HK Recommended Bitrate? Increase based on bandwidth tool?

[xavier4or 0]

Was playing around with the HK tools and I noticed on the HK bandwidth tool said I should increase my set bitrate from 6144 to 12288. And for all 6 cameras?!?

 

I am nervous this would negatively effect the camera bandwidth since I would be doubling the bitrate. The cameras are Hikvision, 5MP.

 

Thoughts?

[ArtP 0]

I've played with the bitrate on my two HK 3mp.

 

No matter where I set bitrate, the actual stream coming from two camera's combined, never exceeds 2,700 or so at 25 frames and 1920x1080. I don't notice any image quality change either, regardless where I set bitrate. I think I have mine set at 8192.

 

Mine are recording full time to a powerful NAS, without much other network traffic, so the network is certainly not saturated and the NAS can handle anything thrown at it.

 

Lovely documentation from those guys, eh?

[xavier4or 0]

How can you tell the actual incoming bitrate? I would like to do this as well!

 

 

No matter where I set bitrate, the actual stream coming from two camera's combined, never exceeds 2,700

[ArtP 0]

My Synology NAS has those stats, live, on its startup page.

 

If you're using Windows you can, control-alt-delete, task manager, networking tab, then do the math. (make sure nothing else is running that uses meaningful bandwidth)

 

Example:

My PC has a 1Gbps link speed, that is 1,000 megabit. It does not matter my cameras are connected at 100mb. And.... Windows is only looking at one way traffic, not the full duplex, which is 1gbps each way (I've never seen it documented, but testing proves it).

 

If my network utilization is at 3%, that equates to 30 megabits per second , or 3.75 MegaBYTES per second. (8 bits per byte).

 

You may have a 100mb connection, so you would be dividing and multiplying by 100, not 1000 as I am doing.

 

There is network overhead and background tasks eat some of this bandwidth (DNS queries for example), so the numbers you get are rough but easily accurate enough to trust. Try the same test with nothing running and you will find your utilization is somewhere under .02%. If I "floor" my system by copying a 20 GigaBYTE file from my NAS to my PC, I can see my network utilization bounce between 75-98% while my NAS is showing speeds around 90 MegaBYTES per second.

 

For fun you can do the same while you perform an internet speed test.

 

I should also mention, my two cameras look at mostly static views where compression plays a big role. Viewing a busy downtown scene would certainly use more bandwidth and compression would not play as large a role.

[MaxIcon 0]

A low bit rate won't show any problems on static scenes, or if there's not a lot of detail. When there's a lot of motion and a lot of detail, you're more likely to see pixelization or blockiness if your bit rate is too low.

 

If you don't see any change when bit rate is changed, you probably have VBR enabled. Typically, the bit rate setting will be the max bit rate, and it'll bump up when you've got lots of changing pixels.

 

Some cams will display bit rate on the web view. I use Blue Iris, which shows it in real time for each cam, but in MB/s, not Mb/sec, so you have to multiply by 8 to bet to Mb/s. You can install the demo version of BI to watch the cams.

 

Likewise, installing Process Explorer will let you graph bit rate over time, but it shows aggregate bit rate for network usage, rather than breaking them out as individual cams.

 

Hik's recommending that high a bit rate because of your 25 fps setting. The first step to reducing it, if either network traffic or stored file size are a concern, would be to drop your frame rate. Many people run 10-15 fps for surveillance.