|
Written by Tom Mordasky
|
|
Wednesday, 11 October 2006 |
Set Airport Express free
 The Apple Airport Express hub has the potential to change the way people think about their music. Tracks from iTunes could now be easily streamed throughout the house or office. Of course, like many things, this feature came at a price. Only audio from iTunes could be streamed. Fortunately, where there is a will there is generally a way. The folks at Rogue Amoeba have brought us Airfoil, a simple to use helper app that can forward audio from any source and stream it to as many Airport Express stations as your heart desires.
Airfoil can be demoed for free, though it is limited to ten minuets of audio streaming before basically blasting static instead of your favorite Neil Diamond tunes. Registration is $25 and will of course remove the time limit. Set up is a simple as it could possibly be, with the window opening up and recognizing any remote speakers on your network automatically. Basic streaming is now ready to begin. By default, Airfoil is set to “Hijack” audio from a single application source. Simply choose your desired app from the pull down list at the bottom of the window. It recognizes all of the standard potential sources, such as the built in audio of the system, built in and external microphones, Line in, widgets and of course, applications. It can even stream audio from an external source such as a USB radio dongle. A quick list of common ones such as iTunes, Quicktime and Windows Media Player gets you started. Don’t see your app on the list? Simply select it from the pull down dialog and its ready to go.
The default setting is for Airfoil to monitor a single application at a time, If you prefer it can also be set to monitor all system audio, regardless of the source. To do so will require the installation of the Soundflower plug in, (Requires a separate, included installer.) Once the source is selected the audio stream is controlled by the original application. Thus, volume and playback can be handled normally within the respective window of the source app, with Airfoil simply forwarding the stream along to the remote speakers. Or, if you prefer, Airfoil can adjust the volume of each destination independently as well as apply basic EQ presets similar to those found in iTunes. For audio devices such as home theatre systems, where multiple audio channels are present, airfoil can specify the final destination of each audio channel independently.
The skinny on buffer sizes, delays and multiple speakers: With any stream of data there is nearly always a buffer, a lag of information of a few moments to help insure that the destination (in this case speakers) does not get ahead of the source, causing gaps in the data. In the networking world, buffers are rarely an issue, but in the audio world they can be. Airfoil is no exception. It allows the user to specify a buffer size. Smaller buffers make for a shorter audio lag but increase the likelihood of gaps in the playback. A larger buffer will insure better playback but with a noticeable lag. Adjust the volume and it takes a moment for the results to be heard; that’s the buffer.
The true challenge comes when you try to stream to multiple sources with multiple buffers. The whole purpose of the buffer is to cancel random flaws in the stream. Syncing multiple buffers and canceling multiple random data flaws is an even greater challenge. This factor is no doubt why it took Apple a while to introduce the feature themselves. Basically, the buffer affects the audio in two distinct ways. First, there is the rather minor flaws that slip by when streaming to more than one source at a time. It’s not bad but it can be noticeable. Second, is the more problematic lag caused by the buffer itself. Try streaming to a remote source and play the audio locally at the same time and the two will be out of sync. Movies or videos are a no go as well, as the audio will lag the video by a noticeable margin. Users can opt for a fully synchronized playback, complete with the occasional flaw or “Pure” playback where the destinations will be outputting a higher quality audio that may not sync perfectly.
Once everything is up and running, the program performs remarkably well. I was streaming audio successfully from pretty much any source I could think of to both my Airport Express stations with few if any noticeable hiccups. 802.11G environments are ideal, if you have a mixed network those pesky and pokey 802.11B cards may cause the same audio gaps that iTunes itself is notorious for. The newer firmware for the base stations themselves seem to have lessened this issue considerably, however it does still happen from time to time. Since Apple introduced multiple speaker support in iTunes a little thunder has been stolen from this otherwise great app. Still, it gives the user more control over audio streaming than iTunes alone. Its ability to stream audio from separate apps is unrivaled.
 |
The Good: Streams audio from any source to any number of Airport Express stations.
The Bad: The same buffer problems inherent to the technology limit Airfoils abilities as well.
The Skinny: If you regularly use any audio applications other than, or in addition to iTunes this is the streaming solution you need.
|
|
