converting mp3s to aac in itunes

in iPod + iTunes + AppleTV edited January 2014
will this downgrade the quality further than importing the cd directly to aac?

i used to keep everything mp3 cuz of my car mp3 player but i dont drive anymore. so ide rather save the space. thanks.


  • Reply 1 of 6
    Yes, this will downgrade the quality. Both MP3 and AAC are lossy formats; so, encoding in one from the other will always cause you to lose some data.

    If at all possible, delete the MP3s and rip new files from the originals.
  • Reply 2 of 6
    cam'roncam'ron Posts: 503member
    Yeah, I had just started doing that then noticed when i right clicked on an mp3 it gave me that option. So, I thought i'de pose the question before I went any further since I would save hours of work.

    ps. can u tell the difference at all between aac and mp3? is aac at 128kps just as good quality with smaller file size than mp3 at 192kps?
  • Reply 3 of 6
    dmband0026dmband0026 Posts: 2,345member
    It should be better. Even an Mp3 @ 128k will be a larger file size than AAC @ 128k. I can tell the difference, AAC is without a doubt better quality.
  • Reply 4 of 6

    Originally posted by DMBand0026

    Even an Mp3 @ 128k will be a larger file size than AAC @ 128k.

    This is incorrect.

    The bit rate, 128kbps, is a actually measure of the data throughput. An hour of 128kbps audio encoded in MP3 will take the same amount of space as an hour of 128 kbps audio encoded in AAC.

    I just did a test of this theory. The two resulting MP3 and AAC albums from the same 50-minute source CD were within a mere 800 KB in size of each other. 38.7 MB and 39.5 MB totals... and the AAC was the bigger one! That discrepancy can simply be attributed to the different encapsulation methods used by the two formats.

    The real difference lies in that the AAC is more efficient at the same bit rate, meaning that a 128 kbps AAC file will sound better and more acoustically accurate than a 128 kbps MP3 file. This is why some people say things like "a 128 kbps AAC is roughly equivalent to a 160 or 192 kbps MP3".

    Anyhow, I'm moving this thread to Digital Hub, home of all things iTunes-related.
  • Reply 5 of 6
    a_greera_greer Posts: 4,594member
    going from compressed format to compressed format is the digital eqivalent of going from tape to tape, every generation looses quality, either re rip them or just live with the mp3's (they realy arent that bad)

    recording/compressing 101:

    the copy is only as good as the source
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