The following step-by-step tutorial shows you how to convert 3GP to iPhone 4S video on Mac OS X (including Mac OS X 10.6 Snow Leopard and OS X 10.7 Lion) using iPhone Video Converter for Mac so that you can transfer 3GP to iPhone 4S and watch 3GP video on iPhone 4S.
Add 3GP Files
Download the latest version of iPhone Video Converter for Mac, install and run it.
Click the "Add Files" button to import the 3GP files stored on your Macintosh HD. Then you can get the video information in the manager panel.
Select Output Format
After the 3GP files are imported, go to the "Output" panel. Click the "Profile" drop-down list to choose the format that best fits your needs. Here, you may choose "iPhone MPEG-4 Video" as the output video format.
Note: You may not be satisfied with the profile provided to you. In this case, you can click the "Customize..." button next to "Profile" box to customize a profile. In the following "Profile Settings" Window, you can adjust Video Size, Frame Rate, Encoder, Bitrate; Audio Sample Rate, Channels, Encoder, Bitrate, etc to meet your specific needs.
Start to Convert 3GP to iPhone 4S
When all settings are done, click the "Convert Now" button to start convert 3GP to iPhone 4S.
Transfer Output to iPhone 4S
After you get the output files, launch your iTunes and transfer them to your library. Then you will be able to transfer the converted files to your iPhone 4S with the sync of iTunes.