1. On the use of hierarchical prediction structures for efficient summary generation of H.264/AVC bitstreams Luis Herranz, Jose´ M. Martı´nez Image Communication 2009

2. Outline Introduction System Framework – Skimming Unit (SU) – Coding order – Generation of the summary – Presentation of the summary Experiment

3. Introduction MPEG-2 prediction structure

4. Introduction Hierarchical prediction structure in H.264/AVC using P frames (delay 0)

5. Introduction Hierarchical prediction structure in H.264/AVC using B frames (delay 8)

6. System Framework Analyzing input bitstreamGenerating the summarized bitstream # frames selected Skimming unit (SU) -The selection of SUs -Temporal level

7. Skimming Units Skimming Unit (SU) Temporal layer Index 1 1

8. Skimming Units Overlapped SUs

9. Generation of the Summary Bit stream adaptation guided by skimming parameters

10. Presentation of the Summary Constant frame rate Variable frame rate – Signaling the changes of frame rate – Using a predefined set of SPSs

11. Summarization Modalities Frame selectionSkimming curve

12. Image Storyboard Clustered using K-means algorithm

13. Video Skimming Face detection Moving median filter (a) Frames with face detected (b) Skimming parameters -- 32 frames per GOP (c) Skimming parameters -- 2 frames per GOP

14. Fast Preview Motion activity Median filter (a) Filtered activity (b) Skimming parameters -- 32 frames GOP (c) Skimming parameters -- 2 frames GOP

15. Subjective Evaluation Visual distortionSemantic distortion

16. Performance Evaluation Coding efficiency and processing time

17. Performance Evaluation Bit stream extraction – Low computational cost – Faster generation of the bit stream

18. skim storyboard Fast playback