[CAnet - news] Excellent report on desktop video conferencing- telephony

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[Thanks to Dirk van der Woude for this pointer -- BSA]



Hi,

You might be interested in the attached report on video 
telephony: what does it take to have it universally available.

We asked Eem Valley's Paul Sijben to evaluate all aspects,
including a detailed technical review of available hardware 
at consumer price level. A few 'secrets' of today's webcams
are revealed.

An approach is identified that will VHS-like quality at a 
symmetrical bandwidth of 5-10Mb/.

Below is the Executive Summary. The report is archived on 
the Citynet site at:
www.citynet.nl/upload/What-does-it-take-to-get-good-videotelephony.pdf

greetings,
Dirk


================================ 


Video telephony is one of the most appealing possibilities promised by
broadband Internet. There are huge advantages to being in a telephone call
and being able to see the other person. As has been known for quite some
time, the nuances of face, body and arm gestures add a wealth of information
to communication. Good video telephony adds quality to telecommunica-tion
that reduces the need for people to physically travel to meetings. Good
video telephony can prevent the elderly and less mobile from becoming
isolated. For video telephony to be widely accepted it needs to be easy to
use, provide sufficient quality and be affordable. 

Unfortunately good video telephony is not universally available. Today,
video telephony usually implies that a group of people gather around a table
and watch a TV showing a similar group of people around another table.
Personal video telephony usually means watching postage stamp sized people
in a PC screen, whose image is refreshed occasionally. 

In this report we address the question; when a country like the Netherlands
is 2nd in the world in broadband penetration and if video telephony is one
of the most appealing broadband applications, why is good video telephony so
hard to come by? 

Many of today's videophones are difficult to use or privacy invasive. Adding
a traditional receiver and some buttons familiar from regular telephones may
address both of these issues.

For a usability standpoint we would like to see the videophone as a
standalone device with a telephone-like handset. A few buttons will allow de
caller to "dial" the called and a simple button will allow calls to be
accepted and terminated. A few buttons for starting and stopping the video
streams and to mute the sound will enable an affordable videophone for
anyone who can handle a regular telephone. 

In this report we have shown that the state of the art is mostly determined
by bandwidth limitations. However, broadband Internet is making huge strides
forward. The introduction of symmetrical Internet with high guaranteed
speeds offers opportunities for video telephony, finally there is the
opportunity for good image quality at acceptable costs. The approach
identified in this report will work with symmetrical bandwidth of 5-10Mb/s
and will deliver an image quality comparable to that of VHS video with
acceptable delays. 
If there is the will and the bandwidth, nothing will stand in the way of
general use of video te-

Table of Contents
Executive Summary..............3 
About the Author.................5
Table of Contents.................7 
1 Introduction.................9
1.1 Existing video telephony applications.......................9 
1.1.1 MSN Messenger....................9
1.1.2 D-link DVC-1000..................10 
1.1.3 D-link DVC-2000..................11
1.1.4 Polycom V500.....................11 
1.2 Video telephony and bandwidth..11
1.3 Issues with video telephony today .12 
2 Properties of good video telephony.....13
2.1 Introduction........13 
2.2 Image quality.....13
2.3 Usability.............14 
2.3.1 Professional use...................14
2.3.2 Private use..15 
2.3.3 Domestic Privacy..................15
2.3.4 User requirements................16 
3 Anatomy of video telephony...............17
3.1 Introduction........17 
3.2 Bandwidth..........17
3.3 Delay.................19 
3.3.1 Delay at capture..................20
3.3.2 Network delay.....................20 
3.3.3 Delays in processing the video.......21
3.4 Streaming..........21 
4 Towards good video telephony...........23
4.1 Introduction........23 
4.2 Unlimited bandwidth....................23
4.3 Conclusion.........23 
Annex A Camera Measurement..................25
A.1 Introduction........25 
A.2 Test setting.........25
A.3 Base measurement.......................25 
A.4 The secrets behind webcams........26
A.5 Improving webcam behavior.......27 
A.6 New technology; not faster..........27




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