RealText--Text Synchronization with Digital Media
February 22, 1999
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RealText is the new text format developed by Real
Networks. It allows text to be streamed over web as part of
Synchronized Multimedia Integration Language (SMIL) and
synchronized with other
Real media types in the G2
Player from RealNetworks. Rule will discuss other media types
such as RealPix, RealVideo and RealAudio in later articles.
SMIL is a recommendation from the World Wide Web
Consortium (W3C) that allows for the creation of time-based
multimedia delivery over the web.
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Its ironic that one of the most innovative new uses of text
on the web comes from the company that popularized video delivery
over the Internet. When it comes to bandwidth, text is cheap
compared to video or graphics. Text is the original medium of
the Internet and is an integral part of all web pages.
RealNetworks
has not forgotten text when creating
SMIL
(Synchronized Multimedia Integration Language) for the Real G2 Player.
RealText is a new format for displaying and controlling text in
the Real G2 Player. RealText is a well written spec making it
easy to further illustrate video and graphics with synchronized text.
Real World RealText
Creating a presentation with
SMIL
for delivery over 28.8 modems is an
ambitious undertaking. Even using
RealPix,
graphics take up large
parts of
multimedia
presentation. If you add an overlaying audio track
this takes an additional 1K/sec. In a graphics presentation if your
graphics are 10K each then you can only show a new "slide"
in a presentation every 10 seconds. In cases like this with very
limited
bandwidth
RealText can be invaluable in providing additional
information while adding only minor overhead to the bandwidth.
Most of the numbers I mentioned above were arrived at by real world
testing at Discovery Channel Online, where I created one of the
early Channels for the G2 Player. Discovery wanted to augment their
News Brief offering with a
SMIL
presentation. Originally plans
called for streaming video, graphics, audio and text. After
some experimentation, we realized that even with the best compression
in the world there was no way to deliver a multimedia news slide
show of this caliber over 28.8 connections. In the end, the video
was dropped and a slide show, along with backing audio, was used.
At the bottom of the screen we had the News headlines appear at
the beginning of the story and then a highlighting dot appears
next to each story as it is discussed. The headlines are also
hot clickable so that the user has random access to any of
the stories merely by clicking on it. In this case the text is
the standing element which also provides a method of
navigation.
The Discovery Channel News Brief is a default in the RealPlayer
G2 Channel Bar or can be seen
here.
Contents:
What Can It Do
General Info
Positioning
Conclusion
What Can It Do
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