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Multimedia Conferencing
with SIP
Orit LevinChief Architect
March, 2003
RADVISION Business
TBU: Enabling TBU: Enabling Technologies Technologies
Gatekeeper Gatekeeper MGC, …MGC, …
H.324MH.324M
MEGACOMEGACO
NBU: Networking NBU: Networking SolutionsSolutions
GatewayGateway MCU*MCU*
Servers,Servers,
FW Solutions,…FW Solutions,…
VideoVideoSIPSIP
MGCPMGCP
*MCU= Multiparty Conferencing Unit
H.323H.323
Videoconferencing Network
IP Network
PSTN/ISDN
Wireless 3G/
H.324M
Gateway
GatewayMCU
RADVISION ProductsRADVISION Products
RADVISION TechnologyRADVISION Technology
Gatekeeper/Proxy
RADVISION SIP strategy RADVISION is the leading provider of SIP-
based technologies SIP protocol stack SIP developer tools (proxy, registrar)
RADVISION is pushing for standards Standards for Video Standards for Conferencing
Seamless Protocol Integration with providing full support for all of the existing features of our product line RADVISION supports SIP, H.323 (IP), H.320
(ISDN), H.324M (3G)
What Does it Taketo Have a MultimediaSIP Conference?
Building Blocks
Point-to-Point Call Control Baseline SIP/SDP
Point-to-Point Media Control Video
SIP “Advanced” Call Control SIP conferencing extensions (Optional) Refer Method (Optional)
Conference Control Participants Control Floor Control (Optional)
Point-to-Point Basic Media Description Mechanism RFC 3264 “An Offer/Answer Model with
SDP” Change Media Characteristics by
“Re-INVITE” (or “UPDATE”) Hold/Resume Media Stream
Advanced Scenarios Examples Draft Under definition Will use “Grouping of Media Lines in the SIP”
RFC 3388 Will use “'SDP Simple Capability Declaration'
draft-andreasen-mmusic-sdp-simcap-05.txt
Video support in SIP
“Freeze Picture” Command (Encoder -> Decoder) “Fast Update” Command (Decoder -> Encoder)
* “CODEC” = enCOder DECoder
Two Basic Video Controls
XML Schema in INFO
The IETF draft
“draft-levin-mmusic-xml-media-control-01.txt “
Implemented already by ViaIP MCU (RADVISION) RTC Messenger (Microsoft) eConf (France Telecom)
Tech Currently defines “Fast Update” and “Freeze
Picture” Transported over SIP INFO
SIP forConferencing
SIPPING Conferencing Design team in IETF
SIPPING Requirements Document
SIPPING Framework Document
SIPPING Conference Event Package (NOTIFYs of participant list)
SIPPING Call Control – Conferencing Usage Document
Documents listed at http://softarmor.com/sipping/teams/conf/
SIP Tightly Coupled Conference
Association of User Agents with a single central point – i.e. Focus.
Focus is a UA that Maintains a SIP dialog with each
conference participant and internally correlates among them.
Can be implemented either by a participant or by a dedicated server.
In centralized model, focus does media mixing
In decentralized model, focus controls endpoint mixing
SIP Conference Identification
A SIP Conference is uniquely identified by a globally routable Conference URI.
Focus includes the Conference URI (followed by the feature tag “isfocus”) in the Contact of each message belonging to a conference dialog.
As a result, any RFC 3261 compliant UA can participate in a conference.
A Conference and its URI Exist
Dial In User’s INVITE carries the Conference URI in the
Request-URI. Server’s 200 OK carries the Conference URI in the
Contact.
Dial Out Server’s INVITE carries the Conference URI in the
Contact. Conference-aware user understands the meaning
of “isfocus” feature tag.
Additional Participants Can be added by sending a REFER with the Refer-
To of the Conference URI.
Ad-Hoc Conference Creationusing Conference Factory URI
Definition: an INVITE sent to this SIP URI will “create” an ad-hoc conference.
Conference Factory URI can be programmed on a “Conference” button on a SIP phone, or published on a webpage.
The new Conference URI is returned to the creator in the Contact in the 200 OK.
Participants’ List
“SIP Event Packages for Call and Conference”
draft-rosenberg-sip-call-package-00.txt The Body of NOTIFY Contains a
Conference Information XML Document of MIME Type application/conference-info+xml
List of Users User Identity Status active|departed|booted|failed Etc.
Non-SIP Further PotentialConferencing work in IETF
Conference Policy Control Protocol (CPCP)
Used to create conferences by automata
Used by conference owner to change policies
Media Policy Control Protocol (MPCP) Users control how media is
mixed/presented
Floor Control Protocol
RADVISIONSIP ConferencingSolution
Multimedia Centralized Conferencing
MCU is a SIP User Agent The Conferencing Functions are
Implemented by the MCU whenever possible Mixing of Media Streams Conferencing and Floor Control
The Easiest Task from End User Perspective Looks Like a Point-to-Point Call with the MCU Does not Necessarily Require Special
Conferencing Support
Addressing the Scalability Issue
To Make the Solution More Scalable, the MCUs can be further cascaded
It is Transparent to the End Users
ISDN/CSN
Multimedia Centralized Conferencing
Mobile Phone
PSTN Phone
MS Messenger SIP Videophone H.323 Application
H.320 System
Internet
Video and VoiceMCU
SIP Phone
MCU Key Features Voice Activated or Continuous Presence modes Video Algorithms - H.261,H.263, H.263++ Audio Algorithms – G.711, G.722, G.728,
G.723.1, G.729 A/B, Siren/G722.1
Web based Administration and Conference Control
XML Based 3rd Party Call Control API Video Transcoding Resolution: CIF, QCIF, 4CIF T.120 Data Collaboration
Some features require optional hardware/software
WEB Conferencing and Floor Control
RADVISION’s XML-basedOpen API:
Create/Terminate Conference
Take/Release Conference Control
Invite/Disconnect Participant
Get Conference List and details
Get Number Of Participants In Conference
Get Participant Details
Get Conference Video Configuration
Lock/Unlock Participant Video
Mute/Enable Audio Channel
Conferencing Control API
IM1st Ad-hoc Conferencing
Integration with the Microsoft RTC Conference initiation by adding a
“Conference Assistant” Buddy to the IM chat
Existing conference control Video window is logically attached to
multiparty IM
IMst – I
IM1st – II
IM1st – III
Thank You