Temporal trajectory filtering for bi-directional predicted frames
In this work the application of a temporal in-loop filtering approach for B-frames in video compression based on the Temporal Trajectory Filter (TTF) is investigated. The TTF constructs temporal pixel trajectories for individual image points in the P-frames of a video sequence, which can be utilized to improve the quality of the reconstructed frames used for prediction. It is shown, how this concept can be adapted to B-frames despite the fact that these already use temporal motion information to a great extent through the flexible choice of reference frames and prediction modes. The proposed filter has been integrated into the H.264/AVC encoder using the extended profile with hierarchical B-frames and was tested on a wide range of sequences. The filter produces bit rate reductions of up to −4% with an average of −1.6% over all tested sequences while also improving the subjective quality of the decoded video.