Multimedia Information

1
Multimedia Information

• Internet Multimedia - Lecture 3

2
Information quality and reliability

• A reliable communication implies reliable
  information but..
• Other factors influence its quality e.g.
• Timeliness of the delivered information
• Speed or frequency of the information provision
• Completeness of the information
• Selectivity of the information
• Relevance or specificity of the information

3
Information

• What is information?
• How is it
• derived?
• communicated?
• used?
• Any event produces information
• much of this is now stored as
• text, image, audio, video and in databases

4
Information

• Users of information often have many choices but
  some restrictions
• bandwidth
• access equipment
• physical proximity
• cost considerations etc.
• Is the information of the right type?
• will it provide what is required?

5
Horse Race example

• Towcester - Going Soft
• 4.10 Hartford Handicap Chase 3m 1f 3,849 (5
  declared)
• 1 1-1F13 Kilmington (29) J Gifford
  9-11-10....P Hide
• 2 -32443 Texan Baby (BEL) (7) N
  Twiston-Davies 9-11-5..C Llewellyn
• 3 PP3UP Ballydougan (10) (CD) R Matthew
  10-10-8......S Curran
• 4 5-24P3 Gold Pigeon (9) (D) B Rothwell
  9-10-0.Mr S Durack (5)
• 5 1F4022 Steeple Jack (43) K Bishop
  11-10-0.....R Greene
• Betting 6-4 Texan Baby, 7-4 Kilmington, 4-1
  Steeple Jack, 8-1 Gold Pigeon,
• 25-1 Ballydougan

6
More horse race information

• A typical result would be
• TOWCESTER
• 410 (3m 1f) 1, Ballydougan, S Curran (16-1)
• 2, Kilmington, (15-8 Fav)
• 3, Texan Baby(BEL), (5-2).
• 5 ran. 22, dist. (R Matthew)
• Tote 20.40 3.30, 1.10. Dual Forecast
  20.00. CSF 43.30.
• Full interpretation requires contextual
  information

7
Information structure

• Example horse race information
• Only the basic information is presented
• There is only an indication of 6 previous runs
• No information of what events were attempted
• No indication of previous opposition
• No information on preferred
• distance, going, race type, course etc.
• Little evidence in the result of what happened
  except the outcome
• More information from a video recording or more
  detailed comments

8
Channel considerations

• Video information needs a high bandwidth channel
• (e.g. satellite broadcast of horse race)
• Audio could be used over lower bandwidth channel
  but some information is lost
• Picture/text can be used in newspapers and
• Text only on Teletext and computer stored
  information
• Databases are used to store information for later
  retrieval
• Indexed on
• horse name, race time/date, jockey, trainer etc.
• Multimedia would aid in the dissemination of this
  information - appropriate info for users access
  device

9
Information structure

• Raw data contains information
• This information will contain structure
• If more data is available then..
• more information should be able to be extracted
• (some data may be no use - e.g. blank video
  screen)
• Some information structures are better related to
  one medium than others
• Information can usually be extracted to suit most
  media
• E.g. A video can be processed to give
• still images, audio extract, text synopsis
• All result in loss of information

10
Information structure in computers
11
Structure

• The levels may each have a different encoding and
  structure
• This may impose restrictions on
• information storage and retrieval or
• performance
• Good quality systems should not restrict the
  information requirements
• Example
• Distributed storage of WWW pages restricts access
  time
• Coding restricts date information - Y2K problem?

12
Encoding

• Most appropriate encoding determined by
• structure of the information
• users need and intended use
• as an example - consider different maps - each
  scale has a different level of detail but could
  all be generated from the same GIS
• available channels
• Available channel will determine the scope of the
  information that can be communicated
• limits to quality, response time, usability etc.
• Users needs example - Horse race information
• gambler needs only the result
• trainer may need video or more detailed text/audio

13
Encoded information objects
14
Text

• ASCII uses 7-bits per character
• Efficient storage and transmission
• uses a limited symbol set (2626 punctuation)
• Only applies to English
• Other versions can be used for other symbol sets
• New encoding of text based on Unicode
• a 16-bit system that encompasses all language
  symbols

15
ASCII
16
Structured information

• Structured information can be very efficient
• Structure imparts meaning
• this is easier than with free text
• example - 29 WV1 1LL could be used to retrieve an
  address
• There can be problems
• querying databases can produce masses of data
  unless the query is specified to exact limits
• Example
• A driver database could be queried for a John
  Smith in Wolverhampton but would produce a large
  response if the Wolverhampton is missed out of
  the specification of the query.

17
Audio

• Audio information has many different standards
• Some of the differences are due to differing
  requirements of systems
• Two common standards
• CD-quality stereo audio and mono speech quality
• A. CD uses 44.1 kHz sampling, 2 x 16 bit channels
  
• 44 100 x 16 x 2 1 411 200 bps
• B. Mono speech uses 8 kHz sampling on 1 x 8-bit
  channel
• 8000 x 8 x 1 64 000 bps (ISDN rate!)

18
Image

• Two main types of image
• bit-mapped or graphic images
• bit-mapped are generally pictures
• graphic images are generally line drawings or
  graphic designs
• Each has different storage and transmission
  requirements

19
Image 2

• Diverse set of standards
• JPEG is commonly used and a robust, open,
  international standard
• others are GIF, TIFF, TGA, etc..

20
Video

• The most complex of multimedia types
• Transmission and storage requirements determined
  by
• Frame rate (15-30 is common)
• Size of display (can be changed to suit
  transmission rate)
• Resolution used (can be determined by display)
• Colour depth (depends on requirements 8-24 bit)
• Typical figures
• Video conferencing quality
• 15 fps, 160 x 120 pixel window, 16 colours
• 15 x 160 x 120 x 4 1 152 000 bps (about 1Mbps)

21
Mixed information types -Multimedia?

• When various media types combined into single
  coherent object
• Examples - text, database, stills, animation,
  graphic, video, audio
• Communication links use channels which can be
  shared by different media types
• Recent advances in computer/communications has
  significantly expanded possibilities for
  multimedia use
• Multimedia not unique to computers - e.g.
  childrens story tapes/books

22
Multimedia examples

• Sound Video
• advs familiar concept, effective
• disadvs familiarisation contempt , TV/cinema,
  passive etc.
• digitisation various transfer synchronisation
  methods
• Sound Image
• e.g. slide show audio commentary/music
• advs portable, flexible, simple
• disadvs needs preplanning, lacks movement
• digitisation straightforward transfer
  synchronisation not critical

23
Multimedia - more examples

• Hardcopy Image Text
• e.g. picture album, brochure
• advs familiar, simple, portable
• disadvs lacks movement, content inflexible,
  copying (?)
• digitisation design important
• Sound Text
• e.g. language learning pack
• advs easy to use, familiar
• disadvs selected replays difficult, lacks
  visuals
• digitisation more effective linksflexibility,
  easily added visuals

24
Selection of media

• The examples given indicate the diversity
  available
• Long history of traditional uses of mixed media
  types
• Some mixtures and styles of mixing are more
  recent
• Digitisation tends to present more options, but
  opens up more complex design issues (HCI)
• Availability of information in a particular form
  often means inclusion but
• Selection and design should reflect delivery
  purpose and user preferences/needs

25
Linkage between Media Types

• Traditional links between media types used in an
  application tend to be retained in digitised
  formats
• Use of single device (computer) often simplifies
  linking and synchronisation
• Two forms of links
• different types present for automatic viewing
• e.g. text with an inserted picture (in-line link)
• explicit optional link from text to a musical
  soundtrack
• external hyperlink

26
Synchronisation

• Not particularly problematic - except for some
  cases of audio/video transmission
• Even off-the-shelf broadcast packages have
  difficulties with attaining lip-synch quality
• Audio can by synched to the beginning of frames
  but constraints relating to channel capacity and
  hardware/ software affect performance
• Audio and image/text synchronisation is much
  easier
• image change(s) at specific point(s) in audio
  track

27
Multimedia Issues

• Vary depending on application
• Core issues
• access
• how achieved
• how regulated
• cost restrictions
• equipment constraints
• awareness ?
• Bandwidth conflicts ?
• Timeliness
• Confidentiality
• Socialising

28
Another core issue - content

• Content control
• regulatory control (law and professional code of
  conduct)
• code of practice (self-imposed/conditions of
  access)
• IRC/Chat Forums can reach over international
  boundaries
• Local rules (e.g. Video conferencing/Closed Group
  forum, discussion board)
• Parental control packages

29
Interface requirements

• Computer/Internet based Multimedia is open to
  many platforms and environments via standards
• Standards can be open, proprietary, or from other
  sources
• Some inconsistency
• e.g Media player, RealPlayer, QuickTime
• Min requirements can specify
• Screen size
• Colour depth no. of bits
• Sound sample processing - sampling rate sample
  size
• Video resolution, frame rate
• Video capture/audio standard etc.,
• Internet connection/network

30
Usage implications (computer based)

• Technical capability to achieve planned service
  needs to be considered
• E.g video links need to have appropriate
  bandwidth and machine/peripheral availability
• Cater for average and peak activities
• Specialist technical support
• Testing and training
• Costing

31
Standards

• Many available
• Streaming
• Audio
• Video
• International standards
• JPEG, MPEG, SMIL

32
Summary

• Information has inherent structure
• Structure can
• be used to simplify storage or transmission
  requirements (results)
• reduce usefulness (Y2K)
• Different information types have different
  transmission requirements
• Information types should be used to suit user
  needs
• channel available,
• information need,
• other requirements.

33
Summary

• Mixed media is not new
• Educational use for decades
• Computers make it more useable
• Easier to construct and maintain
• Streaming allows most mixed media to be delivered
  easily over the Internet
• Broadband allows greater use of video