This page will have a list of nice-to-have tests for discussing the unobservability of a DS connection.

1. When compared to a single baseline video:
   1. How much is a video different from the baseline when carrying payload?
   2. What variables of the payload (overlay size, cell cize, framerate, location, etc) affect unobservability the most?
   3. Is there a significant difference in the network traffic between multiple runs of the baseline video? How much?
   4. Are we able to stream a payload carrying video which looks alike the baseline video (even between the boundaries of a duplicate run of it)?
2. When compared to similar (same-user) baseline videos:
   1. How much is the difference between similar videos of the same user? Can we grab several videologs and establish a baseline for that user's behaviour? (assuming, let's say, he always places a call on his living room.)
   2. If that baseline can be established, would the window for inserting payload be more relaxed? (like, using more space on the frame for placing an overlay or changing cell sizes?)
3. When compared to a multiple user baseline videos:
   1. How much can we change the payload features assuming that a DS call stays within a “random” regular Skype call boundaries? Probably more than in the previous scenarios.

Ultimately:

1. What is the throughput/observability ratio?

And also:

1. How does bandwidth limitation and packet dropping/delay impact a regular video traffic?
2. How does bandwidth limitation and packet dropping/delay impact DS unobservability? Does a previously unobservable flow become observable?

1. Try an aggressive unobservability combo (meaning less throughput) when dealing with a given call sample (not interesting, a call is usually different);
2. Try a mildly aggressive unobservability combo to suit the baseline of a given user.
3. Try an relaxed unobservability combo (meaning more throughput) to suit a general “Skype call baseline”.

1. How does bandwidth limitation impact DS covert channel? Does error rate increase with less bandwidth? (Maybe, more quantization on codec)
2. How does packet dropping/delay impact DS covert channel? Is payload recognition affected with packet loss/delay?
3. If the censor effectively interrupts the video feed, how long does it need to do it to do harm to a DS connection? How much time does DS need to recover from an active attack?