Properties of ALAC in mp4

Brett Hoyle kickbits at
Mon Jun 13 09:52:03 CEST 2011

Yes I think the files are always inside the mp4 container, there is no
pure/raw alac files outside of the mp4 container afaik.

The issue is small and wont effect many. But I also think the .alac file
extension will never be used for anything else now, so assuming files with
.alac are simply wrongly named .m4a files will not cause any issues.

The alac-in-mp4 file format through some form of confusion seems to have
claimed ownership of the extension even if it will now not use it.

Unless anyone wants to chime in and say they have seen .alac files as
something other than wrongly named alac-in-mp4 files.

-----Original Message-----
From: Lukáš Lalinský [mailto:lalinsky at] 
Sent: Monday, 13 June 2011 2:03 PM
To: taglib-devel at
Subject: Re: Properties of ALAC in mp4

2011/6/13 Brett Hoyle <kickbits at>:
> Hehe I have no idea, just in my test suite of files which I would have 
> generated many many moons ago I have some alac and some m4a. I would 
> assume maybe dbpoweramp made them but looks like current version of 
> that would name them .m4a.
> From google results:
> Sonos a major networked media player product refers to alac as .alac:
> _faqid
> =80#var_g

This example actually shows why I ask. Are the .alac files actually

"Apple Lossless data is stored within an MP4 container with the filename
extension .m4a"
"ALAC File Extension is: .alac "

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