Changyun Wang Under the Supervision of Dr.Turner. The Access Grid is an Internet-based model for video conferencing developed by the Future Lab(FL)within the Mathematics and Computer Science (MCS) division of Argonne National Laboratories(ANL). Basic functionality.
The Access Grid is an Internet-based model for video conferencing developed by the Future Lab(FL)within the Mathematics and Computer Science (MCS) division of Argonne National Laboratories(ANL)
. Screen sharing
. Audio: encoding using one or more microphones (via a mixer)
. Video: encoding or “capture” using one or more cameras
. Audio presentation using one or more speakers
. Video display via one or more computer monitors and/or
video projection techniques
. Display of PowerPoint “slides” under the control of presenter located either on-site or at a remote site.
. Screen sharing/whiteboard via VNC.
The Access Grid model revolves around two pieces of software:
vic: the video conferencing tool, and
rat: the robust audio tool.
and involves several other applications
the Multicast Beacon
Virtual Network Computing
vic and rat were developed as part of the Internet Multicast backbone, or MBONE, which provided multicast services over the unicast Internet backbone (using "tunnels", or "bridges", between multicast nexus sites).
The Access Grid model relies upon the ability to send and receive Internet Multicast traffic to and from all conference nodes.
An individual vic stream will generate from 10Kbps to 4Mbps of network traffic. A large conference may generate 20Mbps.
Vic was developed by Steve McCanne and Van Jacobson at the Lawrence Berkeley Labs. It is intended to link multiple sites with multiple simultaneous video streams over a multicast infrastructure.
vic CAN perform 2 basic functions:
rat is a recent version of the Visual Audio Tool, also developed by Steve McCanne and Van Jacobson at the Lawrence Berkely Labs. rat allows multiple users to engage in a audio conference over the Internet in multicast mode. rat can perform 2 basic functions:
Operators at each site involved in an Access Grid conference typically keep in touch by using software originally developed for online "role-playing" games generically called Multi-User dragons and Dungeons" games, or "MUDs". (MUD functionality is similar to that of Inter net Relay Chat operating with access control.)
Argonne runs a MUD server for use by Access Grid operators who run MUD clients on their desktop systems. tkMOO-lite is currently the recommended MUD client for this purpose, but others, such as Tiny-Fugue in the Unix environment can be used as well.
To help diagnose multicast network problems during conferences, Argonne promotes the use of the NLANR multicast "Beacon" monitoring system, which includes three pieces of software:
Coordinating multiple group conferences can be complicated. Argonne has developed a collection of web pages and Java applications that can simplify the process.
The Virtual Venue is basically a web-page that lets users select a "conference" to attend. In this context a "conference" is composed of
If your systems are Virtual Venue-enabled, the display system operator can click on a conference room name and the vic, rat and MUD applications running on the video display, video capture and audio processing systems will all be started with target addresses and settings appropriate to the selected conference room.
This coordination is accomplished by running an "event server" and the event controller on the display system, along with "event listeners" on the video capture and audio processing systems.
The Gentners can use 3 different connectivity infrastructures:
The audio capture computer:
The video capture computer system converts analog video from cameras and/or VCRs, etc. to digital for transmission by vic over the multicast network.
Receives video content over the network and displays it on the PC monitor as well as one or more other monitors and/or video projectors if desirable (using the ability of Win2K to display its console screen across multiple video cards)
. Windows 2000
The speaker's podium computer runs:
Configuration suggested by Argonne: Some laptop powerful enough to run PowerPoint