What is the easiest way to put existing raw LC-AAC files into a container such as m4a? I have several hundred 256 kbps/48 bit depth VBR aac stream recordings from an Internet radio station which I listen to frequently. They are superb quality but there is no way I know to add metadata tags to raw aac files, so I would like to put them in a container without decoding the audio and then re-coding it, just adding metadata. Maybe I'm being a little too fussy about not changing the audio in the process? I do have software (NCH Switch) for converting aac files to m4a, but it messes with the audio in the process which I would like to avoid.
ffmpeg is the to-go tool, and lots of other tools that do so are just front-ends to ffmpeg.
Quicker than typing,
@sveakul posted this somewhere else: https://getmusicbee.com/forum/index.php?topic=23193.0
MP4Creator is also a valid option.
As mentioned, ffmpeg will work, but I prefer to use MP4Box (https://github.com/gpac/gpac/wiki/MP4Box) (downloads (https://gpac.wp.imt.fr/downloads/)). I created a (windows) script a number of years ago to do this:
:: Name: aac2m4a.cmd
:: Purpose: Configures mp4box to package raw aac audio into m4a file
:: Author: jaybeee
:: Revision: June 2021 - v2
@ECHO OFF
SETLOCAL ENABLEEXTENSIONS ENABLEDELAYEDEXPANSION
:: variables begin with v
:: set name of this script without file extension
SET vMe=%~n0
:: set name of the parent directory where this script resides
SET vParent=%~dp0
:: set location of mp4box ** CHANGE ME **
SET vmp4box="C:\Program Files\GPAC\mp4box.exe"
:: call mp4box to place all raw aac files in current directory in m4a container and save to m4a directory
MKDIR m4a
FOR %%f IN (%*) DO %vmp4box% -add %%f "m4a\%%~nf.m4a" -new
:: if you prefer to process the entire directory, then uncomment below command (remove ::), making sure to comment the above FOR command
::FOR %%f IN ("*.aac") DO %vmp4box% -add "%%f" "m4a\%%~nf.m4a" -new
:: Finish
ECHO Finished m4a creation
:: pause can be used to view the extraction details
PAUSE
:END
ENDLOCAL
ECHO ON
@EXIT /B 0
Copy and paste the above into a text file and rename it
aac2m4a.cmd.
Then drag and drop the aac file(s) onto the
aac2m4a.cmd file and they'll be individually (losslessly) remuxed into a m4a container and placed into a
m4a directory.
Or, as you can see from the script, you can process an entire directory by double-clicking the
aac2m4a.cmd after having made the changes to the script (uncomment one command and comment the other).
Simple but effective.
What is the easiest way to put existing raw LC-AAC files into a container such as m4a? I have several hundred 256 kbps/48 bit depth VBR aac stream recordings from an Internet radio station which I listen to frequently. They are superb quality but there is no way I know to add metadata tags to raw aac files, so I would like to put them in a container without decoding the audio and then re-coding it, just adding metadata. Maybe I'm being a little too fussy about not changing the audio in the process? I do have software (NCH Switch) for converting aac files to m4a, but it messes with the audio in the process which I would like to avoid.
Hi Thorrall! If you are referring to files with the .aac filename extension as "raw LC-AAC" files that's not what they are. They are ADTS stream files. The best way to convert them to m4a is with ffmpeg. Here is a sample conversion that includes using the appropriate filter to convert ADTS to AAC (m4a):
ffmpeg -i 1.aac -c copy -bsf:a aac_adtstoasc 1.m4a
That works great for me with AAC-LC files. It will also convert HE-AAC files but the resulting m4a will not have the proper settings to trigger HE-AAC playback. Recent versions of ffmpeg should automatically use the bitstream filter aac_adtstoasc so including that in the command is optional. In that case the command would be:
ffmpeg -i 1.aac -c copy 1.m4a
Cheers,
Phil
The answers from four months ago accomplish this. And also jaybee's script can be altered to accommodate drag+drop ffmpeg'ing.
But please be careful about the phrase "convert", as it is commonly associated with transcoding.