Converting MP3 to AAC

Discussion in 'Mac Apps and Mac App Store' started by Josh396, Dec 21, 2004.

  1. Josh396 macrumors 65816


    Oct 16, 2004
    Peoria/Chicago, IL
    My iTunes library is starting to approach 20 gb with about 95 songs encoded in mp3 at 192 kbps. I would like to encode them to aac at 128 or 160 but I've heard you shouldn't convert mp3 to aac. Would there be a great loss in quality if I was to do so? I'm not looking for the songs to be perfect but pretty good quality. Thanks for any advice

    Edit: I meant to say 95 percent of the songs not 95. I don't think 95 songs would be worth to reencode to aac.
  2. dav macrumors 6502

    Jun 29, 2004
  3. strider42 macrumors 65816


    Feb 1, 2002
    I would think you'd get a pretty good loss of quality. Mp3 is a lossy format, so its already thrown out a bunch of info contained in the original recording. AAC is another lossy format and will throw out still more, different information from the MP3 file. The result is that you've lost an awful lot of information and it will most likely sound noticeably worse.

    Of course, the easy way to check this is to simply try it and see if you can handle it, I doubt you'll be pleased with the results.

    So you're best bet is to reencode from original recordings (you do have original recordings right, cause you legally ripped all of these from your own CD collection right?), or simply leave them alone. If space is a real consideration, consider just ugprading yoru hard drive. New drives are pretty cheap nowadays.
  4. pncc macrumors regular

    Jul 23, 2002
    I wouldn't do it. Conversion will result in loss of quality. If you have the original CDs (which you should if this is legal music right???), re-rip them if you want to, you won't save much space though.
  5. johnnyjibbs macrumors 68030


    Sep 18, 2003
    London, UK
    If you've only got 95 songs out of 20GB encoded in MP3 192kb, I wouldn't bother converting those ones. You'll gain about 2MB of space (ok a bit more, but not that much) and lose quality by converting those ones to AAC.

    Use 128kb AAC (or 160 if you prefer) for future encoding but leave MP3s as is.
  6. titaniumducky macrumors 6502a


    Nov 22, 2003
    I've done this before with a lot of songs without a seemingly large loss of quality but it should theoretically be bad. Definitely try it yourself.
  7. Makosuke macrumors 603

    Aug 15, 2001
    The Cool Part of CA, USA
    Generally a bad idea, particularly since AAC and MP3 throw out different information, so you're screwing up the music in two different ways by re-encoding.

    That said, since 192k MP3 is pretty high (meaning not a whole lot thrown out), if you're not picky at all reencoding at 128k AAC probably won't be a horrible loss of quality. It'll be significantly worse than encoding directly fro CD to 128AAC, but not as bad as, say, 192k MP3 to 160k AAC, which would be a waste of space, or something silly like 128k MP3 to 128k AAC, which would do nothing but make the music sound worse.

    Go to the CDs if at all possible--just set iTunes to import and eject when you insert a CD, and it's pretty quick--do it while websurfing or watching TV or something.
  8. bartelby macrumors Core


    Jun 16, 2004
    On a similar theme...

    I have 5000+ mp3s, the majority at 192kbps, and I want to convert them to 128.
    Is there any software that will do this automatically (I've tried Audion, but it's far too slow)?

  9. neut macrumors 68000


    Nov 27, 2001
    here (for now)
    i wouldn't do that, but iTunes can do that for you. set your import settings, sort by type, select all your MP3s, and choose the 'convert to MP3' selection fron the drop down menu. :)

    compressing compressed files is never a good idea though...

    on my music server im approaching 300GB of music ... mostly apple lossless. ;)

  10. jxyama macrumors 68040


    Apr 3, 2003
    i have converted a lot of my songs from AAC 160kbps to AAC or MP3 128kbps.

    i don't really notice the difference. at least, not to the degree that i feel compelled to bother re-ripping all the songs from the CDs again.

    i do, however, notice the difference compared to iTMS 128 kbps...
  11. TrenchMouth macrumors 6502

    Nov 21, 2002
    the day that the version of iTunes came out that allowed for ripping as AAC files i deleted all my music that i owned and began re-ripping in 128AAC files. Just seemed like a good idea. of the couple hundred MP3 files that i still have most are 192. I had one album that was 256MP3 and i converted it to 128AAC. I can deffinately hear the sound quality difference. Compressing and already compressed format results in crap.m4a

    i would recommed against it. Just deal with what you have, or find the origional your house...cause its yours.... :cool:
  12. neut macrumors 68000


    Nov 27, 2001
    here (for now)
    to those who can't hear the difference ... cymbals give it away bad. listen to various degrees of compression and you can hear what sounds like a phaser slowly eating away at your frequecies ... it will also show up in silent parts (woosh ... ).

    i go apple lossless when i have access to the CDs. im thinking of backing up to DVD (that's going to take awhile). :rolleyes:

  13. maya macrumors 68040


    Oct 7, 2004
    somewhere between here and there.
    As others here have mentioned you are going to compress an already compressed mp3 file to re-compress it again to AAC format.

    You are going to loose a lot of quality you are better off waiting for HE-AAC and ripping your CD again.

    Unless you have mp3 encoded @ 320k and encoding it to AAC at 128k that would be fine however still not recommended. :)
  14. Loge macrumors 68030


    Jun 24, 2004
    I agree about the cymbals. However, I always find that silence sounds okay at 128 kbps. ;) :p
  15. neut macrumors 68000


    Nov 27, 2001
    here (for now)

    i meant the where there should be silence :) ... usually as a sound falls off it gently drifts away, but with compression the sound will have that same phaser effect.

    that is, unless you have a tube amp for your iPod; then it might sound kinda cool. :)

  16. Sweetfeld28 macrumors 65816


    Feb 10, 2003
    Buckeye Country, O-H
    to all of you that say not to do it i would have to say, your right on the fact that you may lose some quality, but its not enought to notice.

    I have done this many times and can never tell the diffrence. However, when ever i do this i usually am going from a .mp3 (which is always between 128-192 or higher, i never go below 128) to AAC 128.

    I thought it would be a bad idea if you are going form mp3 128 to aac 128, because during the recompression process the computer has to take that song and resample it in the diffrent format (acc). Thus, this would discard some of the song info. But, when you are going from a larger song file, with a greater bit rate (mp3 192) and go down to a AAC 128, it throws out the extra data that it doesn't need. The end result however, is the same song with the same quality, at a smaller size, in a diffrent format.

    Put it this way, i have almost 7,500 songs (27.54 GB) in my library, but when they all were mp3's, before i converted them, my library was 37.74 GB. The biggest reason i converted them is because i was running out of space on my HD, and because they couldn't all fit on my 30GB iPod.

    I would have to say that you should try it first, and see if you can tell the diffrence. Take a cd import the songs as mp3's at 192. Then after doing this, select your songs which are mp3's, right click or control click and go down to "convert to acc". After they have been copied as the AAC format, listen to the two diffrent versions (mp3 192 vs. AAC 128), and tell me what diffrences you can hear, if any. You may notice a little diffrence between the songs if they were imported as mp3 128, and the converted to AAC 128 but not much.

    Let me know, or us, what you find out.

  17. jaromski macrumors regular


    Jun 18, 2004
    let your consciense be your guide. (tm, disney)

    function conscience(array ratings)

    foreach (rating in ratings)

    case "****": // 4 stars
    case "***": // 3 stars
    case "**":
    case else: default:
    who_gives_a_flying_****(); // mp3 ok here nothing to see folks, move along



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