[eksasol]

Edit: Sorry I miss read your post the first time. It seem you want to playback 3GP files, I'm guessing from your computer. 3GP is not a format but a container and within it usually contain MPEG4 format videos.

You can use "VLC Player" which support just about any video formats. Or if you use Windows Media Player or Media Player Classic, try installing "ffdshow" which is an encoder and decoder that will enable WMP or MPC to support all the extra video and audio formats.

If you need to convert the videos, then I recommend WinFF to everyone, it is a batch video and audio converter. It utilizes ffmpeg which support a large amount of formats. There are presets for many popular portable devices so just select the preset to convert and click convert. It's very easy to use, but is also very efficient. You can get it at winff.org.