Motion compensated prediction is a powerful tool to reduce temporal redundancies
between frames and is used extensively in MPEG-1 and MPEG-2 video coding standards
as a prediction technique for temporal DPCM coding. The concept of motion compensation
is based on the estimation of motion between video frames, i.e. if all elements in a video
scene are approximately spatially displaced, the motion between frames can be described
by a limited number of motion parameters (i.e. by motion vectors for translatory motion of
pels). In this simple example the best prediction of an actual pel is given by a motion
compensated prediction pel from a previously coded frame. Usually both, prediction error
and motion vectors, are transmitted to the receiver. However, encoding one motion
information with each coded image pel is generally neither desirable nor necessary. Since
the spatial correlation between motion vectors is often high it is sometimes assumed that
one motion vector is representative for the motion of a "block" of adjacent pels. To this aim
images are usually separated into disjoint blocks of pels (i.e. 16x16 pels in MPEG-1 and
MPEG-2 standards) and only one motion vector is estimated, coded and transmitted for
each of these blocks (Figure 2)
Motion compensated prediction is a powerful tool to reduce temporal redundanciesbetween frames and is used extensively in MPEG-1 and MPEG-2 video coding standardsas a prediction technique for temporal DPCM coding. The concept of motion compensationis based on the estimation of motion between video frames, i.e. if all elements in a videoscene are approximately spatially displaced, the motion between frames can be describedby a limited number of motion parameters (i.e. by motion vectors for translatory motion ofpels). In this simple example the best prediction of an actual pel is given by a motioncompensated prediction pel from a previously coded frame. Usually both, prediction errorand motion vectors, are transmitted to the receiver. However, encoding one motioninformation with each coded image pel is generally neither desirable nor necessary. Sincethe spatial correlation between motion vectors is often high it is sometimes assumed thatone motion vector is representative for the motion of a "block" of adjacent pels. To this aimimages are usually separated into disjoint blocks of pels (i.e. 16x16 pels in MPEG-1 andMPEG-2 standards) and only one motion vector is estimated, coded and transmitted foreach of these blocks (Figure 2)
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