This paper introduces a bi-prediction scheme with only a motion overhead as for unidirectional prediction. It combines motion vectors found by template and block matchings with the overlapped block motion compensation (OBMC). An optimal window function is designed based on a model-based framework. Additionally, the concept of adaptive motion merging is incorporated to enable a template-matching-free implementation. Three algorithms featuring different performance and complexity trade-offs are implemented using the TMuC-0.9-HM software and tested with the common test conditions. Relative to the anchor, the best of them achieves an average BD-rate saving of 2.2%, with a minimum of 0.2% and a maximum of 4.7%.