A S t r e a m i n g M e d i a P r i m e r :
H O W D O I P U T M Y S T R E A M I N G M E D I A O N T H E W E B ?
INTEGRATING STREAMING MEDIA
How do I link my streaming media to my Web page?
If you use a standard HTML tag, browsers will download the streaming media fi le just as if it
was being served by a Web server that is, the fi le must download completely before being played from
the user's hard drive as you know, this is not streaming.
To differentiate between a downloadable media fi le and a streaming media fi le, a media metafi le is used.
The link you insert into your Web page points to the metafi le, which is posted on the Web server. The
metafi le, which is a simple text fi le, invokes the correct media player on the client desktop, locates the
selected streaming media fi le on the streaming media server and, as the streaming media fi le downloads,
redirects it from the browser to the media player.
Metafi le extensions and streaming media fi le extensions
Architecture Metafi le Extensions Streaming Media File Extensions
RealMedia .rpm or .ram .rm
Windows Media .asx, .wax, or .wvx .asf or .wmv (.wma for audio)
QuickTime .mov or .sdp .mov (sometimes .qt or .qti)
The QuickTime approach is a bit different from RealMedia and Windows Media. In the QuickTime
architecture, the streaming instructions are embedded right into the movie as a hint track, and the link
from the Web page goes directly to the streaming server. But some browsers will automatically attempt
to open an RTSP URL with the specifi ed default player, which may not be QuickTime. To be sure the
QuickTime player is invoked, a form of metafi le which Apple calls a reference movie can be employed;
to take advantage of QuickTime's answer to MBR alternate bit rate fi les a reference movie must be
used. A reference movie is a separate, tiny .mov fi le published on your Web server. When invoked, the
reference movie calls up the appropriate streaming (i.e., hinted) movie fi le from the streaming media
server. Live feeds in QuickTime use a more standard metafi le scheme, with a text fi le format called SDP
(Session Description Protocol); the SDP fi le is published on the Web server and points to the proper
location on the broadcasting media server.
Integrating streaming media into a rich media experience
[SMIL] is a simple but powerful
A Web page is often like a three ring circus, with different things going on, in different
markup language that lets you
places, on different timelines. It has been diffi cult for Web developers to synchronize
presentations comprised of assorted components, especially when those components are
coordinate the clips so that they each
served up from different locations via connections that are each subject to their own con
play how, when and where you want
gestion patterns. Synchronized Multimedia Integration Language, or SMIL (pronounced
them to If you are familiar with
smile ), lets Web developers choreograph rich media presentations, including streaming
other Web based markup languages,
media, with comparative ease.
such as HTML, you will pick up
SMIL, based on the language XML, is reputed to be as easy to learn and use as HTML.
SMIL quickly. You'll need to be
It can, of course, be written with a text editor, but there are several convenient SMIL
editors now available for this relatively new technology. In essence, SMIL is to RTSP and
careful, though, because SMIL is less
media servers what HTML is to HTTP and Web servers it is the language that best
forgiving than HTML. Lapses that
takes advantage of the benefi ts of the streaming protocol. And, as HTML is the standard
may not matter in HTML markup,
language used to coordinate the content displayed on Web browsers, SMIL is the language
such as missing quotations marks
that is rapidly becoming the standard for coordinating the content played on media
players. Once your clips (e.g., video, text, still images, animations, etc.) are encoded in
will prevent a SMIL fi le from
their streaming (or other) formats, you assemble your presentation using SMIL.
The end user must have an SMIL enabled media player or browser to take advantage
of SMIL fi les. The latest versions of all three dominant architectures' players and several
others', as well as the newest version of Internet Explorer, are compliant.