Rate-constrained multi-hypothesis motion-compensated prediction for video coding

Multi-hypothesis prediction extends motion compensation with one prediction signal to the linear superposition of several motion-compensated prediction signals with the result of increased coding efficiency. The multiple hypotheses in this paper are blocks in past decoded frames. These blocks are referenced by individual motion vectors and picture reference parameters incorporating long-term memory motion-compensated prediction. In this work, we at most employ two hypotheses similar to B-frames. However, they are obtained from the past. Due to the increased rate for the motion vectors, rate-constrained coder control is utilized. For this scheme, we demonstrate the coding efficiency of multi-hypothesis prediction in combination with variable block size and long-term memory and present bit-rate savings up to 32% when compared to standard variable block size prediction without long-term memory motion compensation