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Next: 8.7 Simulated 20fps Uncompressed Up: 8 Results and Analysis Previous: 8.5 Simulated 10fps Real-Time

8.6 Simulated 20fps Uncompressed Real-Time Video Data

For the case of 20fps video, the testing application generated twenty 14,400 byte parcels at the start each second, again with the first one in the second marked as RELIABLE and each subsequent parcel marked with a two second time-to-obsolescence.

XUDP

Twenty frames per second was enough of a transmission burden to force XUDP into invoking its timed obsolescence mode. According to table 8.7, out of 581 total parcels, 448 were received and 133 were discarded due to timed obsolescence. The transfer finishes in 32.4 seconds, the length of the transfer plus two seconds for the timed obsolescence window.

 

Measurement Result
Total Data Acknowledged 6962.400 KBytes
Total Transmission Time 32.650 seconds
Network Bandwidth Utilization 213.243 KBytes/second
Average Round Trip Time 19.5 milliseconds
Average Window Size 11.0 packets
Total Parcels Received 448 parcels
Total Transmission Time 32.351 seconds
Total Parcels Skipped 133 parcels
Network Bandwidth Utilization (14.4 KBytes/parcel) 199.413 KBytes/second
Average Parcel Reception Frequency 13.848 parcels/second
Table 8.7: XUDP Test 23:41 3/16/97

 

  
Figure 8.17: Parcels Received (XUDP Test 23:41 3/16/97)

  
Figure 8.18: Bytes Acknowledged (XUDP Test 23:41 3/16/97)

  
Figure 8.19: Round Trip Times (XUDP Test 23:41 3/16/97)

  
Figure 8.20: Packets In Network (XUDP Test 23:41 3/16/97)

TCP

The 20fps attempted TCP transfer, of course, received all 581 parcels (table 8.8, but at the expense of an extra four seconds on the transmission time yielded in the XUDP test. TCP was able to handle the bandwidth requirement, transmitting at 228KBytes/second.

 

Measurement Result
Total Parcels Received 581 parcels
Total Transmission Time 36.753 seconds
Total Parcels Skipped 0 parcels
Network Bandwidth Utilization (14.4 KBytes/parcel) 227.639 KBytes/second
Average Parcel Reception Frequency 15.808 parcels/second
Table 8.8: TCP Test 23:39, March 16, 1997

 

  
Figure 8.21: Parcels Received (TCP Test 23:39 3/16/97)

Comparison

Below is figure 8.22, a plot of both the parcel sequence numbers received over time for the 20fps tests conducted on XUDP and TCP. XUDP's timed obsolescence mode performed well, receiving parcels on time. The bottleneck here appears to be XUDP's rather unoptimized architecture; bandwidth requirements approaching 200KBytes/second are pushing the limit of XUDP's resources.

  
Figure 8.22: Comparison of TCP vs. XUDP Parcels Received (Tests 23:39 and 23:41 3/17/97)


next up previous contents
Next: 8.7 Simulated 20fps Uncompressed Up: 8 Results and Analysis Previous: 8.5 Simulated 10fps Real-Time

Mike Andrews
Wed Mar 19 16:07:58 EST 1997