MPEG (Group of Experts in Images in movement) is an international standard, defined by a called committee MPEG formed by the ISO, for the representation codified and compressed of images in movement and audio associate, oriented to digital storage medias.

The disadvantage of this system is that due to his high complexity it needs to lean in specific hardware. MPEG applies to the temporary compression and the space one. The blocks of image and those of prediction of errors have a great space redundancy, that is reduced thanks to the transformation of the blocks from the dominion of the space to the frequency dominion. MPEG requires an intensive computation for its codification, although ratios are obtained from 50:1 to 200:1

Different options exist depending on the use: MPEG-1 defines three types of photograms:

• Photograms I or Intra-photograms, are the normal photograms or of fixed image, providing a moderate compression, in JPEG.
• Photograms P or Predichos: are images predicted from the immediately previous one. A rate of very superior compression is reached.
• Bidirectional photograms B or: they calculate on the basis of the photograms previous and immediately later. It obtains the greater degree of compression at the cost of a greater time of calculation. Standard selected by Video-CD: VHS quality with digital sound.