Looking at File Formats and Digital Preservation: MPEG-4

MPEG-4 Part 14 (which is one part of the Moving Picture Experts Group’s MPEG-4 suite of standards for compressing streams of audio and video) is a file format type also referred to as MPEG-4, mp4, and m4a (among others), used to store digital audio and digital video streams. The official filename extension MPEG-4 Part 14 files is .mp4. (According to the Wikipedia article: MPEG-4 Part 14).

The Library of Congress' site on digital preservation of file formats states, "This format is intended to serve web and other online applications; mobile devices, i.e., cell phones and PDAs; and broadcasting and other professional applications."

According to a page found on NYU’s film preservation site, the fact that MPEG-4 files are able to contain audio, video, and subtitle streams makes it difficult to determine the content of these files, and could cause problems when migrating the files, as the different types are all encoded differently. Apple began using the .m4a file extension to distinguish certain audio files from other types of MP4s, but it is not universally held and some audio MP4s will not have this file extension. The format also includes a standardized intellectual property protection coding which could make it difficult to playback those files in the future.


While the audio MP4 files are considered to be of superior quality with smaller file sizes than MP3s, some say that licensing reasons keep MP4s from becoming more popular. The NYU site states, “The MP4 file is open standard; however, the codecs (compression schemes) are commercially licensed. Over two dozen companies claim patents on the MPEG4 suite. These licenses cover the manufacture and sale of devices or software and, for some content disseminators, levy fees according to number of endusers or the extent of content delivered.” The fact that mp4s are not as widely popular, may mean that they will become obsolete in the future. The NYU site further states that, “The Florida Center for Library Automation (FCLA) digital archive has given the file format a rating of "low-confidence" for its digital preservation recommendations.”

MPEG-4 files can be played by: iTunes, QuickTime Player, Winamp, RealPlayer, VLC Media Player, foobar2000, Avidemuxiola, KSP Sound Player, Media Player Classic, MPlayer, and Nero Media Player.

Apple includes an info page on MPEG-4s; they write that their QuickTime application was the foundation for development of the mulitmedia MP4 files. http://www.apple.com/quicktime/technologies/mpeg4/. They write, "Just as QuickTime does, MPEG-4 also scales to transport media at any data rate — from media suitable for delivery over dial-up modems to high-bandwidth networks." And it seems like this is one of the main importances of this format- it's ability to provide higher quality files over a variety of different data rates. They also write on the Apple site that the MPEG-4 standard allows interoperability between different playback products.