USING Scan Do

®

SCAN CONVERTERS IN

VIDEOCONFERENCING APPLICATIONS

MARKET: Videoconferencing,

DOC. NUMBER: T-08

Distance Learning, Telemedicine

The videoconferencing market has grown expo-

nentially over the past 5 years, allowing more and

more face-to-face meetings to be held across long

distances without the expense and hassle of travel.

One reason videoconferencing has proven to be

such an effective substitute for in-person meetings

is the flexibility that current systems provide for the

display of many different types of information. Not

only can videoconferencing systems transmit and

display images of the people involved in the meet-

ing, but they also allow for the display of static docu-

ments, products and computer presentations. In or-

der for this to occur, all images are fed through a

“codec”, the heart of a videoconferencing system,

which transmits the information in the form of an

NTSC or PAL video signal to various remote loca-

tions. However, codecs are not designed to directly

receive and transmit a computer video signal. The

video signal from the computer must first be con-

verted into NTSC or PAL format, so as to be com-

patible with the codec.

As just described, a codec uses standard NTSC

or PAL video as the format of its transmission signal.

NTSC and PAL video are different from computer

video signals in many ways. The biggest differences

are in their resolutions (number of lines in the re-

spective pictures), the refresh rates (speed at which

the pictures are “painted” on the screens), and the

fact that standard video is interlaced (odd and even

lines are generated in separate passes), whereas

computer video is non-interlaced.

Scan Do scan converters take the non-interlaced,

high-resolution video signal from any computer and

convert it to a high-quality standard video signal,

suitable for transmission by a codec. While the ac-

tual processing that Scan Do scan converters per-

form is quite complex, using the units is simple, in-

volving only a few cable connections from computer

to Scan Do to codec. The codec then sends the sig-

nal over a phone line, to be received by another co-

dec located at the remote site of the videoconference.

This signal is then output to a local video monitor or

This TECHniques will describe how CSI’s family display device.

of Scan Do scan converters can be used to perform

Some people familiar with videoconferencing may

this necessary conversion, allowing for computer- have used “file sharing” as means for accessing com-

generated slides, spreadsheets, photography and puter documents within the context of a

other graphics to be easily integrated into a video- videoconference. Scan converters offer many advan-

conferencing environment.

tages to this technology. Unlike file sharing, scan

4Q Sales

Scan Do, Deuce, TwinSplit and HexiSplit are registered trademarks of Communications Specialties, Inc.

© 1999, Communications Specialties, Inc.



Page 2:

USING Scan Do SCAN CONVERTERS IN VIDEOCONFERENCING

APPLICATIONS

converters provide

real-time

transmission of the

computer-generated information

without

the need

for an additional modem or additional computer at

the receive site.

If your codec offers both an S-video and video in-

put, connect Scan Do to the S-video input. You will

benefit from a much higher quality image.

Some codecs do not offer multiple inputs for addi-

tional peripheral video equipment. In these in-

stances, Scan Do may still be integrated into the

videoconferencing system by using the auxiliary in-

put of some document cameras. The document cam-

era may then be used to switch between still docu-

ment images and live computer presentations.

For those applications that require multiple view-

ing displays to be connected to the receiving end of

a codec, Communications Specialties manufactures

a full line of video and S-video splitters. Models are

available with 2 and 6 outputs.

•

Scan Do Select .........................................1290

•

Scan Do Pro

II..........................................1291

•

Scan Do Ultra............................................ 1274

•

TwinSplit

®

for S-Video ...............................1802

•

HexiSplit

®

for S-Video ...............................1806

•

HexiSplit for Video .....................................1706

•

Educational Guide:

Scan Converters Buyers’

Guide

•

T-07 Using Deuce

®

Video Scalers in Video-

conferencing Applications

Scan Do , Deuce, TwinSplit and HexiSplit are registered trademarks of Communications Specialties, Inc.

© 1999, Communications Specialties, Inc.