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Multimedia Information. Internet Multimedia - Lecture 3. 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

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Multimedia information

Multimedia Information

Internet Multimedia - Lecture 3

Internet multimedia - Lecture 3


Information quality and reliability
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

Internet multimedia - Lecture 3


Information
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

  • Internet multimedia - Lecture 3


    Information1
    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?

    Internet multimedia - Lecture 3


    Horse race example
    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

    Internet multimedia - Lecture 3


    More horse race information
    More horse race information

    • A typical result would be:

      TOWCESTER

      4:10 (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

    Internet multimedia - Lecture 3


    Information structure
    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

    Internet multimedia - Lecture 3


    Channel considerations
    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 user’s access device

  • Internet multimedia - Lecture 3


    Information structure1
    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

    Internet multimedia - Lecture 3


    Information structure in computers
    Information structure in computers

    Internet multimedia - Lecture 3


    Structure
    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?

  • Internet multimedia - Lecture 3


    Encoding
    Encoding

    • Most appropriate encoding determined by

      • structure of the information

      • user’s 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.

    • User’s needs example - Horse race information

      • gambler needs only the result

      • trainer may need video or more detailed text/audio

    Internet multimedia - Lecture 3


    Encoded information objects

    Complexity

    Video

    Image

    High quality sound

    sound

    Speech quality

    Structured information

    Text

    Size of object

    Encoded information objects

    Internet multimedia - Lecture 3


    Text

    • ASCII uses 7-bits per character

    • Efficient storage and transmission

      • uses a limited symbol set (26+26 + 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

    Internet multimedia - Lecture 3


    Ascii
    ASCII

    Internet multimedia - Lecture 3


    Structured information
    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.

    Internet multimedia - Lecture 3


    Audio
    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!)

    Internet multimedia - Lecture 3


    Image
    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

    Internet multimedia - Lecture 3


    Image 2
    Image 2

    • Diverse set of standards

      • JPEG is commonly used and a robust, open, international standard

      • others are GIF, TIFF, TGA, etc…..

    Internet multimedia - Lecture 3


    Video
    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)

    Internet multimedia - Lecture 3


    Mixed information types multimedia
    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. children’s story tapes/books

    Internet multimedia - Lecture 3


    Multimedia examples
    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: straightforwardtransfer + synchronisation not critical

    Internet multimedia - Lecture 3


    Multimedia more examples
    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 links+flexibility, easily added visuals

    Internet multimedia - Lecture 3


    Selection of media
    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

    Internet multimedia - Lecture 3


    Linkage between media types
    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

    Internet multimedia - Lecture 3


    Synchronisation
    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

    Internet multimedia - Lecture 3


    Multimedia issues
    Multimedia Issues

    • Vary depending on application

    • Core issues:

      • access

        • how achieved

        • how regulated

      • cost restrictions

      • equipment constraints

      • awareness ?

      • Bandwidth conflicts ?

      • Timeliness

      • Confidentiality

      • Socialising

    Internet multimedia - Lecture 3


    Another core issue content
    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

    Internet multimedia - Lecture 3


    Interface requirements
    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

    Internet multimedia - Lecture 3


    Usage implications computer based
    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

    Internet multimedia - Lecture 3


    Standards
    Standards

    • Many available

      • Streaming

      • Audio

      • Video

    • International standards

      • JPEG, MPEG, SMIL

    Internet multimedia - Lecture 3


    Summary
    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.

  • Internet multimedia - Lecture 3


    Summary1
    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

    Internet multimedia - Lecture 3


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