Adding support for additional formats

A suggestion to add support for additional formats. (For example, the *.amr audio file extension) Or to allow adding formats manually. The main (or sole) importance, of course, lies in converting from such formats, rather than to them. For instance, regarding the aforementioned format: if I manually change the file extension to MP3 or WAV, the program converts it successfully and easily—proving that there is no fundamental issue with converting it.