The Mobile Media Converter uses ffmpeg to convert MP3 / WAVE / WMA audio files to AMR files (Adaptive Multi-Rate Codec, *.amr) and vice-versa (AMR to MP3). Also, it can convert your WMV (except WMV ver.9) / MPEG video files to 3GPP (3rd Generation Partnership Project, *.3gp) and vice-versa (MPEG to 3GP).
The program has a very easy-to-use and simple GUI (Graphical User Interface) that helps even the most amateur user. Most of the times, the only data that you must enter is the input file(s) or just drag 'n' drop the input file! The 3GP and AMR formats are used by mobile phones for MMS, for video and sound recordings, etc.
and the best thing of all is it has a linux version which is always a plus point for me.
Download Mobile Media Converter
Miksoft Mobile Media Converter[www.miksoft.net]