Extract audio aac from mp4

mp4box can also do this.

To demux/extract aac from mp4 (assuming audio is the 2nd track):

mp4box -raw 2 video.mp4

This will automatically create output file "video_track2.aac"

If you wanted control over the output filename, you would do

mp4box -raw 2 video.mp4 -out audio.aac

If you wanted to remux back into mp4 container (i.e. for iTunes) you could do:

mp4box -single 2 video.mp4 -out audio.m4a

You could then put this in a batch script to operate over all the files in a directory:

for %%f in ("*.mp4") do (

mp4box -single 2 "%%f" -out "%%~nf.m4a"

)

(batch script inspired by videohelp and stackoverflow)

Download links:

• https://github.com/gpac/gpac/releases

• http://gpac.wp.mines-telecom.fr/downloads/gpac-nightly-builds/

Here’s the actual commands to use since all the provided links don’t actually give them, and anyway: links rot and die so should always be replaced with actual answers on stackexchange.

avconv -i input.mp4 -vn -c:a copy output.m4a

FFmpeg can do it. Here is a list of commands that might come useful for you. Go here for instructions.

Example:

ffmpeg -i INPUT.mp4 -c copy -map 0:a:0 Output.aac

• -i: input file
• -c copy: copies the bitstreams without re-encoding
• -map 0:a:0: selects track from: 1st input file -> audio tracks -> first track (1st audio track from 1st input file)

Note that it would work similarly with avconv, which is a fork of ffmpeg.