Motion vector re-estimation for fast video transcoding from MPEG-2 to MPEG-4

This paper addresses the topic of heterogeneous video transcoding from MPEG-2 to MPEG-4. A new motion vector resampling/refinement method is proposed based on a variability measure, with which fast transcoding is achieved with no deterioration of video quality. The effectiveness of the new method was verified in a computational experiment. The experimental results obtained show that the total SAD (sum of absolute difference) calculation involved in the motion vector refinement is reduced by about 90% when a full-search algorithm is adopted. Moreover, even when the fast algorithm HAVS (horizontal and vertical search) is adopted for the motion vector search, the SAD calculation is reduced by 10-15%.