Editing AAC M4A files

Discussion in 'Digital Audio' started by TheLimpOne, Apr 10, 2009.

  1. TheLimpOne macrumors newbie

    Oct 12, 2008
    Ok so I got some M4A/AAC files with a lot of useless silence in the tracks... I want to be able to put them in a program and edit out the silence, then save without losing any quality. The program I have, Goldwave, can't save in M4A format so it does me no good. Does anyone have any program suggestions?

    Some people may bring up FLAC, I don't have much interest in that though since it doesn't work with iTunes.
  2. Dr Sound macrumors member

    Dr Sound

    Apr 5, 2009
    Roxborough Park Colorado

    You can get a program that can change the Format....

    Also there is another free program that might help called audacity it is 100% free

    check it out here I think with this program and possible a Program to change your formats you should be good to go

  3. ChrisA macrumors G4

    Jan 5, 2006
    Redondo Beach, California
    You should be able to edit the tracks in Garage Band. GB works well. It uses the same audio engine as Logic. GB is not free but you likely already have it on your Mac.

    No matter what software you use there is going to be a de-code and re-encode operation which may loose a small amount.
  4. Dr Sound macrumors member

    Dr Sound

    Apr 5, 2009
    Roxborough Park Colorado

    GOOD CALL...

    I always forget the Hidden Potential in Garage Band...
  5. Teej guy macrumors 6502a

    Aug 6, 2007
    There is no way to edit a lossy file like an AAC or MP3, keep it at the same bitrate and not lose quality.

    Your only options once you've edited the file are:
    1) Save as lossy file again (AAC/MP3) and lose quality
    2) Save as lossless (FLAC/Apple Lossless/AIFF...whatever) and retain the quality level of the original lossy file. It'll take up a whole ton of space and as I said, you'll have the same quality as the original lossy file...whether this is worth it to get rid of the silence and retain the quality is your call.

    EDIT: Luap posted a link to a program called Fission which claims to be able to edit lossy files without the decoding/encoding process that degrades quality. It costs $32. Looks interesting! http://rogueamoeba.com/fission/
  6. Luap macrumors 65816


    Jul 5, 2004
    Which was why I posted a link to Fission. It claims to be able to edit compressed audio file formats with no quality loss. Very few audio editors can do that. I don't use it myself, but it appears to do exactly what the OP is asking for.

    "Edit audio in minutes, not hours. With Fission's streamlined audio editing, you can quickly copy, paste and trim audio, as well as split files. Fission also works with compressed MP3 and AAC formats to edit without the quality loss caused by other editors."

    "Never Lose Quality
    No re-encoding or format switching means Fission never causes quality loss."
  7. Teej guy macrumors 6502a

    Aug 6, 2007
    Interesting...never heard of it...I don't know why I missed your post. I'm going to try it out...thanks!
  8. jackerin macrumors 6502a

    Jun 29, 2008
    How about Quicktime Pro? Cut out the the silence, export to a new MP4 with audio on passthrough.
  9. Teej guy macrumors 6502a

    Aug 6, 2007
  10. TheLimpOne thread starter macrumors newbie

    Oct 12, 2008
    Well Luap, I appreciate the suggestion, it sounds exactly to be what I would want... Unfortunately I only own a PC, so that program wouldn't even be compatible for me. :(

    Guess I should start stating I actually don't own a Mac. If anyone has any recommendations for a PC system though, would be glad to hear them.
  11. jackerin macrumors 6502a

    Jun 29, 2008
    Passthrough does not reencode.

    Not to be a party-pooper, but have you considered asking on a Windows-based forum?
  12. TheLimpOne thread starter macrumors newbie

    Oct 12, 2008
    That was an idea, I don't actually know any though. That and I figured I couldn't be the only PC user on these boards.
  13. Teej guy macrumors 6502a

    Aug 6, 2007
    Cool, I didn't know Quicktime Pro had that functionality.
  14. LoveableRogue, Jan 3, 2012
    Last edited: Jan 3, 2012

    LoveableRogue macrumors newbie

    Jan 3, 2012
    [/COLOR]Hi Guys,

    You clearly know what you're talking about regarding audio files, so if I may be bold enough to hijack this 2009 thread:

    I've pulled music into my iTunes collection from several different sources, such as the iTunes store, CDs, WMA, RealAudio, etc.

    On Apple's recommendation, I've optimized the sound quality of all my 7,500 songs by going:

    ---> iTunes ---> Advanced ---> Create AAC version

    I like my iTunes collection to be in VERY neat order.

    Therefore, if I find a digital version of a rarity by, for example, The Eagles, I don't just add it to my iTunes collection, and leave it at that.

    Instead, I grab ALL my Eagles songs, and convert them ALL to AAC for a SECOND time, in the strict chronological order in which they were originally recorded and/or released, so that when I view my entire iTunes collection via "Date Added," all my Eagles songs are not just together in one block, but in addition, they're simultaneously in strict chronological order.

    The problem which I've noticed is that every time I convert what is already an AAC file to being an AAC file for a second, third, fourth, or fifth time, iTunes says that the new file size is regularly larger OR smaller than the previous file size.

    Sometimes larger, sometimes smaller, sometimes the same size.

    There doesn't seem to be a pattern.

    Therefore, three questions:

    01. Why do some AAC files get bigger, some get smaller, but others stay the same size ?

    02. Every time I "Create AAC version" of a file which is already an "AAC Version" WITHIN iTunes, and then I delete the first AAC file, am I losing anything more than NEGLIGIBLE sound quality in the second AAC file ?

    Please say no !

    03. In view of the fact that my iTunes collection has 7,500 songs in it, is there a way for me to MINIMIZE the size of an AAC file without losing sound quality ?

    Please say yes !

    Suggestions about how to decrease the AAC file sizes in bulk would also be very welcome.

    I'm running iTunes 10.5.2 (11), within OSX 10.6.8, on a 13" MBP.

    Thanks, guys.

    Happy new year to my fellow MacHeads.


    Michael T
    London, England


    There we go, an 8.5 mb AAC file has just become an 8.4 mb AAC file.

    However, a 17.7 mb AAC file has just grown to 18.2 mb.

    What's going on ?

    Is the process not the same as simply duplicating a Word document, or a Jpeg photo, both of which always duplicate to exactly the same size ?

    Apologies for the multiple postings.


    London, England.
  15. Jolly Jimmy, Jan 3, 2012
    Last edited: Jan 3, 2012

    Jolly Jimmy macrumors 65816

    Jolly Jimmy

    Dec 13, 2007
    1. Lossy compression formats like MP3 an AAC aren't designed to re-encode files this way.
    2. Yes. Every time you do this you lose information. If you've transcoded files multiple times then there is definitely a chance you will hear a loss in quality compared to the originals.
    3. No. It varies between codecs, but generally speaking, smaller files = less quality.


    Sorry, not really the answers you were hoping for I know...

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