MacWorld on Express and iTunes
MacWorld on Express and iTunes. The part I found interesting:
For those wondering if AirPort Express supports MP3, AAC, or any other specific file formats, the answer is no. AirPort Express supports Apple’s Lossless Compression technology — and everything that your iTunes streams across the network to Airport Express is compressed using that technology.
iTunes does the heavy lifting. When iTunes plays back standard audio content (AAC, MP3, audiobooks, music streams), it decompresses those file formats and creates what’s essentially a raw, uncompressed audio stream. That stream is compressed on the fly using Apple’s Lossless Compression, encrypted, and sent to the AirPort Express.
…
If iTunes is playing back a digital multichannel file format like AC3 (Dolby Digital) or DTS, those bitstreams are wrapped in Apple’s compression and encryption, and then decoded at the other end. In those cases, AirPort Express would end up streaming the raw AC3 or DTS stream via an optical cable to your home theater receiver for decoding.
Cool.
June 9th, 2004 at 1:30 pm
Woah… not really so cool… it goes on to say that essentially iTunes decodes the mp3/aac/whatever into raw audio, then reencodes it into apple’s lossless format and then sends it along…
that is ALOT of CPU cycles… i.e. you better have the latest Apple HW… :(
I wonder why not just shoot it out as it is? Alot of work for nothing… Weird…
Or perhaps I am not understanding something?
June 10th, 2004 at 2:18 am
true, it’s quite a few extra cycles, but word on the street has it that the lossless codec takes less compute power on both ends; it’s been optimized for efficiency. thus, whatever chip is in the Airport Express might not be able to handle AAC. At least they’re not transcoding anything, keeping the quality the same as the original. Of course, the other drawback is that you can’t hack any other player to stream to the AE; i don’t think Apple’s LAC is openly available, even through licensing…least not that I know of.
June 11th, 2004 at 2:30 am
It’s still alot of work. Also, I seriously doubt the AE is the part actually “playing” the tracks (therefore it doesn’t need mp3/aac/et al decoders)…
Either way, it is damn cool. :)
June 11th, 2004 at 2:47 am
Well, if it’s receiving ALAC packets and streaming directly to an off-the-shelf stereo system, something in that pipeline definitely has to decode it :)
If the AE allowed even just mp3 streams to arrive from a non-iTunes source, it’d appeal to quite a few more in the audience.
one step at a time, I suppose.