3GP is a simplified version of the MPEG-4 Part 14 (MP4) container format, designed to decrease storage and bandwidth requirements in order to accommodate mobile phones and mobile devises. It stores video streams as MPEG-4 Part 2 or H.263 or MPEG-4 Part 10 (AVC/H.264), and audio streams as AMR-NB, AMR-WB, AMR-WB+, AAC-LC or HE-AAC. A 3GP file is always big-endian, storing and transferring the most significant bytes first. It also contains descriptions of image sizes and bitrate.