Converting .mp3 to .m4a for gapless playback

Discussion in 'Digital Audio' started by RoboWarriorSr, Apr 8, 2014.

  1. RoboWarriorSr macrumors 6502a

    Joined:
    Feb 23, 2013
    #1
    I have quite a few songs in 320 .mp3 containers. I would like for some of them converted to .m4a so gapless playback could be enabled. When using the conversion feature in iTunes, does it replace the songs with the newly converted files and delete them? If not, how does it organize the songs after converting them? Would hate to comb through files to delete songs that are replicated.
     
  2. blueroom macrumors 603

    blueroom

    Joined:
    Feb 15, 2009
    Location:
    Toronto, Canada
    #2
    iTunes autoconversion will downsample on the fly when syncing to your iOS device. It doesn't affect the .mp3 when adding it to your iTunes library.

    XLD can convert audio.
     
  3. RoboWarriorSr thread starter macrumors 6502a

    Joined:
    Feb 23, 2013
    #3
    Converting .mp3 to .m4a for gapless playback


    It will? Good thing you told me before then. So to just change the container from .mp3 to .m4a, I would need to use XLD?
     
  4. Julien macrumors G3

    Julien

    Joined:
    Jun 30, 2007
    Location:
    Atlanta
    #4
    Keep in mind converting from one lossy format to another is a BIG no, no and substantially lowers quality. You should only start with the Lossless originals (CD).
     
  5. Nermal Moderator

    Nermal

    Staff Member

    Joined:
    Dec 7, 2002
    Location:
    New Zealand
    #5
    No, you don't need to use XLD; converting in iTunes will give you two copies of the songs (so you may wish to sort by Kind and mass-delete the old MP3s afterwards). This is different from the "compress and sync" feature that blueroom was talking about above.

    However, as Julien said, it's better to go back to the original CDs. If the metadata matches then iTunes will replace the existing tracks instead of create duplicates.
     
  6. blueroom macrumors 603

    blueroom

    Joined:
    Feb 15, 2009
    Location:
    Toronto, Canada
    #6
    Where does iTunes convert MP3's to AAC? When I copy music into iTunes it does no conversion. When I sync it will on the fly convert for the iOS device only.
     
  7. Julien macrumors G3

    Julien

    Joined:
    Jun 30, 2007
    Location:
    Atlanta
    #7
    Right click.

    [​IMG]
     
  8. blueroom macrumors 603

    blueroom

    Joined:
    Feb 15, 2009
    Location:
    Toronto, Canada
    #8
    Ahh, after it's already in the library. I'll stick with XLD as it can do it before iTunes adds it. Plus XLD can also delete the original if desired.
     
  9. RoboWarriorSr thread starter macrumors 6502a

    Joined:
    Feb 23, 2013
    #9
    Converting .mp3 to .m4a for gapless playback


    Doesn't the iTunes AAC converter lower to quality to 256 Kbps? The music I want converted is 320 Kbps and in .mp3. All I want is to change the container file to .m4a without quality loss so gapless playback can be enabled. The song I want converted are mainly some pop songs that wouldn't really benefit from 600+ Kbps files. Any music that uses a lot of acoustic music/ some instrumental I have in the original lossless format since they would benefit a lot more from the added quality.
     
  10. Nermal Moderator

    Nermal

    Staff Member

    Joined:
    Dec 7, 2002
    Location:
    New Zealand
    #10
    You can't just do a container swap; an .m4a container can't legitimately contain MP3 data.
     
  11. Julien macrumors G3

    Julien

    Joined:
    Jun 30, 2007
    Location:
    Atlanta
    #11
    Doesn't matter if it's 320kbps (or even 360kbps) you will lose quality. You can't take a lossy file and re-compress into anther lossy file without compounding the loss of quality.
     
  12. blueroom macrumors 603

    blueroom

    Joined:
    Feb 15, 2009
    Location:
    Toronto, Canada
    #12
    If you want high bitrate you might want to consider ALAC which is a lossless Apple codec.
     
  13. RoboWarriorSr, Apr 9, 2014
    Last edited: Apr 9, 2014

    RoboWarriorSr thread starter macrumors 6502a

    Joined:
    Feb 23, 2013
    #13
    Converting .mp3 to .m4a for gapless playback


    Really? I was unaware of that. What would the best way to achieve gapless playback without quality loss. Also some of the file I want to convert I no longer have the CD ( the majority I do though). Also if the .mp3 was encoded with LAME3.99 is gapless playback enabled (I know that LAME can be used to emulate gapless playback)

    ----------


    From what I understand converting a 320 Kbps to ALAC would increase the file size without benefit and possibly decrease quality since it isn't the original file (can't make low quality higher)
     
  14. ChrisA macrumors G4

    Joined:
    Jan 5, 2006
    Location:
    Redondo Beach, California
    #14
    It replicates them. But there is no need to "comb though" the songs. Simply sort them by file type by clicking that column header and all the MP3 are grouped together, select them all at once and delete them all with one click.

    That said, don't expect an audio quality upgrade when transcoding, quality will go the other way.

    ----------

    No. Converting MP3 to ALAC will not reduce the sound quality any worse then it already is. But it will make the files MUCH lager. Maybe 3x larger. Correct it will be no better. But no worse. The final sound is in fact bit per bit identical to the MP3.

    The way it works is the MP3 is decompressed just like if you were to play the song. Then the decompressed data is compress lossless. So it records just like listening to an MP3. That said I do NOT recommend it because the 3X larger files. The only good way to get ALAC is to re-rip the CD.
     
  15. Nermal Moderator

    Nermal

    Staff Member

    Joined:
    Dec 7, 2002
    Location:
    New Zealand
    #15
    The other option, if you're prepared to pay for it (I think it's $25/year in the US), is to use iTunes Match to download 256 kb/s AAC copies of your songs. They'll probably sound similar to the 320 kb/s MP3s.
     
  16. RoboWarriorSr thread starter macrumors 6502a

    Joined:
    Feb 23, 2013
    #16

    How does Apple have .m4a files that are 6~13 mb? I preferably would like to convert .mp3 to .m4a at similar file size to my original 320 Kbps songs.
     
  17. pdjudd macrumors 601

    Joined:
    Jun 19, 2007
    Location:
    Plymouth, MN
    #17
    Apple doesn’t sell 320 kbps files at all. They sell AAC files that are high quality but are more efficient. Trust me, there really isn’t a way to get what you want without lowering the quality. It’s not really about the size of the file, it’s the quality - and cross converting lossy files always involves a loss.
     
  18. RoboWarriorSr thread starter macrumors 6502a

    Joined:
    Feb 23, 2013
    #18
    Converting .mp3 to .m4a for gapless playback


    I have 320 Kbps files just not from Apple. The main issue I have is the fact that I would like to keep the 320 Kbps files I have (not from iTunes) in the same format, MPEG-1, Layer 3. I was hoping that one could convert .mp3 (320 mp3 to 320 AAC) to another format like how one can convert .mkv to .mp4 using Handbrake/MP4Tools at no quality loss
     
  19. Julien macrumors G3

    Julien

    Joined:
    Jun 30, 2007
    Location:
    Atlanta
    #19
    When you convert lossy video (all consumer video is lossy) to another format (like mkv to mp4) you get a loss of quality. You just aren't as likely to notice it as much (but there is a loss of quality) since the ears are FAR more sensitive to compression artifacts than the eyes are.

    Again it is technically impossible to convert from one lossy format to another without a loss of quality.
     
  20. RoboWarriorSr thread starter macrumors 6502a

    Joined:
    Feb 23, 2013
    #20

    I stuck between a hard place and a rock with this one. Thanks for the help guys. Now I'm going to have to break out the old CDs...
     
  21. jon3543 macrumors 6502

    Joined:
    Sep 13, 2010
    #21
    Keep in mind that "loss in quality" does not necessarily imply noticeable loss in quality, and that's what matters. I would not replace your source material with transcoded versions, but it may be acceptable to have iTunes convert higher bitrate files to AAC when you sync. If you're starting with 320 Kbps MP3s, I think you would be quite successful at that. My own experience is that converting MP3 to MP3 to reduce bitrate with LAME introduces noticeable artifacts right away, but converting to AAC goes a lot better. How can you tell? Unless there are blatant artifacts, you will need to use a proper blind AB comparison tool, that will switch you between the two versions without you knowing which one you're listening to. I mainly use foobar2000's ABX comparator on my PC, and when I was testing this a couple years ago, I did find an app for my iPod Touch. Sorry, I don't remember the name.

    That said, I have to question the premise of the thread. I thought Apple's stuff played MP3 gaplessly anyway.
     
  22. RoboWarriorSr thread starter macrumors 6502a

    Joined:
    Feb 23, 2013
    #22
    MP3 does not support gapless playback as mentioned on HydrogenAudio and Wikipedia (http://en.wikipedia.org/wiki/Gapless_playback). It might be possible with LAME 3.0+ but you would need a cue sheet and on most of my songs that isn't avaliable (some of them are encoded in LAME so gapless playback may be enabled on those songs). All songs downloaded from iTunes has gapless payback enabled since they are .m4a which does support gapless payback.
     
  23. jon3543 macrumors 6502

    Joined:
    Sep 13, 2010
    #23
    Per that Wiki article you cited:

    "LAME-encoded MP3 can be gapless with players that support the LAME Mp3 info tag."

    "iTunes-encoded MP3 is gapless when played back in iTunes 7.0 onwards, 2nd generation iPod nanos, and all video-capable iPods with the latest firmware."

    That said, I just encoded my ALAC rip of "The Dark Side of the Moon" with LAME, and listening with headphones in a quiet room, while foobar2000 played it back gaplessly and flawlessly AFAICT, the latest iTunes exhibited a tiny glitch between the first and second tracks. When testing, it matters in iTunes how far back I set the seek bar when monitoring glitches between tracks. If I set it just a couple of seconds before the end of a song, I'm pretty much guaranteed a substantial glitch when the next song starts. If I set it 10 seconds back, it's either perfect, or it has a very tiny glitch. For TDSOTM and the long setback time, only the track 1-2 transition suffered any glitch at all with MP3, and it was very slight. OTOH, the ALAC originals and AAC versions I made were completely flawless for long setback times, including the track 1-2 transition, but they too exhibited glitches when the setback time wasn't long enough. This is on Windows 7x64. No idea how it behaves on a Mac.

    So, for the album I tested, while iTunes wasn't perfect with MP3, it was pretty darn close. If close isn't good enough, well, then you're back to considering the loss in quality when converting MP3 to AAC, which is what the bulk of my message was about, trying to determine if it will be noticeable or not.
     
  24. RoboWarriorSr thread starter macrumors 6502a

    Joined:
    Feb 23, 2013
    #24
    Converting .mp3 to .m4a for gapless playback


    My post to yours did mention the use of LAME to enable gapless payback support on mp3. But anyway since there will be a drop in quality I will be using my CD and Flac files to convert.
     
  25. jon3543 macrumors 6502

    Joined:
    Sep 13, 2010
    #25
    You also mentioned needing a CUE sheet. My source was my ALAC rip which does not have a CUE sheet. I don't know if the track 1-2 tiny glitch would have been eliminated if I had a CUE sheet or ripped to MP3 from the CD. Nor do I know if LAME is a requirement for getting (almost flawless) gapless playback out of iTunes; the Wiki article refers to "iTunes-encoded MP3s" being gapless, and I doubt that's LAME. Anyway, my CDs are in storage, and I'm not dragging them out to test. :D

    If you have the original lossless versions, that's definitely the way to go.

    The "loss in quality" issue for lossy-lossy transcoding is still interesting, because it's always relative to what you can notice, there are ways to reliably assess this, and you will likely encounter it if you have MP3 files and set iTunes to convert higher bitrate files to lower bitrate AAC when it syncs.
     

Share This Page