Transcript Types and Methods of Content Adaptation - TKK

Types and Methods of Content Adaptation
T-110.456 Next Generation Cellular Networks
Timo-Pekka Viljamaa
2.3.2005
Agenda
• Motivation for Content Adaptation
• Types of Content Adaptation
• Methods of Content Adaptation
• Real Life Examples
• Conclusions
• Further Reading
Motivation for Content Adaptation
• Terminal diversity
• Different display size, bandwidth, memory, processing power, UI, etc.
• Available network environment
• Depending on the current location and the terminal support
• UMTS/GPRS/GSM Data
• User preferences
• Information presenting styles
• e.g. scrollable/splitted to several views
• Time issues
• e.g. see utilitarian content quickly/wait for flashy content
• Cost issues
• Definition of Multimedia Unit (MMU)
• The unit of data transmitted over a network containing one or more
multimedia content elements
• e.g. multimedia message in MMS, elements of a web page (typical
composed of several MMUs)
Types of Content Adaption
• Format Adaption
• Characteristics Adaptation
• Appearance Adaptation
• Size Adaptation
• Encapsulation Adaptation
Format Adaption
• Converting original content format to the format also understandable by the
receiver
• e.g. JPG to GIF, MPEG4 to MPEG, AAC to MP3
football.jpg
football.gif
Characteristics Adaptation
• Modifying media object’s characteristics while remaining within a given
format
• e.g. image/video resolution, frame/bit rate, number of colors
295 x 379
590 x 758
Appearance Adaptation
• Modifying the content of an multimedia unit (MMU) for the purpose of
changing how it looks or sounds
• Needed to conform to the capabilities of the receiver and may even
increase usability
• e.g. condensed version from a web page, portrait to landscape mode
Google
(Opera for Mobile S60)
Google (Internet Explorer)
Size Adaptation
•
Reducing the size of an MMU message to match the capabilities of the
receiver and the underlying network environment:
1. Removal of some MMU objects
•
e.g. remove an image from an MMU message
2.
3.
4.
Changing the encapsulation
•
e.g. split an MMU message to several smaller ones
Converting to another format
•
e.g. MP3 to AAC
Characteristics adaptation
•
e.g. quality of the image, number of colors
Encapsulation Adaptation
•
Converting MMU messages from one ”application protocol” to another and
therefore involving repacking a message without altering any of the media
content
•
e.g. splitting an e-mail to a sequence of several SMS messages
From: [email protected]
To: [email protected]
From: [email protected]
foo bar foo bar foo bar foo bar foo
bar foo bar foo bar foo bar foo bar
foo bar foo bar foo bar foo bar foo
bar foo bar foo bar foo bar foo bar
foo bar foo bar foo bar foo bar foo
bar foo bar foo bar foo bar foo bar
foo bar foo bar foo bar foo bar foo
bar foo bar foo bar foo bar foo bar
foo bar foo bar foo bar foo bar foo
bar foo bar foo bar foo bar foo bar
foo bar foo bar foo bar foo bar
To: [email protected]
E-mail
foofoo
barbar
foofoo
barbar
foofoo
barbar
foofoo
bar foo
foo bar
barbar
foofoo
barbar
foofoo
barbar
foofoo
barbar
foo bar
bar foo
foofoo
barbar
foofoo
barbar
foofoo
barbar
foofoo
bar foo
foo bar
barbar
foofoo
barbar
foofoo
barbar
foofoo
barbar
foo bar
bar foo
foofoo
barbar
foofoo
barbar
foofoo
barbar
foofoo
bar foo
foo bar
barbar
foofoo
barbar
bar foo
SMS x 2
Methods of Content Adaptation
• Multimedia Transcoding
• Content Selection
• Rendering at the Client
• Hybrid Approaches
Multimedia Transcoding
• Modifying the properties of multimedia object to meet the capabilities of the
terminal
• Usually automatic process
• The behavior of the adaptation system is programmed in advance
• Can include all previously presented types of adaptation
• Multimedia Transcoding Architecture
Requests/Responses
Application-specific Controller
Capability negotiation
Extracts capabilities info
from protocol, e.g. from
UserAgent Header or
UAProf
Capability DB
Contains the capabilities
of different terminals.
Adaptation Policies Eng.
Decides how the content
should be adapted.
Policies Plugins
Media Adaptation Eng.
Applies transformation
to the media content or
selects the right version.
Media Plugins
MMS
Browsing
GIF
JPEG
SIP IM
Rich calls
WML
H.263
Multimedia Transcoding (2)
• Transcoding of audio visual content
• Decode object  Modify uncompressed  Encode to desired format
• Also partially decoded objects can be modified
• Scalable formats improve the quality and the performance
• Transcoding of nonaudiovisual content
• Nonaudiovisual content is often XML applications
• Can be modified and and/or converted to other XML applications
using XSLT technology or DOM/SAX interfaces
• Transcoding of procedural code
• Complexity makes transcoding unattractive
• Better to make the code itself adaptive or provide different versions
• Advantages and drawbacks
+ Increased usability
+ Automatic process
- May require a lot of processing resources
- Adapted results may not be acceptable or usable
- Copyright issues
Content Selection
• Multiple versions or modality of each multimedia object is stored in the
server and server selects the best version for the given terminal
• The Infopyramid
• A representation scheme providing a multimodal, multiresolution
representation hierarchy for multimedia content
• Modality axis provides the same information under different media
modes
• Resolution axis provides, for a given modality, the content at
different quality levels
Title
Short
story
Full
story
Text
160x 40
120 kbps
QVGA
VGA
Image
8
kpbs
96
kbps
1
Mbps
Video
Modality
64
kbps
128
kbps
Audio
Content Selection (2)
• The Customizer
• After a client’s request selects the best content representation supported
by the client terminal’s capabilities and environment from the
Infopyramid
• Makes content selection decisions in accordance with adaptation
policies
• Seperating content and its representation
• Same content with several representation alternatives
• e.g. CSS and XSLT
• Advantages and drawbacks
+ Selecting less processing intensive than transcoding
+ Increased usability
+ Automatic process after the creation of all versions
+ The quality of delivered content has been validated by the author
+ Solves legal issues
- May require a lot of work from the author to manage the content
- May require a lot of space to store all the different versions
Rendering at the Client
• Adapting the content before the user sees it on the screen by rendering it in
a suitable way for the given terminal
• Theorically can fit content to variety of different screen size
• Binary content can be adapted by the renderer
• The renderer also handles alternative content
• e.g. alternative text instead of an image if ”Show images” turned off
• Advantages and drawbacks
+ The client knows its capabilities best and has the up2date information
+ Content is received on the terminal and can be readapted if needed
- Requires processing resources in the terminal  Not suitable for lowend devices
Hybrid Approaches
• Mixing different adaptations methods together at the same time
• e.g. transcoding can be a part of a content selection system,
transcoding and content selection can be performed on the media
content and the final layout is left to the terminal when rendering
Real Life Examples
• Apache Cocoon
• http://cocoon.apache.org/
• EU Project Consensus
• http://consensus-online.org/
• Nokia MMS Solution
• http://www.nokia.com/nokia/0,,56882,00.html
• Opera for Mobile, Small-Screen Rendering™ technology
• http://www.opera.com/products/mobile/smallscreen/
Conclusions
• Multimedia transcoding works well for automatic adaptation of simple media
content
• But often fails when the content is more sophisticated and requires more
processing resources
 However only option if the client doesn’t perform adaptation
• Content selection gives the author more control on the adapted versions of
the content
• But requires knowledge of target terminal and some work to create the
different versions and establish the selection rules
 Who will do these versions and keep them up2date?
• Rendering at the client should work well because the client obviously knows
its capabilities best and has the up2date information about itself
• But requires large amount of processing resources in the terminal
Is the consuming of processing resources worth it and what to do with
low-level devices?
• No best method for adapting content that suits all situations
 A hybrid approach might work best
Further Reading
• Adapting Multimedia Internet Content for Universal Access (Mohan, R.,
Smith, J.R., Chung-Sheng Li)
• http://ieeexplore.ieee.org/xpl/abs_free.jsp?arNumber=00748175
• MPEG-21 Multimedia Framework
• ISO/IEC TR 2100-1:2004
• http://www.iso.org/iso/en/CatalogueDetailPage.CatalogueDetail?CS
NUMBER=40611&ICS1=35&ICS2=40&ICS3=
• MPEG-21: Goals and Achievements (Burnett, I., Van de Walle, R., Hill,
K., Bormans, J., Pereira, F.)
• http://ieeexplore.ieee.org/xpl/abs_free.jsp?arNumber=1237551
• Interoperable Adaptive Multimedia Communication (Timmerer C.,
Hellwagner, H.)
• http://ieeexplore.ieee.org/xpl/abs_free.jsp?arNumber=01377105
• SVG Mobile (SVG Basic & Tiny)
• http://www.w3c.org/TR/SVGMobile/
• Flash Lite
• http://www.macromedia.com/software/flashlite/
Questions?
Thank you!