Starting to explain who video compression works. It presents lot of historic points and relations with recents technologies.

1. Video compression
First step
Marc-Antoine ARNAUD
January 2015

3. Why ?
Resolution Raw bit rate Compressed bit rate
720p * 69.1 MB/sec Prores422 HQ: 12.2 MB/sec
Mpeg-2 High: 4.2 MB/sec
HD * 155.5 MB/sec Prores422 HQ: 27.5 MB/sec
Mpeg-2 High: 9.4 MB/sec
2K DCI ** 159.3 MB/sec JPEG2000: 15.6 MB/sec (2Kp48 = 31.25 MB/s)
4K DCI ** 637.0 MB/sec JPEG2000: 62.5 MB/sec
* @ 25fps & 8bits/colour
** @ 24fps & 8bits/colour

4. Who to reduce data ?
Increase the quantity of information* based on:
- human perception
- spatial information
- temporal information
Use binary coding tools
* eq. maximize the entropy of the signal

5. Human Perception

6. Human Perception
Bitdepth

7. Human Perception
Gamma

8. Human Perception
RGB YUV
Colorspace

9. Human Perception
4:4:4 4:2:2 4:1:1 4:2:0
Sub-sampling on YUV

10. Human Perception

11. Human Perception
Interlacing

13. Human Perception
image 1:1
display 4:3
image 4:3
display 1:1
image 1:1
display 1:1
Pixel
Aspect
Ratio

14. Human Perception

15. Spatial information
Macroblock

16. Spatial information
Intra Prediction

17. Temporal information

18. Temporal information
Group Of Picture = GOP

19. Temporal information
Motion prediction

20. Temporal information
Motion prediction

21. Temporal information
Motion prediction

22. Temporal information
Motion prediction

24. Spatial information
Intra Frame
Frame by frame encoding

25. Temporal information
Predicted Frame
- Use previous Intra or Predicted frames only

26. Temporal information
Bidirectional Frame
- Previous Intra frames
- Previous Predicted frames
- Next Predicted frames

27. Temporal information
Motion compensation

28. Spatial information
Frequencies

30. Spatial information
Quantification
High frequencies
reduction / suppression

31. Binary encoding
Zig-zag reordering

32. Binary encoding
Statistical approaches
- Huffman (VLC - CAVLC)
- arithmetic encoding (CABAC)

33. Binary encoding
Huffman
dictionary based on
probabilities of symbols

34. Summary

35. Perceptual Effects
Deblocking Filter

36. Temporal / spatial
Scalabilité

37. Human Perception
High
Dynamic
Range

38. Next steps
- Mpeg 2 vs Mpeg 4
vs HEVC vs Prores
- All about
stereoscopic
- Files formats
(MXF, DCP, IMF...)