Society of Motion Picture and Television Engineers European Broadcasting Union Task Force for Harmonized Standards for the Exchange of Program Material as Bitstreams Final Report: Analyses and Results July 1998 Copyright © 1998 of the European Broadcasting Union (EBU) and the Society of Motion Picture and Television Engineers, Inc. (SMPTE). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means – electronic, mechanical, photocopying, recording, or otherwise – without the prior written permission of one of the copyright holders. Edited and laid out by EBU Technical Review on behalf of the EBU / SMPTE Task Force for Harmonized Standards for the Exchange of Program Material as Bitstreams. Contents Preface 1 Executive summary 3 Systems summary 4 Compression summary 4 Wrappers and Metadata summary 6 Networks and Transfer Protocols summary 6 1. Introduction 8 2. Systems 11 2.1. Introduction 11 2.1.1. Systems of the future will do different things 11 2.1.2. Systems of the future will be quite different 12 2.1.3. New workflows will result from integrated control schemes 12 2.1.4. New types of system design are required 12 2.2. Request for Technology 13 2.3. Object model 14 2.3.1. Why object-oriented technology? 15 2.4. System model 15 2.4.1. Structure of the model 15 2.4.2. Activities 16 2.4.2.1. Pre-production 17 2.4.2.2. Acquisition & Production 17 2.4.2.3. Post-production 17 2.4.2.4. Distribution 17 2.4.2.5. Storage 17 2.4.2.6. Transmission & Emission 17 2.4.2.7. Archiving 17 2.4.3. Planes 18 2.4.3.1. Video Essence 18 2.4.3.2. Audio Essence 18 2.4.3.3. Data Essence 18 2.4.3.4. Metadata 18 2.4.4. Layers 19 2.4.4.1. Application layer 19 2.4.4.2. Network layer 19 2.4.4.3. Data Link layer 19 2.4.4.4. Physical layer 20 2.4.5. Control and Monitoring plane 20 2.5. Operations 20 2.5.1. Control 20 2.5.1.1. Strategic 20 Page i 2.5.1.2. Tactical 21 2.5.1.3. Peer-to-peer 21 2.5.1.4. Resource management 21 2.5.1.5. Physical control network issues 21 2.5.1.6. Multiple forms of implementation 22 2.5.1.6.1. Hierarchical 22 2.5.1.6.2. Peer-to-peer 22 2.5.1.7. Essential characteristics 22 2.5.1.8. Logical control layers 23 2.5.1.8.1. Transaction-based control protocols 23 2.5.1.8.2. Functional APIs 23 2.5.1.8.3. Transition to object-oriented studio control by means of proxies 23 2.5.2. Monitoring, diagnostics & fault tolerance 24 2.5.2.1. Feedback 24 2.5.2.2. Failure prediction 25 2.5.2.3. On-line / Off-line diagnostics 25 2.5.2.4. Fault tolerance 25 2.5.2.4.1. Redundancy 25 2.5.2.4.2. Segmentation 25 2.5.2.4.3. Monitoring and verification 25 2.5.2.4.4. Implementation 26 2.5.2.5. Content integrity 26 2.5.3. Data Essence and Metadata management 26 2.5.3.1. Layered model 27 2.5.3.2. File transfer 27 2.5.3.3. Streaming 27 2.5.3.4. Data Essence 27 2.5.3.4.1. Repetition rate of Data Essence 28 2.5.3.4.2. Registration of Data Essence types 28 2.5.3.5. Metadata 28 2.5.3.5.1. Layered structure 28 2.5.3.5.2. Minimum repetition rate of Metadata types 28 2.5.3.5.3. Registration of Metadata types 29 2.5.3.6. Permanence of Data Essence and Metadata 29 2.5.3.7. Data Essence / Metadata capabilities 29 2.5.3.7.1. Capability in storage systems 29 2.5.3.7.2. Capability in transport systems 30 2.5.3.7.3. Videotape storage 30 2.5.3.7.4. Datatape storage 31 2.5.3.7.5. Disk storage 31 2.5.4. Content multiplexing 31 2.5.5. Multiplexing of Essence into containers 32 2.5.5.1. Transferring Essence between multiplexes 33 2.5.5.2. How to deal with opportunistic data over transports 33 Page ii 2.5.5.3. Multiplexing of different systems / formats 33 2.5.5.4. Statistical multiplexing considerations 33 2.5.6. Timing, synchronization and spatial alignment 34 2.5.6.1. Reference signals 34 2.5.6.2. Absolute time reference 34 2.5.6.3. Temporal alignment 34 2.5.6.4. Timing constraints on compressed signals 34 2.5.6.5. Latency and delay 35 2.5.6.6. Spatial alignment 35 2.5.6.7. Hybrid analog / digital facilities 35 2.6. Interconnection options 35 2.6.1. Development of templates 36 2.6.2. Transfer definitions 36 2.6.3. Hard real-time 36 2.6.3.1. Play-to-air 36 2.6.3.1.1. Video 36 2.6.3.1.2. Audio 37 2.6.3.1.3. Data Essence and Metadata 37 2.6.3.1.4. Control 37 2.6.3.2. Live-to-air 37 2.6.3.3. Live recording 37 2.6.4. Soft real-time 37 2.6.4.1. Video and Audio (uncompressed) 37 2.6.4.2. Video and Audio (compressed) 37 2.6.4.3. Data Essence and Metadata 38 2.6.4.4. Control 38 2.6.5. Non real-time 38 2.6.5.1. File transfers 38 2.6.5.2. Control 38 2.6.5.3. Streaming 38 2.7. Migration 39 2.7.1. Placement of existing protocols into the public domain 39 2.7.2. Essential Common Protocols 39 2.7.3. Interoperability between old and new systems 39 2.8. Economic model 39 2.9. Standards 40 2.9.1. Work under way in the SMPTE 40 2.9.2. Standardization efforts yet to be undertaken 40 2.9.3. Summary of standards required 41 2.10. References 41 2.10.1. Object-oriented technologies 41 3. Compression issues 43 3.1. Introduction 43 3.2. Image quality 44 Page iii 3.2.1. Coding method 44 3.2.2. Sampling structure – SDTV 44 3.2.3. Compression pre-processing 45 3.2.4. Video data-rate – SDTV 46 3.2.5. MPEG Group of Pictures 46 3.2.6. Constant quality vs. constant data-rate 47 3.2.6.1. Constant quality (VBR) systems 47 3.2.6.2. Constant bit-rate (CBR) systems 47 3.2.6.3. Interfacing VBR and CBR environments 47 3.2.7. Editing 47 3.2.8. Concatenated compression 48 3.3. Quality levels 49 3.4. Operational considerations 50 3.4.1. Working with existing compression families 51 3.4.2. Agile decoders 51 3.4.3. Native decoders 51 3.5. Family relations 52 3.5.1. Tools available for intra-family transcoding 52 3.5.2. Compatible intra-family record / replay 52 3.5.3. MPEG at 24 frames-per-second rates 52 3.6. Interfaces 52 3.6.1. Status of interfaces for MPEG-2 and for DV / DV-based compression 52 3.7. Storage 53 3.7.1. Data-rate requirements 53 3.7.2. Resource management 53 3.7.3. Audio, Video and Metadata synchronization 53 3.7.4. VTR emulation 53 3.8. Interoperability 53 3.9. Compliance testing 54 3.9.1. Test equipment 54 3.10. HDTV issues 54 3.11. Audio compression 55 3.11.1. Studio operations 55 3.11.2. Compression issues 56 3.11.2.1. Multi-stage encoding and decoding 56 3.11.2.2. Coding frame structure 56 3.11.2.3. Latency issues 56 3.11.2.4. Mixing 56 3.11.3. Use of Audio compression 57 3.11.3.1. Contribution 57 3.11.3.2. Distribution 57 3.11.3.3. Emission 57 3.11.3.4. Archiving 57 3.11.4. Channel requirements 57 Page iv 3.11.4.1. Mono 57 3.11.4.2. Stereo 58 3.11.4.3. The 5.1 format 58 3.11.4.4. Recording of the 5.1 format on professional videotape recorders 58 3.12. Compression issues: recommendations and current status 58 4. Wrappers and Metadata 61 4.1. Introduction 61 4.2. Purpose of Wrappers 61 4.3. Overall concepts - terminology and structure 62 4.3.1. General 62 4.3.2. Storage, Streaming, File Transfer and editing of Content 62 4.3.3. Content structure 63 4.3.4. Essence 65 4.3.5. Metadata 66 4.3.6. Metadata characteristics 66 4.3.7. Overhead 67 4.3.8. Metadata Sets 67 4.4. General requirements 68 4.4.1. Wrapper requirements 68 4.4.1.1. Size of wrapped Content 68 4.4.1.2. Platform neutrality 68 4.4.1.3. Immutability and generation numbering 68 4.4.1.4. History 68 4.4.1.5. Support of transactions 68 4.4.1.6. Property rights 68 4.4.1.7. Compatibility and conversion 69 4.4.1.8. Extensibility 69 4.4.1.9. Other requirements 69 4.4.2. APIs 70 4.4.3. Breadth of application and Wrapper profiles 70 4.4.4. Framework of a solution 71 4.5.