Newnes Guide to DigitalTV

Newnes Guide to Digital TV

Newnes Guide to

Digital TV

Richard Brice

OXFORD AMSTERDAM BOSTON LONDON NEW YORK PARIS

SAN DIEGO SAN FRANSISCO SINGAPORE SYDNEY TOKYO

Second edition

Newnes

An imprint of Elsevier Science

Linacre House, Jordan Hill, Oxford OX2 8DP

200 Wheeler Road, Burlington, MA 01803

First published 2000

Second edition 2003

Copyright # 2000, 2003, Richard Brice. All rights reserved

No part of this publication may be reproduced in any

material form (including photocopying or storing in

any medium by electronic means and whether or not

transiently or incidentally to some other use of this

publication) without the written permission of the

copyright holder except in accordance with the provisions

of the Copyright, Designs and Patents Act 1988

or under the terms of a licence issued by the Copyright

Licensing Agency Ltd, 90 Tottenham Court Road, London,

England W1T 4LP. Applications for the copyright holder’s

written permission to reproduce any part of this publication

should be addressed to the publishers

British Library Cataloguing in Publication Data

A catalogue record for this book is available from the British Library

ISBN 0 7506 5721 9

For information on all Newnes publications, visit

our website at www.newnespress.com

Data manipulation by David Gregson Associates, Beccles, Suffolk

Printed and bound in Great Britain by Antony Rowe Ltd., Chippenham, Wiltshire

Preface to the second edition........................... xiii

Preface to the first edition ................................ xv

1 Introduction ..................................................... 1

Digital television............................................................ 1

Why digital? .................................................................. 1

More channels .............................................................. 3

Wide- screen pictures ................................................... 3

Cinema sound............................................................. 4

Associated services ...................................................... 4

Conditional access........................................................ 6

Transmission techniques .............................................. 6

Receiver technology ..................................................... 6

The future . . . ............................................................... 7

2 Foundations of television .............................. 8

A brief history of television............................................ 8

The introduction of colour ............................................. 9

The physics of light ....................................................... 9

Physiology of the eye.................................................... 10

Psychology of vision ^ colour perception...................... 12

Metamerism ^ the great colour swindle ........................ 13

Persistence of vision..................................................... 14

The physics of sound.................................................... 14

Fourier .......................................................................... 16

Transients ..................................................................... 16

Physiology of the ear .................................................... 17

Psychology of hearing .................................................. 18

Masking ........................................................................ 19

Temporalmasking ......................................................... 20

Film and television ........................................................ 21

Television...................................................................... 22

Television signals ......................................................... 24

H sync and V sync ........................................................ 24

Colour television ........................................................... 26

NTSC and PAL colour systems .................................... 27

SECAMcolour system ................................................... 31

Shadowmask tube ........................................................ 32

Vestigial sideband modulation ...................................... 33

Audio for television ....................................................... 34

NICAM728 digital stereo sound.................................... 35

Recording television signals ......................................... 35

Colour under ................................................................. 36

Audio tracks .................................................................. 38

Timecode ...................................................................... 38

Longitudinal timecode................................................... 38

Vertical interval timecode (VITC) .................................. 40

PAL and NTSC ............................................................. 40

User bits........................................................................ 40

TeletextTM.................................................................... 40

Analogue high definition television ( HDTV) ................. 41

MAC .............................................................................. 43

PALplus ........................................................................ 43

1125/ 60 and 1250/ 50 HDTV systems ......................... 44

1250/50 European HDTV ............................................. 44

625- line television wide screen signalling.................... 44

TheWSS signal ............................................................. 44

Data structure ............................................................... 44

Display formats ............................................................. 46

Telecine and  pulldown ............................................... 46

3 Digital video and audio coding...................... 50

Digital fundamentals ..................................................... 50

Sampling theory and conversion .................................. 51

Theory........................................................................... 51

Themechanismof sampling........................................... 53

Aliasing ......................................................................... 54

Quantization.................................................................. 54

Digital-to-analogue conversion ..................................... 55

Jitter .............................................................................. 56

Aperture effect .............................................................. 56

Dither ............................................................................ 56

Digital video interfaces.................................................. 57

Video timing reference signals (TRS)........................... 59

Clock signal .................................................................. 61

Filter templates ............................................................. 61

Parallel digital interface................................................. 62

Serial digital interface ................................................... 63

HDTV serial interface.................................................... 65

Digital audio interfaces ................................................. 66

AES/EBU or IEC958 type 1 interface ........................... 66

SPDIF or IEC958 type 2 interface ................................ 67

Data .............................................................................. 68

Practical digital audio interface ..................................... 70

TOSlink optical interface............................................... 70

Unbalanced (75 ohm) AES interface ............................ 71

Serial multi- channel audio digital interface ( MADI) ..... 72

Data format................................................................... 73

Scrambling and synchronization................................... 76

Electrical format ............................................................ 77

Fibre optic format.......................................................... 77

Embedded audio in video interface .............................. 77

Error detection and handling......................................... 80

EDH codeword generation............................................ 81

EDH flags...................................................................... 83

4 Digital signal processing ............................... 85

Digital manipulation ...................................................... 86

Digital filtering ............................................................... 86

Digital image processing............................................... 88

Point operations ............................................................ 88

Window operations ....................................................... 89

Transforming between time and frequency domains.... 93

Fourier transform .......................................................... 93

Phase............................................................................ 95

Windowing .................................................................... 96

2- D Fourier transforms................................................. 98

More about digital filtering and signal processing......... 99

Convolution................................................................... 100

Impulse response ......................................................... 100

FIR and IIR filters.......................................................... 101

Design of digital filters................................................... 102

Frequency response..................................................... 103

Derivation of band-pass and high-pass filters............... 105

Designing an IIR filter ................................................... 106

IIR filter design example ............................................... 107

High-pass filter example ............................................... 109

Digital frequency domain analysis ^ the z- transform ... 110

Problems with digital signal processing ........................ 110

5 Video data compression ................................ 112

Entropy, redundancy and artefacts............................... 112

Lossless compression .................................................. 113

De-correlation ............................................................... 114

Lossless DPCM and lossy DPCM ................................ 116

Frame differences and motion compensation............... 117

Fourier transform- based methods of compression ...... 119

Transform coding.......................................................... 119

A practicalmix ............................................................... 123

JPEG ............................................................................ 125

Motion JPEG ( MJPEG)................................................ 127

MPEG ........................................................................... 127

Levels and profiles ........................................................ 128

Main profile atmain level ............................................... 129

Main level at 4 : 2 : 2 profile (ML@4 : 2 : 2P) ............... 129

Frames or fields ............................................................ 129

MPEG coding................................................................ 131

Mosquito noise.............................................................. 135

MPEG coding hardware................................................ 135

Statisticalmultiplexing ................................................... 136

DV, DVCAM and DVCPRO .......................................... 137

6 Audio data compression ................................ 139

Compression based on logarithmic representation ...... 139

NICAM .......................................................................... 140

Psychoacoustic masking systems ................................ 140

MPEG layer I compression (PASC).............................. 141

MPEG layer II audio coding (MUSICAM)...................... 142

MPEG layer III .............................................................. 143

Dolby AC- 3 .................................................................. 143

7 Digital audio production ................................ 145

Digital line- up levels and metering............................... 145

The VUmeter ................................................................ 146

The PPMmeter.............................................................. 147

Opto-electronic level indication..................................... 148

Standard operating levels and line- up tones ............... 149

Digital line-up ................................................................ 149

Switching and combining audio signals ........................ 150

Digital audio consoles ................................................... 151

Soundmixer architecture............................................... 151

Mixer automation .......................................................... 152

Digital tape machines ................................................... 153

Digital two-track recording ............................................ 153

Digitalmulti-tracks ......................................................... 154

Digital audio workstations ............................................. 155

Audio file formats .......................................................... 156

WAV files ...................................................................... 156

AU files ......................................................................... 157

AIFF and AIFC.............................................................. 157

MPEG ........................................................................... 157

VOC .............................................................................. 158

Raw PCMdata............................................................... 158

Surround- sound formats .............................................. 158

Dolby Surround............................................................. 158

Dolby digital (AC-3)....................................................... 161

Rematrixing................................................................... 161

Dynamic range compression ........................................ 161

MPEG-II extension tomulti-channel audio .................... 162

Pro logic compatibility ................................................... 162

IEC 61937 interface...................................................... 162

Dynamic range compression ........................................ 163

Multilingual support....................................................... 163

EditingMPEG layer II audio........................................... 163

8 Digital video production................................. 164

Swi4tching and combining video signals ...................... 164

Digital video effects ....................................................... 166

What is a video transition?............................................ 166

The cut.......................................................................... 167

The dissolve.................................................................. 167

The fade........................................................................ 169

Wipes............................................................................ 169

Split-screens ................................................................. 170

Keys .............................................................................. 170

Posterize....................................................................... 171

Chroma-key .................................................................. 172

Off- line editing.............................................................. 174

Computer video standards............................................ 175

Vector and bitmap graphics ^ whats the difference? ... 177

Graphic file formats ....................................................... 178

Windows Bitmap (.BMP)............................................... 179

PCX .............................................................................. 179

TARGA ......................................................................... 179

GIF................................................................................ 179

JPEG ............................................................................ 180

Computer generated images (CGI) and animation....... 180

Types of animation ....................................................... 181

Software........................................................................ 182

2D systems ................................................................... 182

Paint-system functions.................................................. 182

Compositing.................................................................. 188

Morphing and warping.................................................. 189

Rotorscoping................................................................. 190

3D graphics and animation........................................... 191

Matrices ........................................................................ 192

Imaging ......................................................................... 194

Light .............................................................................. 195

Ray tracing.................................................................... 197

Hard disk technology .................................................... 198

Winchester hard disk drive technology ......................... 199

Other disk technologies ................................................ 199

Hard drive interface standards...................................... 200

IDE drives ..................................................................... 200

SCSI ............................................................................. 201

Fibre channel ................................................................ 201

Firewire ......................................................................... 201

RAID ............................................................................. 202

RAID 1 (mirroring)......................................................... 203

RAID 2 (bit striping with error correction)...................... 203

RAID 3 (bit striping with parity) ..................................... 203

RAID 4 (striping with fixed parity) ................................. 204

RAID 5 (striping with striped parity) .............................. 204

Media server ................................................................. 204

Open media framework ................................................ 205

Virtual sets .................................................................... 205

The master control room............................................... 205

Automation.................................................................... 206

Editing and switching of MPEG-II bitstreams................ 208

The ATLANTIC Project................................................. 209

Mole............................................................................ 209

9 The MPEG multiplex ....................................... 210

A  packetized interface ............................................... 210

Deriving the MPEG-II multiplex ..................................... 211

The PES packet format................................................. 211

Transport stream .......................................................... 213

Packet synchronization................................................. 213

Packet identification...................................................... 213

Programassociation tables and programmap tables .... 213

Error handling ............................................................... 214

The adaptation header.................................................. 214

Synchronization and timing signals .............................. 214

Systemand program clock references .......................... 215

Presentation timestamps .............................................. 215

Splicing bitstreams........................................................ 216

Conditional access table............................................... 216

DVB service information ............................................... 216

Conditional access........................................................ 217

SimulCrypt andMultiCrypt............................................. 217

Channel coding............................................................. 218

Randomization (scrambling) ......................................... 218

Reed-Solomon encoding .............................................. 219

Convolutional interleaving............................................. 220

Standard electrical interfaces for the MPEG- II

transport stream............................................................ 221

Synchronous parallel interface ..................................... 221

Synchronous serial interface ........................................ 222

The asynchronous serial interface................................ 223

10 Broadcasting digital video........................... 225

Digital modulation ......................................................... 225

Quadrature amplitude modulation ................................ 225

Modulation for satellite and cable systems ................... 229

Establishing reference phase ....................................... 230

Convolutional or Viterbi coding ..................................... 230

Terrestrial transmission ^ DVB-T (COFDM) and US

ATSC ( 8- VSB) systems .............................................. 231

Coded orthogonal frequency divisionmultiplexing

(COFDM) ...................................................................... 232

Practical COFDM.......................................................... 233

Adding a guard period to OFDMmodulation ................. 233

The advantages of COFDM .......................................... 234

8-VSBmodulation.......................................................... 235

Hierarchical modulation ................................................ 237

Interoperability .............................................................. 238

Interoperability with ATM .............................................. 238

ATMcell and transport packet structures ...................... 239

11 Consumer digital technology ...................... 240

Receiver technology ..................................................... 240

Current set-top box design ........................................... 242

Circuit descriptions ....................................................... 243

Set- top box ^ modern trends........................................ 253

Digital tuner................................................................... 253

Incorporation of hard disk drives (PVR) ........................ 257

COFDMfront-end for DTV-T ......................................... 257

D- VHS.......................................................................... 258

DVD .............................................................................. 259

Track structure.............................................................. 259

Data rates and picture formats ..................................... 260

Audio............................................................................. 261

Control .......................................................................... 262

Regional codes ............................................................. 262

The DVD player ............................................................ 263

CPSA (content protection system architecture)............ 264

Analogue copy protection ............................................. 264

Copy generationmanagement system (CGMS)............ 264

Content scrambling system .......................................... 265

DVD Recordable ( DVD- R) .......................................... 266

General servicing issues............................................... 267

Static and safety ........................................................... 267

Golden rules ................................................................. 267

Equipment..................................................................... 268

DVD faults..................................................................... 268

PSU faults ..................................................................... 269

12 The future ...................................................... 270

Leaning forward and leaning back ................................ 270

Hypertext and hypermedia............................................ 271

HTML documents ......................................................... 271

Anchor tags................................................................... 272

Images .......................................................................... 273

MPEG-IV ^ object-oriented television coding................ 273

Objects and scenes ...................................................... 274

The language................................................................ 275

Virtual realitymodelling language (VRML) .................... 275

Practical VRML files...................................................... 282

MPEG- IV audio............................................................ 284

Structured audio ........................................................... 285

Structured audio orchestra language............................ 285

Text-to-speech systems................................................ 286

Audio scenes ................................................................ 288

MPEG- VII and metadata.............................................. 289

Index ................................................................... 291

Preface to the second edition

In the four years or so since I started work on the first edition of this book,

digital television has changed from being a reality to a common place. My

own family is proof of this. Whether the children are watching a wide

choice of programmes via digital cable in Paris or, more recently, a similar

choice carried by digital satellite in the UK, they have come to expect the

benefits that digital television brings; more channels, better quality,

interactivity etc. In addition to this ubiquity, there have been some real

technical developments too. The inclusion of a hard drive within the set￾top box, speculated on in the first edition, has now become a reality with

the personal video recorder or PVR permitting the tapeless time-shifting of

programmes and true video-on-demand (VOD) movie channels.

But it is not simply in the broadcast areas of television that we have seen

huge advances in the last few years. The adoption of the DV camcorder

and the proliferation of digital editing software on personal computer

platforms has spread digital technology to the videographer as well as the

broadcaster. Most of all, the DVD and the availability of reasonable priced

wide-screen televisions have changed the public’s perception of the

quality boundaries of the experience of watching television. This edition,

therefore, has sought to cover in more detail these trends and develop￾ments and, to that end, you will find herein expanded sections on DVD,

the inclusion of sections on DV video compression and how it differs from

MPEG.

As a general rule, nothing dates so comprehensively in a technical book

as a chapter titled ‘The future’! However, lest one believe that the pace of

change makes it impossible for the non-specialist to follow, I am pleased

to say that digital television has undergone several years of consolidation

rather than revolution and the final chapter remains as relevant as it was

when it was originally written.

xiii