An integrated approach to block based motion estimation for video coding

In video communication systems motion compensation techniques allow one to remove temporal redundancy among frames in order to achieve reductions in the bit rate. Block based approaches are widely used for such a task, since they offer a good balance between performance and complexity; however, the resulting motion fields still present spatial and temporal redundancies, the exploitation of which would allow a greater bit rate reduction. The motion estimation method proposed attains such a goal, maintaining the block based partitioning of the resulting field. It uses a spatio-temporal prediction followed by a lossy coding of the residual field by vector quantization. The prediction is based on autocompensation, enhanced with the aid of some additional parameters so that it provides a stationary error field. The statistical distribution of such a residual field allows vector quantization to perform efficiently, even when the method is applied to video sequences with extremely varying motion activities. Both the prediction and the vector quantization simply use an index for each block to code its motion vector. Finally, the indexes are spatially organized in two single images that are coded with a region based technique