ELIS – Multimedia Lab An Introduction to Digital Television Rik Van de Walle vakgroep Elektronica en Informatiesystemen (ELIS) faculteit Ingenieurswetenschappen Universiteit Gent - IBBT Gaston Crommenlaan 201 bus Ledeberg-Gent t: f: secr: e: URL: multimedialab.elis.ugent.be

2/41 ELIS – Multimedia Lab Why digital TV? Better image quality More channels Multiple audio channels Subtitles The most important: applications The whole new world of services

3/41 ELIS – Multimedia Lab Example services EPG

4/41 ELIS – Multimedia Lab Example services Super teletext

5/41 ELIS – Multimedia Lab Example services Enchanced broadcast

6/41 ELIS – Multimedia Lab Example services Game

7/41 ELIS – Multimedia Lab Example services Banking

8/41 ELIS – Multimedia Lab Link to MHP Multimedia Home Platform (MHP) defines a generic interface between –interactive digital applications –the terminals on which those applications execute

9/41 ELIS – Multimedia Lab MHP application types Interactive vs. non-interactive –feedback channel or not DVB-J DVB-HTML Built-in guides: –EPG (Electronic Program Guide) –ESG (Electronic Service Guide) –information about TV programs –UI built into operating system

10/41 ELIS – Multimedia Lab MHP MHP API Platform independent interface Hide actual system resources

11/41 ELIS – Multimedia Lab MHP plugins Platform specific or application-like plugins

12/41 ELIS – Multimedia Lab MHP Profiles Enhanced broadcast Interactive broadcast Internet access

13/41 ELIS – Multimedia Lab MHP Profiles Enhanced broadcast –the most limited profile –video stream –simple applications digital teletext

14/41 ELIS – Multimedia Lab MHP Profiles Interactive broadcast –interaction –feedback-channel

15/41 ELIS – Multimedia Lab MHP Profiles Internet access –full internet connection –complicated services

16/41 ELIS – Multimedia Lab MHP Devices Devices –set-top boxes Scart connection like VCR (Videocassette Recorder) prices starting from 50 € –integrated TV sets Firmware can be updated from broadcast or manually

17/41 ELIS – Multimedia Lab MHP Devices Low-end typical specifications –32 MB Flash memory –~150 MHz processor –minimum color palette –remote control, no keyboard –CA module (Controlled Availability) –tuner (C/T/S)

18/41 ELIS – Multimedia Lab MHP Devices Main stream / high end specifications –32-bit color –hard disk –broadband –DVD-recorder –high definition

19/41 ELIS – Multimedia Lab Remote controller MHP defines –arrow keys –OK –TXT –numbers 0-9 –color keys (in this order): red, green, yellow, blue There are also other keys, that are not required

20/41 ELIS – Multimedia Lab Payment Conditional Access Card –defined in DVB-MHP version –enables commercial channels, but pay-per-view-services are not supported Smart Card –user authentication, transactions, paying via TV –defined in DVB-MHP version 1.1

21/41 ELIS – Multimedia Lab MHP Graphics 32-bit colors –MHP minimum palette ( colors) 3 layers: –background –video –graphics Java drawing primitives

22/41 ELIS – Multimedia Lab MHP Graphics Image formats –JPEG, GIF, PNG, MPEG I-Frame One resident font –Tiresias Screenfont Scaled video Combined web graphic and TV artist skills needed!

23/41 ELIS – Multimedia Lab MHP layers: Background

24/41 ELIS – Multimedia Lab MHP layers: Video

25/41 ELIS – Multimedia Lab MHP layers: Graphics

26/41 ELIS – Multimedia Lab MHP layers: background Only one still image MPEG I-Frame bitmap Always full-screen Opacity cannot be set

27/41 ELIS – Multimedia Lab Layers: video MPEG-video from TV-stream Video is scalable –full screen, 1/4, 1/16 –other if supported by device Some devices support multiple simultaneous video streams, but this is not required by MHP-standard

28/41 ELIS – Multimedia Lab Layers: graphics Graphic layer Application graphics

29/41 ELIS – Multimedia Lab TV as multimedia platform Poor sharpness Bright colors saturate Interlaced –image consist of two separate set of horizonal lines Many aspect ratios (4/3, 14/9, 16/9) –pixels are not squares Resolution is small (PAL 720x576) Hz (and Hz)

30/41 ELIS – Multimedia Lab TV as multimedia platform Environment: extremely UNcontrolled –viewing distance –lighting –attention level –social aspects

31/41 ELIS – Multimedia Lab DVB-J Special Java platform for digital television JVM is part of OS A few interfaces

DVB-J

33/41 ELIS – Multimedia Lab DVB-J Interfaces Java –Basic interfaces lang, util, beans... –Graphical libraries AWT, JMF –Service interfaces JavaTV Java Havi DAVIC DVB

34/41 ELIS – Multimedia Lab DVB-J Interfaces HAVi –Home Audio Video Interoperability –display and user interface libraries Java Havi DAVIC DVB

35/41 ELIS – Multimedia Lab DVB-J Interfaces DAVIC –Digital Audio Visual Council –payment interfaces –infrastructure interfaces –tuning interfaces Java Havi DAVIC DVB

36/41 ELIS – Multimedia Lab DVB-J Interfaces DVB –Digital Video Broadcasting –extensions and limitations to Java-interfaces –data access interfaces –I/O-device interfaces –security interfaces –other interfaces Java Havi DAVIC DVB

37/41 ELIS – Multimedia Lab DVB-HTML Digital Video Broadcasting – HyperText Markup Language HTML-like environment for television Technologies –XML, XHTML, CSS, DOM, ECMAScript Basic principles –pages or 'screens' are received from media carusel –same way of thinking as in normal teletext service

38/41 ELIS – Multimedia Lab Modern version of Teletext services DVB-HTML services are very often called as supertext-tv services It will replace the normal teletext services New services possible but most launched applications are the same as in normal teletext (with pictures) So... pretty limited progress compared to 'the good old times'

39/41 ELIS – Multimedia Lab DVB-HTML services Very close to normal HTML and XHTML/XML services Standardized by W3C –includes many features that are not currently implemented to real products –DVB-MHP project describes the minimum level which has to be followed Makes it possible to publish content easily from other content management systems, etc.

40/41 ELIS – Multimedia Lab DVB-HTML services Few example services –news –extra information about tv-series or events –traffic jam information –bus timetables –subject specific portals –payment services order new services or products via television requires feedback channel!

41/41 ELIS – Multimedia Lab Questions? References –Jaakko Alajoki –Kaarlo Lahtela –Vesa Tikkanen