wxWidgets, each of which has a reflection in Audacity.

Higher-level abstractions result from related lower-level ones. For example, the BlockFile system is a reflection of and is built on wxWidgets' wxFiles. Lower down in the diagram is a narrow strip for platform-specific implementation layers.

Both wxWidgets and PortAudio are OS abstraction layers, containing conditional code that chooses different implementations depending on the target platform.

Reception
As free and open-source software, Audacity is very popular in education, encouraging its developers to make the user interface easier for students and teachers.

Audacity won the SourceForge 2007 and 2009 Community Choice Award for Best Project for Multimedia.

Jamie Lendino of PC Magazine recently rated it 4/5 stars Excellent and said: "If you're looking to get started in podcasting or recording music, it's tough to go wrong with Audacity. A powerful, free, open-source audio editor that's been available for years, Audacity is still the go-to choice for quick-and-dirty audio work."

CNET rated Audacity 5/5 stars, calling it "feature-rich and flexible". Preston Gralla of PC World said: "If you're interested in creating, editing, and mixing you'll want Audacity." Jack Wallen of Tech Republic praised its features and ease-of-use.

In The Art of Unix Programming (2003), open-source software advocate Eric S. Raymond wrote of Audacity: "The central virtue of this program is that it has a superbly transparent and natural user interface, one that erects as few barriers between the user and the sound file as possible."

Some reviewers and users have criticized Audacity for its inconvenient UX design, unsightly GUI and comparative lack of features compared with Adobe Audition. Matthew McLean wrote: "Audacity looks a bit more dated and basic, but this will be appealing to many folks who’re just starting out".

In May 2021, after the project was acquired by Muse Group, there was a draft proposal to add opt-in telemetry to the code to record application usage. Some users responded negatively, with accusations of turning Audacity into spyware. The company reversed course, falling back to error/crash reporting and optional update checking instead. Another controversy in July 2021 resulted from a change to the privacy policy which said that although personal data was stored on servers in the European Economic Area, the program would "occasionally [be] required to share your personal data with our main office in Russia and our external counsel in the USA". That July, the Audacity team apologized for the changes to the privacy policy and removed mention of the data storage provision which was added "out of an abundance of caution".

Version history
This table shows the major and minor releases of Audacity. Patches are omitted.