Strange bugs with iTunes and iphone, when trying to transfer and listen files in mp3. In m4a everything is all right. Is there any way to convert all mp3 files to m4a and save all tags and covers? Thanks.

1 Answer 1


The conversion & the discard of the old mp3 will have to be done in 2 steps, so you need to make sure you've enough disk space to temporarily store double the amount of space the mp3s currently take up. If not, you'll have to do the conversion/discard in small batches, one album at a time.

Start in iTunes Prefs > General > Import Settings...
Set to AAC Encoder.

Then, back in iTunes main window, switch to My Music & sort by Songs, which makes things easier to find.
If it doesn't show already even if you scroll the window to the right, then right-click the top of the columns in the main window & add a column for Kind.

Click this column to sort by Kind

The sort is simply alphabetical, so at the top will be AAC files, Apple Lossless etc., further down MPEG [mp3s] Below that may be other file types so make sure you don't accidentally select any of those.
Click the top MPEG file, scroll down & shift/click the last one.

Right click one & Select Create AAC version.

Wait until the process is finished - minute or hours depending on how many tunes...

You then need to find all the original mp3s that will still be in their original locations, now with an AAC file next to each one.

Navigate to your iTunes Music folder ~/Music/iTunes/iTunes Media/Music hit Cmd ⌘ F & type mp3. The search will offer name matches: mp3 or kind is mp3 audio, pick kind.
Assuming you converted all your mp3s, anything showing in that search result can now be deleted. Simply select all & Trash.

To be certain, relaunch iTunes & scroll down the song list, making sure nothing has an exclamation mark ! at the left, which would indicate a missing file.

One you're sure, you can empty the trash.

  • This is a good answer, +1. I’d like to just add that MPEG is inherently confusing, here and everywhere, since the Moving Picture Experts Group decided to create a universally crappy acronym under which both mp3 and mp4 files fall despite completely different A/V codecs.
    – njboot
    May 9, 2016 at 7:20
  • yup, inherently confusing, as most users think of mp3 rather than MPEG [which, as you say don't even describe it, mp3 is more accurate] & unfortunately they also often think 'mp4' where they should be thinking 'm4a'. To add to that confusion, they're listed as AAC, Apple Audio Codec :/
    – Tetsujin
    May 9, 2016 at 7:41
  • hence, the confusion...:) mp3=MPEG 1 audio using ___ de facto (lossy) codec. m4a = MPEG 4 audio encoded using a lossless codec (AAC).
    – njboot
    May 9, 2016 at 8:00
  • kind of ... MPEG-2 Audio Layer III strictly speaking, & m4a is not necessarily lossless, it's a lossy format, just not as lossy as 'mp3'. The lossless version is usually listed as Apple Lossless or Apple MPEG-4 Audio (Apple Lossless) to differentiate, though there are maybe 7 different types of 'm4a' to add to the confusion, Low Delay & HE variants ;-)
    – Tetsujin
    May 9, 2016 at 8:48
  • and so we descend...lol...point is +1 for the answer, cheers buddy :)
    – njboot
    May 9, 2016 at 9:15

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