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