FAST MACROBLOCK MODE SELECTION BASED ON MOTION CONTENT CLASSIFICATION IN H.264/AVC Ming Yang, Wensheng Wang ICIP 2004

Outline Introduction Introduction Macroblock classification Macroblock classification Macroblock mode selection process Macroblock mode selection process Simulation result Simulation result Conclusion Conclusion

Introduction H.264/AVC introduces many advanced coding techniques: – –Multiple reference picture – –tree-structured motion estimation H.264/AVC enhance the coding efficiency significantly while dramatically increase the computational complexity.

Introduction MB is categorized into two classes, complex motion macroblock (CMB) and simple motion macroblock (SMB) with a fuzzy classifier Different mode search orders are performed with distinct early termination schemes according to the classification.

Macroblock classification Inter-16x16 ︰ MBs move the same direction Inter-16x16 ︰ MBs move the same direction Inter-8x8 ︰ MBs Inter-8x8 ︰ MBs may have complex motion that its parts have different directions or different velocities

Macroblock classification SMB (simple motion block) SMB (simple motion block) –SKIP/DIRECT –Inter-16x16 Inter-16x8 Inter-8x16 CMB (complex motion block) CMB (complex motion block) –Inter-8x8 Inter-8x4 Inter-4x8 Inter-4x4 –Intra-16x16 Intra-4x4

Macroblock classification Membership ： the probability of MB that belongs to CMB Membership ： the probability of MB that belongs to CMB ModemembershipModemembership SKIP0.0DIRECT0.0 Inter-16x160.1Inter-16x80.2 Inter-8x160.2Inter-8x80.8 Intra-4x41.0Intra-16x161.0

Macroblock classification µ L, µ T and µ R ： membership of the left, top, and top-right MB w L, w T and w R ： weight coefficients of the left, top, and top-right MB µ c ： membership of current MB

Macroblock classification µ motion – –determine the category to which current MB belongs – –µ motion ∈ [0, 1] If a macroblock belongs to the CMB, the probability that its neighboring blocks also belong to the CMBs is larger than the probability when a MB is SMB and its neighborhood are also SMB, so µ motion is set to 0.4.

Macroblock classification ucuc uTuT uRuR uLuL w T *u T + w R *u R + w L *u L SBM <u motion CBM w L =3/7 w T =2/7 w R =2/7

Macroblock classification sequence SMB Err-Ratio CMB Err-Ratio Correct Ratio Container3.39%2.24%9a.37% Salesman4.50%2.61%92.89% Children8.19%3.46%88.44% Paris10.81%5.71%83.48% Tempete14.23%7.42%78.35% Mobile18.53%9.04%72.44%

Mode selection process SMB SMB RD_cost of DIRECT is large than adjacent MBs? SKIP Inter16x16 Inter8x16 Inter16x8 Inter8x8 Inter4x8 Inter8x4 Inter4x4 Best mode is SKIP Or Inter16x16? YES NO END GO to step3

Mode selection process CMB CMB SKIP Inter8x8 Inter8x4 Inter4x8 Inter4x4 Inter16x16 DIRECT Inter8x16 Inter16x8 More than 2 sub-MB are not Inter8x8 YES NO GO to step3

Mode selection process Best is inter8x8? Intra16x16 Intra4x4 YES NO END Step 3: Step 3:

Mode selection process sequenceET-MBET-RatioCorrect-MBRatio Container % % Salesman % % Children % % Paris % % Tempete % % Mobile % % If the MB has skipped some mode groups except only omitted the two INTRA modes

Simulation result

Conclusion Fast macroblock mode selection algorithm in H.264/AVC is proposed base on the classification of the motion content complexity The method can save 40%−70% of the 4×4 block SAD and SATD calculations over the typical fast motion estimation algorithms such as the DS, HEXBS,4SS, and BBGDS.