International Mobile Telecommunications-2000 (IMT-2000), better known as 3G or 3rd Generation, is a family of standards for mobile telecommunications defined by the International Telecommunication Union,[1] which includes GSM EDGE, UMTS, and CDMA2000 as well as DECT and WiMAX. Services include wide-area wireless voice telephone, video calls, and wireless data, all in a mobile environment. Compared to 2G and 2.5G services, 3G allows simultaneous use of speech and data services and higher data rates (up to 14.4 Mbit/s on the downlink and 5.8 Mbit/s on the uplink with HSPA+). Thus, 3G networks enable network operators to offer users a wider range of more advanced services while achieving greater network capacity through improved spectral efficiency.
The International Telecommunication Union (ITU) defined the third generation (3G) of mobile telephony standards – IMT-2000 – to facilitate growth, increase bandwidth, and support more diverse applications. For example, GSM (the current most popular cellular phone standard) could deliver not only voice, but also circuit-switched data at download speeds up to 14.4 kbps. But to support mobile multimedia applications, 3G had to deliver packet-switched data with better spectral efficiency, at far greater speeds.Technical details
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 [7][8], but older versions of the 3GP file format did not use some of its features.[6] 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 in order to accommodate mobile phones.
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
The 3GP file format 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, 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 was registered by the registration authority for code-points in ISO base media file format ("MP4 Family" files).[9] [10] 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.[7]
The 3G2 file format can store the same video streams and most of audio streams used in the 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.[10] 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.[6] For the storage of MPEG-4 media (MPEG-4 Part 2, MPEG-4 Part 3 - AAC, 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.[11]
Some cell phones use the .mp4 extension for 3GP video.
A 3GP file is always big-endian, storing and transferring the most significant bytes first. It also contains descriptions of image sizes and bitrate.
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).
- Some newer/higher-end phones without 3G capabilities may also playback and record in this format (again, with said limitations).
- Audio imported from CD onto a PlayStation 3 when it is set to encode to the MPEG-4 AAC codec will copy onto USB devices in the 3GP format.
Software support
When transferred to a computer, 3GP movies can be viewed on Linux, Mac, and Windows platforms with MPlayer and VLC media player. Programs such as Media Player Classic, The KMPlayer, Totem, RealPlayer, QuickTime, and GOM Player can also be used.
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