What would you say are the key challenges facing integrators building medium and large scale video surveillance networks that function over the Internet?
A: There are probably 3 key network issues here and each has a serious impact on the quality of video streams offered over public networks.
First up there’s packet loss. You get packet loss because packet attenuation and/or re-ordering of data packets over an IP network impacts on the quality of the image stream at the receiving end. Next comes packet delay. The problem for the public domain integrator is that there’s a reliance on third party hardware and comms channels. Who knows what happens once a data stream gets onto a network? Does the path travel over copper, fibre, microwave?
Then there’s the habit telcos have of choking data streams in favour of voice during busy periods. As far as the telco is concerned all data comms are emails and can be sidelined until bandwidth clears up. That’s a policy that works just fine with emails but if you’re trying to view streaming video packet delay caused by router queuing will result in signal disruption or at the very least, a reduction in quality. They can also be delays introduced by packet jitter – essentially that’s the variation in packet arrival time.
It’s fair to say that things are improving – 4G wireless is delivering 90 down and 40 up these days in the right places – that gives a lot of flexibility. Compression is better, too. But everyone finds that in real time internet services can be curiously fickle for no clear reason. Management of streams by VMS is better than it used to be, too.
In our opinion you need to find out how little resolution the client can accept as a live stream if the system is recording locally. You also need to look for CCTV solutions optioned to drive over internet connections of all kinds. Managing expectations may be the most challenging aspect of the process. We haven’t mentioned cyber security as a challenge yet but it will be – not only to configure but to maintain. If you can’t get the performance you need, then dedicated network links may be the answer.
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