Calculating network data throughput requirements?

[SpyGuy10 0]

For IP systems, is there a formula or guide for determining how much network data throughput is required for X cams at Y resolution? It would be even better if different cam resolutions can be taken into account independently (e.g., cam1 @ 1.5MP + cam2 @ D1, etc.).

[Soundy 1]

WAY, WAY too many variables to accurately calculate throughput if you're using VBR (variable bitrate) cameras, because the actual data will depend on things like amount of movement (change in the scene), contrast, saturation, codec used, codec compression settings, bitrate caps, etc. etc. Many will allow you to set a bitrate cap that it won't go over (starts to lower quality to stay under the cap), which will give you a rough number to work from.

 

With CBR (constant bitrate) cameras, most will allow you to define the bitrate, so you can just add up those numbers, and codec varies the picture quality to maintain the bitrate.

[buellwinkle 0]

You can use the Axis Bandwidth Calculator - http://www.axis.com/products/video/design_tool/calculator.htm

[NotoriousBRK 0]

You can use the Axis Bandwidth Calculator - http://www.axis.com/products/video/design_tool/calculator.htm

 

I'd almost recommend NOT using that. It's highly likely to give incorrect results for almost any other application.

 

In order to answer this question it requires knowledge of the camera brand/model being used, encoding type, and a rough guess of the scene lighting/activity.

[thewireguys 3]

^^^^ " title="Applause" /> " title="Applause" /> " title="Applause" /> " title="Applause" /> Totally agree

[SpyGuy10 0]

Once again, thanks to all for the informative responses. So, out of curiosity, since the data load is dependant on the scene lighting and activity (among other things), how exactly does one go about planning an IP CCTV system so that the network is not overloaded? Does everyone just specify CBR cameras, or is there more involved? Is there an online guide or reference (theory and/or practice) that I can read on this subject?

[Soundy 1]

It's all an educated guess

 

Honestly, if you use a calculator, spec for the worst-case scenario, and you'll have lots of overhead. You don't have to spec CBR cameras, but if your ASSUME CBR cameras in your calculations, you should be fine. Again, most VBR cameras I've used also have the ability to set a maximum bandwidth that they won't exceed.

 

Nobody ever got fired for over-engineering a network

[ssmith10pn 0]

I run DU meter on the servers when I feel like im getting close. Once I hit that magic number I start loading cameras on a new server.

Be aware there is upstream traffic also. Depends on how many clients and how much the clients are viewing.

One monitor with 4 cameras is one thing but you start getting tripple or quad monitors with 16 on a screen the traffic goes up quick.

 

That's why I use DU meter because it shows traffic both ways.

 

 

[Soundy 1]

One monitor with 4 cameras is one thing but you start getting tripple or quad monitors with 16 on a screen the traffic goes up quick.

That's when it's time to start looking at cameras with multicast support

[ssmith10pn 0]

Even with Multicast 16 x 4 is a pretty good chunk.