1. CS 414 - Spring 2012 CS 414 – Multimedia Systems Design Lecture 12 – MPEG-2/ MPEG-4 (Part 6) Klara Nahrstedt Spring 2012

2. CS 414 - Spring 2012 Administrative MP1

3. Outline MPEG-2/MPEG-4 Reading:  Media Coding book, Section 7.7.2 – 7.7.5  http://www.itu.int/ITU-D/tech/digital- broadcasting/kiev/References/mpeg-4.html http://www.itu.int/ITU-D/tech/digital- broadcasting/kiev/References/mpeg-4.html  http://en.wikipedia.org/wiki/H.264 http://en.wikipedia.org/wiki/H.264 Available software  Xvid – free software  http://www.bing.com/videos/watch/video/xvid-free-download-mpeg-4- video-codec-for-pc http://www.bing.com/videos/watch/video/xvid-free-download-mpeg-4- video-codec-for-pc CS 414 - Spring 2012

4. MPEG-2 Standard Extension MPEG-1 was optimized for CD-ROM and apps for 1.5 Mbps (video strictly non- interleaved) MPEG-2 adds to MPEG-1:  More aspect ratios: 4:2:2, 4:4:4  Progressive and interlaced frame coding  Four scalable modes spatial scalability, data partitioning, SNR scalability, temporal scalability CS 414 - Spring 2012

5. MPEG-1/MPEG-2 Pixel-based representations of content  takes place at the encoder Lack support for content manipulation  e.g., remove a date stamp from a video  turn off “current score” visual in a live game Need support manipulation and interaction if the video is aware of its own content CS 414 - Spring 2012

6. MPEG-4 Compression CS 414 - Spring 2012

7. Interact With Visual Content CS 414 - Spring 2012

8. Original MPEG-4 Conceived in 1992 to address very low bit rate audio and video (64 Kbps) Required quantum leaps in compression  beyond statistical- and DCT-based techniques  committee felt it was possible within 5 years Quantum leap did not happen CS 414 - Spring 2012

9. The “New” MPEG-4 Support object-based features for content Enable dynamic rendering of content  defer composition until decoding Support convergence among digital video, synthetic environments, and the Internet CS 414 - Spring 2012

10. MPEG-4 Components Systems – defines architecture, multiplexing structure, syntax Video – defines video coding algorithms for animation of synthetic and natural hybrid video (Synthetic/Natural Hybrid Coding) Audio – defines audio/speech coding, Synthetic/Natural Hybrid Coding such as MIDI and text-to-speech synthesis integration Conformance Testing – defines compliance requirements for MPEG-4 bitstream and decoders Technical report DSM-CC Multimedia Integration Framework – defines Digital Storage Media – Command&Control Multimedia Integration Format; specifies merging of broadcast, interactive and conversational multimedia for set-top-boxes and mobile stations CS 414 - Spring 2012

11. MPEG-4 Example ISO N3536 MPEG4 CS 414 - Spring 2012

12. MPEG-4 Example ISO N3536 MPEG4 CS 414 - Spring 2012

13. MPEG-4 Example Daras, P. MPEG-4 Authoring Tool, J. Applied Signal Processing, 9, 1-18, 2003 CS 414 - Spring 2012

14. Interactive Drama http://www.interactivestory.net CS 414 - Spring 2012

15. MPEG-4 Characteristics and Applications CS 414 - Spring 2012

16. Example of MPEG-4 Scene Source: http://mpeg.chiariglione.org/standards/mpeg-4/mpeg-4.htm

17. Media Objects An object is called a media object  real and synthetic images; analog and synthetic audio; animated faces; interaction Compose media objects into a hierarchical representation  form compound, dynamic scenes CS 414 - Spring 2012

18. Logical Structure of Scene CS 414 - Spring 2012

19. Example of Composed Scene CS 414 - Spring 2012 Sprite Object Player Object Composed Scene

20. Video Syntax Structure CS 414 - Spring 2012 New MPEG-4 Aspect: Object-based layered syntactic structure

21. Content-based Interactivity Achieves different qualities for different objects with a fine granularity in spatial resolution, temporal resolution and decoding complexity Needs coding of video objects with arbitrary shapes Scalability  Spatial and temporal scalability  Need more than one layer of information (base and enhancement layers) CS 414 - Spring 2012

22. Examples of Base and Enhancement Layers CS 414 - Spring 2012

23. Coding of Objects Each VOP corresponds to an entity that after being coded is added to the bit stream Encoder sends together with VOP  Composition information where and when each VOP is to be displayed Users are allowed to change the composition of the entire scene displayed by interacting with the composition information CS 414 - Spring 2012

24. Spatial Scalability CS 414 - Spring 2012 VOP which is temporally coincident with I-VOP in the base layer, is encoded as P-VOP in the enhancement layer. VOP which is temporally coincident with P-VOP in the base layer is encoded as B-VOP in the enhancement layer.

25. Examples of Base and Enhancement Layers CS 414 - Spring 2012

26. Temporal Scalability CS 414 - Spring 2012

27. High Level Codec for Generalized Scalability CS 414 - Spring 2012

28. Composition (cont.) Encode objects in separate channels  encode using most efficient mechanism  transmit each object in a separate stream Composition takes place at the decoder, rather than at the encoder  requires a binary scene description (BIFS) BIFS is low-level language for describing:  hierarchical, spatial, and temporal relations CS 414 - Spring 2012

29. MPEG-4 Part 11 – Scene Description BIFS – Binary Format for Scenes  Coded representation of the spatio-temporal positioning of audio-visual objects as well as their behavior in response to interactions  Coded representation of synthetic 2D and 3D objects that can be manifested audibly and/or visibly BIFS – MPEG-4 scene description protocol to  Compose MPEG-4 objects  Describe interaction about MPEG-4 objects  Animate MPEG-4 objects BIFS Language Framework – XMT (textual representation of multimedia content using XML)  Accommodates SMIL, W3C scalable vector graphics and VRML (now X3D) CS 414 - Spring 2012

30. MPEG-4 Rendering ISO N3536 MPEG4 CS 414 - Spring 2012

31. Major Components on MPEG-4 Terminal http://mpeg.chiariglione.org/standards/mpeg-4/mpeg-4.htm CS 414 - Spring 2012

32. Integration and Synchronization of Multiple Streams CS 414 - Spring 2012 Source: http://mpeg.chiariglione.org/technologies/mpeg-4/mp04-bifs/index.htm

33. Synchronization Global timeline (high-resolution units)  e.g., 600 units/sec Each continuous track specifies relation  e.g., if a video is 30 fps, then a frame should be displayed every 33 ms. Others specify start/end time CS 414 - Spring 2012

34. Data Recovery CS 414 - Spring 2012 Reversible Variable Length Codes (RVLC) : variable length code words are designed such that they can be read both in forward and reverse directions QP – quantization parameter HEC – header extension code MP – macro-block

35. MPEG-4 parts MPEG-4 part 2  Includes Advanced Simple Profile, used by codecs such as Quicktime 6 MPEG-4 part 10  MPEG-4 AVC/H.264 also called Advanced Video Coding  Used by coders such as Quicktime 7  Used by high-definition video media like Blu- ray Disc CS 414 - Spring 2012

36. MPEG-4 System Layer Model http://mpeg.chiariglione.org/standards/mpeg-4/mpeg-4.htm SL – sync layer DMIF – Delivery Multimedia Integration Framework

37. MPEG-4 File with Media Data http://mpeg.chiariglione.org/standards/mpeg-4/mpeg-4.htm OD – Object Descriptor BIFS – Binary Format for Scenes Mdat – media data atoms

38. Interaction as Objects Change colors of objects Toggle visibility of objects Navigate to different content sections Select from multiple camera views  change current camera angle Standardizes content and interaction  e.g., broadcast HDTV and stored DVD CS 414 - Spring 2012

39. Hierarchical Model Each MPEG-4 movie composed of tracks  each track composed of media elements (one reserved for BIFS information)  each media element is an object  each object is a audio, video, sprite, etc. Each object specifies its:  spatial information relative to a parent  temporal information relative to global timeline CS 414 - Spring 2012

40. Conclusion A lot of MPEG-4 examples with interactive capabilities Content-based Interactivity  Scalability  Sprite Coding Improved Compression Efficiency (Improved Quantization) Universal Accessibility  re-synchronization  data recovery  error concealment CS 414 - Spring 2012