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  1. JCTVC-A022 Multiple Predictor Sets for Intra Coding Lingzhi Liu Huawei Technologies Co., LTD.

  2. Agenda • Introduction • Multiple predictor sets for intra coding • Encoding and decoding processes • Experimental results • Complexity analysis • Conclusion • Future work

  3. Directional Subset: 8 Directional Prediction Mode • Non-directional Subset: 1 no-directionnel Mode (DC Mode) Introduction • Predictor Set in H.264/AVC • Directional Subset: 8 directional predictors • Non-directional Subset: 1 DC predictor • Works well for general sequences but not enough for complex textures.

  4. Multiple predictor sets for intra coding--Ideas • Introduce more predictors to improve the accuracy of predictors. • Keep current framework. • Keep the prediction method for intra prediction mode. • Easy extension to bigger block size

  5. Multiple predictor sets for intra coding--New predictor set • 1 directional subset: 8 predictors • 1 non-directional subset: 1 predictor Directional subset: Uniformly rotating the directional subset in H.264/AVC of 12.5 degree counterclockwise Template matching as the non-directional predictor

  6. Encoding and decoding processes • Current two predictor sets are supported • One flag on macroblock level to indicate the selected predictor set • The same method is used to predict intra prediction mode from neighbor blocks in spite of which predictor set it belongs to. • Reason: the predictors with same intra prediction mode number in different predictor set have similar texture features • Syntax change: if( transform_8x8_mode_flag && mb_type = = I_NxN ) { transform_size_8x8_flag predictor_set_flag }

  7. Experimental results--testing condition • Jm11.0kta26r1 • Constraint set 1 and 2 (All I-frame, CABAC ), Constraint set 2( All I-frame, CAVLC ) • MPSI is applied to Intra 4x4 and Intra 8x8 prediction for all constrain sets • RDO enabled • RDOQ enabled • Full length CFP test sequences (WQVGA, WVGA, 720P and 1080P) • Use QPs defined in Alpha anchor.

  8. Experimental results--Constraint set 1 and 2 (All I-frame, CABAC )

  9. Experimental results--Constraint set 2( All I-frame, CAVLC )

  10. Experimental results-- MPSI + ALF

  11. Complexity analysis--Encoding time

  12. Complexity analysis--Decoding time

  13. Percentage of predictor sets

  14. Conclusion • A new predictor set with similar subsets as in H.264/AVC is introduced to get better prediction of local images with complex textures. • The same method in H.264/AVC can be used to predict the intra prediction mode. • MPSI achieves 3.14 % bit reduction at Constraint set 1 and 2 (CABAC), and 3.89% bit reduction at Constraint set 2 (CAVLC) on average. • Moreover, MPSI is compatible with other KTA tools, and is able to achieve more coding gain when used together.

  15. Future work • Extend MPSI to block size larger than 8x8 (16x16, 32x32, etc) • Introduce more predictor sets to improve the accuracy of intra prediction for larger block sizes.

  16. Thank you! lzliu@huawei.com