converting MP3 to AAC

Posted:
in iPod + iTunes + AppleTV edited January 2014
I just converted a bunch of my MP3's to AAC, by going into iTunes header Advanced Convert selection to AAC. But now there are copies of all that music in MP3 and AAC. If I choose consolidate library will that fix that and delete all the MP3 copies of the AAC music? Or do I have to do it one by one, in iTunes folders?

Thanks

Comments

  • Reply 1 of 9
    brussellbrussell Posts: 9,812member
    I don't know the answer to your question, but before you delete your MP3s, are you sure you want to do this? It probably won't save you any space, they'll probably decline in quality somewhat, and you can play all your MP3s everywhere you can play your AACs. If you were encoding original CDs into AAC, and then deleting the MP3s, that would be different.
  • Reply 2 of 9
    ghost_user_nameghost_user_name Posts: 22,667member
    Yeah, basically, here is a primer on it...



    The bit rate is how much data is being pushed per second. This means a 192kbps MP3 is going to be the same size as a 192kbps AAC file. In fact, converting an MP3 to AAC is probably going to kill the quality somewhat. I mean, you're recompressing something that is already compressed.



    It isn't worth it.
  • Reply 3 of 9
    Quote:

    Originally posted by M3D Jack

    Yeah, basically, here is a primer on it...



    The bit rate is how much data is being pushed per second. This means a 192kbps MP3 is going to be the same size as a 192kbps AAC file. In fact, converting an MP3 to AAC is probably going to kill the quality somewhat. I mean, you're recompressing something that is already compressed.



    It isn't worth it.




    I have converted a lot of 160 and 192bit MP3's to 128 AAC and I can not tell the difference at all. None of my friends can tell and they are quite surprised when I tell them that this is at 128 AAC.



    There probably is a loss when converting 160+ to 128 AAC but probably not that much that is noticable. I'm sure that if you converted a 160 MP3 to lets say a 192 AAC then there will probably be a noticable difference in the quality.
  • Reply 4 of 9
    idaveidave Posts: 1,283member
    I agree with BRussel and M3D Jack. MP3 files have been compressed, throwing out music information in the process. If you convert, and recompress that file, not only will you have lost the information that was thrown out during the MP3 compression, you'll be throwing out more, different information in the AAC compression process.



    If you really want AAC files, which supposedly sound better at smaller sizes than MP3s, compress from the original CD or get AACs from Apple or other sources. If you can't do that, leave your MP3s as they are!
  • Reply 5 of 9
    I'm in the process of re-ripping my cd collection to aac and I have some cd thats i intially ripped to mp3 and then burned as an audio cd onto a cd-r. I'm wondering how much quality I would lose bu re-ripping one of these audio cd's into aac
  • Reply 6 of 9
    agent302agent302 Posts: 974member
    Quote:

    Originally posted by Ringo20000

    I'm in the process of re-ripping my cd collection to aac and I have some cd thats i intially ripped to mp3 and then burned as an audio cd onto a cd-r. I'm wondering how much quality I would lose bu re-ripping one of these audio cd's into aac



    Going CD -> MP3 -> CD -> AAC should be the same audio wise as going MP3 -> AAC, as in, you will lose sound quality. It's always best to rip from the original CD.
  • Reply 7 of 9
    torifiletorifile Posts: 4,024member
    Quote:

    Originally posted by LoCash

    I mean, you're recompressing something that is already compressed.





    Are we sure that this is what happens? I mean, this is my thinking as well, but...



    If the algorithm is to cut off anything above a certain audio frequency and that's done in the initial mp3 ripping, wouldn't re-ripping it do nothing to what was left?



    Say that mp3 conversion cuts off frequencies above 20khz (I'm totally making that number up). That part of the audio is now gone. Now say that aac conversion also cuts off that part of the audio. There's nothing to cut there because it was already cut. So there should be no loss of quality.



    Again, I'm not sure that this is really how it works, but that's been my understanding of how mp3's compress files. Correct me if I'm wrong. It's happened before.



    Of course it could be that the algorithm just calculates what it's going to cut based on what's there. In that case, there would a degradation of quality.
  • Reply 8 of 9
    lucaluca Posts: 3,833member
    You can sort your music by the audio format rather than by the title or artist or whatever you do now by hitting command-J (view options) and checking the box to view audio format. Then click on the new bar along the top row to sort by audio format. Then you can delete anything of the format you don't want.



    But I would have to agree with the others... there's no advantage to HAVING AAC files, the only advantage is when RIPPING them because you get good quality for less space. If you convert MP3s to AACs, you may as well just reduce the bit rate of all your MP3 music because you'll be removing parts and reducing quality while also reducing the space. I guess if you're REALLY pressed for space then you can go ahead, but otherwise just leave all your music how it was originally ripped.



    Torifile, here's a better example (using arbitrary numbers, I don't have a good idea either):



    MP3s remove sound above 20 khz and below 20 hz. Then, assume that AACs remove sound above 19.5 khz and below 19 hz. Again, these are arbitrary numbers I made up, but if you had ripped the song directly to AAC it would have a range of 19hz - 19.5 khz whereas the MP3 would have 20 hz - 20 khz. An MP3 converted to AAC would have a range of 20 hz-19.5 khz. Basically, they remove different frequencies, so any overlap will result in the final product of an MP3 -> AAC conversion being simply all the frequencies that are NOT deleted by either one. If they both removed the same frequencies, then they would be the same format, not different formats.
  • Reply 9 of 9
    I took a song from my library, 128kps AAC, and then converted it to the same file format and size about 12 times just to see what would happen. Try ripping any track at 16kps. That is what your songs are sounding like, more and more, everytime to recompress them. They sound like RealPlayer documents! Is that what you want, huh? You want it to sound like it's been dragged through the dirt and scratched to shit so much it offends you to listen to it? You are KILLING that sound file everytime you do that! IS THAT WHAT YOU WANT? YOU WANT IT TO DIE? YOU SICK SON OF A?!



    You should really just re-rip from the original CD's, man. I have noticed some loss of? "life" from when I'd recompressed, and it compelled me to just rip them again. Do the right thing. Get your CD's.
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