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.
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.
Many clips have their own encoded information. When you create a RealVideo or RealAudio clip, for example, you can have Helix Producer 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:
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.|
A SMIL clip source tag, such as
<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 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 11.|
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:
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
|For More Information:
The section "Defining Information for
the SMIL Presentation" explains how to write the |
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 has a built-in related info pane meant for displaying information as a presentation plays. Through SMIL, you can open HTML pages in the related info pane at any point in a presentation. This HTML page can augment the presentation information described in this chapter.
|For More Information: See "Opening HTML Pages in the Related Info Pane" for more information.|
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.
||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:
""Multimedia's <smil> & you""
abstract attributes let you add
information to clip source tags and the
<par> group tags. This
information overrides any similar information encoded within the clip itself.
The following table summarizes these descriptive attributes.
||Sets a summary displayed in the "Now Playing" list.|
||Defines the author name.|
||Provides a copyright notice.|
||Creates a title for the "Now Playing" list.|
Each attribute takes a text string for its value. The following example shows the general form these attributes take in a clip source tag:
Whether information is encoded in the clip, or added through SMIL or a Ram file, it appears in the following areas of RealOne Player:
You can use any combination of |
When you have a sequence of individual clips, you can display title and author
information in the "Now Playing" list by omitting a
<seq> tag, as described in
"Creating Sequences Without Sequence Tags". When you leave the
out, as shown in the following example, the individual clip titles display in
When you group clips within a
<excl> tag, the clip titles are
ignored. You should therefore add title, author, and copyright information to
the group tag, as shown in the following example:
As these examples illustrate, the use of
<par> tags affects whether
group or clip information displays in RealOne Player. This, in turn, affects
whether viewers can select parts of the SMIL presentation through clip or
group listings in the "Now Playing" list:
<excl>group, no individual clip or group titles display in the "Now Playing" list, and viewers cannot select portions of the presentation through that list.
<excl>group encloses all other clips or groups, individual clip and group titles display in the "Now Playing" list according to the order in which the clips and groups are listed in the SMIL file.
Whereas clip source tags and group tags can define information about each
clip or group, the SMIL file header can use
<meta/> tags to define
information, such as title, author, and copyright, for the entire presentation.
<meta/> tag uses two attributes,
content, as shown in the
following example, which defines title, author, and copyright information:
Name values, as in|
The presentation information displays in the following areas of RealOne Player:
The following SMIL example defines both presentation and clip information:
Because the sequence of video clips does not use a
<seq> tag, the individual
clip titles display in the "Now Playing" list, indented below the presentation
title, as shown in the figure "RealOne Player `Now Playing' List".
Although the clip, group, and presentation information attributes always display in RealOne Player, the accessibility attributes 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.
||Provides alternate text.||click here|
||Gives a long description to assistive reading devices.||click here|
||Sets the order in which clip information is read.||click here|
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"/>
Unlike browsers that display image |
If the clip includes hyperlinks, the link's |
Each source tag can include a
longdesc attribute that supplements the
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 15, the description should describe the link destination. Here is an
<img src="button3.gif" longdesc="This is the third navigation button. Clicking it opens your browser to the home page for RealNetworks." .../>
When a visually-impaired viewer uses an assistive-reading device, the device
typically reads the values of the
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
readIndex attributes to the clip source tag. Each
which has a default value of 0, takes a positive integer as a value. Here is an
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
longdesc attributes, followed by the
If two or more source tags have the same |
|For More Information: The section "Playing Clips in Parallel" describes parallel groups.|
©2002 RealNetworks, Inc. All rights reserved.
For more information, visit RealNetworks
Click here if the Table of Contents frame is not visible at the left side of your screen.