Low Light Camera Selection questions

[NovoRei]

Questions:

My objective is to monitor a corridor with fast moving objects between 2m to 4m distance from the camera. The image can be BW. Shutter speed and FPS will be high.

If I have the option to install a white flood light or an IR illuminator, which path would preferable considering off the shelf cameras?

Some cameras have 1/1.8 sensor at 2MP and 4MP. Are they usually a true 2MP (larger pixel size) or just downsampled from 4MP? Example ds-2cd3027g2-ls and ds-2cd3047g2-ls.

The minimum illumination stated by manufacturers are always using the smallest focal length lens option? And smallest length with varifocal lens?

 

[NovoRei]

Update and new questions. Bought these two units.

Hikvision DS-2CD2347G2-LU:
Colorvu only, limited to 30fps, not compatible with some NVR and PC-NVR.

Dahua IPC-HDW5442TM-AS-LED:
Not ICR.
Does 60fps.
ROI 4 to 6 does not limit the bitrate. Have to use ROI 1 in the regions of no interest to correctly increase the bitrate in the regions of interest.

The Hikvision encoding seems to be much better capturing small detail in fast moving objects compared to Dahua and uses a lower bitrate while doing so with comparable settings (sharpness, exposure, noise filtering). Is that overall true for other models of the same brand?

Would a true ICR 54xx model be better in IR mode?

Exposure time below ~1/120 creates horizontal dark bands moving vertically. Are there any settings that may remedy this other than changing the ambient light?

Dahua IVS rules tripline/intrusion does not work with fast moving and small objects. Should it work?

Is there a better model that would do 60fps, have the detailed motion picture quality of the Hikvision, with lower exposures, and effective rules of fast/small objects?

 

[wittaj]

No reason to run more than 15FPS, and many us have cams running at 10 to 12 FPS. Movies for the big screen are shot at 24FPS, so I do not think we need that for these cameras LOL. The goal is to get a clean image, not smooth motion.

ROI most have found makes the overall quality worse.

If you do not have enough light, then you need a camera with IR.

Dahua IVS rules work just fine for most, but it depends on the field of view and size of object. IVS on this cam is truly meant for human and vehicle detection. You would probably be better off with Motion Detection if it is something else. And sometimes it is simply operator error in setting up the IVS - they cannot be on the edges of the image - the camera needs time to identify the object and determine if it should trigger - if the line is at the edge, then the object is past it by the time the camera IDs it.

There are differences in the way HIK and Dahua will compress video - trying to compare one bitrate versus the other is like comparing MPG on a Honda versus Toyota. And it comes down to personal preference - some here prefer Hik and others prefer Dahua. Other parameters HIK may have going on that the Dahua doesn't by default, but you should be able to make them generally look the same.

Keep in mind that these type of cameras, although are spec'd and capable of these various parameters, real world testing by many of us shows if you try to run these units at higher FPS and higher bitrates than needed that you will max out the CPU in the unit and then it bugs out just long enough that you miss something or video is choppy or pixelated or you get lost signals. My car is rated for 6,000RPM redline, but I am not gonna run it in 3rd gear on the highway at 6,000RPM...same with these types of units - gotta keep them under rated capacity. Some may do better than others, but trying to use the rated "spec" of every option available is usually not going to work well, either with a car or a camera or NVR.

Look at all the threads where people came here with a jitter in the video or video dropping signal or IVS missing motion or the SD card doesn't overwrite and they were running 30FPS and when people tell them to drop the FPS and they dropped the FPS to 15FPS the camera became stable and they could actual freeze frame the image to get a clean capture. The goal of these cameras are to capture a perp, not capture smooth motion. When we see the news, are they showing the video or a freeze frame screen shot? Nobody cares if it isn't butter smooth...getting the features to make an ID is the important factor. As always, YMMV...

Further, these types of cameras are not GoPro or Hollywood type cameras that offer slow-mo capabilities and other features. They "offer" 30FPS and 60FPS to appease the general public that thinks that is what they need, but you will not find many of us here running more than 15 FPS; and movies are shot at 24 FPS, so anything above that is a waste of storage space for what these cameras are used for. If 24 FPS works for the big screen, I think 15 FPS is more than enough for phones and tablets and most monitors LOL. Many of my cameras are running at 12FPS.

In fact, many times if a CPU is maxing out, if it doesn't drop signal, then it will adhere to the FPS but then slow the shutter down to try to not max the CPU, which then produces a smooth blurry image..that is the video my neighbor gets who insists on running 60FPS. He gets smooth walking people but you can't freeze frame it cause every frame is a blur, meanwhile my 12FPS gets the clean freeze frame. Shutter speed is more important the FPS. We both run the same shutter speed by the way, but his camera CPU is maxing out and something gotta give when you push it that hard.


If your unique case requires that type of FPS, you will find surveillance cameras are not going to meet your needs and you need to get a camera capable of that - or spend some serious money.

We have had recently people come here after purchasing cameras in two instances where they were wanting 60FPS - one was a tennis club and another was a youth soccer club. In both cases they found that these types of cameras were not capable of what they were wanting to do. Sure the cameras could run faster FPS, but it still didn't provide them with the level of detail they were looking for. I recall the soccer club had a decent quality PTZ ($800) that is fine for a residential or retail/commercial installation, but to cover the action of the soccer field it wasn't capable of meeting their needs. And because of the extremely fast motion, it was creating a halo type effect around the action (which can be seen in certain lighting conditions). These cameras are good, but not good enough to catch the rotation of a ball for example.

 

[NovoRei]

...

I understand your point and have read the threads you mentioned. These new gen of cams are just getting too good (spec sheet wise) and could allow their use for new applications. Maybe someone have had some experience similar to ours and may share it. Our infrastructure is composed of hundreds of past gen ip cams in low complexity surveillance applications, so these are "new" for us. Nevertheless the possibility of using them instead of a specialized system, for this application, is attractive due to cost and availability.

Regarding your main point, bandwidth has not been an issue. We have been able to work up to 80Mbits (Cam/Network/CPU client) without a hitch in these two models although 10Mbit is more than enough.

Unfortunately I cannot share pictures/playback to show the differences. But what we need would be a model:

• with the same motion quality per bitrate as this Hik model. The Dahua at 80Mbits does not have the same motion quality as the Hik at 8Mbits. Is this due to Colorvu? Or is the Hik encoding just better? Or is this specific Dahua model poor at encoding? Latest firmware, equivalent configurations, etc.
• 60fps. The Hik only does 30fps.
• Shutter at 1/250 without banding. (We will solve it with better ambient light)
• Motion/Detection rules. We may solve it with some Deepstack customization on the client side.

There are some Axis cams (and other brands) that may achieve this but they are not easily/readily available (we are not based in US/Europe) and cost a bit more because we have to through "solution providers" whereas they only provide additional costs and delays...

 

[wittaj]

ColorVu is simply a marketing term.

There are lots of variables behind the scenes in the algorithms. You would need someone like @Wildcat_1 that can tear apart the coding differences, but you can get the images to match, albeit the settings may be completely different between each one. HIK does a good job of hiding the ability to change the gain for example. It can be done, but the right combination of settings need to be set in order to see it. So of course if their algorithm is adjusting gain and Dahua isn't, that can be one difference. Just one example of many.

Shutter at 1/250 - you must have a ton of light. Neither one of the cameras you selected will do well at night at that shutter speed without a lot of light. You would need to go to the 1/1.2" sensor to start to get close.

I am not talking about the bandwidth of your network. I am talking about the CPU in the camera itself. If you run it at EVERY rated "spec sheet", the little CPU won't be able to keep up. It has been proven time and time again here. Try to run max FPS, max bitrate, MAX IVS rules, etc. and the camera will struggle.

Just keep in mind that "spec sheet wise" is under ideal conditions. Does your vehicle get the spec'd out MPG every fill up? I doubt it LOL.

Without knowing the specialized system that you are trying to create, we can only share with you the capabilities and limitations of surveillance cameras. Maybe these cameras will work, maybe they won't, but we are trying to share with you these limitations so that you are not disappointed when it doesn't accomplish what you want.

If you want true 60FPS, then you need to find a camera that has that as the priority. Otherwise you will get 60FPS from a surveillance camera that looks smooth, but not much else will be of use.

Do a freeze frame capture of motion at night coming from 60 FPS. I bet it is a blur. But watching it realtime probably is silky smooth LOL.

Sure 60FPS can provide a smoother video but no police officer has said "wow that person really is running smooth". They want the ability to freeze frame and get a clean image. So be it if the video is a little choppy....and at 10-15FPS it won't be appreciable. My neighbor runs his at 60FPS, so the person or car goes by looking smooth, but it is a blur when trying to freeze frame it because the camera can't keep up. Meanwhile my camera at 15FPS with the proper shutter speed gets the clean shots.

Again, we are just trying to point out the limitations of these cameras. Since you cannot tell us the application, we cannot say for sure if it will work or not.

But if you don't like what you are getting out of the two cameras you have now, then none in the surveillance camera market will meet your needs.

We wouldn't take these cameras to an NBA game to broadcast, nor would we take the cameras they use at an NBA game to put on a house. Not all cameras are alike and the approach of "a camera is a camera" mentality will result in failure. Another example, I can watch an MLB game and they can slow it down to see the stitching on the baseball. Surveillance cams are not capable of that. You need to find one for the intended purpose.

Watch these, for most of us, it isn't annoying until below 10FPS

 

[wittaj]

I'm not saying my analogy of a car redline or MPG is a perfect analogy, but rather I am pointing out a fact that stuff we buy is always marketed as more capable than it is, especially if you are using all of the features. Does your car get its stated MPG in every situation - NO...

Can a little 4 cylinder base model Ford go up an interstate incline of 4% with the air conditioning at full blast at the speed limit - NO. I remember growing up we would have to turn off the AC going up big hills LOL. We called it turbo boost LOL.

Do you really believe every marketing claim of every product you see on Amazon?

Just like a computer - it is rated for this and that, but if you are running the CPU at 100%, something is going to give. Same with these little cameras with a lot less computing power.

So a few of my cams have a system status screen, and they call it a CPU, so that is why I am calling it a CPU, but this shows this camera running at 8192 bitrate, H264, CBR, and 12 FPS is hitting the camera processor at 47% and jumps to 70% with motion. If I up the camera to 30 FPS, the usage is in the high 90% range, but then with motion, it maxes out and would get unstable.

Or if I keep it at 12 FPS and use the camera motion detection, the CPU in the camera goes to 60% idle.

This would be nice if all cams had this so we could see how our settings impact the performance of the camera. I think running these cams close to capacity is probably harder to overcome than a computer spike at 100% CPU.

At the end of the day, if the consumer wants cameras that can do 30FPS, they will not look at any cameras that do not have that rated spec, so some companies will throw that in to appease the person looking for that. Unfortunately, that is marketing. It takes someone with experience in the industry to know for sure if it is really capable of what marketing says.

And in a few scenarios maybe you can squeak 30FPS out of these cameras - maybe without using IVS or motion detection and just watching a simple feed. But maybe when two users log in, it can't handle it for example. The more features you use, the less likely it will work as one expects.

And if the complaints get bad enough, we have seen firmware updates to popular models that do just that - cut FPS or some other feature...

 

[The Automation Guy]

I really cannot think of a single time where 30 fps wouldn't be more than enough (and really 15fps is generally more than enough). That's faster than movies are recorded at and the same speed as most other video. Why do you feel the need to have 60 fps which is twice as fast as normal video? I really doubt you are trying to capture a subject moving so fast that it is going to require 60 fps to capture it because it will pass the entire camera coverage area in less than 1/30th a second and therefore a camera set at 30 fps might miss the subject completely.

I hope you understand that FPS has nothing to do with shutter speed or the ability of the camera to capture fast motion. A camera that only offers 30 fps still can take images faster than 1/30th of a second and a camera set at only 1 fps isn't taking a 1 second long exposure. You can generally set a CCTV camera's shutter speed to as fast as 1/2000th of a second while the fps setting simply states how many unique images you get per second. So a cameras set with a shutter speed of 1/1000th a second and 30 fps ends up with 30 unique frames all captured at 1/1000th sec - per second of recording time. A camera set at 1/1000th shutter speed but only at 1 fps ends up with 1 unique fps that is also captured at 1/1000th. There would be no difference in the 1fps image and an image from the 30fps camera - the exposure, sharpness, etc, etc, would all be the same. Increasing to 60 fps simply means you have 60 unique images per second. Those extra images have no difference in quality vs a camera set at 30 fps or even one set at 1 fps. The only difference is the number of unique images captures per second. A higher number simply requires more storage and possibly higher network capacity to carry all that extra data.