MPEG-4 Part 14

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"MP4" redirects here. For , see .

MPEG-4 Part 14, formally, ISO/IEC 14496-14:2003, is a multimedia container format standard specified as a part of MPEG-4. It is most-commonly used to store digital audio and digital video streams, especially those defined by MPEG, but also can be used to store other data such as subtitles and still images. Like most modern container formats, MPEG-4 Part 14 allows streaming over the Internet. The official filename extension for MPEG-4 Part 14 files is .mp4, thus the container format is often referred to simply as MP4.

Contents

1 History
2 Data streams
3 File extensions
4 Product support
5 See also
6 External links

History

MPEG-4 Part 14 was based on Apple's QuickTime container format.[link] Although MPEG-4 Part 14 still resembles the QuickTime format, it has been improved upon in many different ways.

Data streams

Almost any kind of data can be embedded in MPEG-4 Part 14 files through private streams; the widely-supported codecs and additional data streams are:

Video: MPEG-4 Part 10 (also known as H.264 and MPEG-4 AVC), MPEG-4 Part 2, MPEG-2, and MPEG-1.
Audio: AAC (also known as MPEG-2 Part 7), MP3 (also known as MPEG Audio Layer 3), MPEG-4 Part 3, MP2 (also known as MPEG Audio Layer 2), MPEG-1 Part 3, CELP (speech), TwinVQ (very low bitrates), SAOL (MIDI).
Subtitles: MPEG-4 Timed Text (also known as 3GPP Timed Text).

Some private stream examples include Nero's use of DVD subtitles (Vobsub) in MP4 files. They are however not a part of the MPEG-4 file format standard and programs are not required to support them.

File extensions

While the only official file extension defined by the standard is .mp4, various file extensions are commonly used to indicate intended content.

Audio generally uses the .mp4 and .m4a extensions.
* Audio that is protected by FairPlay Digital Rights Management as sold through the iTunes Music Store uses the .m4p extension.
* Audio book and podcast files, which also contain data such as chapter markers, images, and hyperlinks, can use the extension .m4a, but more commonly use the .m4b extension.
Video generally uses the .mp4 and .m4v extensions, sometimes also .mp4v.
3G mobile phones use 3GP, a simplified version of MPEG-4 Part 12 (a.k.a MPEG-4/JPEG2000 ISO Base Media file format, MPEG-4 Part 14 is a derivated standard from ISO Base file format too), with the .3gp and .3g2 extensions. These files also store non-MPEG-4 data (H.263, AMR, TX3G).

The common, but non-standard use of the extensions .m4a and .m4v is due to the popularity of Apple Computer's iPod and the iTunes Music Store.

Product support

Most video software supports MPEG-4 Part 14, such as:

External links

[ISO catalog] for purchasing the specification
[MPEG-4 File Formats white paper]
[The MP4 registration authority]
[Mp4]

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