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STREAMINGTECHNOLOGIES ANDSYSTEMS 555able to use the iconoscope to imitate the ways that hu-
man eyes view images for television broadcast (Inventors
Online Museum, 2002). This technology was a key com-
ponent in the advancement of electronic television and
serves as the foundation for the design of the modern elec-
tronic televisions in use today (Fortner, 2002).
Although television may have provided the foundation
for the technology of streaming video, the Internet has
provided the means that has made it available to con-
sumers in their homes and to businesses. The Internet has
revolutionized the computer and communications world
as never before. It has become a worldwide medium for
broadcasting, information dissemination, collaboration,
and interaction between individuals without regard to
location (Leiner et al., 2000).NETWORKING CONCEPTS
Because streaming video is delivered to the user over a
network, it is important to understand the basics of how
the information is handled and transmitted through a net-
work. In essence, networking involves one computer ex-
changing information with another computer. Most Inter-
net address begins with http://. HTTP stands for hypertext
transfer protocol and is a standard or protocol (RealNet-
works, 2000). It tells a browser and computer that HTML
has been sent to it so it can read the incoming information.
In the case of some streaming video locations on the In-
ternet, the addresses start with PNM://, RTP://, or RTSP://.
PNM stands for progressive networks media and it is an
older protocol. However, there are still a number of video
clips in use that use this protocol (RealNetworks, 2000).
RTP stands for real-time protocol, and it is one of the most
commonly used protocols for streaming media on the In-
ternet (Compaq Computer Corporation [Compaq], 1998).
RTSP stands for real-time streaming protocol, which is the
newest protocol (RealNetworks, 2000). In all three cases,
these addresses tell a browser and computer that stream-
ing video has been sent to it. It should be noted that any
computer receiving streaming video must have a special
application installed that can read and play the video. This
topic will be discussed in more detail in the next section.HOW STREAMING WORKS
Streaming involves taking video or audio files, breaking
them down into packets of information, and sending them
to their destination. At the receiving end, the viewer can
then play the video as it is being downloaded. Because
of the way that information flows on the network, it is
easy to see that there would be a number of interruptions
and delays in playing the video. To address this issue, a
technology, called buffering, was developed to ensure that
the playing of the video on the receiving end is smooth.
Buffering is the process where a large number of infor-
mation packets are collected before the playing of the
video begins. Once enough packets have been collected,
the playing of the video will begin. As the video plays, the
buffering will continue until all of the information has
been received. It is important to note that the video is not
stored on the user’s computer; it is received, buffered, and
played.The process described above is referred to as true
streaming. It should not be confused with a method called
pseudo-streaming or progressive download. Pseudo-
streaming users wait until a significant portion of video
file has been downloaded to their computer before view-
ing the video. This method allows users to save files to
the hard drives on their computer for later viewing. Pro-
gressive download works best with very short media clips
and a small number of simultaneous users ( DoIt & WISC,
2002).
Streaming video may involve a video with or without
sound. In the case of a video with sound, the visual por-
tion of the video is delivered on one stream while the au-
dio is delivered on another stream. Technology has been
developed to synchronize these streams at the destina-
tion to ensure that the sound matches up with the ac-
tion being viewed. Streaming files that include more than
one medium are known as rich media. It should be noted
that streaming can include slide presentations, text, video,
audio, or any combination of these.
A number of components are required in order to make
streaming video work on the Internet. First, the user must
have a computer connection to the Internet via a local
area network or modem. The user must also have a Web
browser with the appropriate video player or plug-in in-
stalled. Many plug-ins can be downloaded from the Web
for free. A plug-in works in conjunction with a browser to
play streaming video files. A Web server stores Web pages
or HTML files. Streaming video files are usually kept on
a separate dedicated streaming server. When a streaming
video link is clicked on a Web page, the browser reads the
HTML code and the lets the player/plug-in take over (DoIt
& WISC, 2002). The player accesses the selected video on
the streaming server using the video protocols (RTP and
RTSP) discussed in the previous section. After a few sec-
onds of buffering, the video will start and play.STREAMING TECHNOLOGIES
AND SYSTEMS
A number of technologies are available for streaming
video. The three major technologies are RealOne, Quick-
Time, and Windows Media (DoIt & WISC, 2002). Each
streaming technology has three common hardware and/or
software components: (1) servers and video files; (2) video
players and plug-ins; and (3) compression, encoding, and
creation tools (DoIt & WISC, 2002). The specifics of each
technology will be discussed in more depth in a later sec-
tion in this paper.
Each streaming technology mentioned above may have
its own proprietary server and media file types that they
use. Also, RealOne, QuickTime, and Windows Media have
their own servers that stream files in their own formats.
Therefore, it is important to create video files in a for-
mat that are compatible with the technology and server
that will be used to stream the files. However, and rela-
tively newer product called Helix offers open, comprhen-
sive didital media communication for all players.
In order to play the video file, the user must have the
second component, the player, installed on their com-
puter. Users can download the player from the Web for
free or, sometimes, it is included with the browser. As