Chapter 9: Presentation Information

RealONE Player provides several means for delivering information about a presentation, such as its title, author, and copyright. This chapter covers these information features, and explains the accessibility features available for sight-impaired persons.

Understanding Presentation Information

There are several types of presentation information available. Some types augment other types, some types override other types, and some types are available only to viewers who have devices that read accessibility information.

Information Encoded in Clips

Many clips have their own encoded information. When you create a RealVideo or RealAudio clip, for example, you can have RealProducer encode certain types of information into the clip. Some of this information is used only by Internet search engines, but some is read by RealONE Player. The following are the most common types of information encoded into clips for display by RealONE Player:

title

author

abstract (also called "description")

In general, it's good practice always to encode information in the clip. This ensures that important information, such as a copyright, is present if the clip is not streamed using SMIL. Encoded information is the most basic level of presentation information, but you can override it using SMIL.

For More Information: See the documentation for your production tool for instructions on how to encode information into a clip.

Clip Source Tag and Group Information

A SMIL clip source tag, such as <video/> or <ref/>, can define title, author, copyright, and abstract information for the clip. There are two main advantages to defining this information in SMIL:

You can provide information for any clip, which is handy for clips that do not encode any information internally.

The SMIL information overrides the encoded clip information, letting you modify information without re-encoding the clip.

You can also define title, author, copyright, and abstract information for groups. This information then overrides the information defined for the individual clips. When several clips play in parallel, for example, RealONE Player does not display the title for each clip individually. You may therefore want to define a single group title that RealONE Player displays while the group is active.

For More Information: The section "Adding Clip and Group Information" describes how to add information to clip source tags and group tags. For more on groups, see Chapter 10.

SMIL Presentation Information

Within a SMIL file, you can define information for the entire presentation. This information supplements the clip or group information, but does not override it. This enables you to present two-levels of information to viewers:

The presentation information lasts for the entire presentation.

The clip or group information lasts only as long as each clip or group plays.

Like clip information, the presentation information can give the title, author, copyright, and abstract. But you can also define any other information you wish through the header section <meta/> tags.

For More Information: The section "Defining Information for the SMIL Presentation" explains how to write the <meta/> tags.

Accessibility Information

The accessibility features define a different class of information. RealONE Player typically does not display this information. Instead, the information is read by assistive devices used by sight-impaired persons. This information can help these viewers choose which clips to play, and which links to click.

For More Information: See "Adding Accessibility Information" for more information on these features.

RealONE Player Context Window

RealONE Player on Windows has a built-in context window meant for displaying information as a presentation plays. Through SMIL, you can open HTML pages in the context window at any point in a presentation. On operating systems other than Windows, these pages open in the viewer's default Web browser.

For More Information: See "Opening HTML Pages in the Context Window" for more information.

Coded Characters

In a SMIL header section, or within clip attribute values, quotation marks, apostrophes, ampersands, and angle brackets are interpreted as syntax markers. You need to use codes to have these characters show up as text in RealONE Player. As shown in the following table, codes begin with an ampersand ("&") and end with a semicolon (";"). SMIL interprets these codes the same way as popular Web browsers.

SMIL Coded Characters
Code	Character	Example
`"`	quotation mark	"
`&`	ampersand	&
`'`	apostrophe	'
`<`	left angle bracket ("less than" sign)	<
`>`	right angle bracket ("greater than" sign)	>

For example, to add the following as a title:

Multimedia's <smil> & you

You enter this in the SMIL file:

"&quot;Multimedia&apos;s &lt;smil&gt; &amp; you&quot;"

Adding Clip and Group Information

The title, author, copyright, and abstract attributes let you add information to clip source tags and group tags. The following table summarizes these descriptive attributes.

Clip and Group Information Attributes
Attribute	Value	Function
`abstract`	`clip_abstract`	Sets summary displayed in RealONE Player.
`author`	`author_name`	Defines author name.
`copyright`	`copyright_notice`	Provides copyright notice.
`title`	`title_text`	Creates a title that displays in the playlist.

You can use any combination of these attributes in each group or clip source tag, but RealNetworks highly recommends that you always include title attribute values, which appear in the RealONE Player playlist. Each attribute takes a text string for its value. The following example shows the general form these attributes take in a clip source tag:

<ref src="..." title="title" author="name" copyright="date" abstract="abstract"/>

Tips for Defining Clip Information

The following points explain the relationship between clip information set through SMIL and information encoded in a clip.

For a sequence or parallel group, use title, author, copyright, and abstract attributes in the <par> or <seq> tag instead of the clip source tags. With a parallel group or sequence, clip titles are ignored, and only the group title shows in the RealONE Player playlist.

A title, author, copyright, or abstract attribute in an <excl> tag is ignored. This information must be defined for individual clips or parallel groups.

If a title is not encoded in the clip or specified through a title attribute, the clip's URL is used in the RealONE Player playlist and the "recent clips" list.

Defining Information for the SMIL Presentation

Whereas clip source tags can define information about each clip, the SMIL file header can use <meta/> tags to define information, such as title, author, and copyright, for the entire presentation. Each <meta/> tag uses two attributes, name and content, as shown in the following example:

<head>
  <meta name="title" content="Bob and Susan Discuss Streaming Media"/>
  <meta name="author" content="RealNetworks Media Productions"/>
  <meta name="copyright" content="(c)1998 RealNetworks"/>
  <meta name="abstract" content="Bob and Susan, two Internet technology 
experts, discuss the future of streaming media."/>
 </head>

Tip: Name values, as in name="title", must be lowercase. When defining long content such as an abstract, don't use line breaks or tabs within a content value.

Managing Presentation Information

This section will be added in a later version of this guide.

Adding Accessibility Information

Whereas some attributes are displayed in RealONE Player, others function only with assistive reading devices used by visually impaired viewers. The following table summarizes the attributes that help make your presentation accessible to all viewers. RealNetworks encourages you to add these attributes to your presentation.

Accessibility Attributes
Attribute	Value	Function	Reference
`alt`	`text`	Provides alternate text.	click here
`longdesc`	`text`	Gives a long description to assistive reading devices.	click here
`readIndex`	`integer`	Sets the order in which clip information is read.	click here

Including an Alternate Clip Description

Each clip source tag can include an alt attribute that uses short, descriptive text as its value. This alt value displays in RealONE Player when the viewer moves the screen pointer over the clip. It is good practice always to include an alt attribute for each clip. In the following example, the text "Introductory Video" displays when the viewer moves the screen pointer over the clip:

<video src="video1.rm" alt="Introductory Video"/>

Note: Unlike browsers that display image alt text before the images are downloaded, RealONE Player does not display alt text for clips before they play.

Tip: If the clip includes hyperlinks, the link's alt value or URL displays in place of the clip's alt text. For more on alt in hyperlinks, see "Displaying Alternate Link Text".

Using a Long Description

Each source tag can include a longdesc attribute that supplements the alt attribute. Some assistive-reading devices can read this long description for visually-impaired viewers. If you turn the clip into a hyperlink as described in Chapter 14, the description should describe the link destination. Here is an example:

<img src="button3.gif" longdesc="This is the third navigation button. Clicking it opens your browser to the home page for RealNetworks." .../>

Setting the Clip Read Order

When a visually-impaired viewer uses an assistive-reading device, the device typically reads the values of the title, alt, and longdesc attributes in each clip source tag. When clips play in parallel, the device reads the attributes in the order that the clip tags appear in the <par> group. To change this order, you can add readIndex attributes to the clip source tag. Each readIndex attribute, which has a default value of 0, takes a positive integer as a value. Here is an example:

<par>
  <img ... alt="Link Button 1" longdesc="Start next video" readIndex="1"/>
  <img ... alt="Link Button 2" longdesc="Visit home page" readIndex="2"/>
  <video ... alt="Presentation Video" readIndex="0"/>
</par>

In the example above, the video source tag has the lowest readIndex value, so an assistive device reads that clip's alt attribute information first. Next, the device reads the first image's alt and longdesc attributes, followed by the second image's alt and longdesc attributes.

Note: If two or more source tags have the same readIndex value, clip information is read according to the order that the clip source tags appear in the markup.

For More Information: The section "Playing Clips in Parallel" describes parallel groups.