Presented By
Vijay V. Patole

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ABSTRACT
This seminar provides an introduction to a language SMIL (Synchronized Multimedia Integration Language).The World Wide Web Consortium’s (W3C) SMIL format for encoding multimedia presentations for delivery over the web is a little known but widely used standard. The seminar discusses the features and benefits of SMIL language over other formats. This seminar also focuses on some of the SMIL’s basic concepts and structure. The Synchronized Multimedia Integration Language (SMIL, pronounced “smile") enables simple authoring of interactive audiovisual presentations. SMIL is typically used for multimedia presentations which integrate streaming audio and video with images, text or any other media type. It is created specifically to solve the problems of coordinating the display of variety of media on the websites.
Hence, In the first phase of the Web, the W3C gave us HTML, which allows one to express an idea like a magzine and newspaper can with text, images. Now with W3C's SMIL we can synchronize the text, images, audio and video in a document and make it viewable around the world. This is An evolution in communication, a simple to use, yet as powerful medium.
CHAPTER 1
INTRODUCTION
SMIL is typically a language for delivering multimedia contents on to the web. Multimedia is defined as the integration of multiple media elements into one: viz text, graphics, audio and video are coupled up together with computer’s interactive power. During the last couple of years the area of multimedia on the internet has increased explosively. This area is expected to be one of the most important on the internet .For Example, Consider an application where a video is played for 5 sec’s ,then the audio is played in parallel with the video and after 10 sec’s an image is displayed on the screen.
Hence, in general there must be a way to describe synchronization between different media elements that make up a continuous multimedia presentation. This can be achieved by many formats like Java, Html, and Flash etc. One such approach is the use of SMIL language. SMIL is a simple, vendor-neutral markup language designed to let Web builders of all skill levels schedule audio, video, text, and graphics files across a timeline without having to master development tools or complex programming languages.
SMIL is:
• Powerful –
SMIL marks a significant step toward making it easy to create low bandwidth, TV-like content on the Web. It offers a new level of control over synchronized multimedia by allowing individual components of a presentation to be choreographed across a timeline in relation to each other. It also lets you control the layout, appearance, and exit time of each file.
• Flexible –
What makes SMIL different from other multimedia presentation tools is that instead of forcing each component into a single video file, the text-based SMIL file merely references each file by its URL. Since the media files exist outside of the SMIL file, they retain their individual file sizes; there's no file-size bloat to slow download times.
• Simple –
SMIL's text-based format also makes multimedia presentations easy to edit. If you want to change when an audio component within a complex presentation begins, you can just edit the SMIL file. You don't have to rebuild the entire presentation from scratch.
• Interactive –
As an application of XML, SMIL supports hyperlinks, which makes it the first Web-specific multimedia language to offer true interactivity. For example, a Web builder could create a presentation about Amelia Earhart's solo flight across the Atlantic, making areas of the route clickable so that people watching it could get statistics about specific locales.
History of SMIL:
There are two versions of SMIL viz SMIL 1.0 and SMIL 2.0 yet released. The first version SMIL 1.0 came up in June 1998 whereas the second version SMIL 2.0 was recommended in August 2001. The CD-ROM community and the Web multimedia community suggested that it would be beneficial to adopt a declarative format for expressing media synchronization on the Web as an alternative and complementary approach to scripting languages. Following a workshop in October 1996, W3C established a first working group on synchronized multimedia in March 1997. This group focused on the design of a declarative language and the work gave rise to SMIL which became a W3C recommendation in June 1998.
A second Synchronized Multimedia Working Group (SYMM) was established in February 1999. The mission of the SYMM Working Group was to continue W3C’s work on synchronized multimedia that started with SMIL 1.0 SMIL 2.0 became a W3C Recommendation on 9 August 2001.
CHAPTER 2
The SMIL Overview
2.1SMIL versions
There are three versions of SMIL yet released viz SMIL 1.0, SMIL 2.0, SMIL 3.0. The goal of SMIL 3.0 was to extend the development of SMIL as a declarative XML-based timing and synchronization language, and advance the corresponding timing model. SMIL 3.0 provided much more functionality than SMIL 2.0 in following ways:
• New markup was added, for example for
• Transition effects
• animation
• author-defined windows
• improved event-handling (events can come from UI or from network)
• hierarchical layout
• Authoring adaptive content (e.g. to have the same document display on a PC and on a mobile device).
• SMIL 3.0 is defined as a set of reusable markup modules. This allows reuse of SMIL syntax and semantics in other XML-based languages, in particular those that need to represent timing and synchronization. For example:
• SMIL modules could be used to provide lightweight multimedia functionality on mobile phones
• SMIL timing, content control, and media objects could be used to coordinate broadcast and Web content in an enhanced-TV application.
• The SMIL Animation Recommendation is being used to integrate animation into W3C’s Scalable Vector Graphics language (SVG).
• SMIL 3.0 improves the accessibility features of SMIL 2.0. It allows authors to include closed audio descriptions as well as closed captions in their SMIL presentations. On the whole, SMIL 3.0 is just a development of SMIL 2.0 and works much like SMIL 2.0, though it has much more functionality and of Course some differences in notation and structure.
2.2 How SMIL Works
SMIL provides a mechanism for content applications to interface with different internet protocols such as RTSP (Real Time Streaming protocol) and HTTP (Hypertext Transfer Protocol). It enables Web developers to divide multimedia content into separate streams and files, and send them individually to an end- user’s computer. These files are then together displayed as a single multimedia stream. Each object is accessed with a url, which means that the presentation can be made of objects arriving from more than one place and that objects can be easily reused in multiple presentations. The ability to separate out static file For example: text and images from non-static media makes the multimedia content smaller. Thus it does not take so long to travel over the internet.
The SMIL documents are streamed via RTSP but the documents shown in Windows Media Player are sent through different protocols, the picture support is sent via HTTP and the continuous material like audio or video, are sent through MSBP. The difference between the two processes is as shown in fig 3.2
2.1 Transmission of SMIL documents
It can be observed that HTTP downloads files without regard to timelines, making clips with timelines more likely to stall. Although Real Server can also use HTTP, URLs for media clips streamed by Real Server begin with rtsp://, which causes it to use Real-time Streaming Protocol (RTSP). Designed specifically for streaming, RTSP enables Real Server to adjust streaming data to keep clips playing smoothly. When two clips play side-by- side, for example, RealPlayer communicates with Real Server about each clip's progress, indicating how much data it needs to keep playback synchronized. Real Server can then adjust the data flow to compensate for changing network conditions, reducing low priority data if necessary to ensure that crucial data gets through. Communication like this is not possible through HTTP.
2.3 Implementation of SMIL
Basically SMIL is a derivative of XML. It carries with it the rules of XML as well as few of its own. This makes the language easy to read and understand. For instance, like XML, all tags must have both beginnings and endings. To create smil documents a simple text editor is sufficient. VIM (vi editor) editor is generally preferred because of its capability in syntax highlighting. The syntax is similar to HTML. Hence it is easier for non-java programmers to use SMIL.