questions about NVR terminology

[MythicFrost]

Hi all,

When looking at various NVRs (Dahua, Uniview, VIP Vision, Hik) I see some terminology that I don't quite understand and was hoping I may be able to get some clarification on. (Did a lot of Googling but couldn't find the answers myself.)

This is an example of an NVR I'm looking at:
Dahua DHI-NVR5208-8P-4KS2 - 8 Channel Network Video Recorder: 12MP(4K), Pro Series

In the description of the unit a few things are written:

1. Up to 12 Megapixel (4K Ultra HD) Resolution Recording for Preview and Playback
Does this mean it can let you preview/playback one 4k camera (8MP) and then multiple substreams at a lower quality (not exceeding 4MP total) at the same time?
Is this talking about streaming remotely or about viewing the streams on a monitor via the HDMI cable, or both?

2. 4-ch@8MP(30fps), 16-ch@1080P(30fps)
What does this affect exactly? I want seven 4k 30 FPS cameras recording 24/7.
Does this mean it can't do that?

3. Max 320Mbps Incoming Bandwidth
I used a few different cctv bandwidth calculators online and it estimated 120Mbps @ 4k 30 FPS w/ H.265 decoding.
Is that accurate? If I'm well under the bandwidth requirement then does that mean it could handle 7 cams @ 8 MP - 30 FPS?

Just in case it's relevant, below is a little bit of info about what I hope to be able to do:

• Seven 4k 25-30 FPS cameras (varifocal / motorized not important) for residential for 24/7 operation.
• I would like to be able to watch a monitor (when at home) showing footage from all cameras at the same time and click one to view the full 4k resolution footage.
• Additionally, I want to be able to tune in remotely via my smartphone and see an overview of all cameras and click one to view higher resolution footage.

I would appreciate any help, advise, recommendations, etc.

Cheers!

 

[tigerwillow1]

My best guesses:
1. The highest pixel count camera you can use is 12 megapixel.
2. If all your cameras are 8MP at 30 FPS, the most it will support is 4 of them. If they're 2MP (1080P) at 30 FPS it will support 16 of them. I'm guessing they figure these configurations are near the 320Mbps limit.
3. What you want to do might work but is not guaranteed. You are able to trade off between compression quality and bps, as well as frame rate and bps. You might want to reconsider if the 30 FPS is necessary. It's not for security purposes. My NVR is spec'd at 320Mbps and I run 16 cameras with no difficulty, but it's a mix if 2MP and 4MP cameras running at 10 FPS.

 

[looney2ns]

Study this: Cliff Notes
Don't chase megapixels, 4MP is plenty.

 

[MythicFrost]

My best guesses:
1. The highest pixel count camera you can use is 12 megapixel.
2. If all your cameras are 8MP at 30 FPS, the most it will support is 4 of them. If they're 2MP (1080P) at 30 FPS it will support 16 of them. I'm guessing they figure these configurations are near the 320Mbps limit.
3. What you want to do might work but is not guaranteed. You are able to trade off between compression quality and bps, as well as frame rate and bps. You might want to reconsider if the 30 FPS is necessary. It's not for security purposes. My NVR is spec'd at 320Mbps and I run 16 cameras with no difficulty, but it's a mix if 2MP and 4MP cameras running at 10 FPS.

1. Oh cool, thanks!
2. I wondered that - but I thought perhaps that 320 limit was based on a less efficient codec (H.264 or the other) where the bandwidth is actually quite big. Bandwidth is just the bitrate right? If the camera's bitrate is 10Mbps then it uses 10Mbps of bandwidth? Or is there more to it than that?
3. I see I see. It'd certainly not be a problem if I only used 4MP cameras instead of 8. I'll have a look at that.

Study this: Cliff Notes
Don't chase megapixels, 4MP is plenty.

Having a thorough look over the link, thank you!
I'll probably be back with questions after

-------------------

So for night time performance is the most important thing the sensor size + aperture?

I liked the look of this 4k camera: Dahua 2831R
It has a 1/1.8" 8MP sensor and F1.9 Aperture.

But compared to this one which is 4MP: Dahua 5442R
It has the same 1/1.8" 4MP and a F1.6 Aperture.

So the 4MP will provide better lighting at night, but the 8MP better detail during the day?

 

[Teken]

Some things to keep in mind is bandwidth will be directly related to many parameters such as the set resolution (2-4-8MP), FPS, and if the cameras are defined to use CBR / VBR.

Obviously the type of video codec plays a huge role too. If you review any of the online guides comparing H.264 vs H.265+ the amount of storage space and bandwidth required is night & day.

None of this of course addresses (IF) your internal network infrastructure and level of service from the ISP will support what you seek unless paid for now and in place.

Meaning you need at least a symmetrical 50 up / 50 down - more is obviously better!

If this forum and others are any sort of gauge as to what hardware is present. It spans from dollar store quality to full on enterprise.

Before you spend a dime on any camera system insure your network is capable of supporting the same. At the local level it all starts with properly installed solid copper CAT-6 (23 AWG) cable or better.

Next is a first tier 24-48 POE+ / POE++ Switch. Followed by a Router / AP’s spec’d to move GB data 24.7.365 without dropping packets and burning out.

If you plan to use a consumer router for 24.7.365 4K WiFi streaming to a mobile device good luck. Dedicated Access Points (AP) will offer you better even coverage, range, and throughput.

As noted up above if you intend to access the same video offsite. This all hinges upon your ISP service plan with sufficient upload speed & bandwidth. Which doesn’t even address the hardware & software you intend to use to connect remotely to view the same.

If you have anything older than a three years for a tablet / phone. Good luck using the bloatware smart applications. If this is through a VPN connection viewing 16-32 cameras tiled.

Good luck viewing those 16-32 cameras all at 4K video resolution!

 

[wittaj]

Right now the 5442 series Dahua cams are the best combo of MP/sensor size.

8MP will need at least double the amount of light as a 4MP on the same sensor. Nighttime is where we need the good video and image.

I do not chat to my neighbors that I have cameras. Some have noticed, but most do not. When we had a door checker in my neighborhood a couple years ago or so at 3am and the neighbors with cameras were talking how their great arlo, ring doorbell, Lorex, Foscam, and reolinks (many of these at 4k) captured that something happened but the police couldn't find any useful video from them (one had their car broken into and his camera is less than 10 feet from his car) and they were chatting how this is just an accepted fact from camera systems. I just stood there smirking to myself.

One of them joked that my cameras probably didn't catch anything since I don't have a car on the driveway and they skipped me. I let them see what my cameras captured and they were blown away. The money shot that got all their stolen stuff back was my 2MP varifocal 50 feet away zoomed in to a spot on the sidewalk at the street where the perp walked past and my LPR got their plate. They were shocked my 2MP cameras were blowing away their 4K cameras...and one with sense started buying cameras like mine since they would work with his Lorex DVR. He was all ticked that his $1,300 Lorex 4k box kit was being beat by a 2MP camera LOL, but he recognized now what is preached on this site about not chasing MP and went with 2MP cams to replace his 4K cams...

 

[mat200]

..

So for night time performance is the most important thing the sensor size + aperture?

I liked the look of this 4k camera: Dahua 2831R
It has a 1/1.8" 8MP sensor and F1.9 Aperture.

But compared to this one which is 4MP: Dahua 5442R
It has the same 1/1.8" 4MP and a F1.6 Aperture.

So the 4MP will provide better lighting at night, but the 8MP better detail during the day?

Hi @MythicFrost

Q: Given the same tech and size of sensor: So the 4MP will provide better lighting at night, but the 8MP better detail during the day?
A: Yes, that is a good generalization that helps you decide which way to go.

Of course there's more to it - but as a general rule that works very well without getting into more complicated comparisons. ( i.e. we assume all other aspects of the cameras are similar... DSP chips, algorithms, compute power per mp, ... )

 

[MythicFrost]

Some things to keep in mind is bandwidth will be directly related to many parameters such as the set resolution (2-4-8MP), FPS, and if the cameras are defined to use CBR / VBR.

Obviously the type of video codec plays a huge role too. If you review any of the online guides comparing H.264 vs H.265+ the amount of storage space and bandwidth required is night & day.

I'd be getting something that supports H.265+ as it has the best compression afaik.

None of this of course addresses (IF) your internal network infrastructure and level of service from the ISP will support what you seek unless paid for now and in place.

Meaning you need at least a symmetrical 50 up / 50 down - more is obviously better!

If this forum and others are any sort of gauge as to what hardware is present. It spans from dollar store quality to full on enterprise.

I have 250/25. The best internet in Australia unless you're one of the lucky few that can get 1000/50.

Before you spend a dime on any camera system insure your network is capable of supporting the same. At the local level it all starts with properly installed solid copper CAT-6 (23 AWG) cable or better.

Are you talking about my local network, from the cams to the NVR/PC, or the internet? My network does 250/25 but I'm not sure if that indicates if the cabling is good enough.

Next is a first tier 24-48 POE+ / POE++ Switch. Followed by a Router / AP’s spec’d to move GB data 24.7.365 without dropping packets and burning out.

If you plan to use a consumer router for 24.7.365 4K WiFi streaming to a mobile device good luck. Dedicated Access Points (AP) will offer you better even coverage, range, and throughput.

I'd need at most 8-12 cams. Definitely thinking 4k is the wrong direction and will probably look at 2-4MP units now.
No idea what an access point is, so that's another thing to Google!

As noted up above if you intend to access the same video offsite. This all hinges upon your ISP service plan with sufficient upload speed & bandwidth. Which doesn’t even address the hardware & software you intend to use to connect remotely to view the same.

If you have anything older than a three years for a tablet / phone. Good luck using the bloatware smart applications. If this is through a VPN connection viewing 16-32 cameras tiled.

Good luck viewing those 16-32 cameras all at 4K video resolution!

It'll mostly be on-site, occasional checking the tiles of 8 or so cameras remotely from my phone (at D1 resolution) and maybe looking at one at full resolution.

Right now the 5442 series Dahua cams are the best combo of MP/sensor size.

8MP will need at least double the amount of light as a 4MP on the same sensor. Nighttime is where we need the good video and image.

Good to know, thanks!

I do not chat to my neighbors that I have cameras. Some have noticed, but most do not. When we had a door checker in my neighborhood a couple years ago or so at 3am and the neighbors with cameras were talking how their great arlo, ring doorbell, Lorex, Foscam, and reolinks (many of these at 4k) captured that something happened but the police couldn't find any useful video from them (one had their car broken into and his camera is less than 10 feet from his car) and they were chatting how this is just an accepted fact from camera systems. I just stood there smirking to myself.

One of them joked that my cameras probably didn't catch anything since I don't have a car on the driveway and they skipped me. I let them see what my cameras captured and they were blown away. The money shot that got all their stolen stuff back was my 2MP varifocal 50 feet away zoomed in to a spot on the sidewalk at the street where the perp walked past and my LPR got their plate. They were shocked my 2MP cameras were blowing away their 4K cameras...and one with sense started buying cameras like mine since they would work with his Lorex DVR. He was all ticked that his $1,300 Lorex 4k box kit was being beat by a 2MP camera LOL, but he recognized now what is preached on this site about not chasing MP and went with 2MP cams to replace his 4K cams...

That's awesome. Was it a PTZ unit? Are they still good during the day?

Hi @MythicFrost

Q: Given the same tech and size of sensor: So the 4MP will provide better lighting at night, but the 8MP better detail during the day?
A: Yes, that is a good generalization that helps you decide which way to go.

Of course there's more to it - but as a general rule that works very well without getting into more complicated comparisons. ( i.e. we assume all other aspects of the cameras are similar... DSP chips, algorithms, compute power per mp, ... )

Thanks! So I think I'll definitely look at 2-4MP cameras now. That simplifies things a bit!

 

[Teken]

I was speaking about the cabling within your LAN (in your home) and not from the ISP modem / router. You want to do this once, and right, so no Siamese type wiring that incorporates 12 VDC & RJ45 Ethernet cable. If the wiring already exists not much you can do now but use what you have. Now, if the wiring hasn't been installed and deployed in its final location.

Purchase name brand certified CAT-6 solid copper (23 AWG) CMR Ethernet cable that is in wall or what is known in the industry as Riser cable. Do not use or install any CCA (Copper Clad Aluminum) Ethernet cable in a wall, cavity, enclosed space. As it is not in wall rated and doesn't have a fire rating. CMP plenum cable is intended for installation within the air ducts and returns and has a higher flame retardant and off gassing of VOC's.

A (AP) or Access Point is essentially the WiFi antenna in a separate box vs the same one integrated into a consumer router. The benefit of using a dedicated AP is it allows you to place them in strategic locations to reduce signal loss from building structure and material. The latest rage of Internet is what people often refer to as Mesh.

This so called Mesh routing and connectivity has been present for decades in Enterprise . . .

The benefit of a mesh WiFi system is no matter where you are in your home the signal and connection to that end device like your tablet is the same as if you were next to the router / AP. All of this on paper works, but in reality, even in an enterprise environment the results are hit or miss depending upon hardware, protocol, and configurations.

Even though the so called WiFi 6 standard has been ratified and is being used in a limited amount of hardware. If you intend to purchase any new hardware you should jump on the WiFi 6 bandwagon to future proof your network. It's probably going to take ten years for the market to even adopt it in their wares. This is proven by the very fact in 2021 WiFi 5 (AC) still isn't being widely used in cheap hardware.

The fact the market continues to use 2.4 wireless N and older protocols shows you how very slow the technology industry is!

 

[saltwater]

If you have existing wiring in place and it's Cat 5E, don't despair, it WILL work. There will be nothing to stop you from building your system as per advice above. Yes, if starting out, go with Cat 6 or better.

 

[MythicFrost]

I was speaking about the cabling within your LAN (in your home) and not from the ISP modem / router. You want to do this once, and right, so no Siamese type wiring that incorporates 12 VDC & RJ45 Ethernet cable. If the wiring already exists not much you can do now but use what you have. Now, if the wiring hasn't been installed and deployed in its final location.

Purchase name brand certified CAT-6 solid copper (23 AWG) CMR Ethernet cable that is in wall or what is known in the industry as Riser cable. Do not use or install any CCA (Copper Clad Aluminum) Ethernet cable in a wall, cavity, enclosed space. As it is not in wall rated and doesn't have a fire rating. CMP plenum cable is intended for installation within the air ducts and returns and has a higher flame retardant and off gassing of VOC's.

A (AP) or Access Point is essentially the WiFi antenna in a separate box vs the same one integrated into a consumer router. The benefit of using a dedicated AP is it allows you to place them in strategic locations to reduce signal loss from building structure and material. The latest rage of Internet is what people often refer to as Mesh.

This so called Mesh routing and connectivity has been present for decades in Enterprise . . .

The benefit of a mesh WiFi system is no matter where you are in your home the signal and connection to that end device like your tablet is the same as if you were next to the router / AP. All of this on paper works, but in reality, even in an enterprise environment the results are hit or miss depending upon hardware, protocol, and configurations.

Even though the so called WiFi 6 standard has been ratified and is being used in a limited amount of hardware. If you intend to purchase any new hardware you should jump on the WiFi 6 bandwagon to future proof your network. It's probably going to take ten years for the market to even adopt it in their wares. This is proven by the very fact in 2021 WiFi 5 (AC) still isn't being widely used in cheap hardware.

The fact the market continues to use 2.4 wireless N and older protocols shows you how very slow the technology industry is!

I see I see, interesting thanks!
I don't think I have any ethernet cables in the wall -- there is a coaxial port which the modem screws into, and then the router connects to the modem via ethernet which may or may not be Cat 6.

If you have existing wiring in place and it's Cat 5E, don't despair, it WILL work. There will be nothing to stop you from building your system as per advice above. Yes, if starting out, go with Cat 6 or better.

Well that's good to know. I don't think there is any existing wiring. The modem just goes straight into the coaxial port.

 

[saltwater]

I don't think I have any ethernet cables in the wall -- there is a coaxial port which the modem screws into, and then the router connects to the modem via ethernet which may or may not be Cat 6.

Well that's good to know. I don't think there is any existing wiring. The modem just goes straight into the coaxial port.

It seems your internet is suitable, more suitable than mine (100/5 - it's a joke), so you can forget that side of things for the time being.

Where ever you want your cameras you will have to run ethernet cable, and so you might as well go with Cat 6. You will have to pick a point in your house where you want your NVR to reside and that is where all the ethernet cables end up. The NVR does not need to be physically located next to your modem/router, though the two will be connected by an ethernet cable. Of course this can be easier said than done depending upon the construction of your house. Double-storeys are problematic as you don't want your cameras up high under the eaves (easier to install) but for a double-storey trying to place cameras mid-height is a more challenging exercise.

 

[Flintstone61]

chasing megapixels

 

[Mark_M]

2. 4-ch@8MP(30fps), 16-ch@1080P(30fps)
What does this affect exactly? I want seven 4k 30 FPS cameras recording 24/7.
Does this mean it can't do that?

What I have been told is that this is "preview" resolution.
So when you're logging into the NVR and it is showing you footage, this is a the max resolution it will process. When you download the footage you'll get it at full quality.

 

[MythicFrost]

It seems your internet is suitable, more suitable than mine (100/5 - it's a joke), so you can forget that side of things for the time being.

Where ever you want your cameras you will have to run ethernet cable, and so you might as well go with Cat 6. You will have to pick a point in your house where you want your NVR to reside and that is where all the ethernet cables end up. The NVR does not need to be physically located next to your modem/router, though the two will be connected by an ethernet cable. Of course this can be easier said than done depending upon the construction of your house. Double-storeys are problematic as you don't want your cameras up high under the eaves (easier to install) but for a double-storey trying to place cameras mid-height is a more challenging exercise.

Yeah, I was 100/5 until I switched to NBN recently. If you've got HFC, hopefully you'll be able to get a nice 100/20 or 250/25 plan. The upload is so much better.

Single-story, thankfully so that might simplify things a little bit. Thanks for the info!

What I have been told is that this is "preview" resolution.
So when you're logging into the NVR and it is showing you footage, this is a the max resolution it will process. When you download the footage you'll get it at full quality.

Ohhh right, makes sense! Thank you.