Given by Januasz Bulawa,Tom Stachowiak at Rome Lab Quarterly Review for CIV on October 1 96. Foils prepared 22 February 97
Outside Index
Summary of Material
OpenDVE (InSoft Technology) Basis |
Architecture of Conference Manager |
Summary of NPAC VIdeo and Audio Conferencing System |
Outside Index Summary of Material
Januasz Bulawa,Tom Stachowiak |
Basic functionality: |
session management |
event distribution |
data distribution |
System features: |
commonality |
modularity |
platform neutrality |
interoperability |
Collaborative environment |
OpenDVE Architecture |
AUDIO PLUGIN |
VIDEO PLUGIN |
WHITEBOARD |
CONFERENCE MANAGER |
OpenDVE Library API |
OpenDVE Conference Engine |
Network Layer |
Architecture of Conference Manager integrated with Netscape browser |
CM PLUGIN |
HTML server |
Initiator side |
Participant side |
DAEMON |
CM PLUGIN |
Video tool features: |
uses two types of compression - H.261 and H.263 |
takes advantages of the H.263 codec on fast machines |
for slower machines enables switching to the faster H.261 compression |
H.263 vs. H.261 |
the same quality with 30-50% of bits usage |
half pixel prediction |
negotiable options: unrestricted motion vector, advanced prediction, syntax-based arithmetic coding, PB-frames |
Audio Tool features: |
uses two types of compression: GSM 06.10 speech codec and Intel/DVI ADPCM codec |
GSM codec offers better compression ratio but worse speech quality - it is good for less reliable networks |
ADPCM compresses audio just four times but it has much better quality |
GSM 06.10 codec |
used in digital cellular telephony standard |
based on the RPE-LTP compression algorithm |
Intel/DVI ADPCM codec |
less computionally intensive than G.721 |
produces very good quality for voice signals and reasonably good quality for music |