Home > Articles > Web Development

The SMIL Specification

  • Print
  • + Share This
This chapter is from the book

This chapter is from the book

SMIL 1.0

SMIL 1.0, the first specification of the Synchronized Multimedia Integration Language, was offered as a recommendation by the W3C in 1998 and is a model of simplicity. With only a few SMIL tags under your belt, you can easily create most SMIL presentations.

As stated in the specification, the goals of SMIL 1.0 were basic:

  • To describe the temporal (time) behavior of the presentation

  • To describe the layout of the presentation on the screen

  • To associate hyperlinks with media objects

The resulting language is probably best summed up as HTML for multimedia. With SMIL 1.0, you have a text-based language that is built for multimedia on the Web. What really makes it powerful is that right out of the box, it comes ready to handle time. After years of using CD-ROM multimedia presentation approaches that had been roughly patched up for Web use, SMIL 1.0 showed a new direction.

Timing Media

SMIL 1.0 controls the timing of media with two basic elements: <seq> for the sequential synchronization of media objects and <par> for the parallel synchronization of media objects.

    <seq> (for sequential) is used to play one piece of media right after another. With it, you can tell your SMIL player that you want your first media clip to be followed by a second.

    <par> (for parallel) ensures that two independent pieces of media play at the same time. For example, using the <par> element, you can instruct a music clip to play in synchronization with a set of images.

Of course, you can combine these two basic building blocks in almost any fashion. For example, by nesting two <par> elements inside a <seq> element, one grouping of media clips running at the same time will be followed by a second block of assorted media objects also running in parallel. See Figure 3.1 for an illustration.

The capability to give the viewer a cohesive presentation from assorted media objects is incredibly important when evaluating SMIL as a potential Web multimedia approach. With other Web multimedia environments, the presentation of media is authored and output as a fixed work. If you want to provide other playback options using those same media objects, you need to recombine and output your content to match your intent. An example of a fixed Web multimedia would be a QuickTime movie that includes an interactive Flash layer. Once the final movie file is created, the interactivity is fixed. Rearranging the media objects and changing the interactivity requires re-authoring the file.

Figure 3.1  In this example, each block of media clips will play in parallel, but the first block (clips 1-3) will play before the second (clips a-c).

With SMIL, all the media objects maintain their status as independent media objects that can be pulled together as needed. For example, if you desire a different look for your presentation, a simple rearrangement of the <par> and <seq> elements in the SMIL document can easily achieve this effect. So either by your hand or automatically by a program running on a server, the presentation's organization and use of available media objects can be changed instantly to suit your intent, the viewer's hardware and software parameters, or the viewer's interests.

Media Layout

Timing and synchronization of media objects is very important, but that is only half the problem. HTML authors have long struggled with how to get Web pages to look the way they want them to. Thankfully, SMIL comes with built-in layout control.

The <layout> element determines how objects are displayed in the presentation space. Within the <layout> element, playback areas can be specified using the <region> tag. For example, suppose that you want to display video at the top of the presentation window accompanied by descriptive text at the bottom as in Figure 3.2. The SMIL <layout> element can be employed to create two regions: one for the playback of the video segment and another to display the text.

Figure 3.2  Defining playback areas using <layout> and <region>.

The <layout> element adds to the object-oriented power of the SMIL timing and synchronization elements. To reach our goal in the preceding example (video accompanied by text) using other multimedia authoring tools, it would be necessary to "burn" the descriptive caption text into the video and output it as such. If you wanted to change that text, you would have to go back to the original source files and create a new version of your video. With SMIL, the descriptive text can be kept as a separate media object and positioned in a <region> below the video with <layout>. Now, changing the captioning requires modifying only your text.

Old-Fashioned Linking

Of course, multimedia on the Web is pretty limited if it stays only within the confines of one start-to-finish presentation. As a delivery mechanism, CD-ROM is currently still more effective at delivering multimedia efficiently. A Web multimedia language needs to offer a functionality that cannot be contained on a single CD-ROM: hyperlinking to other materials and presentations.

SMIL 1.0 did not disappoint. Like HTML, SMIL offers the capability to link through an anchor element to another Web element. Notice the term "Web element" instead of "media element." With a Web-based presentation, a SMIL object can link to another media object, but it can just as easily link to a Web page.

SMIL 1.0 also offers internal anchors. In this fashion, a link can jump within a SMIL document much like an internal reference in a long HTML page might move you down to a specific chapter.

Anyone for a <switch>?

Serving Web multimedia to an audience that might come to your presentation from a variety of places with a variety of equipment has the potential for creating authoring headaches. HTML authors have long faced this challenge and have used client-side scripting and server-side detection to offer up content that best matches the individual situations of their site visitors.

To help solve this problem for the multimedia author, SMIL offers the <switch> element. Do you have a visitor who speaks French? Give them a French version of your presentation with <switch>. Is the visitor using a slow modem or speeding along with a broadband connection? Determine the data rate and <switch> to the proper media files to match. Now site visitors can receive content tailored to their personal situations.

The <switch> element is indispensable in allowing the author freedom to work directly within the parameters of a specific audience member.

Limitations of SMIL 1.0

The SMIL 1.0 specification was a good starting point for a fledgling Web multimedia language. It is simple enough to learn quickly and generic enough that it can be adapted to almost any Web multimedia player. But, like any first effort, limitations existed.

RealNetworks enthusiastically jumped out front as the first major player to adopt SMIL. To get the most out of its G2 player, however, RealNetworks created two SMIL-based proprietary languages that met the need for low-bandwidth display of streaming text and images. RealText and RealPix provide text effects and transitions not available when using standard SMIL 1.0.

Whereas RealNetworks was a solid advocate for the first SMIL specification, Microsoft responded with criticism. Pulling out of the SMIL effort before the SMIL 1.0 recommendation was made by the W3C, Microsoft later offered a proposal to incorporate SMIL in with standard HTML.

These new interests would require a more powerful and complex language. SMIL 1.0 needed an update.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020