Soundflower

Soundflower is a nifty Mac OS X audio driver that allows to re-route audio from applications to any output. As far as I know, Soundflower is at the core of the commercial softwae Audio Hijack, but Soundflower in its raw and simple form is free and open source.

Download

https://code.google.com/p/soundflower/

HOWTO record audio with Audacity and Soundflower

Here is a short HOWTO for recording any audio played on the Mac with Audacity and Soundflower:

• Launch System Preferences
• In the "Sound" panel, select the "Output" tab and choose "Soundflower (2ch)" as the default output. All sound output now goes to the Soundflower audio driver and for the moment you will no longer hear anything on your speakers or headphones.
• Launch Soundflowerbed.app. An icon appears in the menubar somewhere on the right-hand side. Select the icon.
• From the popup menu, select "Built-in output", or any other output device. Soundflower now routes all audio to the selected device so that you can still hear what is happening on the system.
• Launch Audacity
• Select "Soundflower (2ch)" as the input device
• Start recording
• By default Audacity records a simple mono track. If the sound is stereo, you can record a stereo track by simply selecting "Stereo" in Audacity.
• To configure some low-level settings of the "Soundflower (2ch)" device (e.g. sample rate), launch the "Audio MIDI Setup" app, then select the "Soundflower (2ch)" device, then select the "Output" tab on the right-hand side.
  • In the lower region of the right-hand side pane there are also sliders to adjust the volume of each channel
  • While the "Soundflower (2ch)" device is the default output device, you can use the volume keys on your keyboard to watch how this affect the volume settings
  • Usually the keys should change only the "M" slider, which affects all the device channels simultaneously
• If an application produces sound on more than just two channels, it may make sense to use the "Soundflower (64ch)" device to capture those channels separately.