Curlew is an easy to use, Free and Open-Source Multimedia converter for Linux.
MystiQ
Easy to use and elegant Multimedia converter.
ساؤنڈ کنورٹر
soundKonverter is a frontend to various audio converters.
ڈی اے ڈی بی ایف
DeaDBeeF lets you play variety of audio formats, convert between them, customize the UI almost any way you want, and use many additional plugins which can extend it even more.
سیان
The ciano is a multimedia converter for all the format you need.