How many Megabytes can my Gigabit Lan handle?
  • Dear Ben,

    I got a question and i hope you can help me.

    I am a Little confused at the moment. I will try to keep it simpel.

    I got a LAN with gigabit speed i our house and my switches are all gigabit switches all connected with Cat6 cables. Then i got a couple of Macs and 2 NAS, all running with Gigabit speeds and it works really good for streaming High quality movies ect. and even when i am copying files from my Netgear NAS or my WD NAS i have no problems to get reading speeds hitting 70 Megabytes per second over the LAN, but when i got my 6 cameras running alone on the LAN i can only transfer about 1,2 Megabytes from all the cameras to my Macs without getting bandwith problems? (Green dropouts)

    Is this normal? or what do i miss there?

    Hope you get the point.... Thanks! ;)
  • This doesn't sound like a network bandwidth issue, but rather a CPU limit.

    I would look in Activity Monitor to see that CPU usage is below 50% and actual network load. A gigabit connection easily handles 16 2 mp cameras with about 5-7 megabytes/sec.

    There is something else awry cause the dropouts.

    1. Handshake issue with ethernet hardware (unlikely if those Macs talk to your NAS's) at 70 MB/sec.

    2. Router "fabric" insufficient to handle the packet load. Also, unlikely

    3. Aging router internal power supply causing packet drops. Possible if router is more than three years old.

    4. Something chewing up CPU cycles on the Mac. Make certain you aren't using any text or graphic overlays in SS. That chews up CPU cycles with decompression and recompression.

    5. One of your network trunks between your Mac and camers is actually 100 mb rather than gigabit. Check each router port and verify your wiring is allowing gigabit
  • BTW, all your cameras are wired, not wifi connected, right?

    If they are wifi connected, that is the most probable problem.
  • Hi thanks for your reply guykuo! It seems that VTDecoderXPCService is causing my macpro 3,1 to use about 250% in activity monitor? I read the answers here on the forum but dont find the fix?
  • A few more things to add:

    - Open the Camera Info window in SecuritySpy and check the following:

    Frame Rate: it could be that your cameras are streaming at high frame rates - this would use up both network bandwidth and CPU cycles on your Mac. I would recommend 5-10fps for general-purpose video surveillance (you can change the frame rate of a camera via its web interface).

    Format of incoming video: this should show H.264. If it shows JPEG, then you will probably want to change this to H.264, because JPEG uses more network bandwidth and storage space (change this via the Format setting under Preferences -> Cameras -> Device in SecuritySpy).

    - 250% VTDecoder CPU usage is not necessarily anomalous - this could be perfectly reasonable for the resolution and frame rates of your cameras. To check if your Mac is struggling to keep up, look at the "idle" figure in the bottom left of Activity Monitor when you have the CPU tab selected - what does this read? Anything below 10% indicates that you are getting towards the Mac's CPU processing capacity.
  • Thanks Ben, i will reduce the frame rate, and update to a better Mac.

    Kind regards ;)
  • Dear Ben,

    I got some good news! It seems that i found the reason for the VTDecoderXPCService problem on my Mac resulting in using to much resources on my Mac Pro.

    I did read the posting here on the forum, but couldn't find a solution to the problem.

    So i did research a lot the last days and today i found the the reason why VTDecoderXPCService are using so much resources on my Mac.

    I always dissable Spotlight in the commandline to prevent Spotlight to do indexing on my Mac Pro, because i also use my Mac for audio & video editing to.

    Today i saw a crashreport popping up in activity monitor and i did notice that VTDecoderXPCService in activity monitor was suddenly using much less resources.

    After some research i found the solution! This is for people who have disabled spotlight at some time.

    You must go to Terminal and enter the following commands, one after each other.

    sudo mdutil -i off /
    sudo rm -rf /.Spotlight*
    sudo mdutil -i on /

    (If you see the following message:

    (mdutil[1766:78805] Metadata.framework [Error]: mdsCopyStorePaths failed: (268435459) (ipc/send) invalid destination port
    Spotlight server is disabled.)

    when you enter the command in terminal, just ignore it and enter the above commands, after each other and then reboot! Important!)

    Your Mac will now "Kick Ass". SS are now only taking up 82% instead of 300% with 85% idle!!! Have Fun! No more need for a new Mac! ;)
  • Hi @Einstein this is great news, many thanks. Hopefully this will be a good solution for other users too.

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