1. PNG/JPG Detection Algorithm
Application and Desktop Sharing
Omer Boyaci, Henning Schulzrinne, Department of Computer Science, Columbia University
What is Application Sharing?
Application Sharing Models 1 4
Application specific
+ Efficient
- Participants need application
- Application has to be modified
Generic
- Inefficient (sometimes)‏
+ Participants don't need application
+ All applications are supported
Sharing an application with multiple users
There is only one copy of the application
Participants do not need application itself
Briefly, participants
receive screen updates
send keyboard and mouse events 3 2
Host
Participant
Participant
Windows Server Architecture
Multimedia Support
The effect of Packet Loss
Challenges
Participants may have different bandwidths
Some participants may join lately.
The effects of packet losses
Reliable multicasting (NACK)
Some regions require different encoding
Related Work
UltraVNC
Region>
40,000px ?
-1,0,1
MAST
Multicast
Application
Sharing
Tool
coordinates
PNG Size
Retransmissions
NACK mechanism for lost packets
NACK suppression for multicasting
Minimizing the loss effect
Small PNG images
Around 1500 bytes
Several scan lines
counter
YES
Time Stamp
New
Region ?
Create a record
&
Start Checking
Region record
YES NO
Detected ?
Continue
Checking
Use Detected
Format NO
YES
PNG/JPG Detection Algorithm