How to convert a m4a sound file to mp3?

I tried to convert an .m4a file to an .mp3 file using ffmpeg with the following command:

$ ffmpeg -i music.m4a music.mp3

Unfortunately, I got a zero byte-sized file returned as output. The output of the command is as follows:

FFmpeg version 0.6-4:0.6-2ubuntu6.2, Copyright (c) 2000-2010 the FFmpeg developers built on Sep 16 2011 17:11:24 with gcc 4.4.5 configuration: --extra-version=4:0.6-2ubuntu6.2 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-vaapi --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-x11grab --enable-libdc1394 --enable-shared --disable-static WARNING: library configuration mismatch libavutil configuration: --extra-version=4:0.6-2ubuntu6.2 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-vaapi --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i686/cmov --cpu=i686 --enable-shared --disable-static --disable-ffmpeg --disable-ffplay libavcodec configuration: --extra-version=4:0.6-2ubuntu6.2 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-vaapi --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i686/cmov --cpu=i686 --enable-shared --disable-static --disable-ffmpeg --disable-ffplay libavformat configuration: --extra-version=4:0.6-2ubuntu6.2 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-vaapi --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i686/cmov --cpu=i686 --enable-shared --disable-static --disable-ffmpeg --disable-ffplay libavdevice configuration: --extra-version=4:0.6-2ubuntu6.2 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-vaapi --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i686/cmov --cpu=i686 --enable-shared --disable-static --disable-ffmpeg --disable-ffplay libavfilter configuration: --extra-version=4:0.6-2ubuntu6.2 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-vaapi --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i686/cmov --cpu=i686 --enable-shared --disable-static --disable-ffmpeg --disable-ffplay libswscale configuration: --extra-version=4:0.6-2ubuntu6.2 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-vaapi --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i686/cmov --cpu=i686 --enable-shared --disable-static --disable-ffmpeg --disable-ffplay libpostproc configuration: --extra-version=4:0.6-2ubuntu6.2 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-vaapi --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i686/cmov --cpu=i686 --enable-shared --disable-static --disable-ffmpeg --disable-ffplay libavutil 50.15. 1 / 50.15. 1 libavcodec 52.72. 2 / 52.72. 2 libavformat 52.64. 2 / 52.64. 2 libavdevice 52. 2. 0 / 52. 2. 0 libavfilter 1.19. 0 / 1.19. 0 libswscale 0.11. 0 / 0.11. 0 libpostproc 51. 2. 0 / 51. 2. 0
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'music.m4a': Metadata: major_brand : M4A minor_version : 0 compatible_brands: M4A mp42isom Duration: 00:00:03.41, start: 0.000000, bitrate: 66 kb/s Stream #0.0(und): Audio: aac, 44100 Hz, mono, s16, 63 kb/s
Output #0, mp3, to 'music.mp3': Stream #0.0(und): Audio: 0x0000, 44100 Hz, mono, s16, 64 kb/s
Stream mapping: Stream #0.0 -> #0.0
Encoder (codec id 86017) not found for output stream #0.0

How can I convert an .m4a sound file to an .mp3 file format?

2

12 Answers

The simple way to do it is:

ffmpeg -v 5 -y -i input.m4a -acodec libmp3lame -ac 2 -ab 192k output.mp3

If you want a script to wrap that, try aac2mp3, which should work for you. (The syntax for that last statement was pulled from there.) Inline code included below:

#!/bin/bash
#
# $Id: aac2mp3,v 1.2 03/30/2008 10:00 Daniel Tavares () -
# Based on Script - rali Exp $
#
#
# Convert one or more AAC/M4A files to MP3. Based on a script example
# I found at:
#
ME=`basename ${0}`
FFMPEG="/usr/bin/ffmpeg"
EXT="mp4"
BITRATE="128"
do_usage() { # explanatory text echo "usage: ${ME} [-b nnn] [-e ext] [-f] [-c] [-r] [-v] [-h] [file list]" echo " Convert music from AAC format to MP3" echo " -m /path/app Specify the location of ffmpeg(1)" echo " -b nnn bitrate for mp3 encoder to use" echo " -e ext Use .ext rather than .m4a extension" echo " -f Force overwrite of existing file" echo " -c Delete original AAC|M4A file(s)" echo " -v Verbose output" echo " -h This information" echo "" echo "For recursive directory, use: find -name '*.${EXT}' -exec ${ME} "{}" [args] \;" exit 0 }
do_error() { echo "$*" exit 1 }
file_overwrite_check() { if [ "$FORCE" != "yes" ] then test -f "${1}" && do_error "${1} already exists." else test -f "${1}" && echo " ${1} is being overwritten." fi }
create_mp3() { # use ffmpeg(1) to convert from AAC to MP3 file_overwrite_check "${2}" test $VERBOSE && echo -n "Converting file: ${1}" ${FFMPEG} -v 5 -y -i "${1}" -acodec libmp3lame -ac 2 -ab ${BITRATE}k "${2}"; if [ $? -ne 0 ] then echo "" echo "Error!" do_cleanup do_error "Exiting" fi test $VERBOSE && echo ". OK" }
do_cleanup() { # Delete intermediate and (optionally) original file(s) test ${RMM4A} && rm -f "${1}" test $VERBOSE && echo ". OK" }
do_set_bitrate() { test $VERBOSE && echo -n "Setting bitrate to: $1 kbps" BITRATE=$1 test $VERBOSE && echo ". OK" }
GETOPT=`getopt -o l:m:b:e:cfhrv -n ${ME} -- "$@"`
if [ $? -ne 0 ]
then do_usage
fi
eval set -- "$GETOPT"
while true
do case "$1" in -m) FFMPEG=$2 ; shift ; shift ;; -b) do_set_bitrate $2 ; shift ; shift ;; -e) EXT=$2 ; shift ; shift ;; -f) FORCE="yes" ; shift ;; -c) RMM4A="yes" ; shift ;; -v) VERBOSE="yes" ; shift ;; -h) do_usage ;; --) shift ; break ;; *) do_usage ;; esac
done
test -f $FFMPEG || do_error "$FFMPEG not found. Use \"-m\" switch."
if [ $# -eq 0 ]
then # Convert all files in current directory for IFILE in *.${EXT} do if [ "${IFILE}" == "*.${EXT}" ] then do_error "Not found ${EXT} in this folder." fi OUT=`echo "${IFILE}" | sed -e "s/\.${EXT}//g"` create_mp3 "${IFILE}" "${OUT}.mp3" do_cleanup "${IFILE}" done
else # Convert listed files for IFILE in "$*" do test -f "${IFILE}" || do_error "${IFILE} not found." OUT=`echo "${IFILE}" | sed -e "s/\.${EXT}//g"` create_mp3 "${IFILE}" "${OUT}.mp3" do_cleanup "${IFILE}" done
fi
exit 0

6

This worked for me on Ubuntu 14.04:

avconv -i input.m4a ouptut.mp3

To obtain the avconv command, install libav-tools :

sudo apt-get install libav-tools

3

SoundConverter can do this without having to mess around on the command-line, and it's available in the Ubuntu Software Center:

5

I needed an alternate solution because - my files were sitting in recursive subdirectories - I had spaces in paths.

So I eventually settled for :

 find . -type f -name '*.m4a' -exec bash -c 'avconv -i "$0" "${0/%m4a/mp3}"' '{}' \;

Then deleted the original files :

find . -type f -name '*.m4a' -exec bash -c 'rm "$0"' '{}' \;

3

I created a script to do this.

My requirements were:

• Must maintain as many tags as possible
• Must retain album artwork if exists
• Must be 320K mp3s

Works on all m4a files in a directory, and outputs the new shiny Mp3s into a folder the script creates called Mp3. Warning; this script overwrites existing Mp3s in the output folder if they have the same name. Also uses files 'metadata.txt' and 'metadata2.txt' as temp files.

You'll need to install avconv if it doesn't exist already.

I couldn't figure out how to persist the 'Year' tag into ID3v1 tags, so I didn't enable that option.

#!/bin/bash
files=*.m4a
#create output folder if it doesnt exist
if [ ! -d Mp3 ]; then mkdir Mp3
fi
for file in $files; do mp3File=${file/%m4a/mp3} avconv -y -i "${file}" -f ffmetadata metadata.txt sed -e 's/^date=\(.*\)$/TYER=\1/' -e 's/^major_brand=.*$//' -e 's/^minor_version=.*$//' -e 's/^creation.*$//' -e 's/^compatible.*$//' -e 's/^encoder=.*$//' <metadata.txt >metadata2.txt avconv -y -i "${file}" -i metadata2.txt -ab 320k -map_metadata 1 -id3v2_version 3 "Mp3/${mp3File}"
done

Save it as 'convert.b', and then run the script by typing:

% bash convert.b

2

Sometimes avconv and ffmpeg don't work so cleanly, so:

sudo apt-get install faad lame
faad myfile.m4a -w | lame - myfile.mp3

always works for me.

2

Old question, but I don't see a very simple solution: Use VLC

In VLC you can load a .m4a file and convert it to .MP3 very easyllie.

1. Open VLC (no need to load any file)

2. Click on Media or press CTRL+R

3. Click on Conver/Save

4. On Profile select MP3

5. Select destination

6. Click on Start and wait. To know if it doing something or not, look at the time bar.

I hope this will be usefull for somebody.

1

In Ubuntu 20.04 the original command works out of the box:

ffmpeg -i music.m4a music.mp3

You probably need the unrestricted libav packages in medibuntu repository. Personally I would compile the latest ffmpeg with all codecs, as easy as 123

1

On my L-Ubuntu, libav-tools was not available. I installed winff :

sudo apt-get install winff

which provides a graphical tool to convert audio and video files from and into many different formats.

Just tried : it works fine for .m4a to .mp3 :-)

Otherwise vlc also does a great job playing .m4a files :

sudo apt-get install vlc

Nautilus Script

This Nautilus Script allows user to convert selected file(s) like m4a files --skipping any mp3 or non-audio files-- to mp3 format in the same location using ffmpeg. The new mp3 files will have the highest variable bitrate and preserve most tags, except the year.

#!/bin/sh
#Nautilus Script to convert selected file(s) - excluding any non-audio and MP3 file(s) - to MP3 format at highest quality with VBR (Variable Bit Rate)
OLDIFS=$IFS
IFS="
"
for filename in $@; do
filetype="$(file -bi "$filename" | awk -F "; " '{print $1}' | awk -F "/" '{print $1}')"
if [ "$filetype" != audio ]; then
echo "Skip non-audio file"
else
filesubtype="$(file -bi "$filename" | awk -F "; " '{print $1}' | awk -F "/" '{print $2}')"
if [ "$filesubtype" != mpeg ]; then
file_name_in=$(basename "$filename")
file_name_out="$(basename "$filename" | sed 's/\.[^.]*$//').mp3"
ffmpeg -loglevel quiet -y -i "$file_name_in" -acodec libmp3lame -aq 0 "$file_name_out"
fi
fi
done
IFS=$OLDIFS
/usr/bin/canberra-gtk-play --id="dialog-information" &
notify-send "Selected file(s) converted to MP3 format, excluding any non-audio and MP3 file(s)" -i gtk-dialog-info -t 5 -u normal

I know this question is a bit old, but I think people still see this question (like me), so I share what I have found that worked for me and has a nice UI: fre:ac (). To use in ubuntu just download the binary for ubuntu, decompress and run the file calle freac, that's it. Enjoy!