Multihypothesis motion-compensating predictors combine several
motion-compensated signals to predict the current frame of a video signal.
This paper applies the wide-sense stationary theory of multihypothesis
motion compensation for hybrid video codecs to multihypothesis
motion estimation.
This allows us to study the influence of the displacement error correlation
on the efficiency of multihypothesis motion compensation.
Reducing the displacement error correlation between the hypotheses
decreases the variance of the multihypothesis prediction error.
We derive a property for the displacement error correlation
coefficient for an optimal multihypothesis motion estimator in the
mean squared error sense.
We observe for the wide-sense stationary model that jointly optimal
motion estimation improves the prediction performance and reduces the
prediction error variance up to 12 dB per accuracy refinement step
compared to 6 dB per accuracy refinement step for uncorrelated
displacement errors.
Consequently, the gain of multihypothesis motion-compensated prediction
with jointly optimal motion estimation over motion-compensated prediction
increases by improving the accuracy of each hypothesis.
We also discuss the combination of hypotheses with additive noise
and extend the predictor by the optimum Wiener filter.
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