Global Serverless Videoconferencing over IP Thomas C. Schmidt, Matthias Wählisch, Hans L. Cycon,...
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Transcript of Global Serverless Videoconferencing over IP Thomas C. Schmidt, Matthias Wählisch, Hans L. Cycon,...
Global Serverless Videoconferencing over IP
Thomas C. Schmidt, Matthias Wählisch, Hans L. Cycon, Mark Palkow
{schmidt, mw, hcycon, mpalkow}@fhtw-berlin.deFH 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
VCoIPCommunication 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
Note: LDAP allows for authentification & encryption
Required Optional
VCoIPHostNumber VCoIPMcastGroup
VCoIPServicePort VCoIPAppID
VCoIPServiceProtocol VCoIPAppProtocol
VCoIPTimeStamp VCoIPMimeType
mail VCoIPPrivateipHostNumber
cn VCoIPPrivateipServicePort
VCoIPStatusFlag
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
real-time on a 500 MHz Pentium Machine
with data-rates below 200 kbit/s
More efficient than MPEG4 or H.263 coders
Wavelet Coder and Decoder
DW T Q PC
IDW T IQ IPC/IAC
AC
PACC: Principle of Partioning, Aggregation and Conditional Coding
Image
Image
Lossless Decorelation Lossy Quantizer Lossless entropy coderPACC
PACC Decomposition
Wavelet Transform
03.02.2001 Wavele tprojekt H.L.Cycon 6
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 &
look-up.
Future Development:
Future of PACC Codec part of ITU-T H264
/MPEG Advanced Video Codec (AVC)
Future directory location via DNS Service
Record