Performance of motion estimators over MPEG coder considering frame delay analysis

We evaluate the performance of motion estimators over an MPEG coder as a function of frame delay. This delay, resulting from the use of bidirectional prediction, contributes to a significant portion of the overall communication delay. Seven fast motion estimation algorithms are considered in our analysis. Modifications of the successive elimination algorithm, proposed by Oliveira and Alcaim (see Proc. International Picture Coding Symposium, Berlin, Germany, p.467-72, 1997) provided the best performance for frame delays ranging between three and nine frames. We show that, for image sequences with full motion content, the benefits of bit rate reduction may not compensate the increase in delay. In order to reduce the bit rate in 26%, an additional delay of six frames has to be introduced. In general, this is not tolerated by most real-time video communication applications