Am I maxing out my network?

[magohn 0]

Hello All,

 

I am still in the process of setting up a home CCTV - PC based - system. I have three of the Sharx 30fps IP (WiFi) cameras, a Wifi PTZ and a wired Trendnet IP camera.

 

I have discovered that if I add more than three of the cameras at one time, I notice (any combo) the frame rate drops to approx 2 fps and cameras begin to disappear/reappear in the CCTV software. Keeping the # of cameras to <=3 and the system is much more stable with fps approx 5-7.

 

Should'nt a Linksys 54mbps "G" router handle more than this bandwidth demand? I figure 2-3mbps = approx 12mbps for 4 cameras. This is way under the 54mbps the router can handle.

 

I do have other devices connecting to the same router but they are things like laptops and desktops that use bandwidth "on demand".

 

Can anyone comment if my expectations are high? I am about to order a Axis 214 and I am now concerned that my network cant handle it.

 

Could it be my PC based CCTV hub? Its a P4 3.0ghz, 512mb ram (I have another 1gb on order) ? Could the low ram amount cause this behavior?

 

Thanks, John

[Guest]

Hello All,

 

I am still in the process of setting up a home CCTV - PC based - system. I have three of the Sharx 30fps IP (WiFi) cameras, a Wifi PTZ and a wired Trendnet IP camera.

 

I have discovered that if I add more than three of the cameras at one time, I notice (any combo) the frame rate drops to approx 2 fps and cameras begin to disappear/reappear in the CCTV software. Keeping the # of cameras to <=3 and the system is much more stable with fps approx 5-7.

 

Should'nt a Linksys 54mbps "G" router handle more than this bandwidth demand? I figure 2-3mbps = approx 12mbps for 4 cameras. This is way under the 54mbps the router can handle.

 

I do have other devices connecting to the same router but they are things like laptops and desktops that use bandwidth "on demand".

 

Can anyone comment if my expectations are high? I am about to order a Axis 214 and I am now concerned that my network cant handle it.

 

Could it be my PC based CCTV hub? Its a P4 3.0ghz, 512mb ram (I have another 1gb on order) ? Could the low ram amount cause this behavior?

 

Thanks, John

 

 

Well wireless is never easy, it is like if you have other WIFI near your house they can also "steal" resources from yours.

 

Normally the WIFI Routers broadcast on channel 1 to 13 and in fact if there are several using channel 1 (as often is factory default) they will all be using the same frequency. So if 3 WIFI ROUTERS/ACCESS POINTS is near eachother, they should use channel 1, 7 and 13 for optimal use. If a number 4 WIFI ROUTER is coming a long and use channel 4, it will in fact have some effect on both WIFI ROUTERS using channel 1 and 7.

 

A H264 Codec IP camera running at 30FPS would need minimum:

 

CIF = 0,5Mbit

4CIF = 2Mbit

1,3MP = 5-8Mbit

 

Also 512MB ram is very little for IP cameras, been hardware compression cards and analog cameras probably no problem, but you can never have enough RAM or in fact you can since 32Bits have some limitation around 3GB.

 

Hope this helps a bit!

 

 

JD

[magohn 0]

Thanks JD - that is all good info.

 

As far as other routers are concerned, we are lucky enough to be living "out of town" on a private 3-acre lot away from other people/routers. I do have one neighbor who's SSID I can "see", but I think his effect on my setup is negligible.

 

Your point about IP cameras and ram is something I'm not clear on. If all the "work" is being performed in the camera itself and then transmitted to the PC/Software - wouldnt the RAM cost be negligible because the work has already ben done within the camera?

 

I do see how RAM is needed for the PC software to perform motion detection comparisons faster but don't see how this would affect the FPS coming from the camera as the work is already "done". Any comments welcome!

 

Thanks again, John

[Guest]

Thanks JD - that is all good info.

 

As far as other routers are concerned, we are lucky enough to be living "out of town" on a private 3-acre lot away from other people/routers. I do have one neighbor who's SSID I can "see", but I think his effect on my setup is negligible.

 

Your point about IP cameras and ram is something I'm not clear on. If all the "work" is being performed in the camera itself and then transmitted to the PC/Software - wouldnt the RAM cost be negligible because the work has already ben done within the camera?

 

I do see how RAM is needed for the PC software to perform motion detection comparisons faster but don't see how this would affect the FPS coming from the camera as the work is already "done". Any comments welcome!

 

Thanks again, John

 

Hi!

 

What cameras are you using and what codec? As in my example I used H264 if it is Mjpeg at 30FPS speed that will mean that the computer needs to recive the data and with Mjpeg the data amount will be much larger even if both the H264 camera or the Mjpeg camera have done the encoding at the camera site.

 

JD

[magohn 0]

Hello,

 

Thanks for replying. I am using Sharx IP cameras.

 

http://www.sharxsecurity.com/products.html#pet - SCNC2607

 

They appear to be great little camera - 30 fps MPEG4 codec

 

Based on your theory I just did a test. I bypassed the CCTV software and went directly to the Web site that is served from within the IP camera. I changed the FPS to 30 fps (from 10) and then viewed the stream from the same internal Web site (not the CCTV spawned Web site) . True enough, the camera displayed 25-30 fps, and then I heard the fan of the PC hosting the CCTV software go into overdrive.

 

I was viewing the 30fps on a second PC, the PC hosting the CCTV software is a completely separate box but it WAS working hard when I viewed the stream on the second PC.

 

Perhaps this is my issue - the 512mb just cant handle > 3 cameras and cr@ps out with camera disconnects and low fps? Does it sound reasonable to assume? The host PC was definitely working hard when viewing 30 fps on the second PC.

 

Thanks so far, John

[Guest]

Hello,

 

Thanks for replying. I am using Sharx IP cameras.

 

http://www.sharxsecurity.com/products.html#pet - SCNC2607

 

They appear to be great little camera - 30 fps MPEG4 codec

 

Based on your theory I just did a test. I bypassed the CCTV software and went directly to the Web site that is served from within the IP camera. I changed the FPS to 30 fps (from 10) and then viewed the stream from the same internal Web site (not the CCTV spawned Web site) . True enough, the camera displayed 25-30 fps, and then I heard the fan of the PC hosting the CCTV software go into overdrive.

 

I was viewing the 30fps on a second PC, the PC hosting the CCTV software is a completely separate box but it WAS working hard when I viewed the stream on the second PC.

 

Perhaps this is my issue - the 512mb just cant handle > 3 cameras and cr@ps out with camera disconnects and low fps? Does it sound reasonable to assume? The host PC was definitely working hard when viewing 30 fps on the second PC.

 

Thanks so far, John

 

I think you should take a break and wait for the RAM and then have a go again and come back if still problems

 

JD

[Soundy 1]

I don't think RAM is your problem, at least not directly. Overall data throughput is probably a bigger issue if you're recording all these cameras - the bottleneck could be the amount of RAM, the motherboard's bus chipsets, the drive I/O, or any combination thereof. At those relatively small bandwidth streams, I think disk I/O speed is going to be more of a problem than the amount of RAM; your machine is probably bogging down trying to do that along with all its other processes.

 

Also, don't expect a "G" router to give you a SUSTAINED 54Mbps with multiple streams like that. That speed, as I recall, is half-duplex, so you'll get "interruptions" as the recorder communications back with the cameras. The more constant load you place on the wireless connection, the more it will suffer. It's not the router choking, it's just a limitation of WiFi spec.

 

In this case, I fully expect that the camera dropouts are caused by network bottlenecks, not by the computer. Try shutting down the CCTV software and browse all three cameras on their web viewers at the same time, preferably on a more powerful machine (if you have one)... if the dropouts continue, and you're only viewing the cameras (not recording them), then the problem is likely the network.

 

One thing you can do, try throttling back your cameras to 10-15fps. At 15fps, you'll be hard-pressed to tell the difference from 30fps unless you have something moving fast through the scene. Even 10fps will produce fairly smooth motion in most cases.

[magohn 0]

 

I don't think RAM is your problem....I fully expect that the camera dropouts are caused by network bottlenecks, not by the computer. Try shutting down the CCTV software and browse all three cameras on their web viewers at the same time, preferably on a more powerful machine (if you have one)... if the dropouts continue, and you're only viewing the cameras (not recording them), then the problem is likely the network.

...

 

Thanks for your idea!

 

I think you are correct here. Last night I tried all three cameras on a different machine and the fps still averaged 2-5 fps. I also had the CCTV software closed out.

 

However, this AM I tested again and now the FPS shot up to an average of 10 FPS with the CCTV software active, one camera actually hit 20fps for a minute or so. Its as if the network goes thru phases of good/poor performance.

 

I am running DD-WRT on the Linksys router and there are many different options.

 

Any ideas as to how I could test/adjust my network? I guess I could try plugging in a CAT5 cable to a camera and see if that improves things...any other suggestion welcome.

 

John

[Soundy 1]

Even with DD-WRT you're still limited to the capabilities of the hardware and the 802.11g protocol. You might be able to tweak a little more performance out of the radio with some better handling of heavy traffic, but that's probably beyond the scope of this forum (www.dd-wrt.com would be a better place to ask about that).

 

As you say, try plugging one or two cameras directly into the router and see if that helps the wireless framerates. And again, try locking all the cameras to lower framerates, and see if that improves the overall stability for all them.

[Sawbones 0]

Wireless ain't the greatest for sustained data throughput... and that's particularly true for the consumer-grade stuff. Some of the pro-level gear can do it, but your basic Linksys/Dlink/Netgear?

 

You're going to have problems.

 

Here's the thing when you're dealing with network interface cards, whether wired or wireless. You really do get what you pay for when you're buying NICs. Higher-end cards (like the Intel PRO series, and 3COM cards) may only be another 15-20 bucks, but they're faster and more efficient, since they do a lot more of their processing on-the-NIC... that's checksumming, scatter-gather, and other processing loads that cheaper cards off-load to the CPU via the PCI bus. The latter situation with a cheaper card creates more interrupt traffic on the bus, and eats up CPU cycles and precious bandwidth that your computer needs to move all that video data to the processor, and onward to the hard drives.

 

Built-in NICs are often some version of a cheap, minimalist Realtek chipset. If you want to see something interesting, try transferring a bunch of files over your network... like a thousand-song MP3 collection or something, hit CTRL-ALT-DEL to access the Task Manager while it's happening, click the "performance" tab across the top, and watch your CPU load. You'd be amazed how much CPU a cheapo NIC can eat up transferring a large volume of data... and having a bunch of separate video streams coming into a central server is not light duty for a NIC. It's NOT a good place for a cheapo card.

 

I use Intel PRO-1000 gigabit NICs in all my PC-based DVRs. It's worth the money.

[magohn 0]

Thanks Sawbones - all good suggestions. I will test over the next day or so. I would have tested sooner but hte flu came-a-calling...

[thewireguys 3]

With the 54MB your real world throughput is about half that and that is you have line-of-site to the cameras. The farther away and the more stuff you have in-between the more it drops.

[zmxtech 0]

that's right 54Mb will only give 20mb if your lucky !

 

CODEC ...SMMMOOODEC....

 

secret:

Use NO compression and motion detection !

 

 

z