JVET-AF0162 AHG12: Fixes to template matching [J. Chen, R.-L. Liao, X. Li, Y. Ye (Alibaba)]

This contribution reports and fixes the issues in the design of template matching in ECM-10.0. It is reported that the proposed fixes give {-0.01%, 0.05%, 0.03%} in RA and {-0.05%, 0.09%, -0.08%} in LD overall coding gain with no encoding and decoding time increase.

Currently some cost is computed in TM that is never used. The contribution shows that by using the value of this cost some minor gain is achieved in LB.

This was deemed not relevant for action. A ticket might be filed to remove the computation of the value that is not used without a change in performance.