installing ffmpeg on debian is rather tricky (you will need to compile from source).

under CentOS7 it is easy

yum install ffmpeg

and you can substitute avconv command with ffmpeg and the script just works the same. thanks to all involved! GREAT JOB! so a command that works as „substitue“ is package_info_libav_tools_avconv.txt that has similar/same command line options/arguments…

sudo bash;
apt-get update;
apt-cache search libavcodec
libavcodec-extra - Libav codec library (additional codecs meta-package)
libavcodec-extra-56 - Libav codec library (additional codecs)
libavcodec56 - Libav codec library
winff - graphical video and audio batch converter using ffmpeg or avconv
libavcodec57 - Library to encode decode multimedia streams - runtime files
libavcodec-dev - Library to encode decode multimedia streams - devel files
libavfilter6 - FFmpeg filter library
libavfilter-dev - Development files for libavfilter
mencoder - MPlayer's Movie Encoder
libmythavcodec57 - libavcodec package for MythTV

apt-get install libav-tools libavcodec-extra-56;

vim /scripts/;

echo "$1";
avconv -i "$1" -c:a libmp3lame -ac 2 -q:a 2 "$1.mp3";
# save and quit :wq

chmod u+x /scripts/;

to convert aac to mp3 go a

/scripts/ filename.aac
vim /scripts/

echo "$1";
avconv -i "$1" -c:a libmp3lame -ac 2 -q:a 2 "$1.mp3";