Question Converting Purchased AAC to ALAC then back to AAC

Discussion in 'Music Streamers' started by adayasatiger, Jun 10, 2015.

  1. adayasatiger

    adayasatiger
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    Hi all,



    Quick question:



    I've been having some trouble with iTunes Match (long story, purchased aac files don't seem to Match OR upload, just sit in my library 'waiting'), and the only way I've found that makes iTunes upload them is to convert to Apple Lossless (using iTunes) and then add to iCloud. My question is, in the following process:

    Purchased AAC file (256kbit) > Apple Lossless > AAC (Match automatically transcodes the ALAC songs back down to 256kbit to upload the to the cloud), how much loss of quality is there?

    As far as I understand it, the ALAC should be an exact copy of the Purchased AAC (no loss of quality), right? (I realise songs purchased from the official store are already lossy at 256kbit, but can live with that) However, when that lossless file gets converted back to 256kbit during the upload process, are there additional losses incurred? As in, is the end file that I stream from iCloud identical to the Purchased AAC I started with?

    Common sense tells me that they aren't, as the file *has* been re-converted, but as it's essentially the same format (not aac to mp3, so the compression technically uses the same algorithm (does it?), I am holding out hope that maybe they are?

    Any light you can shed on the subject would be MUCH appreciated!
     
  2. larkone

    larkone
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    Are the pre conversion and post conversion files exactly the same size? If they are then there is a good chance there are no losses but to be absolutely sure you would need to put the files through Audio Diffmaker to find out if there is a difference.
     
  3. HeadBanger

    HeadBanger
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    There will be a degradation I'm afraid.

    Whilst you are converting a lossy file to lossless the contents are still lossy - it just hasn't lost any more in the conversion.

    You are then converting this to a lossy format so now you have lost even more of the original as the algorithms are working off an already lossy file.
     
  4. Steven

    Steven
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    You cannot add in what has already been taken out. In fact you are adding extra distortion. Just keep listening to the original aac files without converting,

    Or start afresh. Convert from original cd. There are also more "hi-res" streaming / download sites. Quite expensive mind. See for example qobuz, tidal and hdtracks
     

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