The Difference between MP3s and MP4s

Both the MP3 and MP4 file formats are technologies for compressing large analog files (like those on a store-bought CD) into more compact digital files. The purpose for both technologies is to allow delivery of high-quality media at a fraction of the size. The primary difference between the two file formats is that MP3 is for sound only whereas MP4 is for sound and video.

Prior to the advent of MP3s and MP4s, when media files were compressed, they instantly became significantly diminished in quality. MP3s and MP4s, however, allow for high data compression rates of multiple media streams into a single file with a minimal quality loss.

The MP3 format (aka MPEG-1 Layer III or MPEG Audio Layer III) came into existence in 1992 and rapidly spawned the invention of portable MP3 players (i.e. the Apple iPod, the Microsoft Zune, or the Dell Digital Jukebox), and business models for selling these types of media files (ie. Apple iTunes or Real Rhapsody).

MP3 is an MPEG standard for compressing files that is most often used for transmitting music digitally over the internet. While a store-bought audio CD can hold about 20 songs max., a CD that is encoded using MP3 files can hold up to around 200 songs. Today's MP3 players are capable of storing literally thousands of songs.

When Apple innovated the selling of digital music online, it needed to demonstrate to the music industry, which was at the time embroiled in piracy concerns fueled by Napster, that it could control the legalized distribution of copyrighted media files so that consumers were prevented from stealing music.

Enter the AAC (Advanced Audio Coding) format, also known as the precursor to the MP4 (and consequently MP4 players), a proprietary file format first released in 1999 that gave Apple control over how the music it sold was (and wasn't) used. To boot, Apple professed that this format offered improve sound quality than was possible with MP3s and MP3 players. This format (commonly referred to as QuickTime format) became the basis for the invention by MPEG of the MP4 (also known as ISO/IEC 14496-14:2003).

In addition to audio and video, MP4s can also contain subtitles, pictures, and rich media content like DVD -style interactive menus and interfaces, and 2D and 3D graphics.

A challenge for consumers regarding MP4s is that they can only be played on select devices, such as iPods, the iTunes interface, and other MP4 players and portable MP4 players, whereas MP3s can be played on any digital media device, computer-based and portable MP3 players, and computer-based and portable MP4 players alike. This restricts purchasers of MP4s to using select MP4 players and other compatible devices to enjoy their music and videos, restricting portability as well as flexibility in the types of digital media player and devices that the consumer can purchase in the future without losing the ability to enjoy all the bought-and-paid-for MP4 encoded media in their collection.