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Delivering Object-Based Audio Visual Services

Delivering Object-Based Audio Visual Services. Hari Kalva, Javier Zamora, and Alexandros Eleftheriadis Columbia University, Packet Video 99. Outline. Introduction Architecture Delivery issues Object scheduling Object-to-object communications Content creation Related works. Introduction.

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Delivering Object-Based Audio Visual Services

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  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 additionalshapeinformation • Deliver extra media composition information

  6. Object-Based Coding T1 • Video object (VO) • Video object plane • Video object layer • Scene • Content creation • Same session may contain several video objects T2

  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) VO1, VO2, VOL1_1, VOL2_1, VO3 VO1 VO2 VO3

  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 R2 R1

  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

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