Re: [AVT] Comments on draft-perkins-avt-srtp-vbr-audio-02

If the average VAD overhang time is known by an interceptor, then it  
is still possible to estimate the average talk spurt length (and,  
thus, potentially the language). So the overhang statistics themselves  
should be randomly varied from call to call.

It would indeed be good to see more quantitative analysis, e.g. about:
- The size of the information leak
- How fast the leak shrinks by adding overhang
- How this leak compares to other leaks such as call duration and IP  
addresses.
It would make little sense to close a small leak if bigger ones are  
still wide open.

koen.

Quoting Cullen Jennings:
>
> On the advice to overhang the VAD by a random amount, I think I need  
> more advice to implement this. Clearly if I put a random number from  
> 0 to 1 ms this won't work and if I pick a uniformly distributed  
> random number between 0 and 1 day, it will more or less disable VAD.  
> No complaints about the approach to this but I think I need more  
> advice to be able to implement anything useful.
>
> Is there other research that collaborates the spot-me stuff. I sort  
> of wonder about it at times because the implications of it are that  
> the success at picking the language when the system has all the  
> unencrypted RTP, that the would be better than some of the results I  
> see. I'm not saying I don't believe the spot-me stuff - I would just  
> want to look at it much deeper before I decided and I was wondering  
> what others had found. I often see results where the training data  
> was too closely correlated with the the data used for the test  
> results._______________________________________________
> Audio/Video Transport Working Group
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