Airport Express: 802.11b issues; Compressor conflict?
Airport Express: 802.11b issues; Compressor conflict?
Over the past week we've been covering issues with Apple's new AirPort Express, including problems with 802.11b networks. We continue our coverage on this topic, as well as a report of a conflict with Apple's Compressor software.
802.11b issues Earlier this week we covered reports of audio dropouts when using AirTunes (iTunes broadcasting over AirPort) on a mixed 802.11b/g network and broadcasting via a standard AirPort (802.11b) card. Reader reports indicated that switching the main AirPort Extreme Base Station (if applicable) and AirPort Express to 802.11b-only mode was often successful in alleviating these dropouts. (Note that doing so has the unfortunate consequence of limiting "Extreme"-equipped Macs and laptops to non-Extreme network speeds.) Dave Kupiec points out an Apple Discussions thread on this issue with well over 100 posts.
- Differences in performance between iTunes Sharing and AirPort Express "broadcasting" We've received a number of messages from readers noting that they're experiencing dropouts broadcasting music from their Mac to an AirPort Express via AirTunes, whereas they're able to use iTunes' Sharing feature to play music on one Mac though another Mac over the same AirPort network without dropouts. For example, Marc Hubbard writes:
"This performance [after switching to 802.11b-only mode] is similar to, but not as good as, the performance I was getting several months ago using the iTunes sharing service to listen to songs stored on my TiBook."
To clarify for our readers, iTunes Sharing will almost always exhibit better performance -- meaning fewer dropouts -- than broadcasting via AirTunes to an AirPort Express (unless you "rip" your music at very high bitrates or in uncompressed formats). The reason is that when you access another Mac's iTunes Library via iTunes Sharing, you're transferring music files over the network at whatever size/bitrate they were originally ripped to. AirTunes, on the other hand, decodes your music on the local computer and then re-encodes it using Apple Lossless format before broadcasting it to the AirPort Extreme. Apple Lossless generally results in significantly larger files than common MP3 and AAC versions of the same tracks. (For example, we ripped a sample song at 160kbps AAC, resulting in a 6.3MB file. The same song ripped to Apple Lossless was 31.2MB in size.) Thus broadcasting via AirTunes requires significantly more bandwidth than using iTunes Sharing.
Distance between devices may affect dropouts Several readers have suggested that distance between devices may play a role. This would indeed affect dropouts, as the further an AirPort-equipped Mac/laptop is from a Base Station, the lower the signal strength and, thus, the lower the data throughput. Below a certain data rate, the source Mac/laptop is not able to send enough data to the AirPort Express to avoid dropouts. (As explained above, AirTunes broadcasts music in Apple Lossless format, which requires significantly more bandwidth to broadcast than a typical low-bitrate MP3 or AAC file.)
"I just installed software for the AirPort Express (from its CD) which went okay. After a mandatory restart, 'qmasterd' unexpectedly quit. Qmaster is the process for Apple's Compressor (part of Final Cut Pro HD & DVD Studio Pro). Compressor no longer works, even after multiple restarts. I've removed and reinstalled DVD Studio Pro and Final Cut Pro HD to no avail. Has anyone else had a problem after installing software for an Airport Express?"
Looking at the actual software installed by the AirPort Express CD, we don't see anything that should interfere with Compressor or qmasterd, so this may be a coincidence. If you're using an AirPort Express and Apple's Compressor, drop us an email at Late-breakers@macfixit.com and let us know if you've experienced similar issues.
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