.3GP

Introduction

3GP is the video file of third-generation mobile phones, defined by the 3rd Generation Partnership Project (3GPP). Phones of the 2000s recorded video and sent picture messages as .3gp files. A sister format from 3GPP2, used on CDMA networks, has the extension .3g2.

The files are small and low in resolution. The video is usually H.263, MPEG-4 Part 2 or H.264, and the audio AMR or AAC.

Structure

3GP is built on the ISO base media file format, like MP4. The file is a sequence of boxes, each a 32-bit big-endian size and a four-letter type. The ftyp box at the start names a 3GPP brand such as 3gp4, 3gp5 or 3gp6 (3g2a for 3GPP2), then moov describes the tracks and mdat holds the media.

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