Michael, that's a good question. Do you mean something analogous to a VMS / VNR metric, where the vendor says this box can support max throughput of 80Mb/s or 250Mb/s?
I have never heard of anything like that though I think it could be useful. This is often a problem determining camera support for multistreaming - i.e., how many total streams at what resolution, fps, codec, etc. On the other hand, I am not sure if a single metric is possible because it depends on multiple factors.
I know on the Bosch solutions you can access processor usage via telnet or in the topright corner of the cameras webpage it has a graphical indicator so you can see what happens when you turn on analytics or have multiple streams running out of it.
I do agree. Camera CPU overload is a reccurent issue, especially on entry level range of products. Camera sometime get saturated when generating 2 streams + motion detection ( MD is CPU killer)
Some Smart phones still using Mjpeg, requires that you generate a VGA Mjpeg in addition to your master HD, H264... double coding isn't also appreciated by entry level camera CPUS...
I have asked to some vendors to add a CPU indicator for installers to prevent them from too bad installations
Then the other point is that NVR/VMS get also saturated : one key stress test is to launch a Fast Speed Playback on 4 or 8 cameras...
If you imagine that normally , you are recording 4 Mb/s for 12 fps ( so 0,5 MB ) when you do fast speed you can have 60 fps/s , so 5 x 4 Mbs, and then 20 Mb/s multiplied by 8 cameras = 160 Mb/s during ...and your are supposed to keep on recording all your cameras (even motion detect is a 24/24 recording with auto delete if no alarm)
Most NVR are given for 60, 80 or 120 Mb/s ....so you can imagine.
This is calculated by using Port miroing feature on the managed switch to "see" (Wireshark / Networx..etc) what really happens on the input or output NVR port.