Convert .m4a to .aac

brandon6684

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Dec 30, 2002
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For AAC files, my phone only recognizes .aac files not m4a or mp4. While I can seem to change the extension from .m4a to .mp4 without problem, I apparently can't do the same with .aac. I'm assuming it's a different container format or something. Is there some way to do it in OS X?
 

brandon6684

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Dec 30, 2002
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.m4a is AAC. I didn't know that .aac was an extension, but have you tried changing .m4a to .aac?
That's what I said. For some reason renaming an m4a or mp4 as aac doesn't work. Even iTunes or VLC won't play it despite them being naturally able to play .aac files.
 

vandlism

macrumors 6502
Jun 20, 2007
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That's what I said. For some reason renaming an m4a or mp4 as aac doesn't work. Even iTunes or VLC won't play it despite them being naturally able to play .aac files.
I have never heard of the .aac suffix. That's pretty ridiculous. .m4a is the common suffix for AAC format audio files and there are variations on that too (m4p and m4b).
 

brandon6684

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Dec 30, 2002
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I have never heard of the .aac suffix. That's pretty ridiculous. .m4a is the common suffix for AAC format audio files and there are variations on that too (m4p and m4b).
I can understand them not supporting .m4a since it's a non-standard extension that Apple just pulled out of their ass, but no mp4 seems odd. I've heard of AAC files using the aac extension before, but I didn't know it was a different container format that the standard mp4(which m4a just seems to be a renaming of).
 

vandlism

macrumors 6502
Jun 20, 2007
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Well the use of m4a has it's purposes. The extension mp4 makes things very difficult as it would be hard to determine what exact form of mpeg-4 one would be working with by using the file extension on its own. I could discuss this to no end, but if you have QuickTime Pro or some other audio editing software, I would suggest trying to export the sound file as a regular mpeg-4 file. It could be that the sound file is in a certain container and needs a bit more than an extension change.
 

Krevnik

macrumors 68040
Sep 8, 2003
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I can understand them not supporting .m4a since it's a non-standard extension that Apple just pulled out of their ass, but no mp4 seems odd. I've heard of AAC files using the aac extension before, but I didn't know it was a different container format that the standard mp4(which m4a just seems to be a renaming of).
.m4a is an MP4 file that is renamed so that iTunes knows it is 'safe' to store ID3 tags in it. These tags are stored as user data in the file, so most players that support AAC in an MP4 file will play it back and just ignore the tags if they don't support them.

.aac is AAC without any container around it. Just the raw stream. You would need something like ffmpeg which can output raw streams to disk, stripping away the MP4 container from the audio data. This file format is really just a cheap-ass way to avoid paying the MPEG-4 licensing fees on the file format, and just paying the license fees for AAC itself.
 

yellow

Moderator emeritus
Oct 21, 2003
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.m4p is a PROTECTED file, purchased from the iTunes Music Store. The only thing you can play it in is iTunes. And you have to be a registered user to play the song. Simply changing the file extention doesn't magically unprotect the song.
 

brandon6684

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Dec 30, 2002
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.m4a is an MP4 file that is renamed so that iTunes knows it is 'safe' to store ID3 tags in it. These tags are stored as user data in the file, so most players that support AAC in an MP4 file will play it back and just ignore the tags if they don't support them.

.aac is AAC without any container around it. Just the raw stream. You would need something like ffmpeg which can output raw streams to disk, stripping away the MP4 container from the audio data. This file format is really just a cheap-ass way to avoid paying the MPEG-4 licensing fees on the file format, and just paying the license fees for AAC itself.
Ah, okay. That I can do.
 

Krevnik

macrumors 68040
Sep 8, 2003
3,256
658
.m4p is a PROTECTED file, purchased from the iTunes Music Store. The only thing you can play it in is iTunes. And you have to be a registered user to play the song. Simply changing the file extention doesn't magically unprotect the song.
Not what was asked, but thanks anyways.