How to extract aac audio from an mp4 file to m4a

Question

How can I extract the aac audio from an mp4 file?

I tried with ffmpeg and -acodec copy but if i use mp4 as output it will still encode the video and I get the same file size.

If I use m4a as output it will somehow still encode the video and I get almost the same filesize.

With aac as output I can't open the file in puddletag although the file size suggests the video was stripped

Thanks in advance

score 38 · Accepted Answer · edited Dec 22 '18 at 17:28

38

I finally found the solution myself in using mp4 or m4a as output format and adding -vn to prevent also copying the video.

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

(Source: https://superuser.com/a/706622/180675)

Seems simple now :]

Fast and lossless stripping

edited Dec 22 '18 at 17:28

Martin Thornton

6,016

answered Mar 22 '14 at 16:59

Turtlepurple

901

At least on November, 2022, the command that actually works is ffmpeg -i input.mp4 -vn -c:a aac output.m4a i.e. the copy parameter must be replaced by aac. – Yuri Sucupira Nov 20 '22 at 18:15
1

@YuriSucupira the command in the answer worked perfectly well for me (Jan 2024, ubuntu 22.04) – Rob Audenaerde Feb 09 '24 at 15:07
1

@RobAudenaerde Maybe it's because I'm currently (2024-02-09) using XUbuntu 24.04 (development/testing/unstable build). Even though this is a cutting-edge version (since its stable release is going to happen only 2 months from the date of this post), I believe it's important that I report here what worked for me because it seems that those who migrate to version 24.04 on April 2024 are going to experience the same issues that I did (and, therefore, are going to have to use the same command that I used). – Yuri Sucupira Feb 09 '24 at 18:49
@YuriSucupira the command in the answer worked fine for me and does what the question suggests, which is to copy or extract the audio stream directly from the input file, unmodified. Your command differs in that it is instructing ffmpeg to re-encode the audio into the AAC format. Both commands technically work and have their advantages. If you want to preserve the original unmodified audio, then the command in the answer should be used. If you aren't sure that the input contains AAC m4a audio and must have the output be in that format, then your suggested command should be used. Cheers. – Randy Burden Nov 20 '24 at 20:16

score 5 · Answer 2 · answered Jun 04 '14 at 16:58

5

Another option:

MP4Box -add infile.mp4#audio outfile.m4a

MP4Box is part of the gpac package.

answered Jun 04 '14 at 16:58

ʇsәɹoɈ

974
9
12

score 1 · Answer 3 · edited Nov 08 '18 at 13:41

Just for fun, you can also do it by using vlc. The script below strips all *.mp4 files in the current directory to *.m4a. There are some error messages which can be ignored.

#!/bin/bash

quote=\"  
executable="/usr/bin/vlc"
argument3=vlc://quit

#parameters
accessvalue=file
muxvalue=mp4

for x in *.mp4; do
    inputname="${x}"
    strippedname=${x%.mp4}
    outputname=${strippedname}.m4a
    quote_outputname=${quote}./${outputname}${quote}
    echo ${inputname}
    echo ${quote_outputname}
    qtranscode=#transcode{vcodec=none}: # rm this commnt, cont' nxt line !!
    standard{access=$accessvalue,mux=$muxvalue,dst=${quote_outputname}}
    argument1="$inputname"
    argument2=--sout=$qtranscode
    "$executable" -I dummy "$argument1" "$argument2" "$argument3"
done

How to extract aac audio from an mp4 file to m4a

3 Answers3