airport express questions

I believe that Kijanki is saying that airtunes protocol utilizes apple lossless as the file type from the pc to endpoint. So any file sent via airtunes is converted to lossless and then back- aiff, aac, mp3, etc.

That is how I understand it works as well.

Robr45 - That's what I meant, except I don't thing it goes back to MP3. If you start with MP3, for instance, Apple Lossles Compressor will uncompress it to some temporary format to compress again into APLL and then on receiving end it uncompresses to temporary format again to convert it to s/pdif format that goes out to toslink - no need to invoke MP3 compressor again. I'm not sure if it even needs to uncompress on receiving end - it might have algorithm converting APLL to s/pdif on the fly.

if something starts as mp3, it will end up as mp3. the codec that the AE uses won't add bits to the file to make it anything else. thats like saying compress a picture of 3Mb over the network, then have the codec on the other end create a 12Mb picture out of it. can't happen. the AE is a fancy modem that uses a codec to transfer data from a source to a destination.

Rbstehno

If you take Jpeg and convert it to compressed TIFF(G3) and uncompress it later you won't get jpeg anymore but much larger file. That's exactly what is happening with MP3.

In order to be compressed into APLL it has to be decompressed first and MP3 format is lost forever. APPL file size will be larger than original MP3 but smaller than one compressed from original recording since MP3 lost part of the data.

Airport Express have no way of knowing what was original format used to convert to APLL. Everything looks the same and only amount of detail is different.

Perhaps you meant that Airport Express decompressed file has amount of data (quality) equivalent to original MP3.

you can't add bits of information that wasn't there in the beginning. if you send 8 bits of info to an airport express, even after all of the codec manipulation, you will get 8 bits of useful information after the AE. sure you might get 24 bits after the conversion, but it will still only be 8 useful bits. for example, once you rip a cd to a low quality format, say mp3, it will always be mp3 quality, you have lost all of the info and will not get it back. sure you can convert it to acc/apll/etc..., but it will always sound like mp3, those compressed/dropped out bits are gone forever.