Bandwidth calculations? Synology NAS?

[Vaunt 0]

I'm designing a system with a capacity of ten 1080p resolution IP dome cameras. They each have a 10/100Mb interface, which will go back to a 10/100/1000 switch. The switch will talk with my NVR.

 

1) How do I calculate the expected bandwidth needs of a given camera? Obviously too much data will overwhelm the NVR. I assume that since each camera is max 100Mb then 10 are ok on a 1000Mb network. I'd like something a little more rigorous if possible (I have a MS in physics and like equations).

 

2) I couldn't find anything other than a passing reference to Synology's NAS box being used as a NVR. That was kind of my plan. Does anyone have anecdotes?

 

Thanks for the help, I'm a newb.

[Soundy 1]

I'm designing a system with a capacity of ten 1080p resolution IP dome cameras. They each have a 10/100Mb interface, which will go back to a 10/100/1000 switch. The switch will talk with my NVR.

 

1) How do I calculate the expected bandwidth needs of a given camera? Obviously too much data will overwhelm the NVR. I assume that since each camera is max 100Mb then 10 are ok on a 1000Mb network. I'd like something a little more rigorous if possible (I have a MS in physics and like equations).

Actually, depending on the framerate, quality settings, and codec you use, the cameras will probably even work over 10Mbit. Might be a little stuttery if the action ramps up, but the point is, they won't likely be running anywhere near a full 10Mbps in regular use.

 

As far as calculating the actual bandwidth, there are a lot of factors to take into consideration, some of which will vary widely depending on the specific situation:

 

1. Framerate

2. Codec (MPEG-4, MJPEG, and H.264 being most common)

3. Image quality (aka compression level - higher quality = less compression, and vice-versa)

4. In-camera motion detection (reduces bandwidth use when nothing is happening)

5. Image contrast - most forms of compression will use less data for low-contrast scenes than for high-contrast

6. Image sharpness - see above; the sharper edges are, the less compressable the data becomes

7. Movement/traffic level - with any I-frame-based compression, the less movement you have, the less data transmitted

 

And that's just the MAIN considerations! Sometimes the camera manufacturer themselves will provide a bandwidth calculator, and there's a decent generic one available with IP Video System Design Tool from www.jvsg.com. However, those will only provide approximations based on very broad estimates... in practice, it's as much voodoo magic and just plain experience

 

2) I couldn't find anything other than a passing reference to Synology's NAS box being used as a NVR. That was kind of my plan. Does anyone have anecdotes?

 

Thanks for the help, I'm a newb.

Have you checked their product lineup to confirm that the cameras you're using are supported? Not all NAS systems work with all cameras. QNAP, for example, has two different versions of most of their boxes: one that's designed as a general-purpose NAS with SMB shares, iSCSI, web server, MySQL, Bonjour/UPnP media services, etc. etc., and with very limited IP camera support... and one that's pretty much a dedicated NVR with extensive IP camera support and web VMS and not much else. www.qnap.com and www.qnapsecurity.com to see the differences - far as I can tell, the NVRs aren't much but the NAS boxes with different firmware.

 

QNAP has an online demo of their NVRs, BTW... I expect Synology does as well.

[Vaunt 0]

Thanks very much for the insights.... I noticed that the QNAP NVR wants a monitor there to use the video inputs. I'd rather have a NAS that I can access from anywhere on the network. Is there some kind of bandwidth reason that NVRs (i.e. a baby PC) are more effective than NAS?

[Soundy 1]

Thanks very much for the insights.... I noticed that the QNAP NVR wants a monitor there to use the video inputs. I'd rather have a NAS that I can access from anywhere on the network.

I doubt a local monitor is REQUIRED - network access is sort of the point of these things. Did you try their online demo?

 

I've not use QNAP's NVR units, but the NAS models we've used don't even HAVE the option to attach a head - they're network-access ONLY, all configuration through web interface (I think some may provide for console access as well).

 

Is there some kind of bandwidth reason that NVRs (i.e. a baby PC) are more effective than NAS?

No, just that you can usually attach a head and access/configure them locally, which you can't typically do with a NAS.