1. Delivering Object- Based Audio Visual Services Hari Kalva, Javier Zamora, and Alexandros Eleftheriadis Columbia University, Packet Video 99

2. Outline Introduction Architecture Delivery issues  Object scheduling  Object-to-object communications  Content creation Related works

3. Introduction

4. Two Systems Traditional video on demand system (waveform-based coding)  Don’t care the semantic meaning of blocks  Cause high prediction error on object boundaries Object-based delivery system (content-dependent coding)  Different blocks may belong to the same object

5. Cont. Traditional VoD coding  Record motion, color information  Deliver single stream media Object-based (MPEG-4) coding  Record additional shape information  Deliver extra media composition information

6. Object-Based Coding Video object (VO) Video object plane Video object layer Scene Content creation Same session may contain several video objects T1T1 T2T2

7. MPEG-4 Standard Object-based Encode individual objects Allow object delivering with different QoS Allow object accessing through distributed manner over networks Compose presentations with objects Object description Scene description (BIFS: Binary format for scenes)

8. MPEG-4 Standard (cont.) Object description  Specifies the object shape, compression rate and its behavior Scene description  Specifies the spatio-temporal composition and dynamic behavior of scenes

9. Architecture

10. MPEG-4 Server Server component  MPEG-4 encoder  DMIF instance Responsible to transmission and signaling  Object scheduler Schedule the delivery of access units

11. MPEG-4 Client Player component  DMIF instance Managing data access from a network or a file  Elementary stream decoder Typically contains several decoders to handle specific elementary stream (Elementary stream: object descriptor, scene description, AV object data…)  Compositor Besides decoding and displaying, compose a scene from individual objects

12. Delivery Issues

13. Object Scheduling Offered by MPEG-4 server Due to bandwidth and resource constraint Same video object (VO) may contain different video object layer (VOL) VO 1, VO 2, VOL 1_1, VOL 2_1, VO 3 VO 1 VO 2 VO 3

14. Object-to-Object Communications Need to transmit scene description information Content complexity effects performance  Same bandwidth limitation  Large overhead

15. Content Creation Additional burden on the client to track multiple clocks Difficult to synchronize objects from variant sources R1R1 R2R2

16. Other Problems Numerous, short-appearance objects  Calling for a high rate of establishment and release of numerous short-term transport channels with appropriate QoS. Network delays Data loss

17. Related Applications Animation video creation News reporting