ELIS – Multimedia Lab An Introduction to Digital Television Rik Van de Walle vakgroep Elektronica...
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Transcript of ELIS – Multimedia Lab An Introduction to Digital Television Rik Van de Walle vakgroep Elektronica...
ELIS – Multimedia Lab
An Introduction toDigital Television
Rik Van de Walle
vakgroep Elektronica en Informatiesystemen (ELIS)faculteit Ingenieurswetenschappen
Universiteit Gent - IBBTGaston Crommenlaan 201 bus 8
9050 Ledeberg-Gentt: 09 33 14914 f: 09 33 14896
secr: +32 9 33 14911
e: [email protected]: multimedialab.elis.ugent.be
<An Introduction to Digital Television><Ghent – November 2008> 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
<An Introduction to Digital Television><Ghent – November 2008> 3/41
ELIS – Multimedia Lab
Example services
• EPG
<An Introduction to Digital Television><Ghent – November 2008> 4/41
ELIS – Multimedia Lab
Example services
• Super teletext
<An Introduction to Digital Television><Ghent – November 2008> 5/41
ELIS – Multimedia Lab
Example services
• Enchanced broadcast
<An Introduction to Digital Television><Ghent – November 2008> 6/41
ELIS – Multimedia Lab
Example services
• Game
<An Introduction to Digital Television><Ghent – November 2008> 7/41
ELIS – Multimedia Lab
Example services
• Banking
<An Introduction to Digital Television><Ghent – November 2008> 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
<An Introduction to Digital Television><Ghent – November 2008> 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
<An Introduction to Digital Television><Ghent – November 2008> 10/41
ELIS – Multimedia Lab
MHP
• MHP API• Platform independent interface• Hide actual system resources
<An Introduction to Digital Television><Ghent – November 2008> 11/41
ELIS – Multimedia Lab
MHP plugins
• Platform specific or application-like plugins
<An Introduction to Digital Television><Ghent – November 2008> 12/41
ELIS – Multimedia Lab
MHP Profiles
• Enhanced broadcast• Interactive broadcast• Internet access
<An Introduction to Digital Television><Ghent – November 2008> 13/41
ELIS – Multimedia Lab
MHP Profiles
• Enhanced broadcast– the most limited profile– video stream– simple applications
• digital teletext
<An Introduction to Digital Television><Ghent – November 2008> 14/41
ELIS – Multimedia Lab
MHP Profiles
• Interactive broadcast– interaction– feedback-channel
<An Introduction to Digital Television><Ghent – November 2008> 15/41
ELIS – Multimedia Lab
MHP Profiles
• Internet access– full internet connection– complicated services
<An Introduction to Digital Television><Ghent – November 2008> 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
<An Introduction to Digital Television><Ghent – November 2008> 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)
<An Introduction to Digital Television><Ghent – November 2008> 18/41
ELIS – Multimedia Lab
MHP Devices
• Main stream / high end specifications – 32-bit color– hard disk– broadband– DVD-recorder– high definition
<An Introduction to Digital Television><Ghent – November 2008> 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
<An Introduction to Digital Television><Ghent – November 2008> 20/41
ELIS – Multimedia Lab
Payment
• Conditional Access Card – defined in DVB-MHP version 1.0.1– 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
<An Introduction to Digital Television><Ghent – November 2008> 21/41
ELIS – Multimedia Lab
MHP Graphics
• 32-bit colors – MHP minimum palette (140+48 colors)
• 3 layers:– background– video– graphics
• Java drawing primitives
<An Introduction to Digital Television><Ghent – November 2008> 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!
<An Introduction to Digital Television><Ghent – November 2008> 23/41
ELIS – Multimedia Lab
MHP layers: Background
<An Introduction to Digital Television><Ghent – November 2008> 24/41
ELIS – Multimedia Lab
MHP layers: Video
<An Introduction to Digital Television><Ghent – November 2008> 25/41
ELIS – Multimedia Lab
MHP layers: Graphics
<An Introduction to Digital Television><Ghent – November 2008> 26/41
ELIS – Multimedia Lab
MHP layers: background
• Only one still image• MPEG I-Frame bitmap• Always full-screen• Opacity cannot be set
<An Introduction to Digital Television><Ghent – November 2008> 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
<An Introduction to Digital Television><Ghent – November 2008> 28/41
ELIS – Multimedia Lab
Layers: graphics
• Graphic layer• Application graphics
<An Introduction to Digital Television><Ghent – November 2008> 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)• Flickering @50 Hz (and even @100 Hz)
<An Introduction to Digital Television><Ghent – November 2008> 30/41
ELIS – Multimedia Lab
TV as multimedia platform
• Environment: extremely UNcontrolled– viewing distance– lighting– attention level– social aspects
<An Introduction to Digital Television><Ghent – November 2008> 31/41
ELIS – Multimedia Lab
DVB-J
• Special Java platform for digital television• JVM is part of OS• A few interfaces
DVB-J
<An Introduction to Digital Television><Ghent – November 2008> 33/41
ELIS – Multimedia Lab
DVB-J Interfaces
• Java– Basic interfaces
• lang, util, beans...
– Graphical libraries• AWT, JMF
– Service interfaces• JavaTV
JavaHaviDAVICDVB
<An Introduction to Digital Television><Ghent – November 2008> 34/41
ELIS – Multimedia Lab
DVB-J Interfaces
• HAVi– Home Audio Video Interoperability– display and user interface libraries
JavaHaviDAVICDVB
<An Introduction to Digital Television><Ghent – November 2008> 35/41
ELIS – Multimedia Lab
DVB-J Interfaces
• DAVIC– Digital Audio Visual Council– payment interfaces– infrastructure interfaces– tuning interfaces
JavaHaviDAVICDVB
<An Introduction to Digital Television><Ghent – November 2008> 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
JavaHaviDAVICDVB
<An Introduction to Digital Television><Ghent – November 2008> 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
<An Introduction to Digital Television><Ghent – November 2008> 38/41
ELIS – Multimedia Lab
Modern version of Teletext services
• DVB-HTML servicesare very often called as supertext-tv services
• It will replace the normal teletext services• New services possible
but most launched applications are the sameas in normal teletext (with pictures)
• So... pretty limited progress compared to'the good old times'
<An Introduction to Digital Television><Ghent – November 2008> 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 levelwhich has to be followed
• Makes it possible to publish content easilyfrom other content management systems, etc.
<An Introduction to Digital Television><Ghent – November 2008> 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!
<An Introduction to Digital Television><Ghent – November 2008> 41/41
ELIS – Multimedia Lab
Questions?
• References– Jaakko Alajoki– Kaarlo Lahtela– Vesa Tikkanen