Combining Media 8

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.

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.

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

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.

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

Reasons for Using Actions Reason for associating actions with events  To provide interactivity Users can control the system’s behavior. Users can direct the flow of information that they receive. Events that occur at specific times  Allow time-based behavior and synchronization to be introduced into systems  Actions in timeline Provide non-linearity

Multimedia Scripting Scripting language  Perform computations on the attributes of objects  Create new objects  Affecting their appearance and behavior  Triggered by event

WWW Client-side Scripting Server-side  Enable an HTTP server to communicate with other resources, such as databases, and incorporate data obtained from them into its response.  Web pages dynamically form time-varying data Client-side  Appearance and behavior of Web pages  Allowing code has been downloaded from Internet to run on your system.  Scripts cannot access any local resources such as files make any network connections Their interaction with server is limited to requesting new resources and posting information form HTML forms. Secure but limited  Provide feedback to user

HTML and Hypermedia Link: href attribute Helper applications Plug-in OBJECT: HTML 4.0, preferred way Netscape: EMBED

OBJECT OBJECT has content.  The content is displayed only user agent is unable to display the object.  Support arbitrary media  PARAM, name and vale Controller = false, autoplay=true, loop=true

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.

Limitations Web browsers are not designed to fully support multimedia features Limited coordination of media elements

The Problem Lots of Bits  Images, audio and video are beyond Internet design specs  Results in space/ time constraints at: the server the network( s) the client Not All Bits are Equally Important  Time between samples often more important than bits in sample,  for example lip synchronization (but not always...) Content may be Distributed Across Network  Need to synchronize presentation Objectives  Add synchronization to the Web  Allow interoperability  Use declarative format, preferably text — thus XML

Solution Use of a single timeline for all media Creation of time-based multimedia delivery over the web Synchronization Coordination

What Is SMIL? SMIL stands for Synchronized Multimedia Integration Language SMIL is pronounced "smile" SMIL is a language for describing audiovisual presentations SMIL is easy to learn and understand SMIL is an HTML-like language SMIL is written in XML SMIL presentations can be written using a text-editor SMIL is a W3C standard  SMIL 2.0 August 2001 

What Is SMIL?

A Simplified SMIL Example

What Can SMIL Do? SMIL can be used to create Internet or Intranet presentations SMIL can be used to create slide show presentations SMIL has been described as the Internet answer to PowerPoint SMIL presentations can display multiple file types (text, video, audio...) SMIL presentations can display multiple files at the same time SMIL presentations can display files from multiple web servers SMIL presentations can contain links to other SMIL presentations SMIL presentations can contain control buttons (stop, start, next,...) SMIL has functions for defining sequences and duration of elements SMIL has functions for defining position and visibility of elements

SMIL Files A SMIL file contains all the information necessary to describe a multimedia presentation SMIL files are stored with the extension *.smil A SMIL file contains the following:  The layout of the presentation  The timeline of the presentation  The source of all multimedia elements

How to Play a SMIL File? You will need a SMIL player. Different SMIL players can be found  RealOne Platform by RealNetworks has full support for SMIL 2.0  SMIL Player by InterObject supports the SMIL 2.0 Basic Profile With Internet Explorer 5.5 or later, SMIL elements can be inserted into HTML files This way any SMIL presentation can run over the Internet as standard HTML files

SMIL in HTML Adding References  Adding a "time" namespace definition to the tag  Adding an element to import the "time" namespace  Adding a element to define the class "time".time {behavior: url(#default#time2)}

SMIL Timing time formats:  hh:mm:ss.f  number [h|min|s|ms]  wallclock (YYY-MM-DDThh:mm:ss+zone) Duration  The duration ( dur ="5s") attribute When To Start?  The begin ( begin ="2s") attribute

SMIL Sequence - the most common SMIL element - defines a sequence The element can have a number of attributes:  begin, dur, repeatCount.t {behavior: url(#default#time2)} I will display for one second I will display for two seconds I will display for three seconds

SMIL in Parallel Objects inside the element will be played at the same time  Attributes: begin, dur, endsync = "first"|"last"|id(clip), repeatCount.t {behavior: url(#default#time2)} I will display for one second I will display for two seconds

SMIL Transitions IE 6 supports transitions based on the SMIL 2.0. Transitions are implemented with the element  Attributes: type, begin, mode, from, to Transition Filters  fade, barnDoorWipe, barWipe, clockWipe, ellipseWipe, fanWipe, irisWipe, pushWipe, slideWipe, snakeWipe, spiralWipe, starWipe

SMIL Media Elements Attributes: erase src type

Reading List Check: 8-Combining Media /