Converting ADTS-AAC (.aac) to MP4 or M4A

I am going to make this post short and highly technical.

First and foremost, I must emphasize that MP4 files and sound encoded in Advanced Audio Codding (AAC) format are not suitable for donation of contents with free license to Wikimedia Commons or other free content hosts in countries with patent laws.

Assuming that you have already extracted your AAC audio track to a .aac file with ADTS format, download and prepare GPAC MP4Box and issue the following command at Command Prompt:

mp4box.exe -add "source file.aac" "destination file.m4a"

Replace “source file.aac” with the path (relative or absolute) of your .aac file and “destination file.m4a” with the path of the .m4a file to be created. Be advised, .aac files containing a raw or ADIF streams are not supported.

I strongly advise using .m4a extension with MP4Box to make sure it stores additional audio related data. If the file must have a .mp4 extension, rename it after conversion. Note that AudioMonkey v4.0 refused to play .mp4 files but has no problem with .m4a files created this way.

An alternative to MP4Box is the majestic FFmpeg but I won’t be covering it here.