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RealVideo Overview
Configuring Your Web Site
After encoding your RealAudio and RealVideo files,
you are ready to attach the files to Web pages. The following
sections explain the construction and use of RealVideo content
on your Web site. When you have your RealServer set up, use this
information to showcase audio and video content from your site.
To get the most out of your RealVideo content, educate
your Web site's visitors about RealVideo. Let people know that
they can listen and view your clips instantly, without download
delays. Identify each clip with a RealVideo bubble icon to distinguish
it as real-time video.
You may obtain the above graphic from RealNetworks' Logo and Usage site at:
http://www.real.com/company/guide/index.html
Capture the graphic from within your Web browser by right-clicking
(Windows) or Control-clicking (Macintosh) it and saving it to
file.
Make it easy for your visitors to get RealPlayer by providing
a link to the RealNetworks home page at:
http://www.real.com/
HTML documents use hyperlinks to connect Web pages.
RealVideo material is also reached via links. However, RealVideo
links you put into your HTML pages are not direct references to
RealVideo files. Instead they are references to metafiles which
contain information needed to establish a connection between your
RealServer and your listener's RealPlayer and to initiate playback.
To create a link between two of your Web pages, you
might add the following text to an HTML document:
<A HREF="sect2.htm">Continue to Section 2</A>
A visitor to your site could click the text, and
your Web server would then deliver the appropriate section of
your document.
If you employed the same syntax to create a link
to a RealVideo file, your visitor's click would prompt your Web
server to deliver your RealVideo data. But, your Web server cannot
stream RealVideo for real-time playback. Only your RealServer
can do that.
Your Web server can, however, convey information
to a user's RealPlayer that enables that Player to establish a
direct connection to your RealServer. Once in place, this direct
connection is used to stream to the Player and to carry commands
(such as seek or pause) back to your RealServer.
Instead of pointing to a file, your Web page is set
up to point to a metafile. This metafile, in turn, contains the
URL (Uniform Resource Locator) of the file (or files) you want
associated with the hyperlink. The user's browser passes the URLs
to RealPlayer, which retrieves .rm files from your RealServer.
Creating Metafiles
Metafiles contain the addresses of RealVideo (.rm)
or RealAudio (.ra) files. These addresses are in the form of URLs.
They begin with a locator type, followed by a specific address.
The locator type identifies the protocol used to exchange information
between client and server. Common locator types include http and
ftp.
The locator type used by RealVideo software is pnm
(RealNetworks Metafile). Addresses you put into a metafile
begin with pnm://
To create a metafile:
- Use a text editor (such as Notepad)
to create a file containing a RealVideo URL. The contents of your
file should be in the following form:
- pnm://hostname/path
For example, to provide access to a RealVideo file
called hello.rm the text of your metafile would be:
- pnm://www.server1.com/hello.rm
Where www.server1.com is the DNS name of the
machine running your RealServer, on which you store your RealVideo
files.
If you want more than one file to play when the user
clicks your link, create a metafile containing several URLs (on
separate lines with no intervening blank lines). For example,
if your metafile contains:
pnm://www.server1.com/hello.rm
pnm://www.server1.com/welcome.rm
pnm://www.server1.com/coolstuff.rm
the Player automatically plays your three files in
sequence. A listener can use the Clip menu on the Player to move
forward and backward between clips (.rm files).
- Save your metafile in the "Text Only with
Line Breaks" format, using a .ram file name extension.
For example, you could save the three lines shown
above in a file named 3track.ram on your Web server.
- In your HTML document, reference the metafile
in a hyperlink, followed by a reference to RealVideo icon (so
that RealVideo icon is displayed to the left of the file) as follows (one line):
<A HREF="http://www.real.com/welcome.ram">
<IMG SRC="http://www.real.com/pics/rvfile.gif"
align=left border=0> Welcome!</A>
Where welcome.ram is the metafile.
File Name Extensions
Each metafile that you create must be saved with
(or renamed to have) a file name extension. This extension tells
your Web server what the metafile is, to ensure that the enclosed
URL is handled properly.
RealVideo System uses two metafile types: .ram and
.rpm. These different file name extensions are passed on by your
Web server and, ultimately, tell the user's Web browser which
application to launch to play the referenced file:
.ram file - Browser launches RealPlayer
.rpm file - Browser launches RealPlayer Plug-in
(see below)
Note You must configure your Web server to understand that the extension .ram refers to
the MIME type x-pn-realaudio (detailed instructions for configuring a variety of Web servers are available in the Server
Administration Guide).
Customizing Calls to Video and Audio Content
Optional arguments may be added to metafiles to finesse
what is seen and heard by users when they click your RealVideo
link. You may alter the point in a clip at which play starts or
ends, or the Title, Author, and Copyright information is displayed
by RealPlayer.
Add the options to your metafile following the URL
to which they apply. Options must be preceded by a ? (question
mark) and separated from each other by an & (ampersand). The
syntax is as follows:
pnm://www.real.com/test.rm?[opt1]&[opt2]
Changing Start and Stop Times
To create a link that starts playing a clip from
a point other than the beginning of the file, use the start
command. Specify the time into the clip at which play should begin.
For example:
pnm://www.real.com/test.rm?start="30"
would result in playback starting thirty seconds
into the video file.
The format for the start time is as follows:
start="dd:hh:mm:ss.ss"
Tenths of seconds are separated from seconds by a
decimal point; the other units of time are separated by colons.
The time is interpreted from right to left, and it is not necessary
to specify days, hours, or minutes if these are not relevant.
Similar to the start option is the end
option. For example, the metafile text:
pnm://www.real.com/test.rm?end="5:30"
is used to provide for playback of test.ra that terminates
five minutes and thirty seconds from the start of the clip.
Note The end time is always measured from the actual start of the data
in the file, even in the case where playback begins elsewhere.
For example, the line:
pnm://www.real.com/test.rm?start="30"&end="5:30"
is used to start play of test.rm from the thirty-second
mark and to stop play five minutes later.
Changing Title, Author, or Copyright Information
The following options exist to change RealVideo descriptive
information from the metafile:
title="new title"
author="new author"
copyright="new copyright"
Strings can be changed independently or in combination.
Changing information in this manner does not change
what is stored in your RealVideo file-only what is displayed when
it is accessed through this particular metafile. This functionality
is especially useful if, for example, you have one large .ra file
that contains your band's entire CD, and you want to credit the
author of each song as it plays. You could create a multi-clip
.ram file as follows:
pnm://www.server/band.rm?end="5:30"&title="Song1"
pnm://www.server/band.rm?start="5:31"&end="7:45
"&title="song2"&author="Joe Smith"
HTTP streaming enables content providers to stream
RealVideo clips from a World Wide Web server. While this method
is not as robust, it provides a reasonable method for providing
short RealVideo content to a limited number of users.
Before you can stream RealVideo clips through HTTP,
you must define the following MIME types for your World Wide Web
server
audio/x-pn-realaudio (files with a .ra, .rm or .ram file extension)
audio/x-pn-realaudio-plugin (files with a .rpm file extension)
Some World Wide Web servers are pre-configured with
these MIME types.
Note If you are running
a Web page off an ISP server, send mail to the ISP administrator
asking them to configure RealPlayer mime type.
To stream RealVideo content using HTTP:
- Copy your encoded RealVideo files
(files with the .rm extension) to your World Wide Web server.
- Use a text editor (such as Notepad)
to create a metafile containing a RealVideo URL. For example,
the contents of your file should be in the following form:
- http://hostname/path
- where hostname is the name of your World Wide
Web server. For example: www.real.com
- Note Refer to "Creating
Metafiles". This file works similarly, except it
uses http as the protocol instead of pnm.
- Save your metafile as text using a .ram file
name extension.
- In your HTML document, reference the metafile
in a hyperlink. For example:
- <A HREF="file.ram">
- <A HREF="http://hostname/file.ram">
You can use relative or complete paths. If you use
complete paths, you must include both the hostname and the complete
path. For example:
- <A HREF="http://www.real.com/home/welcome.ram">
- When a user clicks on the link,
the audio or video file(s) begin to download. RealPlayer begins
playing after a few seconds; it does not need to wait for the
entire file to be downloaded.
RealVideo System enables seamless integration of
RealPlayer Controls into your Web page layout. You can place individual
interactive components, such as a play button or image window,
anywhere on your page, just as you would place an image using
the <IMG> tag in HTML.
RealVideo offers two products which, in conjunction
with the most popular Web browsers, enable "in page"
audio controls.
- RealPlayer Plug-in provides Player-like
features to browsers that support the Netscape Navigator Plug-in
architecture. This plug-in also works in Internet Explorer 3.0.
- RealPlayer Control for ActiveX works
with Internet Explorer 3.0 and Visual Basic applications to provide
RealVideo playback capabilities.
Using RealPlayer Plug-in
The Plug-in runs as an adjunct to Web browsers that
support Netscape's Plug-in architecture. This RealPlayer Plug-in
is included in the Player installation.
The <EMBED> tag specifies Plug-in attributes
in HTML pages in much the same way that the <IMG> tag specifies
image attributes. The basic <EMBED> tag for RealVideo contains
only the attributes SRC, WIDTH, and HEIGHT, as shown below:
<EMBED SRC=metafile.rpm WIDTH=width_value
HEIGHT=height_value>
For example:
<EMBED SRC="sample1.rpm" WIDTH=300 HEIGHT=134>
creates an in-page Player that is 300-pixels wide
and 134-pixels high.
For the Plug-in, metafiles are stored with a .rpm
file name extension.
The name tag is supported as an option with JavaScript
to refer to a specific plug-in.
Note Do not place the <EMBED> tag within a table.
| Feature | Description
|
| SRC Attribute | The SRC attribute specifies RealVideo metafile to be accessed. RealPlayer Plug-in is associated with a .rpm file name extension. This extension tells the user's Web browser to load RealPlayer Plug-in rather than the stand-alone RealPlayer.
For the user's Web browser to correctly identify .rpm files, you or your system administrator must first configure the .rpm MIME type in your Web server. Users do not need to configure their Web browsers to recognize the .rpm MIME type. The plug-in architecture automatically sends .rpm files to RealPlayer Plug-in. Files with a .rpm extension are identical to .ram files, except for the extension.
|
| WIDTH and HEIGHT Attributes | The WIDTH and HEIGHT attributes specify the size of the embedded RealVideo component. Unlike images, Plug-ins do not size automatically. The WIDTH and HEIGHT can be specified in pixels (the default) or as a percentage of the Web browser window (for example: WIDTH=100%).
Note If the WIDTH and HEIGHT attributes are not included, the Plug-in may appear as a tiny (and useless) icon with some browsers.
If you want your Plug-in component to maintain an absolute size, specify HEIGHT and WIDTH in pixels. If you want the Plug-in graphic to scale with the Web browser window, specify size as a percentage. For example, if you want to fit the entire width of the Web browser window, use WIDTH=100%.
|
| CONTROLS Attribute | The CONTROLS attribute of the <EMBED> tag allows you to place individual control elements within your page. You can use multiple <EMBED> statements to construct a custom interface, made up of individual controls. CONTROLS supports the following values: All, ControlPanel, InfoVolumePanel, InfoPanel, StatusBar, PlayButton, StopButton, VolumeSlider, PositionSlider, PositionField, StatusField, ImageWindow.
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Preparing HTML Pages for Browsers that Cannot Use the Plug-in
Some Web browsers do not support plug-ins. You can create HTML
pages that are enhanced for plug-ins but which also work for other
browsers. Simply use the <NOEMBED> tag to include HTML statements
for use by Web browsers that do not support Plug-ins.
The <NOEMBED> command should appear after an
<EMBED> command and take the following syntax:
<NOEMBED> HTML to be ignored </NOEMBED>
For example, the command:
<EMBED SRC="sample1.rpm" WIDTH=300 HEIGHT=134>
<NOEMBED> <A HREF="sample1.ram">Play the clip
using the stand-alone Player! </A></NOEMBED>
would show a page with the Plug-in if your page were
accessed by a browser supporting Plug-ins, and would otherwise
display the message "Play the clip using the stand-alone
Player!" (and allow playback with the standard Player).
Using RealPlayer Control for ActiveX
You can embed RealPlayer Control for ActiveX in HTML
pages using the Object tag.
The following is an example of RealPlayer Control
<OBJECT> in an HTML page.
<OBJECT
ID=RAOCX
CLASSID="clsid:CFCDAA03-8BE4-11cf-B84B-0020AFBBCCFA"
HEIGHT=140
WIDTH=312>
<PARAM NAME="SRC" VALUE="pnm://audio.real.com/file.rm">
<PARAM NAME="CONTROLS" VALUE="all">
</OBJECT>
Note Directory names cannot have spaces.
Embedded Object Parameters
| Feature | Description
|
| OBJECT | Tag is used to embed RealPlayer Control for ActiveX. There should be one <Object> tag per RealPlayer Control on the page.
|
| CLASSID | Specifies the control's CLSID. This value is always "clsid:CFCDAA03-8BE4-11cf-B84B-0020AFBBCCFA" for RealPlayer Control for ActiveX.
|
| HEIGHT | Specifies the control's height on the HTML page. A value of 0 makes the control invisible.
|
| WIDTH | Specifies the control's width on the HTML page. A value of 0 makes the control invisible.
|
| PARAM | Specially embedded tag for supplying parameters to the ActiveX object.
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The following properties are available with the PARAM Parameter:
| Parameter | Description
|
| SRC | Sets the source of RealVideo or RealAudio clip. The SRC location can be pnm, file or http protocol. This parameter is required.
|
| CONTROLS | Sets the visible components of the control. Valid CONTROLS include All, ControlPanel, InfoVolumePanel, InfoPanel, StatusBar, PlayButton, StopButton, VolumeSlider, PositionSlider, PositionField, StatusField, and ImageWindow.
|
| CONSOLE | Sets a console name used to link multiple control instances. All controls with the same console name work together. For example, if you have multiple Play and Stop buttons on the same page, the console name would enable them to control the same RealVideo or RealVideo clip. Call this function once for each instance of the Play or Stop button you want to link.
The console name. "_master" links to all instances. "_unique" links to no other instances.
|
| AUTOSTART | Sets whether or not the control automatically starts playing once the source data is available. Valid values are TRUE or FALSE.
|
| NOLABELS | Suppresses the Title, Author, and Copyright label text in the controls window. The text strings in the fields are still displayed.
|
| RESET | Resets RealPlayer Control for ActiveX playlist. Valid values are TRUE or FALSE.
|
| AUTOGOTOURL | Specifies how a URL is handled. Valid values are TRUE or FALSE. TRUE indicates that RealPlayer Control for ActiveX automatically forwards the URL event to the browser. FALSE indicates that the OnGotoURL VBScript event is used instead.
|
Specifying How the Control Should Look
The CONTROLS attribute allows you to place individual
control elements within your page. The CONTROLS attributes for
the Netscape Navigator Plug-in and RealPlayer ActiveX Control
are the same. The following explains the output of each attribute:
All - Displays a full Player view including the Control Panel, Information-and-Volume
Panel and Status Bar.
Minimum Width: 21%
Maximum Width: 100%
Minimum Height: 23%
Maximum Height: 80%
InfoVolumePanel - Displays the Title, Author, and Copyright information panel and the volume
slider.
Minimum Width: 21%
Maximum Width: 100%
Minimum Height: 12%
Maximum Height: 50%
For example:
<script Language=JavaScript>
function playSource()
{if (navigator.appName == "Netscape")
{document.javaPlug1.DoPlayPause();}
else
{RAOCX.DoPlayPause();}
}
</script>
InfoPanel - Displays the
Title, Author, and Copyright information.
Minimum Width: 20%
Maximum Width: 100%
Minimum Height: 10%
Maximum Height: 50%
ControlPanel - Displays the play/pause button, the stop
button and the position slider.
Minimum Width: 21%
Maximum Width: 100%
Minimum Height: 8%
Maximum Height:25%
StatusPanel - Displays
the Status Panel showing informational messages, current time
position, and clip length. If you do not embed a Status Panel
in your page, error messages are displayed in the Web browser's
status bar.
PlayButton - Displays the play/pause button.
Minimum Width: 5%
Maximum Width: 100%
Minimum Height: 2%
Maximum Height: 25%
StopButton - Displays the stop button.
Minimum Width: 5%
Maximum Width: 100%
Minimum Height: 2%
Maximum Height: 25%
VolumeSlider - Displays the volume slider.
Minimum Width: 4%
Maximum Width: 100%
Minimum Height: 10%
Maximum Height: 100%
PositionSlider - Displays the position slider.
Minimum Width: 8%
Maximum Width: 100%
Minimum Height: 5%
Maximum Height: 25%
PositionField - Displays the field of the Status Bar showing
position and clip length.
Minimum Width: 10%
Maximum Width: 100%
Minimum Height: 4%
Maximum Height: 25%
StatusField - Displays the message text area of the Status
Bar.
Minimum Width: 13%
Maximum Width: 100%
Minimum Height: 4%
Maximum Height: 15%
ImageWindow - Displays the video image.
Minimum Width: 100%
Maximum Width: 100%
Minimum Height: 100%
Maximum Height: 100%
StatusBar - Displays the status field, position field, channels (stereo/mono).
Minimum Width: 21%
Maximum Width: 100%
Minimum Height: 5%
Maximum Height: 14%
ActiveX Methods and Properties
Methods
Methods are functions that control the performance
of the Control. Unless otherwise noted, these methods have no
return values and no parameters.
| Method | Description
|
| DoPlayPause | Plays or pauses the current clip. Equivalent to clicking the Play/Pause button.
|
| DoStop | Stops the RealAudio clip. Equivalent to clicking the Stop button.
|
| DoNextItem | Skips to the next clip in a .ram file that contains multiple clips. A .ram file is a RealAudio metafile that points to one or more RealAudio files.
|
| DoPrevItem | Skips to the previous clip in a .ram file that contains multiple clips. A .ram file is a RealAudio metafile that points to one or more RealAudio files.
|
| CanPlayPause | Tests if Play/Pause function is available. Returns TRUE or FALSE
|
| CanStop | Tests if Stop function is available. Returns TRUE or FALSE.
|
| HasNextItem | Tests if the next clip function is available. The next clip function is available when the connected source is a .ram file that contains multiple clips, and the current clip is not the last clip in the .ram file. Returns true or false.
|
| HasPrevItem | Tests if the previous clip function is available. The previous clip function is available when the connected source is a .ram file that contains multiple clips, and the current clip is not the first clip in the .ram file. Returns true or false.
|
| AboutBox | Opens the Copyright information for the control.
|
| EditPreferences | Opens the Preferences dialog box. Enables the end user to set his/her RealAudio preferences. These preferences are global to all RealAudio clients on the machine.
|
| HideShowStatistics | Shows or hides the Connection Statistics dialog box.
|
| IsStatisticsVisible | Tests if the Connection Statistics dialog box is displayed. Returns true or false.
|
| DoGotoURL(url, target) | Causes the control to attempt a navigation to the specified URL in the specified frame target. The container must support URL browsing. Parameters: string URL, string target.
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Object Properties
The object properties are set within Visual Basic and specify
properties about the control.
| Property | Description
|
| Source | Specifies the URL of the RealAudio clip to play. The Source location can be pnm:, file: or http: protocol.
|
| Controls | Returns/Sets the visible components of the control. Valid CONTROLS include ALL, ControlPanel, InfoVolumePanel, InfoPanel, StatusBar, PlayButton, StopButton, VolumeSlider, PositionSlider, PositionField, and StatusField.
|
| Console | Sets a console name used to link multiple control instances. All controls with the same console name work together. For example, if you have multiple Play and Stop buttons on the same page, the console name would enable them to control the same RealAudio clip. Call this function once for each instance of the Play or Stop button you want to link. The console name master links to all instances while unique links to no other instances.
|
| Autostart | Sets whether or not the control automatically starts playing once the source data is available. Valid values are TRUE or FALSE.
|
| NoLabels | Suppresses the Title, Author, and Copyright label text in the controls window. The text strings in the fields are still displayed.
|
| AutoGotoURL | Specifies how a URL will be handled. Valid values are TRUE or FALSE. TRUE indicates that the RealAudio ActiveX Control will automatically forward the URL event to the browser. FALSE indicates that the OnGotoURL VBScript event will be sent instead.
|
Java and JavaScript Methods
Methods are functions that control the performance
of the Java enabled RealAudio Plug-in.
| Method | Description
|
| SetSource(String Source) | Specifies the URL of the RealAudio clip to play. The Source location can be pnm:, file: or http: protocol.
|
| SetControlsString(String ControlsString) | Returns/Sets the visible components of the control. Valid CONTROLS include ALL, ControlPanel, InfoVolumePanel, InfoPanel, StatusBar, PlayButton, StopButton, VolumeSlider, PositionSlider, PositionField, and StatusField.
|
| SetConsoleName(String ConsoleName) | Sets a console name used to link multiple RealAudio Plug-in instances. All RealAudio Plug-ins with the same console name work together. For example, if you have multiple Play and Stop buttons on the same page, the console name would enable them to control the same RealAudio clip. Call this function once for each instance of the Play or Stop button you want to link. The console name master links to all instances while unique links to no other instances.
|
| SetAutoStart(Boolean bAutoStart) | Sets whether or not the RealAudio Plug-in automatically starts playing once the source data is available. Valid values are TRUE or FALSE.
|
| SetNoLabels(Boolean bNoLabels) | Suppresses the Title, Author, and Copyright label text in the RealAudio Plug-in window. The text strings in the fields are still displayed.
|
| DoPlayPause() | Plays or pauses the current clip. Equivalent to clicking the Play/Pause button.
|
| DoStop() | Stops the RealAudio clip. Equivalent to clicking the Stop button.
|
| DoNextItem() | Skips to the next clip in a .ram file that contains multiple clips. A .ram file is a RealAudio metafile that points to one or more RealAudio files.
|
| DoPrevItem() | Skips to the previous clip in a .ram file that contains multiple clips. A .ram file is a RealAudio metafile that points to one or more RealAudio files.
|
| CanPlayPause() | Tests if Play/Pause function is available. Returns TRUE or FALSE
|
| CanStop() | Tests if Stop function is available. Returns TRUE or FALSE.
|
| HasNextItem() | Tests if the next clip function is available. The next clip function is available when the connected source is a .ram file that contains multiple clips, and the current clip is not the last clip in the .ram file. Returns true or false.
|
| HasPrevItem() | Tests if the previous clip function is available. The previous clip function is available when the connected source is a .ram file that contains multiple clips, and the current clip is not the first clip in the .ram file. Returns true or false.
|
| AboutBox() | Opens the Copyright information for the control.
|
| EditPreferences() | Opens the Preferences dialog box. Enables the end user to set his/her RealAudio preferences. These preferences are global to all RealAudio clients on the machine.
|
| HideShowStatistics() | Shows or hides the Connection Statistics dialog box.
|
| IsStatisticsVisible() | Tests if the Connection Statistics dialog box is displayed. Returns true or false.
|
CallBack Methods
CallBack methods are functions that provide notification from
the RealAudio engine. CallBack methods can only be used with
Java applets by implementing the RAObserver interface.
| Method | Description |
| onClipOpened(String shortClipname, String URL)
| Sent when a clip has been opened. |
| onClipClosed() | Sent to indicate that no clip is currently open.
|
| onShowStatus(String status) | Sent to indicate that the status text is changing.
|
| setAutoGoToURL(boolean bAutoGoToURL)
| Specifies how a URL will be handled. Valid values are true or false. True indicates that the RealAudio Plug-in will automatically forward the URL event to the browser. False indicates that the OnGoToURL event will be handled by the Java applet instead.
|
| onGoToURL(String url, String target)
| Sent when a URL event has been encountered for the currently playing RealAudio clip. This event will only occur if the AutoGotoURL property is false.
|
Advanced Control Attributes
The more exciting features of RealPlayer Plug-in
and RealPlayer Control for ActiveX may be utilized by specifying
custom attributes within your HTML documents.
Removing Text Labels from Controls
If your Web page is in a language other than English,
or if you want to use RealVideo Description fields to display
information other than Title, Author, and Copyright, you may remove
the Title, Author, and Copyright Labels from the information area.
Controls that display Title, Author, and Copyright information
for a clip, support a NOLABELS=TRUE attribute.
For example, allowing the default behavior
<EMBED SRC="use_lbl.rpm" WIDTH=350
HEIGHT=80 CONTROLS=InfoPanel>
or specifying NOLABELS=FALSE
<EMBED SRC="use_lbl.rpm" WIDTH=350 HEIGHT=80
CONTROLS=InfoPanel NOLABELS=FALSE>
results in the following display.
On the other hand, using NOLABELS=TRUE, for example:
<EMBED SRC="no_lbl.rpm" WIDTH=350
HEIGHT=80 CONTROLS=InfoPanel NOLABELS=TRUE>
produces the following InfoPanel:
Starting Clips Automatically
Adding an AUTOSTART=TRUE attribute tells the user's
browser to automatically begin playing your clip when the page
is visited. You can use this feature to begin narration, to play
a welcome message or start a video.
Since only one clip can play at a time, if you specify
AUTOSTART for more than one control instance, only the last control
to load will play. The order in which your files are delivered
is dependent on the Web server and on the browser's cache size.
This is not necessarily the order in which you put them within
your HTML. Therefore, you should specify AUTOSTART for only one
control instance per page.
Playing Clips with a Hidden Control or Plug-in
If you want to play RealVideo or RealAudio clips
without having a visible Plug-in control, you hide the control.
By embedding a Plug-in in your page that has its size set to width=2
height=0, no image appears on your Web page. You can control the
Plug-in with JavaScript.
For example:
<script Language=JavaScript>
function playSource()
{if (navigator.appName == "Netscape")
{document.javaPlug1.DoPlayPause();}
else
{RAOCX.DoPlayPause();}
}
</script>
<A HREF="#" onClick="playSource()
"><IMG RC="button.gif"></A>
<OBJECT ID=RAOCX CLASSID="
clsid:CFCDAA03-8BE4-11cf-B84B-0020AFBBCCFA"
WIDTH=2 HEIGHT=0>
<PARAM NAME="SRC" VALUE="pnm://audio.real.com/
welcome.rm">
<PARAM NAME="CONTROLS" VALUE="
PlayButton">
<embed src="start.rpm" Width=2 Height=0
Controls=PlayButton name=javaPlug1>
</OBJECT>
The above example works in both Netscape and Internet
Explorer. Only one control will appear on the Web page.
Making Controls Work Together
RealVideo System allows you to embed any number of
RealVideo elements within a Web page. Normally, each tag instance
refers to different video content. Sometimes, however, you may
want to link two or more controls together. For example, you can
create a play button and an image window that work as a pair.
To include multiple components that work together,
specify a CONSOLE attribute for each control and assign this the
same value in each instance. For example:
<EMBED SRC="sample1.rpm"
WIDTH=30 HEIGHT=33 CONTROLS="PlayButton"
CONSOLE="Clip1">
<EMBED SRC="empty1.rpm" WIDTH=182
HEIGHT=144 CONTROLS="ImageWindow"
CONSOLE="Clip1">
Note Each
<EMBED> tag must have a unique SRC attribute (if the same
source is specified for two tags, one is ignored). Create a dummy
.rpm file (named, for example: empty1.rpm) for a second control
accessing a clip. Put a hard carriage return (ASCII code 13) into
the dummy file.
Specifying a CONSOLE value of " master" links a particular control to all other RealPlayer Controls on
the page. Use this value, for example, to add a Status Bar to
display information for all clips, for example:
<EMBED SRC="sample1.rpm"
WIDTH=300 HEIGHT=33 CONTROLS="StatusBar"
CONSOLE="_master">
Because many platforms, including Windows, only support
one volume setting, all volume sliders act on the same underlying
value and affect all clips regardless of CONSOLE name. For this
reason, you may want to include only one volume slider per page,
with no reference to a .rm file in its associated .rpm file.
If you only include an ImageWindow control on the
Web page, the video stream may still be controlled by using the
context sensitive pop-up menu. For Windows users, right-click
the ImageWindow; Macintosh users, click and hold the mouse button
until the pop-up menu appears.
Continue to Synchronized Multimedia
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