Mac Bugs

OS X-specific issues
OS X has a very different audio hardware interface to most other operating systems. As a result, there may be no (or greyed out) Mixer Toolbar, or only one audio recording source available to Audacity, which will be identified as "Default Source". You will need to click on the Mac hard disk, then on Applications > Utilities >  Audio-MIDI Setup and select your required recording source (e.g. Line In) in the Audio Input section so that it becomes the source that Audacity will use. This is how Audio-MIDI Setup looks in OS X 10.4:



In OS X 10.0 and 10.1 there was no Audio-Midi Setup, so choose your recording source at System Preferences > Sound in the Apple Menu.

If you are on OS X 10.4 or higher and are using the current Audacity version, this has a later version of our PortAudio interface and may enable you to select sources in Audacity's input selector (or possibly in the "Recording Device" drop-down in the Devices tab of Preferences ).

Active issues
Many differences between the OS X and other platforms relate to the audio platform API - in the case of Mac OS X, this API is called Core Audio.

Audacity should not be run inside the DMG image
You should not run Audacity from within the DMG image it's distributed in and must not separate the Audacity application from the folder it came in. Otherwise:
 * You won't be able to save or export files without changing the directory you are saving or exporting to
 * You will be warned that "Critical Nyquist files cannot be found" and will not be able to use Audacity's optional plug-ins.

Always install Audacity thus:  Double-click the downloaded DMG to mount it. Drag the "Audacity" folder from the newly mounted DMG to the "Applications" icon underneath "Places" on the left of Finder. Alternatively you can instead copy the "Audacity" folder to any other location of your choosing.  Eject the DMG in the "Devices" section on the left of Finder, then launch the Audacity application from the "Audacity" folder that you copied. 



Loss of sound after running Audacity
If you have lost sound on your system after connecting headphones for an Audacity session then removing them, try connecting your headphones again then gently manipulate the headphones plug up/down and left/right so as to bend back the internal component to its correct position. Do this several times if necessary so that the internal switch for the headphones is fully released.

Playthrough
Although Apple Audio MIDI Setup has a "Thru" checkbox for playing audio that is being recorded, this is usually grayed out. Recording playthrough has in fact been disabled since the early days of OS X, and it is left to applications to provide this. In Audacity, try either "hardware playthrough" or "software playthrough" on the (this is on the  tab in current Audacity Beta). Hardware playthrough doesn't always work, but has no delay and does not load the CPU. You can also obtain software playthrough using a free application called LineIn. Software playthrough will have delay and some CPU load.

No built-in streaming audio recording
Macs have no ability to record streaming as it plays on the built-in sound device as can be done on Windows and Linux (if the sound device has that capability). It is possible to record streaming audio from the built-in microphone, but this a very lossy method that also picks up all ambient noise. Alternatives:
 * Join the line-out to line-in, then recording from the built-in input set to line-in
 * Capture the stream digitally with applications other than Audacity, before it reaches the sound card (using Soundflower to do this gives Audacity a direct way to record the captured stream)
 * Download the stream, if its web address is known

For more details, see the Mac section of Recording audio playing on the computer.

Support and setup for external audio devices
Some external audio devices (for example, some USB microphones or headets and most USB or Firewire input/output interfaces) won't work correctly in Audacity unless the device is set up in /Applications/Audio MIDI Setup, as well as doing so in Audacity.   If you connected your external device while Audacity was open, click and restart it, so that Audacity can see the device  In Audacity, select the device at in the "Recording Device" box (and in the "Playback Device" box if appropriate) (these preferences are under "Audio I/O" in earlier Betas) On the same tab, choose the number of "Recording Channels" required  Open the :  Click the Audio Devices tab and make sure on the left-hand (input) side that your device is selected in the "Default Input" and "Properties For" boxes - in the image above our device is called "USB Audio Codec"  Match the input sample rate and channel mode in Audio MIDI Setup in all places - with your Audacity settings, and with any settings on the device or in its control software: for example, if the Audacity Project Rate at bottom left is 44100 Hz and you're recording in stereo, set the Audio MIDI input "Format" boxes to "44100.0 Hz" and "2 ch-16 bit"  If you are playing back to the device, go to the right-hand (output) side of Audio MIDI Setup, set the device as Default Output and System Output, and similarly match the settings in the "Format" boxes to your settings in Audacity and in the device 

Audio Units issues

 * AU GraphicEQ cannot be resized in use. See the Audio Units page for a workaround.
 * AU MatrixReverb cannot be used on a mono track. See the Audio Units page for a workaround.
 * Some older third-party AU plug-ins can be very slow to load on launch or unload on exit, or may completely hang Audacity on launch. See the Audio Units page for a workaround.