dirac_YUV420Down2x2: 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/dirac_YUV420Down2x2 - from package: dirac

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

Error in other languages:
dirac_YUV420Down2x2: bevel nie gevind nie
dirac_YUV420Down2x2: comandă negăsită
dirac_YUV420Down2x2: comando não encontrado
dirac_YUV420Down2x2: commande introuvable
dirac_YUV420Down2x2: command not found
dirac_YUV420Down2x2: käsku ei ole
dirac_YUV420Down2x2: không tìm thấy lệnh
dirac_YUV420Down2x2: komanda nerasta
dirac_YUV420Down2x2: Kommando nicht gefunden.
dirac_YUV420Down2x2: kommandot finns inte
dirac_YUV420Down2x2: komut yok
dirac_YUV420Down2x2: nie znaleziono polecenia
dirac_YUV420Down2x2: níor aimsíodh an t-ordú
dirac_YUV420Down2x2: no se encontró la orden
dirac_YUV420Down2x2: no s'ha trobat l'ordre
dirac_YUV420Down2x2: opdracht niet gevonden
dirac_YUV420Down2x2: parancs nem található
dirac_YUV420Down2x2: perintah tidak ditemukan
dirac_YUV420Down2x2: príkaz nenájdený
dirac_YUV420Down2x2: příkaz nenalezen
dirac_YUV420Down2x2: команда не найдена
dirac_YUV420Down2x2: командата не е открита
dirac_YUV420Down2x2: 命令找不到
dirac_YUV420Down2x2: コマンドが見つかりません