An MPEG-4 file, known also as an MP4A, is a format used for audio tracks. Since its release in the late 1990s, the format has become commonly used along with .MP3s, .WAVs and .WMAs. The developers of the format released a second version of the format in 2004 to further improve its audio quality capabilities. The format's developers also created the MP4 video format in conjunction with the audio MP4A format. Typically files with the .MP4 extension are known to be video files and the .MP4A extension used for strictly audio tracks.
The Motion Picture Experts Group released the MP4 audio format in 1999. This group is an international organization made up of audio and visual professionals producing audio and video file formats for media devices. Their creations include the MPEG-2, MPEG-3 and MPEG-4 file formats among others. MPEG created the MP4A file format as means of highly compressing audio while still retaining sound quality. The rise in popularity of the internet created a large demand for audio in the online world. Web owners desired a format that would keep file size to a minimum but preserve as much audio quality as possible; the MP4 met this need.
Common Uses of MP4A Files
The MP4A format is often used on streaming audio websites because the reduced file size allows for quicker loading. The MP4A format can be found on MP3 players like the iPod, Microsoft Zune, SanDisk Sansa etc and also on digital media players like Apple's iTunes software. Video game systems such as the XBOX 360 and PlayStation 3 also utilize MP4A files.
MP4A files utilize Audio Advanced Coding technology. This AAC encoding allows the MP4 format to retain audio sound quality while cutting unnecessary data from the file. The Federal Digital Preservation Agency documents that AAC technology allows the MP4A format to provide a higher fidelity experience than the more common MP3 audio format, as published in their digital sustainability report on the MPEG-4 format. This Federal agency works under the Library of Congress in charge of preserving digital copies of files registered with the library.
The MP4A format can reproduce up to 48 different audio tracks in stereo format. This includes 16 low-frequency tracks, 16 overdub/multilingual tracks and 16 data stream tracks. Allowing for 48 tracks increases the acoustic accuracy of original sound recording. The MP4A format also includes support for Apple Lossless encoding, a high fidelity compression standard used in every Apple product including the iPod, iPad, iPhone and Mac computers.