MPEG
MPEG (Moving Pictures Experts Group) is a standard defined
under
International Standards Organization ISO for
compression of digital video and
audio.
The official name of the standard is ISO / IEC JTC1 SC29 WG11.
MPEG specifically defines a compressed bit stream, that is, it defines decompression algorithms. The compression algorithm, on the other hand, is up to the individual content provider or manufacturers.
This allow companies to maintain a competitive edge based on advantages in compression algorithms.
MPEG uses of
block-based, motion compensated prediction with 8 bit (adaptive) quantization.
A two-dimensional (8 x 8 pixel)
Discrete Cosine transform gives 63 spatial "frequency" coefficients of each image. Run-length coding is applied to these coefficients.
Mostly used MPEG formats are
- MPEG 1 Used in CD-based storage media (e.g., CD-I, CD-rom). Bit rates of about 1.5 Mbit/s
- MPEG 2 is adopted for Digital Video Broadcasting
(DVB). Typical bit rates are 3 .. 8 Mbit/s.
MPEG 2 can be multiplexed, either into a program stream (PS) or a transport stream (TS). In broadcast applications, transport streams are preferred as they can contain several video programs in parallel.
For storage on CD-like media, such as the Digital Video Disc,
program streams are more popular.
- MPEG 3 was originally intended for High Definition TV, which did not appear to become a market success in the late
eighties.
- MPEG 4. To be used in mobile communication. Bit rates are on the order of 64 kbit/s.
