Using RealPix markup, you can create streaming slideshows from still images in JPEG, GIF, and PNG formats. You can even define transition effects, such as fades and wipes, that occur between images. Coupled with an audio soundtrack, RealPix makes a viable alternative to video for low-bandwidth connections. This chapter explains the RealPix markup. Appendix F provides a quick reference for RealPix tags and attributes.
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For More Information: RealSlideshow provides a graphical user interface for creating RealPix presentations. See "RealSlideshow Presentations". |
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Tip: To see RealPix examples, get the zipped HTML version of this guide as described in "How to Download This Guide to Your Computer", and view the Sample Files page. |
A RealPix slideshow consists of a RealPix markup file, which uses the file
extension .rp
, along with any number of images. For each slideshow, you
define an overall duration, and indicate when each image appears during the
presentation timeline. RealPix automatically expands or shrinks each image to
fit in a display area that can be any size. The markup also lets you define
several transition effects:
You can stream a RealPix slideshow by itself, or you can use SMIL to combine RealPix with other clips, such as a RealAudio soundtrack. Using SMIL 2.0, you can augment your slideshow with many features. If you stream a slideshow alongside a video sequence, for example, you can use SMIL transition effects to fade the videos in and out. In fact, because SMIL 2.0 provides transition effects, you can use just SMIL 2.0 to assemble a slideshow. As the following sections explain, though, RealPix and SMIL 2.0 offer different advantages for delivering slideshows.
![]() |
View it now!
(requirements for viewing this sample)
All three of these samples are similar in appearancethey all display a slideshow of images along with RealText clips that provide narrationbut each uses a different production technique: 1. The first sample uses RealPix and SMIL 1.0 to provide backwards compatibility with earlier versions of RealPlayer. 2. The second sample uses RealPix and SMIL 2.0 to add SMIL transition effects to the RealText clips. 3. The third sample is made entirely with SMIL 2.0, using SMIL transition effects for both the images and the RealText clips. |
A streaming slideshow created with RealPix provides the following advantages over a slideshow defined through SMIL 2.0:
RealPix is compatible with RealPlayer versions earlier than RealOne Player, such as RealPlayer 7 and RealPlayer 8. SMIL 2.0 works only with RealOne Player and later. To coordinate multiple clips, you can use SMIL 1.0 along with RealPix to reach the widest RealPlayer audience.
![]() |
For More Information: For more on the two versions of SMIL, see "SMIL 1.0 and SMIL 2.0". |
RealPix maximizes the efficiency of image streaming. Now matter how many images the slideshow contains, a RealPix presentation needs just one stream from Helix Universal Server. In contrast, a SMIL 2.0 slideshow may require a separate Helix Universal Server stream for each image in the slideshow. RealPix is better suited, therefore, for long slideshows that contain a lot of images.
Under stable network conditions, RealPix guarantees that RealOne Player does not have to pause the slideshow to buffer more data. It does this by gauging the bandwidth required to stream all of the images against the slideshow timeline. It then streams enough preroll data to ensure that the slideshow does not have to pause once it begins to play. Achieving the same results using SMIL 2.0 may require the use of advanced SMIL features such as prefetching, which Chapter 19 explains.
If you reuse an image in a RealPix slideshow, RealOne Player caches the image in memory until it is no longer needed. A RealPix slideshow can thereby redisplay images without consuming more bandwidth. A RealPix slideshow does not have access to the cache of another slideshow playing concurrently, though, and each cache is deleted when the slideshow ends.
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Note: No version of RealPlayer maintains a disk cache of images shown in a RealPix or SMIL presentation. Nor can viewers copy or download images. Viewers therefore do not have access to copyrighted image files shown in a RealPix or a SMIL 2.0 presentation. |
RealPix lets you display just part of a source image, zoom in or out on an image, and pan across an image. Although you can duplicate these effects using SMIL layout and animations, which are described in Chapter 12 and Chapter 17, respectively, the RealPix markup lets you create these effects more easily.
Creating a slideshow with SMIL 2.0 alone provides these advantages over using RealPix:
Your SMIL 2.0 file will contain all the required presentation markup. This can make it easier to coordinate each image with, for example, a separate audio clip. When you use RealPix, you need a RealPix file to define the slideshow, and a SMIL file to coordinate the slideshow with other clips, such as the soundtrack.
As Chapter 16 explains, SMIL 2.0 provides over 100 styles of transition effects. You can run each transition effect in a forward or reverse direction, for example, or use partial or repeating effects. You can also apply SMIL transition effects to any type of visual clip, including Flash animations and videos. RealPix, on the other hand, provides about a dozen transition effects for still images only. It doesn't offer extra features found in SMIL transition effects, such as border colors and blends. SMIL 2.0 therefore lets you create a more visually unique slideshow.
Using exclusive groups and SMIL 2.0's advanced timing features, you can create an interactive slideshow that advances to a new image only when the viewer clicks a button, for instance. RealPix slideshows, on the other hand, always display images automatically according to the predefined RealPix timeline.
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For More Information: For more on SMIL exclusive groups, see "Creating an Exclusive Group". Chapter 14 covers advanced SMIL timing. |
For a RealPix presentation, you can use illustrations, scanned images, or pictures taken with a digital camera. Images can be in JPEG, PNG, GIF, or animated GIF format. You'll likely need image editing software such as Adobe Photoshop to prepare images. You should know the basics of creating graphics for the Web, such as JPEG compression and GIF color palettes. When preparing your presentation, maintain three sets of images:
The original set includes the unedited files you start with, such as original images off a scanner. Keep this set in case you need to change an image in the working set by, for example, restoring an area you cropped out. Leave these images uncompressed.
The working set comprises the files that you have edited. You may want to crop the original images, for example, or combine them to form new images. Keep these files uncompressed so that you can edit them further if necessary.
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Tip: Images do not need to be the same sizes. By default, RealPix expands or shrinks all images to fit a predefined display area. |
A presentation set consists of the compressed files (GIF, JPEG, or PNG) used in the presentation. For a given working set, you may have several presentation sets. For instance, you may have slightly compressed images for a high-bandwidth presentation, heavily compressed images for a low-bandwidth version.
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For More Information: The section "Images" provides details on the supported image formats. The section "Controlling an Animated GIF Image" explains how to start a GIF animating within a slideshow. |
JPEGTRAN is a freeware program that optimizes JPEG (.jpg) images for
streaming with RealPix. It modifies them so that if a packet of image data is
lost, RealOne Player can still decode and display remaining packets. If you do
not use JPEGTRAN on your images, RealOne Player cannot decode packets
following a lost packet, and a substantial part of the image may not display.
JPEGTRAN is included in the utilities
folder of the zipped HTML version of
this manual. You can also run JPEGTRAN from the RealPix bandwidth
calculator, which is also included in the utilities
folder.
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Tip: Because running JPEGTRAN may increase or decrease the image file sizes slightly, run this program on your JPEG images before you calculate the image streaming times, as described in "Managing RealPix Bandwidth". |
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For More Information: See "How to Download This Guide to Your Computer" for instructions on getting a local copy of this guide. |
When you stream a RealPix slideshow to RealOne Player, transparent areas in GIF and PNG images show underlying images or background colors within the slideshow. Transparency does not extend to underlying SMIL regions, though. So if your RealPix presentation appears in front of a video in a SMIL presentation, the video does not show through transparent image areas.
If your presentation consists solely of streaming RealPix images, you have full control over the RealPix timeline. When you combine RealPix with another clip such as RealAudio, however, you may want to display the RealPix images at specific points in the other clip's timeline. In these cases, finish the other clip first, then assemble your RealPix presentation so that it coordinates with the other clip's final timeline.
When working with an audio track, for example, think about the order of the images, deciding at which points in the audio timeline each image must display. When you are ready to assemble your RealPix presentation, play back the audio and note where you want to add each image. This will establish your RealPix timeline.
Once you have determined a timeline for your presentation, and have decided how to show the images, you are ready to create a RealPix presentation. You may find it easier to create a storyboard to lay out the images and transition effects. Or you may want to dive right in, using the presentation in progress as your guide. Either way, carefully consider the bandwidth implications as you place your images and set the start times and durations.
![]() |
For More Information: See "Managing RealPix Bandwidth". The section "Step 5: Organize the Presentation Timeline" explains issues involved with multiclip timelines. |
A RealPix file is a plain text file that uses the file extension .rp. The RealPix
markup starts with the <imfl>
tag, and ends with the </imfl>
tag. The following
example shows a simple RealPix file with the most basic attributes. This
sample simply fades in two images in sequence, then fades out to a solid blue:
<imfl> |
RealPix requires a <head/>
tag that defines overall presentation attributes,
such as the duration, the display area size, and the streaming bit rate. After the
<head/>
tag, <image/>
tags define each image used in the presentation, and
assign each image a unique ID (its "handle"). Effects tags such as <fadein/>
select an image handle, and define the RealPix timeline through their start
attributes. Not all effects specify an image, though. A <fadeout/>
tag, for
instance, specifies a fade color rather than an image handle.
The syntax rules for RealPix markup are similar to those for RealText and SMIL:
<fadein.../> |
In RealPix, only the <imfl>
tag, which uses the end tag </imfl>
, does not close with a slash.
<!-- This is a comment --> |
You do not have to create RealPix slideshows through static markup files. A broadcast application can monitor a folder for new images, and broadcast them through Helix Universal Server as part of a live RealPix presentation. A sample broadcast application is included with the Software Development Kit (SDK) available for download at this Web page:
http://proforma.real.com/rnforms/resources/server/realsystemsdk/ind ex.html
When you stream your RealPix presentation to viewers over a network, you need to consider the bandwidth (bit rate) the presentation will consume. You don't need to consider bandwidth if copies of the presentation files will reside on each viewer's desktop computer, however. This section helps you to determine your presentation's bandwidth usage, which can affect how you construct the RealPix timeline, and helps you decide how large to make your slideshow images.
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Tip:
The easiest way to calculate the streaming times for each
image is to use the RealPix bandwidth calculator. This
calculator is included in the utilities folder of the zipped
HTML version of this manual. See "How to Download This
Guide to Your Computer" for instructions on getting a local
copy of this guide.
|
The table "Maximum Streaming Rates" lists the maximum recommended
streaming rates for different network connections. To reach viewers with 56
Kbps modems, for example, a presentation should not require more than 34
Kilobits of data per second. When you stream RealPix together with another
clip, such as a soundtrack, you must take into account the bandwidth
required by each clip. If you use a 16 Kbps RealAudio soundtrack, for instance,
you have 18 Kbps left for RealPix images when streaming over 56 Kbps
modems (34-16=18
).
The bandwidth your RealPix presentation consumes depends on the total size of the image files and the presentation length. To get a rough estimate of this bandwidth, add together the sizes of all image files used in the presentation. Convert this total to Kilobits using the chart below. Then divide by the RealPix presentation length in seconds.
Using This Measurement | Do This to Get Kilobits |
---|---|
Megabytes | Multiply by 8192 |
Kilobytes | Multiply by 8 |
bytes | Divide by 128 |
bits | Divide by 1024 |
For example, if your image files add up to 200 Kilobytes, multiply 200 by 8 to get 1600 Kilobits. A presentation that lasts two minutes, for instance, uses an average of 13.3 Kilobits per second:
(200 Kilobytes x 8)/120 seconds = 13.3 Kilobits per second |
If your RealPix target is 18 Kbps, your presentation should stream smoothly with bandwidth to spare. Suppose that the image files add up to 300 Kilobytes, however. In this case, the average streaming speed required is 20 Kbps, which exceeds the 18 Kbps target:
(300 Kilobytes x 8)/120 seconds = 20 Kilobits per second |
This slideshow can still stream over a 56 Kbps modem, but it may have a longer preroll (initial buffering) than desired. RealPix calculates how much image data must stream to RealOne Player before the slideshow starts in order to keep the slideshow from rebuffering once it begins to play. In other words, if your slideshow has too much image data to stream during the length of its timeline, excess data streams before the slideshow starts to play. The viewer, though, must wait for this data to arrive before the slideshow can commence.
To illustrate the effects of preroll, suppose that you plan to stream a two-
minute slideshow at 18 Kbps. This presentation can deliver 2,160 Kilobits of
data (18 x 120
). If the images add up to 300 Kilobytes (2,400 Kilobits), the
presentation has an extra 240 Kilobits of data to stream. At 18 Kbps, this
means 13 seconds or longer of preroll. In this situation, you can either accept
the longer preroll, which may tempt viewers to quit the slideshow before it
starts, or modify the slideshow to use less bandwidth.
![]() |
For More Information: "Buffering" explains the basics of preroll. For tips on how to modify or manage preroll, see "Lowering RealPix Preroll" and "Masking Preroll With Other Clips". |
Dividing the total image size by the presentation length provides only a rough estimate for preroll. It assumes that all images are about the same size, are streamed at regular intervals, and appear only once. You may still run into excess preroll, though, if you use large images, or a lot of images, early in the slideshow timeline. To prevent this, ensure that each image has enough time to stream to RealOne Player before it must display. The following table helps you to estimate how much time is required to stream an image over a 56 Kbps modem (maximum streaming rate of 34 Kbps), when you combine RealPix with various RealAudio soundtracks.
RealAudio Codec | RealPix Bandwidth | Streaming Time for Each Kilobyte of Data | Data Streamed Every 5 Seconds |
---|---|---|---|
No Audio | 34 Kilobits/second | 0.24 seconds | 20.8 Kilobytes |
6 Kbps Music | 28 Kilobits/second | 0.29 seconds | 17.2 Kilobytes |
8 Kbps Music | 26 Kilobits/second | 0.31 seconds | 16.1 Kilobytes |
11 Kbps Music | 23 Kilobits/second | 0.34 seconds | 14.7 Kilobytes |
16 Kbps Music | 18 Kilobits/second | 0.5 seconds | 10 Kilobytes |
20 Kbps Music | 14 Kilobits/second | 0.57 seconds | 8.8 Kilobytes |
The table indicates that if you use an 8 Kbps RealAudio music soundtrack, for
example, you have 26 Kilobits per second of bandwidth available for Realpix
images. At this rate, it takes about 0.31 seconds to stream each Kilobyte of
image data. If an image is 44 Kilobytes, for example, it requires about 13.6
seconds (44 x 0.31
) to stream to RealOne Player. The first time this image
appears in the slideshow, it should follow the preceding image by 14 seconds
or more. For convenience, the last table column indicates how much image
data can stream to RealOne Player approximately every five seconds.
![]() |
Note: Once RealOne Player has received a RealPix image, it caches the image in memory, so you can reuse the image within the same slideshow without having to stream the image data again. RealOne Player deletes this cache when the slideshow ends. |
If your RealPix presentation requires excessive preroll, you can alter the images, modify the timeline, or both. Whenever you alter images, be sure to test that your slideshow retains acceptable image quality. The following are some tips for lowering the slideshow's bandwidth consumption:
You can stream a low-bandwidth clip ahead of your slideshow to mask the
RealPix preroll. For example, you can start the presentation with a RealText
clip that displays opening credits. Or you can use a low-bandwidth RealAudio
voice clip as a narration. As these introductory clips play, Helix Universal
Server takes advantage of the extra bandwidth to stream the RealPix preroll.
To set this up, you assemble the overall presentation using SMIL, placing all
clips in a parallel group, and setting a delay for the RealPix clip with a begin
attribute:
<par> |
![]() |
For More Information:
See Chapter 6 for more on RealText. The
section "Playing Clips in Parallel" explains <par> groups. See
"Setting Begin and End Times" for more on the begin
attribute.
|
![]() |
View it now!
(requirements for viewing this sample)
Play this sample to view a SMIL presentation in which a RealAudio clip and a RealText clip mask the RealPix preroll. |
All information in the RealPix file falls between an opening <imfl>
tag and a
closing </imfl>
tag. This is the only tag in the RealPix markup that uses an end
tag. The <head/>
tag follows the <imfl>
tag in the RealPix file. Unlike the
HTML <head>
tag, the RealPix <head/>
tag does not have a corresponding
</head>
tag. Instead, it closes with a slash:
<imfl> |
The <head/>
tag sets standard presentation information such as the title,
author, and copyright. It also defines necessary parameters such as the
presentation's duration and streaming bit rate. The following table
summarizes all <head/>
tag attributes. An asterisk (*) indicates a required
attribute.
Attribute | Value | Function | Reference |
---|---|---|---|
aspect |
false|true |
Handles image aspect ratios. | click here |
author |
text |
Gives the name of the author. | click here |
background-color |
name | #RRGGBB |
Sets an initial background color. | click here |
bitrate* |
bits_per_second |
Indicates required bandwidth. | click here |
copyright |
text |
Gives the copyright notice. | click here |
duration* |
time_value |
Sets the presentation duration. | click here |
height* |
pixels |
Specifies the presentation height. | click here |
maxfps |
integer |
Sets the maximum frames per second for transition effects. | click here |
preroll |
seconds |
Allots time for initial buffering. | click here |
timeformat |
milliseconds | dd:hh:mm:ss.xyz |
Indicates the format of time attributes. | click here |
title |
text |
Gives the presentation title. | click here |
url |
URL |
Sets a hyperlink URL for images. | click here |
width* |
pixels |
Specifies the presentation width. | click here |
The required width
and height
attributes set the size of the image display area
in pixels. By default, all images are centered within this area, and enlarged or
reduced so that no cropping occurs. The aspect
attribute determines whether
distortion may occur, though. The following example creates a RealPix
playback area 256 by 256 pixels:
<head width="256" height="256".../> |
When you stream just RealPix, RealOne Player's media playback pane expands
to the specified size when the slideshow begins. When you play RealPix with
another clip, you lay out playback regions with SMIL. You typically create for
the slideshow a SMIL playback region that uses the same width and height set
in the RealPix markup. If the SMIL region is a different size, the region's fit
attribute determines how to handle the size difference, such as by scaling or
cropping the entire display area.
![]() |
For More Information:
Chapter 12 describes SMIL layouts in
general. See "Fitting Clips to Regions" for more on the fit
attribute.
|
The timeformat
attribute sets the format the for start
and duration
attributes
used with RealPix effects. RealPix can specify time values in milliseconds or
"normal play time" format, but not with SMIL shorthand timing values such
as "2s"
. The default time format is milliseconds, which means that a time value
such as 5400
is read as 5400 milliseconds (5.4 seconds). Millisecond time
values cannot include colons or a decimal point.
You can also set timeformat
to the normal play time format:
<head timeformat="dd:hh:mm:ss.xyz".../> |
Here, dd
is days, hh
is hours, mm
is minutes, ss
is seconds, x
is tenths of
seconds, y
is hundredths of seconds, and z
is milliseconds. Only the ss
field is
required. With this format, for instance, duration="3"
sets a three-second
duration.
When the time value does not include a decimal point, the last field is read as
the seconds. For example, 1:30
means 1 minute and 30 seconds, whereas
1:30:00
means 1 hour and 30 minutes. Note that with the normal play time
format, all of the following values are equivalent. Each starts the effect 90
minutes after the RealPix presentation begins:
start="1:30:00.0" |
The required duration
attribute sets the length of the entire RealPix
presentation, using the time format specified in the timeformat
attribute. For
example, the following value sets a duration of 50 seconds:
<head timeformat="dd:hh:mm:ss.xyz" duration="50".../> |
All RealPix effects stop immediately when the duration elapses. When the duration time exceeds the time required to complete the effects, the last effect stays frozen onscreen until the duration elapses.
timeformat
attribute in the <head/>
tag.dur
attribute can shorten the time that the slideshow plays, effectively overriding the RealPix duration
attribute. See "Setting Durations" for more about dur
.The required bitrate
attribute specifies the maximum bandwidth the RealPix
presentation consumes. Specify the value in bits per second (bps). For
example, the following value sets a maximum bandwidth of 12000 bps
(approximately 12 Kbps):
<head bitrate="12000".../> |
![]() |
Tip: To convert precisely from Kilobits per second to bits per second, multiply by 1024. |
![]() |
For More Information: "Managing RealPix Bandwidth" explains how to calculate bandwidth requirements for a RealPix presentation. |
The optional title
, author
, and copyright
attributes define information for the
RealPix presentation:
<head title="My RealPix Slideshow" author="Pat Morales" |
When present, these attributes define the values that display for the RealOne Player clip information (File>Clip Properties>View Clip Info). If the RealPix presentation is played through a SMIL file, however, title, author, and copyright information set through SMIL may override the information you set here.
![]() |
For More Information: See "Where Title, Author, and Copyright Information Displays". |
The optional background-color
attribute sets an initial background color. The
default color is black. RealPix backgrounds can use color names, which are
listed in "Using Color Names", or hexadecimal color values, which are
described in "Defining Hexadecimal Color Values". RealPix does not support
RGB colors in the format rgb(
n
,
n
,
n
)
, however. The following example sets the
initial background color to a shade of red:
<head background-color="#E00000".../> |
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Note:
In RealPix, background-color is hyphenated. In SMIL 2.0,
the backgroundColor attribute for regions uses camel case.
|
![]() |
Tip:
During the course of a slideshow, you can change the
background color with the <fill/> tag, which is described in the
section "Painting a Color Fill".
|
The optional preroll
attribute specifies the time to buffer data in RealOne
Player before the start of the RealPix presentation. The following example sets
the RealPix preroll to 40 seconds:
<head preroll="40".../> |
Helix Universal Server always calculates the preroll required for the presentation based on the image file sizes and presentation timing parameters. If this calculated value is larger than the preroll you set, it overrides your specified preroll. Your preroll value is used, however, if it is higher than the calculated preroll value. You therefore need to set the preroll value only if you want an artificially high preroll.
A high preroll can be useful when you stream RealPix with another clip. Suppose that a RealVideo clip starts midway through a RealPix presentation. You can use a high preroll to download a significant portion of the RealPix data before the presentation starts. The RealVideo clip then has more bandwidth available when it begins. It can therefore stream its required preroll without competing with RealPix for bandwidth.
![]() |
Tip: Always balance preroll values with viewer expectations. Viewers may not stay tuned to a presentation that takes a long time to start playing back. To determine the preroll for a clip streamed in parallel with your slideshow, such as an audio soundtrack, open the clip in RealOne Player, and use File>Clip Properties>Clip Source to view the buffering information. |
![]() |
For More Information: For more on preroll, see "Estimating the Required Bandwidth and Preroll". |
The optional url
attribute sets a hyperlink URL for the presentation. When the
viewer clicks a presentation image, the RealPix presentation continues to play
as the URL opens in the RealOne Player media browser pane, or, with earlier
versions of RealPlayer, in the viewer's default Web browser. Individual effects
can also include a url
attribute that overrides the presentation-wide value for
the duration of the effect. For the attribute value, use a fully qualified URL
such as the following:
<head url="http://www.real.com".../> |
![]() |
For More Information:
You can also use the url attribute to open
a streaming presentation in a new RealOne Player media
window. See "Opening a Media Playback Window with a Clip
Link".
|
With its default value of true
, the aspect
attribute keeps an image at its normal
width-to-height ratio when the width
and height
attributes in the <head/>
tag
create a different width-to-height ratio for the playback area. In this case,
images are displayed as large as possible in the playback area without cropping
and distortion. The background color or the preceding image appears in the
areas not covered by the new image. You can turn this off by setting the
attribute to false
:
<head aspect="false".../> |
In this case, RealOne Player fills the defined playback area with each image,
which distorts any images that have width-to-height ratios different from the
display area. Images are never cropped, however. The following figure shows
how a source image fills a display area differently when aspect
is set to false
or
true
.
![]() |
Note:
The aspect attribute in the <head/> tag affects the entire
presentation, but individual effects can override this setting
with their own aspect attributes, as described in "Changing an
Image's Aspect Ratio".
|
![]() |
View it now!
(requirements for viewing this sample)
This sample shows the effects of ignoring and maintaining image aspect ratios. |
The optional maxfps
attribute specifies an integer from 1 to 30 that sets the
maximum frames per second (fps) for RealPix transition effects:
<head maxfps="5".../> |
This attribute is not required because RealOne Player determines the optimal frame rate based on the playback computer's available CPU power. When CPU power is plentiful, RealOne Player renders transition effects at the maximum of 30 fps. It scales down the transition rates accordingly when less CPU power is available.
You can set the maxfps
attribute low to create special effects, though. For
example, maxfps="5"
keeps transitions constrained to no more than 5 fps. This
causes visible jerks in transitions, which may be a desirable effect. Additionally,
you can use maxfps
in RealPix transition tags to balance CPU usage between
multiple RealPix slideshows played simultaneously in a SMIL presentation.
![]() |
For More Information:
Individual effects can override the
presentation value with their own maxfps values. See "Capping
an Effect's Frame Rate".
|
![]() |
View it now!
(requirements for viewing this sample)
This sample displays images at a progressively faster maximum frame rate. |
For each image you use in the RealPix presentation, you add an <image/>
tag
after the <head/>
tag. The <image/>
tag provides the image file location, and
assigns the image a unique handle number. The following table summarizes
the <image/>
tag attributes. An asterisk (*) denotes a required attribute.
Attribute | Value | Function | Reference |
---|---|---|---|
handle* |
integer |
Sets an ID used by transition effects. | click here |
name* |
filename |
Provides the file name and path. | click here |
size |
bytes |
Indicates the file size for Web server delivery. | click here |
mime |
mime_type |
Specifies a mime type for Web server delivery. | click here |
The required handle
attribute assigns a positive integer to the image. Each
handle number within the file must be unique. The RealPix effects tags refer
to the handle number, rather than the file name, in their target
attributes.
Here is an example of an image handle:
<image handle="18".../> |
that an effects tag refers to when fading in the image:
<fadein target="18".../> |
Although it is not required, you may find that using sequential handle
numbers, as well as listing <image/>
tags according to the handle numbers,
helps you to keep the organization of your presentation clear:
<image handle="1".../> |
![]() |
Note:
It is not necessary to follow the handle order when
defining the timeline. The image with handle="3" might appear
first, followed by the image with handle="1" .
|
The required name
attribute specifies the image file name, along with its path
relative to the location of the RealPix file. The file name and path are case
sensitive. When streaming files from Helix Universal Server, folder (directory)
names must not contain spaces. The following example designates an image
file that resides in the same folder as the RealPix file:
<image name="tulip.jpg".../> |
Image files can also reside in folder levels below (but not above or adjacent to)
the RealPix file. This next example indicates that the image file resides one
level below the RealPix file in the images
folder:
<image name="images/tulip.jpg".../> |
The local, relative paths for the name
attribute allow you to develop and test
your RealPix slideshow locally. You do not need to change the name
values
when you are ready to stream your slideshow. In a Ram or SMIL file, you
simply use an HTTP or RTSP URL to request the RealPix file. The images
automatically use the same protocol used to request the RealPix file.
Unlike a SMIL presentation, in which various clips can reside on different servers, RealPix requires that the RealPix file and all image files stay on the same server. This is because Helix Universal Server reads the RealPix file and determines the image file sizes to calculate how much preroll it must stream to RealOne Player before the slideshow can begin.
If you are developing a presentation that plays back locally for all viewers
(rather than streams from a server), you can use absolute, local URLs in the
following format, which includes three forward slashes in file:///
, and uses
forward slashes in path names as well:
file:///C:/My Documents/Images/picture1.jpg |
The optional size
attribute, which works only with RealPlayer 7 or later,
specifies the size of the image in bytes. Include it in the <image/>
tag when
delivering a RealPix presentation with a Web server. RealOne Player can then
determine when to request each image file from the Web server to ensure
smooth playback. Here is an example of an image file approximately 24 KB in
size:
<image size="24000".../> |
The size
attribute is not required when streaming a RealPix presentation from
Helix Universal Server, which determines image sizes directly through the
files. It then calculates when to stream each image to ensure smooth playback
for the viewer's given bandwidth.
![]() |
Note:
Be careful to list the file sizes correctly. If the file is
significantly larger than the value given by its size attribute,
the presentation may stall.
|
The optional mime
attribute works with RealPlayer 7 and later. It specifies the
image mime type, and may be necessary when delivering a RealPix
presentation with a Web server. Here is an example:
<image mime="image/jpeg".../> |
The following are the valid mime types you can use:
GIF images: | mime="image/gif" |
JPEG images: | mime="image/jpeg" |
PNG images: | mime="image/png" |
Helix Universal Server typically determines the MIME type from the image
file's extension, such as .gif or .jpg, making the mime
attribute unnecessary.
You need to include the mime
attribute only on these two conditions:
<image/>
tags use the size
attribute<image/>
tag's name
attribute supplies a file name that does not include a file extension.Most RealPix transition effects tags, which are described in "Creating RealPix Transition Effects", use a common set of attributes that select an image, indicate when the effect occurs within the RealPix timeline, set the effect duration, and so on. The following table summarizes these attributes. The sections on each RealPix tag indicate which of these attributes an effect requires, or can optionally include.
Attribute | Value | Function | Reference |
---|---|---|---|
aspect |
false|true |
Maintains or ignores the image aspect ratio. | click here |
duration |
time_value |
Specifies the effect's total duration. | click here |
maxfps |
integer |
Controls the maximum frame rate. | click here |
start |
time_value |
Gives the effect start time. | click here |
target |
handle |
Indicates the image used for the effect. | click here |
url |
URL |
Sets a link URL while the effect is active. | click here |
The start
attribute is required for all RealPix effects. It specifies the time from
the beginning of the RealPix timeline that the effect occurs. Here is an
example that starts a crossfade at 12.3 seconds into the timeline:
<crossfade start="12.3".../> |
The individual start
times create the timeline for the individual effects, while
the <head/>
tag's duration
attribute sets the overall presentation time. If your
last start
time is 180, for example, make sure that the duration
attribute set in
the <head/>
tag is greater than 180. For more on this, see "Setting the
Presentation Duration".
![]() |
Note:
To specify start and duration values in seconds, you must
set timeformat="dd:hh:mm:ss.xyz" in the <head/> tag. Otherwise,
a value such as start="12" means 12 milliseconds. For more on
the time format, see "Specifying the Time Format".
|
The duration
attribute in an effect tag is unrelated to the duration
attribute in
the <head/>
tag. In an effect tag, the duration
attribute specifies the total time
for the effect to complete. The higher the value, the slower the effect. For
example, the following value causes the fade to complete in 2.5 seconds:
<fadein start="12" duration="2.5".../> |
The duration
attribute affects only a transition effect, and does not control
how long an image or color fill displays. The subsequent effect's start
attribute
controls how long the image or color fill displays. Consider this example:
<fadein target="5" start="12" duration="3".../> |
Here, image 5 starts to fade in at 12 seconds into the RealPix timeline. The
fadein finishes at 15 seconds (12+3
). The image then displays stationary for
three seconds when, at 18 seconds into the timeline, image 6 begins to fade in.
The second fadein completes at 22 seconds into the timeline (18+4
). At that
point, image 6 has completely replaced image 5.
The target
attribute is required for effects that introduce images. It specifies
the <image/>
tag handle of the image, which is described in "Creating an
Image Handle". For example, if tulips.jpg
is defined with the following
<image/>
tag:
<image handle="2" name="tulips.jpg"/> |
you fade tulips.jpg
into the presentation by targeting the handle number:
<fadein target="2".../> |
The url
attribute sets a hyperlink URL that is valid for as long as the image
displays, overriding the URL set through the <head/>
tag, which is described in
"Adding a Presentation URL". When the viewer clicks the image, the RealPix
presentation continues to play as the URL opens in the RealOne Player media
browser pane, or, with earlier versions of RealPlayer, in the viewer's default
Web browser. Use a fully qualified URL like the following:
<fadein url="http://www.real.com".../> |
![]() |
For More Information:
Note that you can use the url attribute to
open a streaming presentation in a new RealOne Player
window. See "Opening a Media Playback Window with a Clip
Link" for more information.
|
The URLs specified by url
attributes open only when clicked. However, when
you stream a RealPix presentation to RealOne Player, you can use SMIL 2.0 to
open HTML URLs automatically. You might open a different HTML page
after each image displays, for example. To do this, create a SMIL 2.0 file that
plays the RealPix presentation, and includes timed <area/>
tags that open
automatically through the actuate="onLoad"
attribute. See "Linking to HTML
Pages" for more information.
![]() |
Tip: You'll need to take into account the bandwidth required to open HTML page URLs as you plan your RealPix slideshow. Otherwise, the slideshow may pause as each page opens. |
![]() |
View it now!
(requirements for viewing this sample)
This sample uses SMIL 2.0 to open a separate HTML page for each slide. |
You can set the optional aspect
attribute to true
or false
in an effect tag to
override the aspect
attribute set in the <head/>
tag, which is described in
"Handling Image Aspect Ratios". The image introduced with the effect then
appears undistorted (aspect="true"
) or distorted (aspect="false"
) if it has a
different width-to-height ratio than the display area. Here is an example:
<crossfade aspect="false".../> |
![]() |
View it now!
(requirements for viewing this sample)
This sample shows the effects of ignoring and maintaining image aspect ratios. |
The optional maxfps
attribute specifies an integer from 1 to 30 that sets the
maximum frames per second for the effect. It overrides any default maxfps
value set in the <head/>
tag, which is described in "Setting the Maximum
Frames Per Second". Here's an example:
<fadein maxfps="5".../> |
![]() |
View it now!
(requirements for viewing this sample)
This sample displays images at a progressively faster maximum frame rate. |
The following sections describe the RealPix tags that you use to introduce images, display transition effects such as fades, and create special effects such as zooms. The section "Using Common Transition Effects Attributes" describes the standard attributes used in many of these effects tags.
The <fadein/>
tag creates a gradual transition from the currently displayed
color or image to another image. A <fadein/>
tag looks like this:
<fadein start="4" duration="3" target="2"/> |
The following figure illustrates a fade from a solid color to an image.
The following table summarizes the attributes that you can use in a <fadein/>
tag. An asterisk (*) denotes a required attribute.
Attribute | Value | Function | Reference |
---|---|---|---|
aspect |
false|true |
Maintains or ignores the image aspect ratio. | click here |
dsth|dstw| |
pixels |
Sets the size and placement of the image that fades in. | click here |
duration* |
time_value |
Specifies the effect's total duration. | click here |
maxfps |
integer |
Controls the maximum frame rate. | click here |
srch|srcw| |
pixels |
Selects part of the source image for the effect. | click here |
start* |
time_value |
Gives the effect start time. | click here |
target* |
handle |
Indicates the image used for the effect. | click here |
url |
URL |
Sets a link URL while the effect is active. | click here |
![]() |
Tip: You can fade in multiple images simultaneously. RealNetworks recommends that these images do not overlap, however, because the appearance may be unpredictable. |
![]() |
View it now!
(requirements for viewing this sample)
Play this sample to watch a simple slideshow of fadein effects. The next sample demonstrates more creative uses of fades. |
The <fadeout/>
tag defines a transition from an image to a color. You can use a
predefined color name or a hexadecimal value, as described in Appendix C.
RealPix does not support RGB colors in the format rgb(
n
,
n
,
n
)
, however. The
following example fades the RealPix display area to yellow:
<fadeout start="10" duration="3" color="yellow"/> |
The following figure illustrates a fade to a solid color.
The following table summarizes the attributes that you can use in a <fadeout/>
tag. An asterisk (*) denotes a required attribute.
Attribute | Value | Function | Reference |
---|---|---|---|
color |
name | #RRGGBB |
Sets the fade color. | click here |
dsth|dstw| |
pixels |
Sets the size and placement of the rectangle that fades out. | click here |
duration* |
time_value |
Specifies the effect's total duration. | click here |
maxfps |
integer |
Controls the maximum frame rate. | click here |
start* |
time_value |
Gives the effect start time. | click here |
![]() |
View it now!
(requirements for viewing this sample)
This sample lets you watch fade out examples. |
The <crossfade/>
tag creates a transition from one image to another, as
illustrated in the following figure. An image should be displaying in the
RealPix area already when you use a crossfade to specify a new image:
<crossfade target="4" start="15" duration="4"/> |
The following table summarizes the attributes that you can use in a
<crossfade/>
tag. An asterisk (*) denotes a required attribute.
Attribute | Value | Function | Reference |
---|---|---|---|
aspect |
false|true |
Maintains or ignores the image aspect ratio. | click here |
dsth|dstw| |
pixels |
Sets the size and placement of the image that fades in. | click here |
duration* |
time_value |
Specifies the effect's total duration. | click here |
maxfps |
integer |
Controls the maximum frame rate. | click here |
srch|srcw| |
pixels |
Selects part of the source image for the effect. | click here |
start* |
time_value |
Gives the effect start time. | click here |
target* |
handle |
Indicates the image used for the effect. | click here |
url |
URL |
Sets a link URL while the effect is active. | click here |
The <fill/>
tag paints a colored rectangle instantly. Use it anytime you want to
fill all or part of the display area. You can fade in an image, for instance, then
fill the display area with a color that paints over the image. You can use a
predefined color name or a hexadecimal value, as described in Appendix C.
RealPix does not support RGB colors in the format rgb(
n
,
n
,
n
)
, however. A
<fill/>
tag looks like this:
<fill start="9" color="#23A134"/> |
The following table summarizes the attributes that you can use in a <fill/>
tag.
An asterisk (*) denotes a required attribute.
Attribute | Value | Function | Reference |
---|---|---|---|
color |
name | #RRGGBB |
Sets the fill color. | click here |
dsth|dstw| |
pixels |
Sets the size and placement of the rectangle that is filled. | click here |
start* |
time_value |
Gives the effect start time. | click here |
The <wipe/>
tag creates a transition from one image to another, either by
having the second image slide over and cover the first image, or by having it
push the first image out of the display area. A typical <wipe/>
tag looks like
this:
<wipe type="push" direction="left" start="10" duration="3" target="2"/> |
The following figure illustrates this effect.
The following table summarizes the attributes that you can use in a <wipe/>
tag. An asterisk (*) denotes a required attribute.
Attribute | Value | Function | Reference |
---|---|---|---|
aspect |
false|true |
Maintains or ignores the image aspect ratio. | click here |
direction* |
left|right| |
Sets the wipe effect direction. | click here |
dsth|dstw| |
pixels |
Sets the size and placement of the image that is wiped in. | click here |
duration* |
time_value |
Specifies the effect's total duration. | click here |
maxfps |
integer |
Controls the maximum frame rate. | click here |
srch|srcw| |
pixels |
Selects part of the source image for the effect. | click here |
start* |
time_value |
Gives the effect start time. | click here |
target* |
handle |
Indicates the image used for the effect. | click here |
type* |
normal|push |
Specifies the type of wipe effect. | click here |
url |
URL |
Sets a link URL while the effect is active. | click here |
![]() |
View it now!
(requirements for viewing this sample)
Play this sample to watch a simple slideshow of wipe effects. The next sample uses a SMIL file to create brush objects, which are described in "Creating a Brush Object", to change the slideshow "background" dynamically. The last sample demonstrates more creative uses of wipe effects. |
The required type
attribute defines the type of transition that occurs:
normal |
New image moves over current image, which remains stationary. |
push |
New image pushes current image out (both images move). |
<wipe type="push".../> |
The required direction
attribute sets the direction the new image moves:
<wipe direction="up".../> |
When you display an animated GIF image in a RealPix slideshow, the GIF does
not automatically begin to animate. Instead, you use the <animate/>
tag to
start the GIF cycling through its frames. This lets you control when the
animation starts, and how long it lasts. An <animate/>
tag looks like this:
< |
The following table summarizes the attributes that you can use in a
<animate/>
tag. An asterisk (*) denotes a required attribute.
Attribute | Value | Function | Reference |
---|---|---|---|
aspect |
false|true |
Maintains or ignores the image aspect ratio. | click here |
dsth|dstw| |
pixels |
Sets the size and placement of a GIF introduced with <animate/> . |
click here |
duration* |
time_value |
Specifies the effect's total duration. | click here |
maxfps |
integer |
Sets the animation's maximum frame rate. | click here |
srch|srcw| |
pixels |
Selects part of the source GIF to display. | click here |
start* |
time_value |
Gives the effect start time. | click here |
target* |
handle |
Indicates the image used for the effect. | click here |
url |
URL |
Sets a link URL while the effect is active. | click here |
If you introduce an animated GIF into the presentation with <animate/>
, the
GIF appears instantly at its start
time, with no transition effect. However, you
can also introduce the GIF with another tag, such as <fadein/>
, then use
<animate/>
to start the animation. Here's an example:
<fadein start="5" duration="1" target="2"/> |
In this example, the animated GIF fades in at five seconds into the timeline. Its first frame remains stationary until 10 seconds into the timeline. The GIF then cycles through its programmed animation sequence for 30 seconds.
![]() |
Note:
The RealPix <animate/> tag is not related to the
<animate/> tag used in SMIL animations, which is described in
"Animation Tags".
|
![]() |
View it now!
(requirements for viewing this sample)
This sample fades in an animated GIF, starts the animation, and fades out. |
The <viewchange/>
tag defines a pan or a zoom. It requires the use of the
source and destination attributes described in "Controlling Image Size and
Placement". A typical <viewchange/>
tag looks like this:
<viewchange start="24" duration="3" srcx="80" srcy="80" srcw="48" srch="48"/> |
Note that <viewchange/>
does not specify an image. The view change always
affects the image currently in the display area. The following figure illustrates
a zoom created with a <viewchange/>
tag.
The following table summarizes the attributes that you can use in a
<viewchange/>
tag. An asterisk (*) denotes a required attribute.
Attribute | Value | Function | Reference |
---|---|---|---|
dsth|dstw| |
pixels |
Sets the size and placement of the destination rectangle. | click here |
duration* |
time_value |
Specifies the effect's total duration. | click here |
maxfps |
integer |
Controls the maximum frame rate. | click here |
srch|srcw| |
pixels |
Selects the size and placement of the source rectangle. | click here |
start* |
time_value |
Gives the effect start time. | click here |
![]() |
View it now!
(requirements for viewing this sample)
With this sample, you can watch pan and zoom examples. |
To zoom in on an image, display the image and then use <viewchange/>
to
define a source rectangle to zoom in on. The following example is taken from
a RealPix presentation that displays in an area 256-by-256 pixels. The source
image is also 256-by-256 pixels. The presentation fades in on the image and
then zooms in, taking three seconds to complete the zoom:
<fadein start="1" duration="2" target="1"/> |
The zoom selects a source rectangle that is 128-by-128 pixels, and that appears in the center of the source image. This source rectangle displays in the full 256-by-256-pixel display area. The following figure illustrates this zoom.
Because this zoom effect does not specify a destination rectangle, the zoom
image fills the entire display area. But you can also use the destination
coordinates (dstx, dsty, dstw, dsth
) to specify a destination rectangle within the
display area.
To pan across an image, display a portion of the source image, then use
<viewchange/>
to move to a different part of the source image. The following
example uses a RealPix presentation that displays in an area 256-by-256 pixels.
The source image is also 256-by-256 pixels:
<fadein start="1" duration="3" target="2"/> |
The presentation fades in an image, zooms in on the upper-left quadrant, then pans to the upper-right quadrant. Each effect takes three seconds to complete. The following figure illustrates this movement.
Because this pan effect does not specify a destination rectangle, the source
rectangle fills the entire display area. But you can also use the destination
coordinates (dstx, dsty, dstw, dsth
) to specify a destination rectangle within the
display area.
When RealOne Player plays a RealPix slideshow, it expands its media playback
pane to the size defined by the <head/>
tag's width
and height
attributes. To
create a simple presentation such as a basic slideshow, you can simply fade the
images in and out of this display area. Images the same size as the display area
appear full-size. Larger images shrink to fit the area, smaller images expand.
You may want to display just a portion of a source image, however. Or you may want to display two images side-by-side. RealPix lets you specify a portion of a source image that appears in the display area. It also lets you determine the size and placement of images in the display area. To understand how this works, keep in mind the following definitions:
<head/>
tag's width
and height
attributes, as described in "Defining the Presentation Size".
To use just a portion of a source image or the display area for an effect, you define the source rectangle, destination rectangle, or both in an effect tag. To do this, you work with the attributes described in the following table.
The offset attributes (dstx
, dsty
, srcx
, and srcy
) default to zero. The destination
rectangle size attributes (dstw
and dsth
) default to the display area width and
height. The source rectangle size attributes (srcw
and srch
) default to the
source image width and height. This means that if you leave the source
attributes out of a tag, the entire source image is used. If you leave the
destination attributes out of a tag, the selected image portion fills the entire
display area.
![]() |
Note:
The aspect attribute, described in "Handling Image
Aspect Ratios", determines how an image appears when the
source and destination rectangles have different width-to-
height ratios.
|
In the example below, both the source image and display area are 256 pixels high by 256 pixels wide. The source rectangle tags display the upper-left quadrant of the source image in the display area, effectively magnifying the source rectangle by a factor of 2. Because the destination rectangle defaults to the display area size, no destination rectangle coordinates are needed.
To introduce this image with a fade, for example, you add the source
attributes to the <fadein/>
tag:
<fadein start="4" duration="3" target="2" srx="0" srcy="0" srch="128" srcw="128"/> |
In the next example, the source image displays in the upper-right quadrant of the display area, effectively reducing the size of the source image by half. No source coordinates are included, so the entire source image displays in the destination rectangle.
To paint the background, then wipe this image into the display area, for
instance, you use a <fill/>
tag followed by a <wipe/>
tag that includes the
destination attributes:
<fill color="#E7651A" start="9"/> |
This example shows a portion of the source image displayed at a slightly larger size in the display area. In this case, both source and destination coordinates are needed to define the source and destination rectangles.
To introduce this image with a fade, for example, you add the source and
destination attributes to the <fadein/>
tag:
<fadein start="1" duration="2" target="5" srx="0" srcy="0" srch="128" srcw="128" |
This section takes you through the process of creating a RealPix presentation step-by-step. Be sure to read "Managing RealPix Bandwidth" before you work through this example. To get playable RealPix sample files, download the zipped HTML version of this guide as described in "How to Download This Guide to Your Computer", and view the Sample Files page.
Suppose that you want to create a RealPix slideshow that contains five images. You want to coordinate the images to a RealAudio background music clip that lasts 3 minutes. You want the slideshow and audio to end after 1-1/2 minutes, though, and to be available to viewers who have 56 Kbps dial-up modems. According to the table "Maximum Streaming Rates", you have 34 Kbps of available bandwidth that you can split between RealAudio and RealPix.
The first step is to determine your RealAudio bandwidth. When you encode a
RealAudio clip with Helix Producer, you can set an option that lowers the
RealAudio bandwidth for the 56 Kbps modem target audience from 32 Kbps
to 20 Kbps. (If you have Helix Producer Plus, you can change this to any
available rate.) At the 20 Kbps RealAudio rate, the RealPix slideshow has 14
Kbps of bandwidth available (34-20=14
).
If you plan to stream with Helix Universal Server, use SureStream RealAudio, and select one or more target audiences at higher bit rates. This enables viewers with faster connections to get better audio quality. When using a Web server, though, you cannot use SureStream.
![]() |
Note: You can determine an audio clip's streaming bit rate and initial buffering time (preroll) by opening the clip in RealOne Player, and giving the File>Clip Properties>Clip Source command. |
![]() |
For More Information: See your Helix Producer user's guide or online help for instructions on modifying RealAudio's streaming bit rate for a given target audience. |
Once you know your target bit rate for your RealPix images, add up the image sizes to get a rough idea of whether your planned timeline is viable. Suppose the following are the images you want to use:
frog.jpg |
24 Kilobytes |
tiger.jpg |
39 Kilobytes |
cows.jpg |
55 Kilobytes |
elephant.jpg |
38 Kilobytes |
hippo.jpg |
38 Kilobytes |
The desired timeline is 90 seconds, with the presentation streaming at 14
Kbps. This means the slideshow can stream 1260 Kilobits (90 x 14
) of image
data, which equals 157.5 Kilobytes (1250/8
). The images add up to 194
Kilobytes, which will make the preroll fairly long. To lower the preroll, you can
either extend the timeline, or reduce the image file sizes. Suppose that
through cropping, resizing, and higher JPEG compression, you modify the
images to these sizes:
The images now total 162 Kilobytes, which is acceptable because it is only slightly over the 157.5 Kilobyte target. To better plan the timeline, it helps to determine how long each image takes to stream, as shown in the table above. To get these numbers, multiply each file size in Kilobytes by 8 to get Kilobits, then divide by your target bit rate (14 Kbps in this example).
Once you have settled your bandwidth issues, you can write your RealPix file. If you know how long it takes each image to stream, you can better adjust the RealPix timeline to keep the preroll as low as possible. It helps to stream the smaller images first, and to space each image out so that it doesn't appear too soon after the preceding image. The following timeline streams images in order from smallest to largest:
Because the first image (frog.jpg
) is scheduled to appear as soon as the
presentation starts, the timing will obviously cause at least an 11.4-second
preroll while the first image streams to RealOne Player. But, as you'll see
below, you can mask this delay by starting the soundtrack before the images
appear.
![]() |
Tip: Keep in mind that the individual streaming times are only a guide to developing the timeline. If an image has a 20-second streaming time, it can still display 15 seconds after another image. Helix Universal Server will always stream all of the image data to RealOne Player before the image is scheduled to display, lengthening the presentation preroll if necessary. |
The RealPix markup might look like the following, which creates a 300-pixel-
by-300-pixel display area, set a streaming bit rate of 14 Kbps, indicates a 90-
second duration, and introduces each image with a four-second fade. The size
parameters in the <image/>
tags are not required when streaming with Helix
Universal Server, but are included anyway to make Web server delivery
possible.
<imfl> |
To combine the RealPix slideshow with the RealAudio soundtrack, you write a
SMIL file that defines the overall presentation. Because RealPix is backwards-
compatible with earlier versions of RealPlayer, use SMIL 1.0 as long as you do
not need the enhanced features of SMIL 2.0. This ensures the widest possible
audience. The following sample SMIL 1.0 file combines the RealPix slideshow
(slideshow.rp
) with the RealAudio clip (soundtrack.rm
):
<smil> |
In this SMIL file, the endsync
attribute in the <par>
tag ends the presentation
when the RealPix slideshow ends, cutting off the RealAudio soundtrack. The
begin="15s"
attribute in the slideshow's <ref/>
source tag delays the RealPix
presentation from starting until 15 seconds after the soundtrack begins to
play. Helix Universal Server uses that time to stream the RealPix slideshow's
preroll. This helps the entire presentation start to play back faster.
![]() |
Tip: It's important always to test your presentation in an actual streaming environment. This may lead you to modify your timing parameters to make the presentation more efficient. |
![]() |
For More Information: For information about SMIL 1.0, see RealSystem iQ Production Guide for Release 8, which is available at http://service.real.com/help/library/encoders.html. |
![]() |
©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. |