Temporal prediction and differential coding of motion vectors in the MCTF framework
Motion compensated temporal filtering (MCTF) is used in wavelet video coding schemes to remove temporal redundancy. Current extensions to MCTF use bi-directional filtering and multiple reference frames to improve the coding performance significantly. However, these extensions lead to an additional cost of coding extra sets of motion vectors. In this paper we propose the use of temporal prediction to reduce the bits needed to code motion vectors. We describe several temporal prediction methods, and highlight the advantages of each scheme. We also use MV prediction during motion estimation, i.e. change the search center and the search range based on the temporal prediction, and describe the tradeoffs to be made between rate, distortion, and complexity. We perform several experiments to illustrate the gains of using temporal prediction, and identify the content dependent nature of such results.