Fast Motion Vector Re-estimation for Video Transcoding from MPEG-2 to MPEG-4

The topic of heterogeneous video transcoding from MPEG-2 to MPEG-4 is discussed. Two algorithms of fast motion vector re-estimation in spatial and temporal domain are proposed respectively. Using existing motion information and direct coefficients of DCT to estimate future motion vector, computational cost can be reduced greatly by proposed algorithms. Encoding process can be speeded up and the quality of reconstructed picture is as good as by full searching. Using the proposed algorithms, real-time requirement for internet communication can be met satisfactorily.