1. Motion Predictors and Motion Estimation in H.264 K. C. Yang

2. Outline Variable Size Block Matching in H.264 Concept of Variable Block Sizes Concept of Variable Block Sizes Motion Vector Predictors in H.264 Motion Vector Predictors in H.264 Fast Integer Motion Estimation for H.264 Video Coding Standard An Unsymmetrical-Cross Multi-Resolution Motion Search Algorithm for MPEG4- AVC/H.264 Coding

3. Motion Estimation Video clip Current frame Reference frame Motion vector

4. Variable Block Sizes in H.264 16  16 16  8 8  168  8 8  4 4  8 4  4

5. Block Type Decision Minimize the cost function m : Motion vector m : Motion vector p : Predicted motion vector p : Predicted motion vector MOTION : Largrange multiplier MOTION : Largrange multiplier c : current frame c : current frame r : reference frame r : reference frame Predicted MV Real MV cr

6. MV predictors UPUR LF UP LF UR

7. MV predictors UPUR LF UPUR LF UPUR LF pMV = median (MV UP, MP UR, MV LF ) pMV UP = MV UP, pMV DOWN = MV LF pMV LEFT = MV LF, pMV RIGHT = MV UR

8. MV predictors pMV a = median (MV UP, MP UR, MV LF ) pMV b = median (MV UP, MP UR, MV a ) pMV c = median (MV a, MP b, MV LF ) pMV d = median (MV a, MP b, MV c ) a b cd UPUR LF

9. Fast Integer Motion Estimation for H.264 Video Coding Standard Andy Chang, Peter H. W. Wong, Y.M. Yeung, and Oscar C. Au The Hong Kong University of Science and Technology ICME 2004

10. Observation Hit ratio (8 x 8 MV = 16 x 16 MV) (MV 8x – MV 16x, MV 8y – MV 16y ) Integer MV Sub-pel MV Foreman QCIF 93%76.6% Stefan QCIF 90%82.6% 01 23 Block 0Block 1

11. Algorithm 8 x 8 block Full search Full search 16 x 16 block MV a, MV b, MV c, median(MV UP, MV UR,MV LF ) MV a, MV b, MV c, median(MV UP, MV UR,MV LF ) 16 x 8 block Up : MV a, MV b, MV UP Up : MV a, MV b, MV UP Down : MV c, MV d, MV LF Down : MV c, MV d, MV LF 8 x 16 block Left : MV a, MV c, MV LF Left : MV a, MV c, MV LF Right : MV b, MV d, MV UR Right : MV b, MV d, MV UR LF UPUR ab cd The ME is performed around the eight neighboring locations of the best predicted MV.

12. Simulation Results On average 69.7% computation saving. Stefan

13. An Unsymmetrical-Cross Multi-Resolution Motion Search Algorithm for MPEG4-AVC/H.264 Coding Peng Yang, Yu-Wen He, and Shi Qiang Yang Tsinghua University, China ICME 2004

14. Algorithm Predictor selection Motion estimation Unsymmetrical-cross search Unsymmetrical-cross search Multi-resolution grid search Multi-resolution grid search Extended hexagon-diamond based search Extended hexagon-diamond based search

15. MV Predictors Selection Higher level Lower level

16. 16 x 16 block (0, 0), default predicted MV (0, 0), default predicted MVOthers (0, 0), default predicted MV, and up layer MV (0, 0), default predicted MV, and up layer MV e.g. e.g. Use the Lagrangian cost function to find the minimum. MV Predictors Selection

17. Unsymmetrical-Cross Search

18. Multi-Resolution Grid Search Extended hexagon-diamond based search

19. Simulation Results Compare with the Fast Full Search in JM6.1 time saving

20. Simulation Results Rate-distortion