Understanding Videoconferencing

A Plumber’s Guide

Bandwidth : What is it?

• The “pipe” that carries electronic info.

• Can come via a phone line, cable TV line, wireless transmission, or fiber-optic cable.

The way it works!

• Every data request requires movement of electronic information.

•“Surfing the web” requires bandwidth, the size/speed of which helps determine how fast you get to the page.

The way it works! (part 2)

Streaming video -15 - 30 pictures and audio EVERY SECOND. Thus a larger pipe is needed.

The way it works! (part 3)

Two way interactive video - double request of streaming video. 15 - 30 pictures per second PLUS audio in BOTH directions independent of each other!

So what’s all this about a

plumber?

• Information - water in the tank of a toilet!

•Click on a Web link - that’s like flushing the toilet.

When you flush, the speed at which the water moves is dependent on several factors, but the primary one is the size of the pipe that is connected to it.

Here’s where it gets interesting

• If you tried to flush the toilet through a 5/8” water supply line (like the one that connects to your kitchen faucet), it would take a LONG time, and it would back up.

• That’s what’s happening when your kids try to download a music video on your home computer over a 56K modem connected to a regular phone line.

Here’s the concept

The way to prevent the backup is to attach a bigger drain pipe. The bigger the pipe, the more information can flow through.

When the pipe is the proper size, the information flows freely. The more information you request, the bigger the pipe you need. Different kinds of information are different sizes.

Data Types and Relative Sizes (not to scale)

Text - small, faucet feed sized pipe required (2.4Kb/s)

Pix and Graphics - med.-sized pipe required (56Kb/s)Audio files - sewer line sized pipe required (56 - 384Kbs)Video files (moving pictures & audio)- Sluice pipe sized pipe required (384-45,000Kb/s)

Understand that every internet connected computer has its own pipe that may vary in size, AND that a connection over the internet may pass through several pipes on the way to getting the data from where it resides to the requestor.

Here’s The Tricky Part

So what???

Types of Interactive Video

IPISDN

Broadband

IP Videoconferencing

• IP - Internet Protocol - Videoconferencing over the Internet

• Once internet access is paid for, NO ADDED COST - potentially the least expensive option

• Think “video phone”

High fault tolerance & reliability, low speed and

predictability

• The Internet began as a military network, ARAPNET, designed to survive a nuclear attack. It was designed to be ultra-reliable, and nearly indestructible. Speed was never an issue, early on.

ISDN

•Integrated Services Digital Network - High Speed Phone Line

•“Video modem”

•Moderately priced, secure, flexible open network

Broadband Interactive Video

• High Quality

• High Reliability

• High Price

3 separate networks to do the same thing!

ISDN

IP

Broadband

BOCES’ Role- What do we do?

•Technical support•Coordination •Training

•Daily classes to expand educational offerings•Virtual Field Trips to places around the globe•Staff Development - opportunities for increased efficiencies and new ways to unite teachers around the region