Transcript MIR - TERENA Networking Conference 2002

Global Serverless
Videoconferencing over IP
Thomas C. Schmidt, Matthias Wählisch,
Hans L. Cycon, Mark Palkow
{schmidt, mw, hcycon, mpalkow}@fhtw-berlin.de
FH für Technik und Wirtschaft Berlin
Email still is the
Killer Communication App.
in Internet - Why ?
 Email is Unique to Computer Networks
 Email is reliable and mature
 Email is easy and free
 Email is accessible everywhere
 Email has full infrastructure support
What about
Videoconferencing over IP
(VCoIP) ?
 VCoIP is Unique to Computer Networks
 VCoIP is reliable and mature
 VCoIP is easy and free
 VCoIP is accessible everywhere
 VCoIP has full infrastructure support
Agenda
 VCoIP communication paradigm
 VCoIP - where < are we > going?
 A distributed communication scheme
 User Location
 Group Conferencing
 The daViCo conferencing System
 Properties, Implementations
 Wavelet Video Codec
 Conclusions & Outlook
VCoIP
Communication Paradigm
Video Conferencing Services request for
 Session Orientation (synchronous service)
 Person Orientation
 Coping with Mobile Users (globally)
 Group Support
 Support of Privacy
Where Are We ?
• Serious Conferencing Applications via ISDN
• ISDN-formed ITU-T Standard H.323
– Heavy burdened Infrastructure with Scaling Deficiencies
– Addressing via Telephone Numbers
– Local Relaying except for Telephony or Meta Directories
• Session Initiation Protocol (SIP, RFC 2543)
– Own SIP Infrastructure or vaguely locatable SIP-Servers
– Addressing <user>@<SIP-server>
• Proprietary Centralised Services (MS NetMeeting)
Are We Going?
Distribution of videoconferencing is retarded by
following the track of H.323 and such:
– Inertia of infrastructure
– Costs
– Inadequate, clumsy solutions
– Insufficient support of communication
requirements
 We need a new ‘internet-like’ approach to VCoIP
VCoIP Distribution Recipes
• Provide an easy, intuitive VCoIP solution
• Provide personal, effortless addressing
• Provide automatic user location
• Remain rigorously neutral to infrastructure
• Avoid costs
• Focus on distributed, decentralised services
• Stick to internet attitudes
A Distributed, Intuitive
Conferencing Framework
o Identify users via Email Addresses
- Well known
- Globally unique
- Suitable for automatic relaying
o Peer-to-Peer principle waives specific infrastructure
- Multipoint conferences via multicasting
o Distributed, hidden information services
o Pure software solution
User Session Location
• Directories in domains locale to users
• Map Email to current Host-IP
• Directory location via
– DNS MX-Record
– Name convention usl.<mx-domain>
• Decentralised administration & authentification
A User Location Scheme
LDAP Session Data
DN: [email protected], dc=application
Required
Optional
VCoIPHostNumber
VCoIPMcastGroup
VCoIPServicePort
VCoIPAppID
VCoIPServiceProtocol
VCoIPAppProtocol
VCoIPTimeStamp
VCoIPMimeType
mail
VCoIPPrivateipHostNumber
cn
VCoIPPrivateipServicePort
VCoIPStatusFlag
Note: LDAP allows for authentification & encryption
NAT Obstructions
NAT Gateways firmly object any Videocommunication.
Traditional ALGs intrude fundamental infrastructure.
Approach:
• Position USL outside NAT range
• Restrain NAT-GW from dropping state information
• Extract IP-Address and Port from packet headers
• Publish extracted address information to USL
daViCo
Videoconferencing Software
Pure Software solution including
• multicast/multipoint video communication
• highly efficient video codec PACC
• MPEG3 audio encoding
• buffer latencies about 100 ms
• application sharing
• implements peer-to-peer model & usl scheme
• designed for best effort transport & effortless use
Wavelet Video Codec
 Real-time video codec based on fast low
complexity wavelet transform
 Transforms whole images without blocking
artefacts
 CIF (352 x 288 pixels) at 25 fps performs in realtime on a 500 MHz Pentium Machine
data-rates below 200 kbit/s
 More efficient than MPEG4 or H.263 coders
with
Wavelet Coder and Decoder
Image
DWT
Lossless Decorelation
Q
Lossy Quantizer
PC
AC
Lossless entropy coder
PACC
Image
IDWT
IQ
IPC/IAC
PACC: Principle of Partioning, Aggregation
and Conditional Coding
PACC Decomposition
Wavelet Transform
Lena 512x512 (Ausschnitt)
Original
JPEG 1:64
WLT 1:64
VCoIP in Praxis
Conclusions & Outlook
 VCoIP solution based on a light-weight peer-to-
peer model.
 Ready-to-use approach for user addressing & lookup.
Future Development:
 Future of PACC Codec part of ITU-T H264
/MPEG Advanced Video Codec (AVC)
 Future directory location via DNS Service Record