NPAC Conferencing System

Tomasz Stachowiak

Project Summary:

The goal of this project is to create a framework for collaborative system which would enable implementation of real-time conferencing applications such as video, audio and whiteboard tools. Initially these applications were implemented using InSoft's OpenDVE software development kit. Since there have been restrictions and limitations for OpenDVE-based conferencing system to be seamlessly integrated in other Web-based archietctures developed at NPAC (e.g. Tango), we decided to develop our own conferencing software infrastructure.

One of our major goals in the development is to integrate the multimedia conferencing tools into the World Wide Web environment so that they are accessible from a Web browser. This has been achieved by using the plugin techniques.

Technology used in this project:

Conference Engine
NPAC Conferencing System (NCS) consists of two main components. The first one is the Conference Engine(CE) whose functions include point-to-point message passing from/to remote hosts, session control and communication between CE and Conferencing Manager (CM) on a local machine. The second component, CM, implement session and user management and presents a graphical user interface to end user.
Video Tool Using H.261 and H.263 compression it offers very low bandwidth having very good picture quality at the same time. H.263 option takes less bandwidth but is more CPU intensive so for slower machines H.261 algorithm is recommended. Speed can be increased even more by choosing Intra frames only option. However it causes significant increase of used bandwidth.
Audio Tool
It can adopt two compression options:
1. GSM - a technique used in digital cellular telephony, very bandwidth efficient but designed specifically for speech transmission.
2. ADPCM - requires higher bandwidth but offers much better quality, good for music quality transmission.
Both option can exchange as high as 8000 sound frames per second.
Whiteboard

Sample pictures

Integrated conferencing environment with audio and video tools running for two participants
Whiteboard