MPEG

The Moving Picture Expert Group (MPEG) is a working group in a subcommittee of ISO/IEC (International Organization for Standardization / International Electrotechnical Commission) in charge of developing international standards for the compression of moving pictures (video), associated audio and their combination. Along with the video and audio coding, MPEG also defines means to multiplex several video, audio and information streams synchronously in one single bitstream.

The basic principle of MPEG video coding is that periodically a complete picture is send and the pictures in between are predicted. Since the decoder can make the same prediction as the coder has made, only the errors on this prediction have to be send.

There are a number of different versions of MPEG:

• MPEG-1: The original standard with a resulting bit rate of around 1,5 Mbit/s with VHS video quality; used for storage such as on a CD-ROM.
• MPEG-2: Optimised for higher quality; typical bit rates of 4 to 9 Mbit/s; used for TV-distribution and DVD; can also be used for high definition TV with bit rates of 80 Mbit/s.
• MPEG-4: Optimised for low bit rates up to only 64 kbit/s; possibilities for interactivity; used for mobile devices and internet distribution¹.
• MPEG-7: Metamodel that describes MPEG-1, 2 or 4 data.

¹Popular video-formats such as DivX and Xvid are based on MPEG-4.