Audacity Projects

Audacity projects:

• Are stored as multiple files: an AUP master file and numerous small audio files in subfolders.
• May save some space by referencing original audio material rather than making a copy (dependencies). Your project will no longer work if you overwrite or move the original audio file(s) on which it depends!

If you want your audio in standard formats like WAV, you must export it because you can't use AUP for this.

AUP files and project files

Audacity projects contain audio clips arranged onto tracks along with additional information. The project's structure is stored in an AUP file, with audio and housekeeping information in numerous small files in a folder in the same directory as the AUP file. For example, if you have a project named "MyProject" there will be a file called "MyProject.aup" and a folder called "MyProject_data".

Whilst this Audacity Project Format makes working with the audio more rapid, the format is not compatible with any other audio program. When you Save an Audacity project, you save in the Audacity Project Format, i.e. as an AUP file. The AUP file cannot be used in an MP3 player.

If you have audio which you want to use in Audacity but which wasn't recorded in Audacity, you will usually need to Import the audio. This is also an option on the File Menu.

The three rules for keeping your Audacity Project happy:

1. Never rename the .aup file or the _data folder.
If you want to rename your project (for example, to save a snapshot at a particular point), use the File > Save Project As command.
2. Always keep the .aup file and the _data folder together in the same directory (folder).
3. If you import an audio file with the "Read uncompressed file directly from the original (faster)" option checked in Import / Export Preferences, never move, rename or delete that file, unless you first copy it into the Audacity project. See File > Check Dependencies for more information.

Dependencies

When you open or import an uncompressed audio file such as WAV or AIFF, Audacity saves time by not making a copy of the file. Instead, it refers back to the original file as you manipulate it within your project (while not ever making any changes to that file unless you tell it to). You must be careful not to modify files that you have open in Audacity with another program. When you save an Audacity project, Audacity will tell you about these dependencies and give you the option of copying all of the audio data into your Audacity project, making it safe to delete, move, or modify the original audio files if you choose. At any time, click on File > Check Dependencies... to see if your project depends on any external files.

Exporting Audio

To use the audio outside Audacity, you Export the audio into another format, as described on the File Menu. The format you need will depend on how you plan to use the audio. For an MP3 player you will want MP3 format. For burning to a CD you will want WAV format.

Gale: Moved the below in from Audacity Project Format for merge...

Bill: I realize this may be a low priority, but I and a few others (based on posts on the forum) would love to see a specification of the Audacity XML.

Audacity project files store information about the entirety of the project - the number of tracks and their time positions, details of clips within the tracks, amplitude envelope points, labels and gain and pan data. In addition, "summary information" is stored which enables the display to be redrawn rapidly without Audacity examining the entire contents.

The .aup and .au files

Audacity projects have a master file that ends with the extension ".aup". In the same directory as the master file is a folder called "_data". This contains one or more subfolders with many small audio files in .au format of size 1 MB or less. The master file describes how to link these smaller files together to make up the clips and tracks in the project. The .aup file is in an XML format and can be opened in a text editor. The individual .au files are uncompressed, using 4 byte floating point numbers. The summary files have the same format as the audio files, but there are fewer of them. Gale: Importing the same WAV aliased in one project and not so in another produces the same number of .auf files in the aliased project as .au files in the other project (at default blocksize)

The structure of the project files is designed to make editing audio faster in Audacity. By updating the .aup file, which is much smaller than the _data folder, Audacity can move audio around in the project without copying large quantities of data from one place to another.

Opening an Audacity project

When you re-open a project with Audacity you should always open the <project_name>.aup top level file.

You should not attempt to open or manipulate any individual .au files.