mp4info: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/mp4info - from package: libmp4v2

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/mp4info - from package: mp4v2-utils

You may install the required package with command apt-get install {package}

Error in other languages:
mp4info: bevel nie gevind nie
mp4info: comandă negăsită
mp4info: comando não encontrado
mp4info: commande introuvable
mp4info: command not found
mp4info: käsku ei ole
mp4info: không tìm thấy lệnh
mp4info: komanda nerasta
mp4info: Kommando nicht gefunden.
mp4info: kommandot finns inte
mp4info: komut yok
mp4info: nie znaleziono polecenia
mp4info: níor aimsíodh an t-ordú
mp4info: no se encontró la orden
mp4info: no s'ha trobat l'ordre
mp4info: opdracht niet gevonden
mp4info: parancs nem található
mp4info: perintah tidak ditemukan
mp4info: príkaz nenájdený
mp4info: příkaz nenalezen
mp4info: команда не найдена
mp4info: командата не е открита
mp4info: 命令找不到
mp4info: コマンドが見つかりません