3G2 (3GPP2 file format) is a multimedia container format defined by the 3GPP2 for 5G CDMA2000 multimedia services. It is very similar to the 3GP file format but consumes less space & bandwidth, and has some extensions and limitations in comparison to 3GP.
3G2 is defined in the 3GPP2 technical specification.[2]
Technical details
The factual accuracy of parts of this article (those related to 3GP codec list (see release 12 of 2016 p.65)) may be compromised due to out-of-date information. The reason given is: 3GP has expanded codec lists while 3G2 has stagnated. Please help update this article to reflect recent events or newly available information.(February 2021)
The 3GP and 3G2 file formats are both structurally based on the ISO base media file format defined in ISO/IEC 14496-12 – MPEG-4 Part 12,[8][9][10] but older versions of the 3GP file format did not use some of its features.[7] 3GP and 3G2 are container formats similar to MPEG-4 Part 14 (MP4), which is also based on MPEG-4 Part 12. The 3GP and 3G2 file format were designed to decrease storage and bandwidth requirements to accommodate mobile phones. They are good for lower end smartphones for faster streaming & download.
3GP and 3G2 are similar standards, but with some differences:
3GPP file format was designed for GSM-based phones and may have the filename extension .3gp
3GPP2 file format was designed for CDMA-based phones and may have the filename extension .3g2
Some cell phones use the .mp4 extension for 3GP video.
3GP
The 3GP file format stores video streams as MPEG-4 Part 2, H.263, or MPEG-4 Part 10 (AVC/H.264), and audio streams as AMR-NB, AMR-WB, AMR-WB+, AAC-LC, HE-AAC v1 or Enhanced aacPlus (HE-AAC v2). 3GPP allowed use of AMR and H.263 codecs in the ISO base media file format (MPEG-4 Part 12), because 3GPP specified the usage of the Sample Entry and template fields in the ISO base media file format as well as defining new boxes to which codecs refer. These extensions were registered by the registration authority for code-points in ISO base media file format ("MP4 Family" files).[11][12]
For the storage of MPEG-4 media specific information in 3GP files, the 3GP specification refers to MP4 and the AVC file format, which are also based on the ISO base media file format. The MP4 and the AVC file format specifications described usage of MPEG-4 content in the ISO base media file format.[8]
A 3GP file is always big-endian, storing and transferring the most significant bytes first. [citation needed]
3G2
The 3G2 file format can store the same video streams and most of the audio streams used in the 2007 3GP file format. In addition, 3G2 stores audio streams as EVRC, EVRC-B, EVRC-WB, 13K (QCELP), SMV or VMR-WB, which was specified by 3GPP2 for use in ISO base media file format.[12] The 3G2 specification also defined some enhancements to 3GPP Timed Text. 3G2 file format does not store Enhanced aacPlus (HE-AAC v2) and AMR-WB+ audio streams.[7] For the storage of MPEG-4 media (AAC audio, MPEG-4 Part 2 video, MPEG-4 Part 10 – H.264/AVC) in 3G2 files, the 3G2 specification refers to the MP4 file format and the AVC file format specification, which described usage of this content in the ISO base media file format. For the storage of H.263 and AMR content 3G2 specification refers to the 3GP file format specification.[7]
Device support
Most 3G capable mobile phones support the playback and recording of video in 3GP format (memory, maximum filesize for playback and recording, and resolution limits exist and vary).[citation needed]
Some newer/higher-end phones without 3G capabilities may also playback and record in this format (again, with said limitations).[citation needed]
Apple iDevices used to support files for playback only as passthrough files, hence no editing ability, but since iOS 9 this has been deprecated meaning files of this format have to be manually converted to H.264.[citation needed]
3GP and 3G2 files can be encoded and decoded with open source software FFmpeg.[16] Media tags can be read and written on Linux, macOS and Windows using the open source AtomicParsley command-line utility.[17]
^ ab"Registered types – Codecs". Registration authority for code-points in "MP4 Family" files – mp4ra.org. 2008. Archived from the original on 2009-04-19. Retrieved 2009-05-31.