Brian's Brain

As I mentioned in my previous post, even though I eventually discarded the idea of building up a Media Center Edition PC at my mountain abode, I still wanted to be able to stream Internet-based audio through my home theater system. Tethering my A/V receiver to my MacBook's headphone jack or S/PDIF digital audio output wasn't a palatable approach, if for no other reason than the fact that I often work on my computer while listening to music, and I don't want to be stuck sitting directly in front of the home theater stack, with a wire leash. But...what about wireless?

I remembered that I had a refurbished Apple Airport Express sitting unused in the garage. Finally, a compelling reason to fire it up! By default, Airport Express only accepts audio streams coming from iTunes (for OS X or Windows). But I was also aware of a slick application from Rogue Amoeba called Airfoil, which I've written about before, and which (by leveraging the open-source community's reverse-engineering of Apple's lossless compression and encryption schemes) broadens Airport Express's reach to encompass audio coming from any OS X or Windows application.

The short story: Airfoil works like a charm. Instead of heavy-handedly kidnapping a computer's audio driver chain, as past programs I've tried do, Airfoil seems to instead fork the audio in two (independently volume-controllable, including mute) directions; to the computer's audio hardware as usual, as well as out the computer's network connection to Airport Express. Airfoil also operates in an application-specific, not global, fashion. And with the latest version 2 of the program, you can even simultaneously send different audio streams from the same computer to different Airport Express units.

By adding Airport Express to my network, I'm also able to benefit from an independent 802.11g access point beyond the one integrated within my router (not strictly necessary, because the residence is so small, but why not?). Some notes on this:

• When you first run the Airport Express setup wizard, you're only presented with a few encryption options. If your preferred approach isn't listed, don't fear; the more general configuration program that you can subsequently access offers additional options (such as 40-bit WEP).
• To disable SSID broadcast, check the 'create a closed network' setup box
• Make sure you disable Airport Express's default setting to distribute DHCP assignments, unless you want it to act more than just a humble access point. The first time I connected to the Airport Express from my MacBook, I couldn't figure out why I could get on the Internet but couldn't see the rest of my LAN (which is on the 192.168.1.xxx subnet) until I realized that I'd been assigned a 10.0.1.xxx subnet address!
• Make sure you set the Airport Express broadcast channel so that it doesn't interfere with other access points or with your wireless-inclusive router. In my case, Airport Express is on channel 11 and the router is on channel 1.

Airport Express can also act as a USB print server, but I didn't try out that particular feature.

Airport Express connects to my router via a HomePlug AV powerline networking spur (i.e. via Airport Express's CAT5 connection, not acting as a wireless bridge...don't forget to enable audio streaming over Ethernet in the Airport Express settings if you follow my lead). I tried streaming audio via Airfoil from two computer sources:

• My Fujitsu Lifebook P-2110, which was both 802.11b- and CAT5-connected to the router, and
• My MacBook, which was both wirelessly direct-connected to the Airport Express and wirelessly connected to the router (802.11g in both cases).

Admittedly, the Lifebook P-2110 test was quite glitch-filled, with both network connection options. But then again, an 867 MHz Transmeta Crusoe coupled to 384 Kbytes of SDRAM makes for a pretty anemic Windows XP Pro system. Keep in mind that Airfoil not only needs to manipulate the PC audio stack, it also needs to losslessly compress and encrypt the audio before sending it out the computer's network port.

Conversely, on the MacBook, everything was smooth sailing, under both OS X and Windows XP Pro. Regardless of how I connected to Airport Express (wireless-direct or via the complex Wi-Fi-plus-CAT5-plus-HomePlug AV intermediary chain), I experienced ~3 second delays for the audio coming out the home theater speakers as compared to the tunes playing through the MacBook's built-in audio hardware. And, as a benefit case study of a multi-core CPU setup, with Airfoil running I still had sufficient spare horsepower even for beefy Flash animations. NewsGator Inbox downloads and other CPU-intensive tasks.

Now, after my positive Airport Express-plus-Airfoil experience, I feel doubly bad that I initially sent my friends Lisa and Peter down the Linksys route a few months back....

Followup: oAEP is an open-source Airfoil alternative for Windows.