Airfoil 1.0.5 review

Apple's AirPort Express base station and its AirTunes software together provide a great way to stream audio wirelessly through your home or office.

However, they have a critical flaw: you can only play sound originating from Apple's own iTunes application. If you want to listen to audio from the likes of Safari, RealPlayer or Windows Media Player, which between them carry a huge range of Internet-based audio content, you are out of luck.

Rogue Amoeba's Airfoil is a tiny application that plugs this weakness by allowing you to send audio from almost any Mac application to AirPort Express. And in practice, it works nearly flawlessly.

Streaming audio is a simple, three-stage process. From Airfoil's clean, single window, you select the application to provide the audio source - a list of open applications is provided on a drop-down menu - and then choose the location of the AirPort Express-enabled speakers that is automatically shown in the remote speakers list. To broadcast, you just click the Transmit button. Good interface design cleverly masks its versatility: esoteric options, such as choosing how Airfoil should deal with gaps in streaming, are only visible when you option-click Transmit.

Airfoil has a persuasive selling point even if you play most of your audio through iTunes. If you use AirPort Express and iTunes alone, you cannot play back audio through your Mac's speakers and the remote speakers simultaneously. With Airfoil, there is no such restriction: you can optionally broadcast to both. This is not something you should try if Mac and speakers are in the same room, as there is a slight, inevitable lag when passing audio through AirPort Express, but it is handy if you are setting up a stream at the other end of the house.

Airfoil's only awkward moment arrives at the point of transmission. It has to launch any application that provides the audio source, so if the source program is already open, you have to quit and re-launch it. Rogue Amoeba does offer a workaround in the form of Instant Hijack, a low-level system enhancement that enables you to hijack already-open applications. It is a hack that many will be wary of, but the alternative is undeniably clunky.

However, this is the only real weakness we could find. Given the technological hurdles that it has had to surmount, Airfoil is remarkably polished and reliable. If you need to wirelessly stream audio from a source other than iTunes, you need Airfoil.