1. R. Hughes-Jones Video_TAG Meeting Oct 1999 Some Studies of H.323 VideoConference Traffic on LANs and WANs Studies done for PPNCG & PIPVIC2 Lab Tests of H.323 kit Comparison with Mbone tools (SHRIMP++) Considerations for use on the WAN Some data from WAN measurements Much of the work is preliminary!

2. R. Hughes-Jones Video_TAG Meeting Oct 1999 Lab Measurements of H.323 on the LAN Simulate a VC on a private LAN –Two 350 MHz Pentium II Windows NT v4.0 _ service pack 4 –The VCON Escort 25 pro PCI cards and Philips camera ( 350 MHz Pentium II + 128 Mbytes mem ensure CPU power / memory not issues) Two way Video of same subject - data rates for 1 Video stream One way Audio or muted LAN Analyzer No. packets/s Kbit/s 10Mbit Ethernet Linux PC tcpdump

3. R. Hughes-Jones Video_TAG Meeting Oct 1999 The Lab Test Conditions  Camera pointing at a static view of a coloured poster on a wall with no movement of the subject – similar to viewing a slide or picture in a talk  Camera observing a subject sitting very still – an approximation to a person listening at a VC as people always wriggle in real life!  Camera observing the head and shoulders of a person talking – probably more like real people in a real VC than the above.  Camera observing a subject making fast constant movement or violent movement, like clapping or waving arms. VCON ‘MeetingPoint’ software used Video resolution CIF Max. frame rate 30 f/s Max. bandwidth 385 kbit/s

4. R. Hughes-Jones Video_TAG Meeting Oct 1999 H.323 on the LAN Subject sitting VERY still Subject talking head as in a VC Subject Making violent movement Just touch the mouse ! Mute video Clap hands The Network load from VCON for various movment scenarios - 386 kbit/s Packet rate & kbit/s depend on movement CIF12cm & 20 cm pictures good

5. R. Hughes-Jones Video_TAG Meeting Oct 1999 H.323 on the LAN The Network Load generated due to External Effects. The effect of Room Lighting.

6. R. Hughes-Jones Video_TAG Meeting Oct 1999 Mbone vic on the LAN The Network load from vic for various movment scenarios - no rate limits Packet rate & kbit/s depend on movement CIF ie ~10cm video pictures Action :Static talking head rub eye talking clap talking Frames/ 16 20 20 30 30

7. R. Hughes-Jones Video_TAG Meeting Oct 1999 H.323 - Traffic Characterisation

8. R. Hughes-Jones Video_TAG Meeting Oct 1999 WAN Considerations Bandwidth:The no. bits/s carried over the network. Determines audio quality, video frame/s Latency: The time for a packet to traverse the network. Vital to audio exchanges, context switches Jitter: The difference between the inter-packet arrival times Critical to current H.323, good video, audio (Mbone rat packets carry redundant data) Network ‘configuration’ measurements: Packet misordering Packet loss Latency & Jitter have distributions and dependencies: time, location, bandwidth, scale, traffic types Considerations apply to unicast and multicast traffic

9. R. Hughes-Jones Video_TAG Meeting Oct 1999 Packet size distributions from Mbone tools vic & rat

10. R. Hughes-Jones Video_TAG Meeting Oct 1999 Variation in packet arrival times How the variation changes with the real time through the VC Variation in the arrival times for packts in a multicast audio stream