MPEG-2

MPEG-2 is a standard for the compression of video and audio. MPEG-2 is optimised for the compression of TV and HDTV with a high quality. MPEG-2 is used for TV-distribution (DVB) over the air, cable and satellite, and on DVD. The typical bit rates for the compression of TV is 4 to 9 Mbit/s. For high definition TV, the bit rate is in the order of 80 Mbit/s.

At first, the MPEG-2 audio standard just consisted of two extensions to MPEG-1. Firstly, the introduction of multichannel coding including the 5.1 channel configuration. Secondly, coding at lower sampling frequencies of 16, 22.05 and 24 kHz to improve te performance at very low bit-rates. Later on, it was realised that giving up backward comptability with MPEG-1 promised a significant improvement in coding efficiency. As a result this led to the definition of MPEG-2 Advanced Audio Coding (AAC).

Other properties of MPEG-2 are:

• Backwards compatible with MPEG-1,
• Full-screen interlaced and progressive video,
• Enhanced audio coding compared tot MPEG-1,
• Multiplexing of video streams (TV channels) in a transport stream,
• Other services, such as:
  • Electronic Programme Guide,
  • Interactive TV,
  • Encryption.

The MPEG-2 standard only defines the function of the encoder. It allows freedom in the design of the decoder.