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Video System Analysis

Choices appear to be:

iChat -

We ran some tests in a Mac cluster on campus. There was no data output for iChat regarding latency, so we attempted in measuring it ourselves. We were able to clearly show that the latency is less than 100ms, but we would need a more accurate timer to get more accurate results.

The video quality seemed to be a small step up from Skype; however, this could be due to the camera on the monitors we were using.

We also did testing of the round trip time between CMU and India, and we were able to conclude that it was approximately 1 second.

*We recently tried to do a 3 person video chat with a friend from India, and we were not even able to chat since the bandwidth usage was too high. However both internet connections were high speed and 1-on-1 video chatting has worked previously with someone from India.

Skype -

We have conducted a Skype video chat experiment between Pittsburgh and Boston. Both locations have high-speed internet.

Here is a quick summary of the parameters we observed:

Upload Bandwidth - 12-13 kbps
Download Bandwidth - 12-13 kbps
Jitter - 20-30 ms and Round Trip Time - 55 ms

For the round trip time, the max observed was 77 ms, and the minimum was 31 ms.

We also tried to disable the audio and failed to observe any significantly visible changes in the parameter values. Doing testing with HD video might change this result.

For HD video, as per the Skype documentation, we need to meet the following requirements:

A) a high-speed broadband connection (we recommend sustained 1 Mbps symmetrical bandwidth or higher)
B) a new HD webcam
C) a PC with a 1.8 GHz processor
D) Skype 4.2 Beta for Windows

We just need a HD webcam to fulfill all these requirements, which we have not been able to get our hands on.

We have tried performing a three way video chat between the following locations: Princeton, Waterloo, and Minneapolis. All locations have high-speed internet connections.

The video quality was as per the quality observed in two-way chat experiments. However, the round trip time, though mostly stable within 47 - 62 ms, showed some spikes as high as 500 ms. The jitter showed high variability ranging between 20 ms to 240 ms.

Upload Bandwidth - 15-16 kbps
Download Bandwidth - 11-12 kbps

We have investigated the subscription requirements.The trial version is good for seven days, and only the initiator of the video chat needs that. If we run out of the trial version, we can always open a new Skype account, add old contacts and initiate our video conference.

We have tested Skype on both Linux and Windows and it seems to run fine on both. However, the UI on Linux is less user friendly that the Windows version.

Ultravideo -

Initially we ran into trouble getting the software installed. The interface seems confusing and the application does not seem to be what we want, a video rental application.

Unreal Media Server -

For the last couple of hours, we have been trying to install the server side for unreal media without any success. We think this is definitely not a good alternative to iChat and Skype for the following reasons

a) The trial version only gives an uninterrupted 10 minutes of streaming video
b) Works only on windows

But the main reason we believe this software is clearly not the best option is the setup overhead. It requires substantial amount of registry tweaking and changing a lot of system configuration stuff. Inspite of doing all these we still haven't reached a point where we can run it!!

We want to know:

• Does it work?
• On what platforms?
• What's the bandwidth requirement?
• Can you fix the bandwidth to avoid hogging bandwidth from audio streaming?
• What's the latency
• What does it take to configure? Can it be scripted?
• We want to use an external camera. What do we need; what can we recommend to others?

Implementation Plan

• Who does what when?

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