Audio Hijack ($16), Audio Hijack Pro ($30), and WireTap (freeware) are Mac OS X utilities for recording the audio output of applications that do not have built-in recorders, such as stand-alone synths, audio-file players, and plug-in hosts. They can also capture internet news and music broadcasts, and Audio Hijack and Audio Hijack Pro can capture your computer's audio input.
WireTap captures all audio appearing at the output of the Mac's built-in audio controller. To use WireTap to record the output of another software application, that application's audio must be routed accordingly. Once recording is started, all audio from all applications, including system sounds, is recorded. You can set WireTap's preferences to save recorded files in a location of your choice, to open the recorded audio file in any application, and to automatically compress the audio in a number of common formats, though not MP3 or AAC (m4a).
Audio Hijack, on the other hand, intercepts the audio output of a single application, applies any effects processing you choose, and routes its output to the audio port specified by the hijacked application. While an application is hijacked, its audio can be recorded to your hard drive, compressed in MP3 or AAC format, and automatically added to your iTunes library. Audio Hijack has a built-in 10-band graphic equalizer with gain, pan, and exciter controls. Audio Hijack Pro offers advanced features, including a collection of 15 DSP plug-ins, support for VST and Audio Unit effects, and the ability to pause and resume recording.
Both Audio Hijack programs have a timer feature (see Fig. 1) that's useful for capturing internet streams and live audio input. You can download WireTap from the Ambrosia Software Web site (www.ambrosiasw.com/utilities/freebies) and Audio Hijack and Audio Hijack Pro from Rogue Amoeba's Web site (www.rogueamoeba.com).