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Two-Way Super Video Transmission
The following graphs represent the packet inter-arrival time and lengths captured by Web Camera 1 transmitting video to Computer 2 and vice versa using the Yahoo! Messenger Super Webcam feature.
Inter-packet Arrival Results
Figure 4.1: Data Packet Flow
Figure 4.2: Data Packet Flow
Figure 4.3: ACK Packet Flow
Figure 4.4: ACK Packet Flow
We can see that with the Super Webcam feature, more packets were sent from the transmitting computer. This is expected as the frames per second were increased from 0.77 to over 8, resulting in an increase in video data. Figures 4.1 and 4.2 show that over 61% of packet had an inter-arrival time of less than or equal to 0.25msec, but also indicate a wide distribution of packet inter-arrival times between 60msec and 130msec. This is best seen in Figure 4.2's positive gradient between these two inter-arrival points.
Figures 4.3 and 4.4 show the widely distributed inter-arrival times of the ACK packets from Computer 2. We can see that 2.4% of packets had an inter-arrival time of less than 0.25msec. We can also see the distinctive M-shape equating to approximately 84% of packet inter-arrival times between 60msec and 130msec. These inter-arrival times correspond to those of data packets sent by Computer 1 (Figure 4.1).
Figure 4.5: Data Packet Flow
Figure 4.6: Data Packet Flow
Figure 4.7: ACK Packet Flow
Figure 4.8: ACK Packet Flow
Figures 4.5 to 4.8 show the packet inter-arrival times of data from Computer 2 and the corresponding ACK packets from Computer 1. We can see in Figures 4.5 and 4.6 that 54.8% of packets arrived with an inter-packet time of less than or equal to 0.25msec. Again we see the widely-distributed packet inter-arrival times between 60msec and 130msec. Figures 4.7 and 4.8 show that the inter-arrival time M-shape between 60msec and 130msec accounted for approximately 82% of the ACK replies from Computer 1. We can also see that 7% of packets had an inter-arrival time of less than 0.25msec.
Packet Length Results
Figure 4.9: Data Packet Flow
Figure 4.10: Data Packet Flow
Figure 4.11: ACK Packet Flow
Figures 4.9 and 4.10 show that 27.7% of data packets sent by Computer 1 were 52bytes long, with a further 38.7% being 1500bytes long. We can also see that Computer 2 replied with 46byte ACK packets.
Figure 4.12: Data Packet Flow
Figure 4.13: Data Packet Flow
Figure 4.14: ACK Packet Flow
8.4% of data packets sent by Computer 2 were 52bytes long and 47.6% were 1500bytes long as seen in Figures 4.12 and 4.13. In Figure 4.14, we see that the receiving computer, Computer 1 sent 46byte ACK packets in reply to the web camera data.
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Last Updated: Monday 28-Jun-2004 10:00:41 AEST URL: Maintained by: Ana Pavlicic apavlicic@groupwise.swin.edu.au Authorised by: Grenville Armitage garmitage@swin.edu.au