YUV420ItoYUV422I: 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 Debian possible default full paths are:

/usr/bin/YUV420ItoYUV422I - from package: dirac

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

Error in other languages:
YUV420ItoYUV422I: bevel nie gevind nie
YUV420ItoYUV422I: comandă negăsită
YUV420ItoYUV422I: comando não encontrado
YUV420ItoYUV422I: commande introuvable
YUV420ItoYUV422I: command not found
YUV420ItoYUV422I: käsku ei ole
YUV420ItoYUV422I: không tìm thấy lệnh
YUV420ItoYUV422I: komanda nerasta
YUV420ItoYUV422I: Kommando nicht gefunden.
YUV420ItoYUV422I: kommandot finns inte
YUV420ItoYUV422I: komut yok
YUV420ItoYUV422I: nie znaleziono polecenia
YUV420ItoYUV422I: níor aimsíodh an t-ordú
YUV420ItoYUV422I: no se encontró la orden
YUV420ItoYUV422I: no s'ha trobat l'ordre
YUV420ItoYUV422I: opdracht niet gevonden
YUV420ItoYUV422I: parancs nem található
YUV420ItoYUV422I: perintah tidak ditemukan
YUV420ItoYUV422I: príkaz nenájdený
YUV420ItoYUV422I: příkaz nenalezen
YUV420ItoYUV422I: команда не найдена
YUV420ItoYUV422I: командата не е открита
YUV420ItoYUV422I: 命令找不到
YUV420ItoYUV422I: コマンドが見つかりません