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Fun With Soundflower

June 30, 2014

Use a free utility to hack your computer’s output, capture Internet audio, and much more

Cycling ‘74 first created the Mac OS X extension Soundflower for Max/MSP to send audio channels to other software, and the simple, open-source tool soon became a way to route audio from one Mac program to another. Its included sibling application Soundflowerbed resides in the Finder Menu Bar and lets you route up to 16 channels of Soundflower to an audio device for monitoring. This powerful, must-have freeware enables some universally useful capabilities.

Fig. 1. Use Soundflower to quickly sample audio from a Web browser.
Sample from a Web Browser The most basic use of Soundflower will open you up to immeasurable sample material from the streaming media available on the Internet. First, go to System Preferences > Sound and choose Soundflower (2ch) as the Output device. That then routes your Mac’s audio to Soundflower, and you can then choose “Soundflower (2ch)” as the input (see Figure 1) for any recording software: a sampler, a DAW, Audacity, etc. Now you can record the audio from applications on your computer, a Web browser for example. It gives you fast access to sampling from the innumerable videos and music on YouTube, or the public-domain trove of media at and other sites.

If you can think of a sound bite you want— famous or obscure—chances are you can have it recorded and available for your production within minutes, something the crate-digging vinyl collectors of old couldn’t have imagined.

Fig. 2. Soundflowerbed lets you route Soundflower channels to different monitoring options.
Record a Multitrack Skype Session If you’re using Skype to record a podcast or maybe even a recording or jam session, Soundflower can help you route your own voice and the Skype audio to separate tracks in a DAW for mixing. First choose Soundflower (2ch) as your Output in System Preferences. Make sure the Input is set to whatever mic you will use for the Skype session.

If you don’t already have Soundflowerbed in your Menu Bar, open to place it there. Then click its icon and select Built-in Output under Soundflower (2ch) (see Figure 2), so that you can monitor the Skype call in your headphones.

Now you will be able to open your DAW and record two tracks; in one track, select Soundflower (2ch) as the input to capture the Skype audio. (This will also capture other system sounds, so try to close unnecessary programs and avoid other system sounds.) In the second track, choose the mic input that you’re using for yourself. Now you can process and mix both sides of the call discretely. There is also a method to record three or more parties in Skype to discrete tracks in a DAW, but it is beyond the scope of this short article. You can find it at


Fig. 3. Routing Soundflower to AU Lab lets you EQ/effect the entire system output.
Equalize a Mac’s Output You may use your computer’s built-in audio output for several media programs: iTunes, Spotify, Quicktime, etc. If you like to have EQ applied to that output’s speakers or headphones, rather than try to equalize every program separately, you can apply a 10- or 31-band EQ to the entire audio output.

Download and install Apple AU Lab, an Audio Unit host and mixer, from the Mastered for iTunes page ( and then restart the Mac. Go to System Preferences > Sound and choose Soundflower (2ch) as the Output. Now open AU Lab from Applications > Utilities; choose Soundflower (2ch) as its input and Built-in as its output; and click Create Document. AU Lab creates a mixer window with Soundflower as the Audio 1 track. Here you can apply any AU plug-in on your Mac to your system’s audio. You may want to go with Apple’s AUGraphicEQ (see Figure 3), a peak limiter or a compressor, depending on your needs.

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