Chapter 13 Combining Media

1
Chapter 13Combining Media
2
Key Points

• There are two models for combining elements of
  different media types page-based and
  synchronization-based.
• Hypermedia is a page-based model that generalizes
  hypertext to include other media types. The World
  Wide Web is an example of a hypermedia system.

3
Key Points

• Helper applications are used by Web browsers to
  display media types they cannot handle
  themselves. Plug-ins are used to extend the range
  of types that can be displayed within the browser
  environment.
• The object element is provided for embedding
  arbitrary media in HTML 4 documents, but img and
  embed are more commonly used.
• An image map is an image containing hot' areas,
  which are associated with URLs. The map element
  performs the association.

4
Key Points

• Multimedia can be organized in time using a
  timeline, as in Director.
• SMIL (Synchronized Multimedia Integration
  Language) is a tag-based language, derived from
  XML, for specifying the temporal structure of a
  presentation.
• SMIL's synchronization elements include par for
  specifying media elements to be displayed in
  parallel, and seq for sequences.

5
Key Points

• Elements within a par element can be synchronized
  with each other using event values.
• Hard synchronization or soft synchronization can
  be applied when media are independently subject
  to unpredictable delays.
• HTMLTime is a proposal to merge SMIL's
  synchronization features with HTML.
• The Web Accessibility Initiative guidelines
  should be followed to ensure that multimedia on
  the Web is accessible to the widest possible
  range of people.

6
Introduction

• There are two models currently in use for
  combining elements of different media types
• Paged-based
• Synchronization-based

7
Paged-based

• Paged-based
• In a two-dimensional arrangement that resembles
  the way text and images are laid out in books and
  magazines.
• Time-based elements, such as video clips and
  sound, are embedded in the page as if they were
  images, occupying a fixed area controls may be
  provided to start and stop playback.
• Linking mechanism
• Linked paged-based multimedia productions are
  known as hypermedia.
• World Wide Web

8
Synchronization-based

• Makes time the central organizing principle
• Presented as a sequence, like a slide show
• Transitions, such as dissolves and wipes, may be
  used to go from one element in the sequence to
  the next.
• Parallelism
• Several video clips may be shown at the same
  time, perhaps overlaid against a s6tatic image,
  or a sound track may play during an animation.

9
Interactive

• Scripting author to write simple programs
• Page-based multimedia
• Temporal organization can be added
• Synchronization presentation
• linking

10
HTML and Hypermedia

• Link href attribute
• Helper applications
• Plug-in
• OBJECT HTML 4.0, preferred way
• IMG previous version
• Netscape EMBED

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OBJECT

• OBJECT has content.
• The content is displayed only user agent is
  unable to display the object.
• P. 422, movie clip
• Support arbitrary media
• PARAM, name and vale, p.423
• Controller false, autoplaytrue, looptrue

12
Links

• A element with a href attribute
• Image map an image containing hot areas
• Shape rect, circle, poly
• P. 424

13
Synchronization-based presentations

• Pure hypermedia no temporal structure
• Timelines for authoring
• Slide show packages
• Transitions wipes, dissolves, ripples, page
  turns
• Timeline-based multimedia
• More complex
• Macromedia Director
• Cast, Cast members, Score
• Sprites can be animated using key frames.
• Sprite properties can be animated.

14
SMIL

• Synchronized Multimedia Integration Language
• Text-based language, no special authoring tool
• SMIL 1.0, 1998
• RealPlayer G2, QuickTime 4.1
• Defined XML DTD

15
SMIL

• Layout elements
• Absolute positioning
• SMIL basic layout language
• Region attribute
• ltpargt, ltseqgt, p.428
• Clock value, hms.ms
• Indefinite, dur
• Figs. 13.3-4
• Id(element-id)(time-value), p.431
• Repeat

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SMIL

• Soft sync, hard sync
• 13.5-8
• SWITCH
• P.435
• Test attribute system-bitrate
• Uni-directional link, p. 436
• Anchor A element in HTML
• source or destination of hyperlink
• P.440

17
HTML TIME

• HTML, SMILL cannot be truly integrated
• HTMLTIME
• Timed Interactive Multimedia Extensions
• Slide shows adding sync to HTML
• Extending HTML goes against current trend
• Temporal stylesheet

18
Accessibility

• Poor eyesight
• Hard of hearing
• Transcripts of speech and song lyrics can be
  provided
• Textual form for a non-visual user agent
• Not all authoring tools and formats provide much
  help, but HTML 4 has features designed to assist
  in making Web pages accessible to everybody.

19
Accessibility

• alt
• If a longer description of an image is required,
  the longdesc attribute can be set to its URL.
• ltIMG SRCflower1.jpeg usemapimage-map-1alt
  Flower image maplongdescflowermap.htmlgt
• A text-based set of links to the same
  destinations as those offered by the image map
• SMIL shares some of features in HTML
• All media elements support alt and longdesc
  attributes.