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I.- History<br />

Distance Education on Demand: (Serv<strong>in</strong>g MPEG on the Internet)<br />

Mark D. Hendricks<br />

Electronic In<strong>format</strong>ion Specialist<br />

IANR Communications and In<strong>format</strong>ion Technology<br />

University of Nebraska-L<strong>in</strong>coln<br />

United States of America<br />

e-mail: ianr023@unlvm.unl.edu<br />

websites: citv.unl.edu, citvsgi1.unl.edu<br />

In the late summer of 1995, the Institute of Agriculture and Natural Resources (IANR) Communications and<br />

In<strong>format</strong>ion Technology (CIT) at the University of Nebraska - L<strong>in</strong>coln (UNL), began to research and assemble<br />

a server for the purpose of experiment<strong>in</strong>g with the possibility of distribut<strong>in</strong>g audio and video <strong>in</strong><strong>format</strong>ion via<br />

Internet. IANR has a long history of us<strong>in</strong>g distance education and <strong>in</strong><strong>format</strong>ion delivery, and this server was a<br />

logical exploratory step for IANR to take.<br />

Putt<strong>in</strong>g the components together was my task, and I began by <strong>in</strong>stall<strong>in</strong>g L<strong>in</strong>ux on a 60 MHz Pentium<br />

Computer, and the X<strong>in</strong>g server software. I had a thirty day trial with the X<strong>in</strong>g software and had never seen<br />

L<strong>in</strong>ux. After about a month, the system was up and runn<strong>in</strong>g and everyth<strong>in</strong>g seemed to work. We digitized<br />

some sample pieces and were able to send them around campus.<br />

II. - Background Technology<br />

MPEG, and specifically MPEG-1 for these purposes, is a standard for distribut<strong>in</strong>g audio and video established<br />

by the Motion Photographers Experts Group. "Stream<strong>in</strong>g" is a process of transmitt<strong>in</strong>g data (<strong>in</strong>clud<strong>in</strong>g MPEG)<br />

over a transmission media (<strong>in</strong> this case, the Internet), without hav<strong>in</strong>g to copy the data to a storage device<br />

before view<strong>in</strong>g the data. What this means <strong>in</strong> that when you are logged on to a server that can "stream" data,<br />

you do not have to wait and download a file before you can use it. Stream<strong>in</strong>g takes on an even greater<br />

significance when you consider the size and nature of the MPEG data we have set out to distribute. The MPEG<br />

files can easily exceed 100 MB and would take a long time to view if you had to download the file before you<br />

could view at it.<br />

The X<strong>in</strong>g software we use requires some description. It consists of several software and hardware components.<br />

The server software I have discussed early is a MPEG database server. The browser software is a software only<br />

MPEG decoder, and can be used to view video over bandwidth as low as 14.4 bps, on PC’s, Mac’s and Unix<br />

mach<strong>in</strong>es. The server software is capable of transmitt<strong>in</strong>g MPEG streams at variable rates, and can actually<br />

take an MPEG stream from an audio or video encoder and simultaneously transmit the signal at several<br />

different bandwidths. For example I could serve a live feed from a video conference at 12 bps, 24 bps, 52 bps<br />

and 112 bps, so that people us<strong>in</strong>g 14.4 and 28.8 bps modems, 56 K l<strong>in</strong>es and ISDN connections could view the<br />

conference at the best bandwidth their systems could support. MPEG and LBR files can also be stored on the<br />

hard drive for on demand replay and can be served at variable rates.<br />

III. - Test<strong>in</strong>g

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