Your Mac is capable of producing sound, as well as playing sound channelled from outside sources. Wouldn’t it be great if you could capture some of those sounds so you could listen to them later? Well, you can – for free – thanks to Cycling ’74’s Soundflower. Here’s how the process works…

Step 1:  Download and install Soundflower

To get started go to cycling74.com/products/soundflower and click on the download button. Once Soundflower has installed on your computer, you’ll be able to channel audio from one application to another. For example, you can take the audio playing in a movie in your web browser and pipe it into QuickTime Player’s audio input, where you can then record it.

Step 2:  Getting started

After you’ve installed Soundflower, go to Sound in System Preferences, and you’ll see it in the Output and Input tabs. Select the Output tab and choose Soundflower (2ch). From now on any sound that would normally come out of your Mac’s speakers, such as email alerts, will be routed through Soundflower.

Step 3:  Configure your capture application

There are a couple of applications on your Mac that can capture Soundflower’s audio – QuickTime Player and GarageBand.

To configure the former, choose File > New Audio Recording. In the Audio Recording window, click on the downward-pointing triangle to the right of the Record button. From the menu that appears, choose Soundflower (2ch). When you’re ready to begin, click Record.

To set up GarageBand launch it and, in the New Project window that appears, choose Acoustic Instrument. This creates a project that contains a single digital audio track. Use the default tempo and time- and key-signature settings that appear in the New Project Template window, and click the Create button. Open GarageBand’s preferences, select the Audio/MIDI tab, and choose Soundflower (2ch) from the Audio Output and Audio Input pop-up menus. Close the Preferences window. If the Info pane for the track doesn’t appear, choose Track > Show Track Info. In the Browse tab of the Info pane, choose Stereo ½ Soundflower (2ch) from the Input source menu. When your Mac emits a sound, you should see it register in the track’s meters. Click Record to capture the audio.

Step 4:  Monitor the sound

As we touched on earlier, when you choose Soundflower as your Mac’s audio output, you’ll no longer be able to hear audio through any attached speakers or headphones.

In order for you to monitor what’s happening, launch the Soundflowerbed application (found in /Applications/Soundflower). Click the menu bar item that appears, and choose your speakers or headphones from the menu. Once you’ve done this, your audio application will capture what your Mac plays, and you’ll be able to listen to the source audio as well.

Again, any sound your Mac makes will be channelled through Soundflower, so you’ll want to disable alert sounds. Additionally, if you change the volume on your Mac, that change will be captured by the application that’s recording Soundflower’s sound. So lay off the volume and mute controls.

You can avoid both of these issues by using Ambrosia Software’s $69 WireTap Studio (www.ambrosiasw.com) or Rogue Amoeba’s $32 Audio Hijack Pro (rogueamoeba.com). Each of these allows you to capture sound from specific programs. You can adjust the volume or fire off system alerts all you like, without affecting the audio that the applications capture.