Free 3GP Video Converter changes the format of mobile video files to something that can be played in MP4 or WAV format - the most widely used formats in modern computers and DVD players. It also performs the process in reverse. This application has an advantage over other similar programs in that you can select a particular portion of the video that you want to extract and convert.
This bonus significantly shortens processing time plus the interface is very simple and self explanatory. There is a field for an input file or a YouTube URL and field for an output path, and lists with preconfigured profiles. The best option, as already mentioned, is that you can trim the video with a simple button along the foot of the interface which then opens in a new window. Simply use the navigation line and special buttons to set start and end the selection markers position. Finally, click "Apply & Close" to switch back to the main program window.
In summary, this is a reliable converter and the fact that you can trim 3GP video files is particularly useful for long edits.