Convert 3GP to captions

The 3GP file was created by the 3rd Generation Partnership Project Group (3GPP). It is primarily designed for transmitting multimedia files taken by cell phone videos and sending them over the Internet.
3GP is the required, standard format for media files sent using Multimedia Messaging Service (MMS) and Multimedia Broadcast Multicast Services (MBMS). Thus, the 3GP video container format was developed with the intention to save on disk space, bandwidth, and data usage, which is why they're often seen created from, and transferred between, mobile devices.