Start a hosting plan from $3.92/mo and get a free year on Tuts+ (normally $180)
Soundflower is a lesser known application among computer musicians which allows inter-application audio routing for Mac OS X. Soundflower creates a virtual audio interface which has a number of inputs and outputs. This virtual interface can be selected as your audio interface in your software to route audio from one application to another for further processing.
Soundflower creates two devices in your audio device list for your use, a 2-channel and a 16-channel variant. The 2-channel variant should be enough in most cases while the 16-channel Soundflower provides opportunities for more complex routing.
Download and Install Soundflower
Soundflower is developed by the great folks at Cycling'74 and is provided as a free download from their website. You can head over to the downloads page on their site and download Soundflower. The installation process is simple and should be done in minutes. Once that is done, you will have Soundflower listed as another audio interface and ready for use.
Setup the Audio Interface in Your Software
Sending audio with Soundflower is really simple. The concept is to have the source application use Soundflower as an output device and have the destination use Soundflower as an input device.
If your software allows separate input and output audio interfaces like Ableton Live, you can select Soundflower as just your input if you would like to send audio into Live or as your output interface if you want to route Live's output to another software. If your software requires both the input and output device to be the same, you will need to manage the audio routing within your software to make sure you do not create a feedback loop.
Note that I mentioned audio software instead of just DAWs. It does not make much sense routing audio from one DAW to anther considering that most DAWs have Rewire support to handle that. With some creativity, you can route audio from anywhere. You could route the audio from standalone software to your DAW to record the output, or even route your DAW output to Skype.
Extending Soundflower with Soundflowerbed
Soundflower is extremely transparent once you have installed it. There are no preferences and no application to launch, just an additional audio interface listed in your audio preferences. This simpicity is the beauty of Soundflower.
However, power users that demand more flexibility can have more control over Soundflower with the use of Soundflowerbed. Soundflowerbed is a menubar app that allows additional routing possibilities and configuration of Soundflower.
Being Creative With Routing
Like I have mentioned earlier, the power of Soundflower really depends on how creative you can get. I am going to list some ways I use Soundflower that you will hopefully find useful.
Route System Audio to Your DAW
You can set your system to use Soundflower as your primary audio interface and all your system audio will be routed to Soundflower. This allows you to route your system audio to your DAW or any other software of your choice. This allows you to record audio from software that do not have preference setting for audio such as your web browser or other basic applications. You can record audio from your web browser such as podcasts, etc.
Route Audio from MAX/MSP Patches
There are lots of cool MAX/MSP patches on the web which can do some really interesting things. However, MAX patches generally run as standalone applications with the exception of MAX for Live patches. Soundflower was originally built with this purpose in mind for integrating MAX patches with an external environment. You can integrate the MAX patches as either sound sources or effects with your DAW.
The possibilities are endless with the ability to route audio between applications on the same computer. Complex routing can create new combinations of tools as you merge the processing abilities of various audio software.