Audacity is a free open source digital audio editor and recording computer software application, available for Windows, OS X, Linux and other operating systems. Audacity was started in the fall of 1999 by Dominic Mazzoni and Roger Dannenberg at Carnegie Mellon University and was released on May 28, 2000 as version 0.8.
As of October 10, 2011, it was the 11th most popular download from SourceForge, with 76.5 million downloads. Audacity won the SourceForge 2007 and 2009 Community Choice Award for Best Project for Multimedia. In March 2015 hosting was moved to FossHub and by December 31, 2016 it had exceeded 32 million downloads there.
In addition to recording audio from multiple sources, Audacity can be used for post-processing of all types of audio, including podcasts by adding effects such as normalization, trimming, and fading in and out. Audacity has also been used to record and mix entire albums, such as by Tune-Yards. It is also currently used in the UK OCR National Level 2 ICT course for the sound creation unit.
Audacity's features include:Importing and exporting of WAV, AIFF, MP3 (via the LAME encoder, downloaded separately), Ogg Vorbis, and all file formats supported by libsndfile library. Versions 1.3.2 and later supported Free Lossless Audio Codec (FLAC). Version 1.3.6 and later also supported additional formats such as WMA, AAC, AMR and AC3 via the optional FFmpeg library.
Recording and playing back soundsScrubbing (Version 2.1.1 and later)
Editing via cut, copy, and paste, with unlimited levels of undo
Conversion of cassette tapes or records into digital tracks by splitting the audio source into multiple tracks based on silences in the source material
A large array of digital effects and plug-ins. Additional effects can be written with Nyquist, a Lisp dialect.
Built-in LADSPA, VST(32-bit) and Nyquist plug-in support
Amplitude envelope editing
Noise Reduction based on sampling the noise to be minimized.
Vocal Reduction and Isolation for the creation of karaoke tracks and isolated vocal tracks.
Audio spectrum analysis using the Fourier transform algorithm
Support for multi-channel modes with sampling rates up to 96 kHz with 32 bits per sample
Precise adjustments to the audio speed (tempo) while maintaining pitch in order to synchronize it with video or run for a predetermined length of time
Adjusting audio pitch while maintaining speed and adjusting audio speed while maintaining pitch
Features of modern multitrack audio software including navigation controls, zoom and single track edit, project pane and XY project navigation, non-destructive and destructive effect processing, audio file manipulation (cut, copy, paste)
Cross-platform operation — Audacity works on Windows, Mac OS X, and Unix-like systems (including Linux and BSD)
Audacity uses the wxWidgets software library to provide a similar graphical user interface on several different operating systems.
LADSPA, VST (32-bit) and Audio Unit (macOS/OS X]) effects now support real-time preview (from version 2.1.0 onwards). Note: Real-time preview does not yet support latency compensation.
Saving and loading of user presets for effect settings across sessions (from 2.1.0 onwards).
Audacity supports the LV2 open standard for plugins and can therefore load software like Calf Studio Gear.
Audacity supports only 32-bit or 64-bit VST audio effect plug-ins, depending on which architecture it was built for, but not both at the same time. It does not support instrument VST (VSTi) plugins.
Audacity lacks dynamic equalizer controls and real time effects while recording.
MIDI files can only be displayed.
Audacity does not natively import or export WMA, AAC, AC3 or most other proprietary or restricted file formats; rather, an optional FFmpeg library is required.
There are warnings on startup when disk space is low (provided the user has not turned that warning off) and during recording the status bar shows the amount of recording time left available. If the user chooses to ignore those and runs out of disk space during editing, audio will be corrupted.
In addition to English language help, the ZIP file of the downloadable Audacity software program includes help files for Afrikaans, Arabic, Basque, Bulgarian, Catalan, Chinese (simplified), Chinese (traditional), Czech, Danish, Dutch, Finnish, French, Galician, German, Greek, Hungarian, Irish, Italian, Japanese, Lithuanian, Macedonian, Norwegian (Bokmål), Polish, Portuguese, Romanian, Russian, Slovak, Slovenian, Spanish, Swedish, Turkish, Ukrainian, and Welsh in its user interface. A partial Bengali help file is also included.
The Audacity website also provides tutorials in several languages.
The free and open nature of Audacity has allowed it to become very popular in education, encouraging its developers to make the user interface easier for students and teachers.
CNET rated Audacity 5/5 stars and called 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 highlighted its features and ease-of-use. Michael Muchmore of PC Magazine rated it 3.5/5 stars and said, "Though not as slick or powerful as programs from the likes of Adobe, Sony, and M-Audio, Audacity is surprisingly feature-full for free software."
In The Art of Unix Programming, Eric S. Raymond says 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."