MPEG stands for the Motion Picture Experts Group, part of the International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC), charged with creating and publishing standards for various areas of technology, respectively. MPEG standards address audio and video formats used online, in television broadcasts, and in DVD media.
A number of MPEG standards are in current use, and more are sure to follow. Some well-known standards are explained briefly below.
MPEG-1: This first set of standards was developed for audio and video compression. Layer 3 is a codec within these standards, known simply as MP3, or the popular audio compression format for music.
This video format was used to store movies on CDs, known as Video CD, or VCD. Quality is equal to that of a VHS tape, and compatibility playback on CD/DVD players is high. One drawback of this standard is that it only supports progressive footage, verses the inclusion of interlaced. These terms relate to the way a picture paints itself across a screen. Progressive monitors (including progressive TVs) paint a picture "from top to bottom" progressively in a single, sequential pass. Interlaced displays paint every other line, then fill in the odd lines in a two-pass process.
MPEG-2: This standard improved on MPEG-1 by including the ability to encode interlaced pictures. It is widely used for digital cable, satellite and over the air digital signals. This format is also prevalent for movies distributed on DVD. Television receivers, DVD players and television stations typically incorporate this standard.
MPEG-2 also contains two container formats: the Transport Stream and Program Stream. These relate to the way digital broadcasts are transmitted and formatted to media, respectively.
MPEG-3: The intention was to make this standard compatible with high-definition TV (HDTV), but this became unnecessary when MPEG-2 extensions expanded that standard's ability to encompass HDTV. At that time, this standard was abandoned.
MPEG-4: Borrowing from the first two standards, MPEG-4 extends functionality of audio/video compression by improving format flexibility. It supports 3-D rendered objects, as well as incorporating the copyright protection scheme known as Digital Rights Management (DRM). This standard can be used for broadcast television, online streaming media, applications such as videophone, and distribution on digital media.
The MPEG-4 standard is developed in “parts” associated with some well-known codecs. For example, DivX, Xvid, Nero Digital and Quicktime6™ are a few codecs that use part 2. A different version of Nero Digital (AVC), and Quicktime (version 7) use part 10, as does the x264 codec. Blu-ray discs and some types of HD DVDs also use this flavor.
MPEG continues to develop (non-sequentially numbered) standards, such as MPEG-7 and MPEG-21, dedicated to multimedia content.