MPEG-4 Part 14

MPEG-4 Part 14 or MP4 is a digital multimedia container format most commonly used to store video and audio, but it can also be used to store other data such as subtitles and still images.[2] Like most modern container formats, it allows streaming over the Internet. The only official filename extension for MPEG-4 Part 14 files is .mp4. MPEG-4 Part 14 (formally ISO/IEC 14496-14:2003) is a standard specified as a part of MPEG-4.

Portable media players are sometimes advertised as "MP4 Players", although some are simply MP3 Players that also play AMV video or some other video format, and do not necessarily play the MPEG-4 Part 14 format.

MPEG-4 Part 14
Relations between ISO Base Media File Format and MP4 File Format
MPEG-4 Part 14 extends over ISO Base Media File Format (MPEG-4 Part 12).[1]
Filename extension.mp4, .m4a, .m4p, .m4b, .m4r and .m4v[Note 1]
Internet media typevideo/mp4
Type codempg4
Developed byInternational Organization for Standardization
Type of formatMedia container
Container forAudio, video and text
Extended fromQuickTime File Format and MPEG-4 Part 12
StandardISO/IEC 14496-14
Open format?Yes

History of MP4

MPEG-4 Part 14 is an instance of the more general ISO/IEC 14496-12:2004 (MPEG-4 Part 12: ISO base media file format) which is directly based upon the QuickTime File Format.[3][4][5][6][7] MPEG-4 Part 14 is essentially identical to the QuickTime file format, but formally specifies support for Initial Object Descriptors (IOD) and other MPEG features.[8] MPEG-4 Part 14 revises and completely replaces Clause 13 of ISO/IEC 14496-1 (MPEG-4 Part 1: Systems), in which the file format for MPEG-4 content was previously specified.[9]

The MPEG-4 file format specification was based on the QuickTime format specification published in 2001.[10] The MPEG-4 file format, version 1 was published in 2001 as ISO/IEC 14496-1:2001, which is a revision of the MPEG-4 Part 1: Systems specification published in 1999 (ISO/IEC 14496-1:1999).[11][12][13] In 2003, the first version of the MP4 file format was revised and replaced by MPEG-4 Part 14: MP4 file format (ISO/IEC 14496-14:2003), commonly named as MPEG-4 file format version 2.[14][15] The MP4 file format was generalized into the ISO Base Media File format ISO/IEC 14496-12:2004, which defines a general structure for time-based media files. It in turn is used as the basis for other file formats in the family (for example MP4, 3GP, Motion JPEG 2000).[3][16][17]

MP4 file format versions
Version Release date Standard Description
MP4 file format version 1 2001 ISO/IEC 14496-1:2001 MPEG-4 Part 1 (Systems), First edition
MP4 file format version 2 2003 ISO/IEC 14496-14:2003 MPEG-4 Part 14 (MP4 file format), Second edition

The MP4 file format defined some extensions over the ISO Base Media File Format to support MPEG-4 visual/audio codecs and various MPEG-4 Systems features such as object descriptors and scene descriptions. Some of these extensions are also used by other formats based on ISO base media file format (e.g. 3GP).[1] A list of all registered extensions for ISO Base Media File Format is published on the official registration authority website. The registration authority for code-points (identifier values) in "MP4 Family" files is Apple Inc. and it is named in Annex D (informative) in MPEG-4 Part 12.[16] Codec designers should register the codes they invent, but the registration is not mandatory[18] and some invented and used code-points are not registered.[19] When someone is creating a new specification derived from the ISO Base Media File Format, all the existing specifications should be used both as examples and a source of definitions and technology. If an existing specification already covers how a particular media type is stored in the file format (e.g. MPEG-4 audio or video in MP4), that definition should be used and a new one should not be invented.[16]

Filename extensions

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

  • MPEG-4 files with audio and video generally use the standard .mp4 extension.
  • Audio-only MPEG-4 files generally have a .m4a extension. This is especially true of unprotected content.
    • MPEG-4 files with audio streams encrypted by FairPlay Digital Rights Management as were sold through the iTunes Store use the .m4p extension. iTunes Plus tracks, that the iTunes Store currently sells, are unencrypted and use .m4a accordingly.
    • Audiobook and podcast files, which also contain metadata including chapter markers, images, and hyperlinks, can use the extension .m4a, but more commonly use the .m4b extension. An .m4a audio file cannot "bookmark" (remember the last listening spot), whereas .m4b extension files can.[20]
    • The Apple iPhone uses MPEG-4 audio for its ringtones but uses the .m4r extension rather than the .m4a extension.
  • Raw MPEG-4 Visual bitstreams are named .m4v but this extension is also sometimes used for video in MP4 container format.[21]
  • Mobile phones use 3GP, an implementation of MPEG-4 Part 12 (a.k.a. MPEG-4/JPEG2000 ISO Base Media file format), similar to MP4. It uses .3gp and .3g2 extensions. These files also store non-MPEG-4 data (H.263, AMR, TX3G). In practice, most (if not all) low end phones and feature phones record in this format, as most (if not all) other mobile phones and smartphones record MP4 files using the .mp4 file extension, and some high end phones can record in .raw.

.MP4 versus .M4A

M4A stands for MPEG 4 Audio and is a filename extension used to represent audio files.

Some file managers, such as Windows Explorer, look up the media type and associated applications of a file based on its filename extension. But because MPEG-4 Part 14 is a container format, MPEG-4 files may contain any number of audio, video, and even subtitle streams, therefore it is impossible to determine the type of streams in an MPEG-4 file based on its filename extension alone.

In response, Apple Inc. started using the .m4a filename extension for MP4 containers with audio data in the lossy Advanced Audio Coding (AAC) or its own Apple Lossless (ALAC) formats. Software capable of audio/video playback should recognize files with either .m4a or .mp4 filename extensions, as would be expected, because there are no file format differences between the two. Most software capable of creating MPEG-4 audio will allow the user to choose the filename extension of the created MPEG-4 files.

Data streams

Most kinds of data can be embedded in MPEG-4 Part 14 files through private streams. A separate hint track is used to include streaming information in the file. The registered codecs for MPEG-4 Part 12-based files are published on the website of MP4 Registration authority (,[22] but most of them are not widely supported by MP4 players. The widely supported codecs and additional data streams are:[23]

Other compression formats are less used: MPEG-2 and MPEG-1
Also MPEG-4 Part 3 audio objects, such as Audio Lossless Coding (ALS), Scalable Lossless Coding (SLS), MP3, MPEG-1 Audio Layer II (MP2), MPEG-1 Audio Layer I (MP1), CELP, HVXC (speech), TwinVQ, Text To Speech Interface (TTSI) and Structured Audio Orchestra Language (SAOL)
Other compression formats are less used: Apple Lossless
Nero Digital uses DVD Video subtitles in MP4 files


MP4 files can contain metadata as defined by the format standard, and in addition, can contain Extensible Metadata Platform (XMP) metadata.[24]

See also


  1. ^ a b 3GPP2 (18 May 2007). "3GPP2 C.S0050-B Version 1.0, 3GPP2 File Formats for Multimedia Services" (PDF). 3GPP2: 67, 68. Archived from the original (PDF) on 7 October 2009. Retrieved 2009-06-12.
  2. ^ "Copyrights and Trademarks".
  3. ^ a b - MP4 Registration authority. "References, MPEG-4 Registration authority". Retrieved 2018-08-29.
  4. ^ ISO (April 2006). "ISO Base Media File Format white paper - Proposal". Archived from the original on 2008-07-14. Retrieved 2009-12-26.
  5. ^ ISO (October 2005). "MPEG-4 File Formats white paper - Proposal". Archived from the original on 2008-01-15. Retrieved 2009-12-26.
  6. ^ ISO (October 2009). "ISO Base Media File Format white paper - Proposal". Retrieved 2014-10-31.
  7. ^ Apple Computer. "MPEG-4 Fact Sheet" (PDF).
  8. ^ RE: QT vs MPEG-4
  9. ^ International Organization for Standardization (2003). "MPEG-4 Part 14: MP4 file format; ISO/IEC 14496-14:2003". Retrieved 2009-06-11.
  10. ^ Apple Inc. (2001). "Classic Version of the QuickTime File Format Specification". Retrieved 2009-06-14.
  11. ^ Library of Congress (2001). "MPEG-4 File Format, Version 1". Retrieved 2009-06-14.
  12. ^ Network Working Group (2006). "MIME Type Registration for MPEG-4". Retrieved 2009-06-14.
  13. ^ International Organization for Standardization (2001). "MPEG-4 Part 1: Systems; ISO/IEC 14496-1:2001". Retrieved 2009-06-11.
  14. ^ Library of Congress (2003). "MPEG-4 File Format, Version 2". Retrieved 2009-06-14.
  15. ^ "MPEG-4 Systems General Issues". July 2001. Retrieved 2010-04-11.
  16. ^ a b c ISO (2008). "ISO/IEC 14496-12:2008, Information technology -- Coding of audio-visual objects -- Part 12: ISO base media file format" (PDF). International Organization for Standardization: 88, 94. Retrieved 2009-05-30.
  17. ^ International Organization for Standardization (2004). "MPEG-4 Part 12: ISO base media file format; ISO/IEC 14496-12:2004". Retrieved 2009-06-11.
  18. ^ Steven Greenberg (2009). "Registration of ftyp's". Retrieved 2009-06-15.
  19. ^ Steven Greenberg (2009). "Complete List of all known MP4 / QuickTime 'ftyp' designations". Retrieved 2009-06-15.
  20. ^ M4b Definition -
  21. ^ Doom9's Forum, MP4 FAQ, Retrieved on 2009-07-15
  22. ^ - MP4 Registration authority, Registered Types - Codecs - ISO Code Points, Retrieved on 2009-07-14.
  23. ^ Chapman, Nigel; Chapman, Jenny (2004). Digital multimedia (2. ed.). Chichester [u.a.]: Wiley. ISBN 9780470858905.
  24. ^ "DataDistiller™ Engine". Digital Confidence Ltd. Retrieved 9 June 2014. MP4 metadata can contain various details about the file author, the software used in its creation, and the time and date in which it was created. The metadata can also be structured in XMP format.

External links

3GP and 3G2

3GP (3GPP file format) is a multimedia container format defined by the Third Generation Partnership Project (3GPP) for 3G UMTS multimedia services. It is used on 3G mobile phones but can also be played on some 2G and 4G phones.

3G2 (3GPP2 file format) is a multimedia container format defined by the 3GPP2 for 3G CDMA2000 multimedia services. It is very similar to the 3GP file format but consumes less space & bandwidth also has some extensions and limitations in comparison to 3GP.

Asynchronous serial interface

Asynchronous Serial Interface, or ASI, is a method of carrying an MPEG Transport Stream (MPEG-TS) over 75-ohm copper coaxial cable or multimode optical fiber. It is popular in the television industry as a means of transporting broadcast programs from the studio to the final transmission equipment before it reaches viewers sitting at home.

Audible (store)

Audible is a seller and producer of spoken audio entertainment, information, and educational programming on the Internet. Audible sells digital audiobooks, radio and TV programs, and audio versions of magazines and newspapers. Through its production arm, Audible Studios, Audible has also become the world's largest producer of downloadable audiobooks. Audible's content is only accessible through special proprietary closed software, including unauthorized-playback prevention by means of an Amazon user name and password.

On January 31, 2008 announced it would buy Audible for about $300 million. The deal closed in March 2008 and Audible became a subsidiary of Amazon. The company is based in Newark, NJ and is expanding its presence in the city with the creation of a new technology center. Audible is the United States' largest audio book producer and retailer.

Audio coding format

An audio coding format (or sometimes audio compression format) is a content representation format for storage or transmission of digital audio (such as in digital television, digital radio and in audio and video files). Examples of audio coding formats include MP3, AAC, Vorbis, FLAC, and Opus. A specific software or hardware implementation capable of audio compression and decompression to/from a specific audio coding format is called an audio codec; an example of an audio codec is LAME, which is one of several different codecs which implements encoding and decoding audio in the MP3 audio coding format in software.

Some audio coding formats are documented by a detailed technical specification document known as an audio coding specification. Some such specifications are written and approved by standardization organizations as technical standards, and are thus known as an audio coding standard. The term "standard" is also sometimes used for de facto standards as well as formal standards.

Audio content encoded in a particular audio coding format is normally encapsulated within a container format. As such, the user normally doesn't have a raw AAC file, but instead has a .m4a audio file, which is a MPEG-4 Part 14 container containing AAC-encoded audio. The container also contains metadata such as title and other tags, and perhaps an index for fast seeking. A notable exception is MP3 files, which are raw audio coding without a container format. De facto standards for adding metadata tags such as title and artist to MP3s, such as ID3, are hacks which work by appending the tags to the MP3, and then relying on the MP3 player to recognize the chunk as malformed audio coding and therefore skip it. In video files with audio, the encoded audio content is bundled with video (in a video coding format) inside a multimedia container format.

An audio coding format does not dictate all algorithms used by a codec implementing the format. An important part of how lossy audio compression works is by removing data in ways humans can't hear, according to a psychoacoustic model; the implementer of an encoder has some freedom of choice in which data to remove (according to their psychoacoustic model).


Avidemux is a free and open-source video editing program designed for video editing and video processing. It is written in C++, and uses either GTK+ or Qt for its user interface.

Extensible MPEG-4 Textual Format

The Extensible MPEG-4 Textual Format (XMT) is a high-level, XML-based file format for storing MPEG-4 data in a way suitable for further editing. In contrast, the more common MPEG-4 Part 14 (MP4) format is less flexible and used for distributing finished content.

It was developed by MPEG (ISO/IEC JTC1/SC29/WG11) and defined in MPEG-4 Part 11 Scene description and application engine (ISO/IEC 14496-11).XMT provides a textual representation of the MPEG-4 binary composition technology, based on XML. The XMT framework accommodates substantial portions of SMIL, W3C Scalable Vector Graphics (SVG) and X3D (the new name of VRML). Such a representation can be directly played back by a SMIL or VRML player, but can also be binarised to become a native MPEG-4 representation that can be played by an MPEG-4 player. Another bridge has been created with BiM (Binary MPEG format for XML).


G.723 is an ITU-T standard speech codec using extensions of G.721 providing voice quality covering 300 Hz to 3400 Hz using Adaptive Differential Pulse Code Modulation (ADPCM) to 24 and 40 kbit/s for digital circuit multiplication equipment (DCME) applications. The standard G.723 is obsolete and has been superseded by G.726.

Note that this is a completely different codec from G.723.1.


HandBrake is a free and open-source transcoder for digital video files, originally developed in 2003 by Eric Petit (a.k.a. "titer" from his SVN repository username) to make ripping a film from a DVD to a data storage device easier. Since then, it has undergone many changes and revisions.HandBrake is available for Linux, macOS, and Windows. It uses third-party libraries such as FFmpeg, libvpx, and x265.

ISO base media file format

ISO base media file format (ISO/IEC 14496-12 – MPEG-4 Part 12) defines a general structure for time-based multimedia files such as video and audio.

The identical text is published as ISO/IEC 15444-12 (JPEG 2000, Part 12).It is designed as a flexible, extensible format that facilitates interchange, management, editing and presentation of the media. The presentation may be local, or via a network or other stream delivery mechanism. The file format is designed to be independent of any particular network protocol while enabling support for them in general. It is used as the basis for other media file formats (e.g. container formats MP4 and 3GP).

Internet video

Internet video or online video is the general field that deals with the transmission of video over the Internet. Internet video exists in several formats, the most notable being AVCHD, FLV, and MP4.

There are several online video hosting services, including YouTube, as well as Vimeo, Twitch, and Youku. In recent years, the platform of internet video has been used to stream live events. As a result of the popularity of online video, notable events like the 2012 U.S. presidential debates have been streamed live on the internet. Additionally, internet video has played an important role in the music industry as a medium to watch music videos and gain popularity for songs.


The M4V file format is a video container format developed by Apple and is very similar to the MP4 format. The primary difference is that M4V files may optionally be protected by DRM copy protection.

Apple uses M4V to encode video files in its iTunes Store. Unauthorized reproduction of M4V files may be prevented using Apple's FairPlay copy protection. A FairPlay-protected M4V file can only be played on a computer authorized (using iTunes) with the account that was used to purchase the video. In QuickTime, M4V videos using FairPlay DRM are identified as "AVC0 Media".

Besides Apple iTunes and the Apple QuickTime Player, M4V files can also be opened and played with Media Player Classic, K-Multimedia Player, RealPlayer, Zoom Player, VLC media player, MPlayer, DivX Plus Player, and Nero Showtime (included with Nero Multimedia Suite). The format without DRM can also be played in the webOS Video Player for use on the Palm Pre, Palm Pixi smartphones. It is also playable by the Android operating system with its video player. It is used as the default video conversion format for HandBrake and Air Video Server on the Macintosh. Some other video players can also recognize and play M4V files if the file extension is changed from ".m4v" to ".mp4".Handbrake-produced M4V files can also be played on the PlayStation 3, with full Dolby Digital 5.1 surround support.

MP4 (disambiguation)

MP4 is MPEG-4 Part 14, a file format.

MP4 may also refer to:

Møller–Plesset perturbation theory of the fourth order in computational chemistry

Mario Party 4, a video game for Nintendo GameCube

Metroid Prime 4, an upcoming video game for Nintendo Switch

MP4 (band), a band made up of UK Members of Parliament

Mammal Paleogene zone 4, a division of the Paleogene period

McLaren MP4/1, the McLaren team's Formula One car

MP4, a 2000 album by Michael Penn


MPEG-4 is a method of defining compression of audio and visual (AV) digital data. It was introduced in late 1998 and designated a standard for a group of audio and video coding formats and related technology agreed upon by the ISO/IEC Moving Picture Experts Group (MPEG) (ISO/IEC JTC1/SC29/WG11) under the formal standard ISO/IEC 14496 – Coding of audio-visual objects. Uses of MPEG-4 include compression of AV data for web (streaming media) and CD distribution, voice (telephone, videophone) and broadcast television applications.


mp3PRO is an unmaintained proprietary audio compression codec that combines the MP3 audio format with the spectral band replication (SBR) compression method. At the time it was developed it could reduce the size of a stereo MP3 by as much as 50% while maintaining the same relative quality. This works, fundamentally, by discarding the higher half of the frequency range and algorithmically replicating that information while decoding.

The technology behind SBR was developed by the former Swedish company Coding Technologies AB (acquired by Dolby Laboratories in 2007) in the late 1990s. It was included in their MPEG-2 AAC derived codec aacPlus, which would later be standardized as MPEG-4 HE-AAC. Thomson Multimedia (now Technicolor SA) licensed the technology and used it to extend the MP3 format, for which they held patents, hoping to also extend its profitable lifetime. This was released as mp3PRO in 2001.It was originally claimed that mp3PRO files were compatible with existing MP3 decoders, and that the SBR data could simply be ignored. The reality was that MP3 players lacking specific mp3PRO decoding capability experienced a significant reduction in audio quality when playing mp3PRO files as only the lower half of the original frequency range is available.mp3PRO development has been abandoned. The format was never standardized and there is no publicly available reference source code or documentation in existence. A very old software encoder/player exists, but is not maintained. Nero's Soundtrax application, bundled in the Nero Multimedia Suite, is capable of encoding and decoding this format into several others. Some versions of the outdated MusicMatch Jukebox player were able to decode and encode this format, too. In the early 2000s, mp3PRO was usable in several portable music players and in popular music software, but its market share has deteriorated rapidly. The codec itself is largely surpassed in quality and efficiency, as well as device and application support, by modern codecs like AAC and its HE-AAC variants which employ the same SBR method.

Nero Digital

Nero Digital is a brand name applied to a suite of MPEG-4-compatible video and audio compression codecs developed by Nero AG of Germany and Ateme of France. The audio codecs are integrated into the Nero Digital Audio+ audio encoding tool for Microsoft Windows, and the audio & video codecs are integrated into Nero's Recode DVD ripping software.

Nero certifies certain DVD player/recorder devices as Nero Digital compatible, and licenses the codec technology to integrated circuit manufacturers.The video codecs were developed by Ateme, and according to an interview with Nero AG developer Ivan Dimkovic, the audio codecs are improved versions of Dimkovic's older PsyTEL AAC Encoder. The audio codec is now available as a free stand-alone package called Nero AAC Codec.

QuickTime File Format

QuickTime File Format (QTFF) is a computer file format used natively by the QuickTime framework.

SUPER (computer programme)

SUPER © [sic] (Simplified Universal Player Encoder & Recorder) with first release on 2005 is a closed-source adware front-end for open-source software video players and encoders provided by the FFmpeg, MEncoder, MPlayer, x264, ffmpeg2theora, musepack, Monkey's Audio, True Audio, WavPack, libavcodec, and the Theora/Vorbis RealProducer plugIn projects. SUPER © provides a graphical user interface to these back-end programs, which are command-line based.

eRightSoft official website states that SUPER © is available in two versions:

SUPER © Freeware versionSUPER © Special Edition (Totally Ads Free with exclusive extended features)

Voice Recorder (Windows)

Voice Recorder (Sound Recorder before Windows 10) is an audio recording program included in most versions of the Microsoft Windows family of operating systems. Its user interface has been replaced twice in the past.

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