MPEG
AcronymMoving Picture Experts Group,small group charged withdevelopmentvideoaudio encoding standards. Since its first meeting1988, MPEG has growninclude approximately 350 members from various industriesuniversities. MPEGISO/IEC JTC1/SC29 WG11.
MPEG has standardizedfollowing compression formatsancillary standards:
- MPEG-1: Includespopular Layer 3 (MP3) audio compression format.
- MPEG-2: Videoaudio standardsbroadcast-quality television. Used on most DVD movies.
- MPEG-3: Originally designedHDTV, but abandonedfavorMPEG-2.
- MPEG-4: Expands MPEG-1support video/audio "objects", 3D content, low bitrate encodingsupportDigital Rights Management.
- MPEG-7: A formal systemdescribing multimedia content.
- MPEG-21: MPEG describes this future standard asMultimedia Framework.
How MPEG works
The MPEG codecs use lossy data compression using transform codecs. In lossy transform codecs, samplespicture or soundtaken, chopped into small segments, transformed into'frequency' space,quantized. The resulting quantized valuesthen entropy coded.
The moving picture coding systems such as MPEG-1, MPEG-2,MPEG-4 add an extra step, wherepicture contentpredicted from past reconstructed images before coding,onlydifferences fromreconstructed pictures,any extra information neededperformprediction,coded.
MPEG standardizes onlybitstream format anddecoder. The encodernot standardizedany way but therereference implementations availablemembers that produce valid bitstreams.
See also:
- Pro-MPEG
