Other

• Preferences
• Sound File Formats
• Envelope Editing
• MP3 Exporting
• General Public License

Preferences

Audio I/O

• Playback Device - Use this control to select the device that will be used for playback / audio output. This is usually only applicable if your computer has more than one sound card.
• Recording Device - Select the devce that will be used for recording / audio input. Note that many devices have multiple sources such as Microphone and Line in - to select the input source you will need to use the Mixer Toolbar.
  For finer control over audio I/O, open your system's Sound control panel or the control panel software that came with your sound card.
• Recording Channels - Use this to select the number of channels to record simultaneously. Select 1 for mono and 2 for stereo. Audacity will support recording more simultaneous channels, but note that most sound cards only support stereo, and even if your sound card supports more than 2 inputs, you need a fast computer and a large, fast hard disk to record many channels for a long time.
  Mono recording is not the same on all computers or sound cards. Sometimes recording mono only records the left channel, and sometimes it mixes the left and right channels.
• Play other tracks while recording new one - When this box is checked, Audacity will play existing tracks when you press record - otherwise it simply records the new track without letting you hear what you've already recorded. You can use this option to record harmonies with yourself or add a voiceover.
  You may notice that when you play the two tracks you recorded together, they aren't synchronized. This is unavoidable to a certain extent, although Audacity tries to minimize it. To fix it, you will need to grab the Time Shift tool and slide one of the tracks around until it sounds right.
• Hardware Playthrough (Mac Only) - plays the audio you are recording straight back out to your headphones or speakers so you can hear it. This option is done in harware, so it is fast and doesn't consume resources. However, it is only possibly if input and output are on the same sound device.
  PC users can do the same thing in their volume control settings, turning up the relevant audio input.
• Software Playthrough - Does the same thing as hardware playthrough, but in software. This means that the audio you hear may be slightly delayed relative to the input, and activating this option will use some more system resources. However, it works on all systems, even if you are recording from one device and playing back through another.
  
  
  

Quality

• Default Sample Rate - This controls the sample rate of new projects. To change the sample rate of an existing project, use the control in the lower-left corner of the main project window.
• Default Sample Format - This controls the default format used to store audio samples. 16-bit takes up the least space and is equivalent to audio CD quality. 32-bit float takes up twice as much space but is much more flexible.
  If you have a fast computer and enough disk space, you should always use 32-bit float samples while editing, and then export your final mix as a 16-bit WAV file (the default).
• Real-time sample rate converter - Audacity has more than one sample rate converter that's used when you have a track that's not the same sample rate as the project. This option lets you set the converter used during real-time playback, which can be different than the one you use during Export or mixing.
• High-quality sample rate converter - Audacity has more than one sample rate converter that's used when you have a track that's not the same sample rate as the project. This option lets you set the converter used during Export and mixing, which can be different than the one you use for real-time playback.
• Real-time dither - Dithering is used when converting high-quality samples with a lot of dynamic range, to CD-quality samples, with less dynamic range. A small amount of dithering can make the audio sound a little bit better, but it can also slow down processing a little bit. This option lets you set the dithering used for real-time playback.
• High-quality dither - Dithering is used when converting high-quality samples with a lot of dynamic range, to CD-quality samples, with less dynamic range. A small amount of dithering can make the audio sound a little bit better, but it can also slow down processing a little bit. This option lets you set the dithering used during Export and mixing.
  
  
  

File Formats

• When importing uncompressed audio files into Audacity
  • Make a copy of the file before editing (safer) - Selecting this means that Audacity will take longer to import files, but it will always have its own copy of any audio you are using in a project. You can move, change, or throw away your files immediately after you open or import them into Audacity.
  • Read directly from the original file (faster) - Selecting this means that Audacity depends on your original audio files being there, and only stores changes you make to these files. If you move, change, or throw away one of the files you imported into Audacity, your project may become unusable. However, because Audacity doesn't need to make copies of everything first, it can import files in much less time.
    
  • Uncompressed Export Format - This lets you select the format that Audacity will use when you export uncompressed files. 11 common options are displayed in the list, but you can also select "Other" and choose a nonstandard file format for Audacity to export.
    
  • Ogg Export Setup - Use this control to set the quality of Ogg Vorbis exporting. Ogg Vorbis is a compressed audio format similar to MP3, but free of patents and licensing fees. A normal quality Ogg Vorbis file is encoded with a quality setting of "5". Note that unlike MP3 encoding, Ogg Vorbis does not let you set a bitrate, because some audio clips are easier to compress than others. Increasing the quality will always increase the file size, however.
  •  Export Setup - Use these controls to locate your MP3 encoder and set the quality of MP3 encoding. Higher quality files take up more space, so you will need to find the level of quality you feel is the best compromise. For more information, see Exporting MP3 Files.Spectrograms
    
    
    

  You can view any audio track as a Spectrogram instead of a Waveform by selecting one of the Spectral views from the Track Pop-Down Menu. This dialog lets you adjust some of the settings for these spectrograms.

  • FFT Size - The size of the Fast Fourier Transform (FFT) affects how much vertical (frequency) detail you see. Larger FFT sizes give you more bass resolution and less temporal (timing) resolution, and they are slower.
  • Grayscale - Select this for gray spectrograms instead of colored ones.
  • Maximum Frequency - Set this value anywhere from a couple of hundred hertz to half the sample rate (i.e. 22050 Hz if the sample rate is 44100 Hz). For some applications, such as speech recognition or pitch extraction, very high frequencies are not important (visually), so this allows you to hide these and only focus on the ones you care about.
    
    
    

  Directories

  Use this panel to set the location of Audacity's temporary directory (folder). Audacity uses this directory whenever you work on a project that you haven't saved as an Audacity Project (AUP file) yet. You have to restart Audacity (close and open it again) for changes to the temporary directory to take effect.

  Interface

  • Autoscroll while playing - Scrolls the window for you while playing, so that the playback cursor is always in the window. This can hurt playback performance on slower computers.
  • Always allow pausing - Normally the Pause button is only enabled while you are playing or recording. Checking this box allows you to set the pause button anytime, which allows you to press Record and not have the recording start until you unpause it. Sometimes starting a paused recording can be faster than starting to record in the first place.
  • Update spectrogram while playing - Because spectrograms are slower to draw, normally they are not drawn during playback, but this option lets you draw the spectrograms anyway.
  • Enable Edit Toolbar - Sets whether or not you want to display the Edit Toolbar, which has some common shortcuts for editing commands.
  • Enable Mixer Toolbar - Sets whether or not you want to display the Mixer Toolbar, which lets you set the volume levels and input source.
  • Enable Meter Toolbar - Sets whether or not you want to display the Meter Toolbar for setting audio recording and playback levels.
  • Quit Audacity upon closing last window - By default on Windows and X-Windows (but not Mac OS), Audacity quits when you close the last project window. If you uncheck this box, Audacity will open a new blank document instead of quitting. To quit Audacity in this case, you must specifically select Exit (or Quit) from the File menu.
  • Enable dragging of left and right selection edges - Normally, when you move the mouse over the left and right edge of a selection, the cursor changes to a left or right pointer, and you can adjust that edge of the selection independently. If you don't like this feature, uncheck this box, and then clicking will always create a new selection (unless you hold down Shift to extend an existing selection).
  • Language - sets the language used by Audacity. Language files are named "audacity.mo" and are found in the "Languages" folder on Windows and Mac OS X, or in /usr/share/locale or /usr/local/share/locale on most Unix systems. Audacity will detect new languages the next time you start it.
    
    
    

  Keyboard

  This panel lets you change keyboard shortcuts. All of the commands that appear in Audacity menus appear on the left, along with a few other buttons that can get keyboard shortcuts. To change a command, first click on the command you want to change. Then type the new keyboard shortcut on your keyboard. Verify that the correct shortcut appears in the box below. If it's what you want, press the Set button. Or to get rid of a keyboard shortcut, press Clear.
  To reset to Audacity's defaults, press the Defaults button. This will get rid of any changes you have made.
  If you have customized your keyboard layout and want to share it with someone else, you can press Save... and save your complete keyboard layout as an XML file that you can share. To load an existing layout, press the Load... button and locate the XML file.

  Mouse

  This panel doesn't let you change anything, but it lets you view all of the commands and actions that you can do using the mouse, many by holding down extra modifier keys.

• Sound File Formats

  Audacity Project format (AUP)

  Audacity projects are stored in an AUP file, which is a format that has been highly optimized for Audacity so that it can open and save projects quickly. In order to achieve this speed, Audacity breaks larger audio files into several smaller pieces and stores these pieces in a directory with a similar name as the project. For example, if you name a project "chanson", then Audacity will create a project file called chanson.aup to store the general information about your project, and it will store your audio in several files inside a directory called chanson_data. While the Audacity Project format is based on XML and is meant to be open, it is not currently compatible with any other audio programs, so when you are finished working on a project and you want to be able to edit the audio in another program, select Export from the File Menu.

  WAV (Windows Wave format)

  This is the default uncompressed audio format on Windows, and is supported on almost all computer systems. Audacity can read and write this format. People working with multichannel audio at very high quality settings, or with very long recordings, should note that the maximum size of a wav file is 2GB.

  AIFF (Audio Interchange File Format)

  This is the default uncompressed audio format on the Macintosh, and it is supported by most computer systems, but it is not quite as common as the WAV format. Audacity can read and write this format.

  Sun Au / NeXT

  This is the default audio format on Sun and NeXT computers, and usually u-law compressed, so it is not a very high quality format. U-law compression is a very simple, fast but low quality way to reduce the size of the audio by about 50%. This format was one of the first audio formats supported by Web browsers, and it is still often used for short sound effects where quality is not as important.
  Audacity exports both 8-bit u-law files, and 16-bit uncompressed files, which are the same quality as wav or aiff files.

  MP3 (MPEG I, Layer 3)

  This is a compressed audio format that is a very popular way to store music. It can compress audio by a factor of 10:1 with very little degradation in quality. Audacity can both import and export this format. For more information on how to export MP3 files from within Audacity, see Exporting MP3 Files.

  Ogg Vorbis

  This compressed audio format was designed to be a free alternative to MP3. Ogg Vorbis files are not as common, but they are about the same size as MP3 with better quality to rival AAC or WMA. Audacity can import and export this format.

• MP3 Exporting

  Audacity cannot encode MP3 files by itself, because the MP3 encoding algorithm is patented and cannot legally be used in free programs. However, Audacity has been programmed to recognize other existing MP3 encoders that you can download separately. All you have to do is obtain the appropriate MP3 encoder for your computer and then show Audacity where it is located.

  If you use...	You need to...
  Windows	Download LAME and look for the file called lame_enc.dll
  Linux/Unix	Download LAME and compile it as a shared object, then look for the file called libmp3lame.so
  Macintosh	Download LAMELib (see our website for more info).

  For links to these MP3 encoders, go to the Audacity web page (http://audacity.sourceforge.net/) and go to the page for your operating system.
  
  The first time you try to export an MP3 file, Audacity will ask you to locate your MP3 encoder. Locate the file indicated above. From then on, Audacity will not need to ask you again and you will be able to export MP3 files easily.

  ---

  General Public License

  Note: Audacity is distributed under the terms of the GNU General Public License (GPL) - the full text of the license is below. All of the source code to Audacity is available from http://audacity.sourceforge.net. However, some of the libraries that Audacity is based on are distributed under the terms of different (but GPL-compatible) licenses.

  Version 2, June 1991

  59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  Everyone is permitted to copy and distribute verbatim copies
  of this license document, but changing it is not allowed.
  

  Preamble

  The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software--to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation's software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Library General Public License instead.) You can apply it to your programs, too.

  When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things.

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