Glossary

The camera adjust the black level (no light) automatically to remove dark noises in the image.

Automatic White Balance. The camera adjust its white balance automatically.

The camera controls its gain value automatically. Too high gain value may result in more noisy and grainy images.

A rolling shutter is an electronic shutter used in electronic cameras. The image sensor reads and resets each pixel in a very fast speed in a serial manner. Thus one image is comprised of pixels sampled from ever so slightly different time. There are some artifacts for very fast moving objects.

When the analog cameras were first invented, we did not have enough technologies to handle bandwidth of D1@30ips full frame. So instead, the early engineers use a technique called interlaced video signal, used in NTSC/PAL, to use time and inter line multiplexing. So the story goes to complicate the old analog camera field image vs frame image, and even/odd fields, giving interlacing zig-zag artifacts of moving objects.

Virtually all IP cameras including DirectIP cameras use progressive scan these days. All images are taken in a progressive way.

However, in most cases, the image sensors use rolling electronic shutter, not a global electronic shutter. It's not perfect, but it is so much better than the interlaced scanned video.

There is only one time, which is UTC 0 time at GMT. all the other times are translated time according to their time zones.  

[NVR]
So when an event or an incident is recorded in NVR, it is very important to make sure that the recorded images are synchronized to the correct time.
DirectIP NVRs use SNTP(Simple Network Timesync Protocol) to synchronize its time to a master time server or can run as a SNTP server to which the time of other NVRs can be synchronized.

[Camera]

When the analog cameras were first invented, we did not have enough technologies to handle bandwidth of D1@30ips full frame. So instead, the early engineers use a technique called interlaced video signal, used in NTSC/PAL, to use time and inter line multiplexing. So the story goes to complicate the old analog camera field image vs frame image, and even/odd fields, giving interlacing zig-zag artifacts of moving objects.
Virtually all IP cameras including DIP cameras use progressive scan these days. all images are taken in a progressive way.
However, in most cases, the image sensors use rolling electronic shutter, not a global electronic shutter. It's not perfect, but it is so much better than the interlaced scanned video.

Image cropping refers to remove of the outer parts of an image depending on the application.

1080p and 720p and 4CIF all have different aspect ratios, and often 1080p IP cameras use cropping for 720p video stream. But this result in different field of view.

DIP cameras use scaling to deal with these different aspect ratios. Instead of cropping out the images, it scales and streches the images maintaining the same field of view regardless of the resolution used.

Extremely wide angle lenses ranging from 180~360 degree. The raw images are warped into a circle.
You can record these raw video and the use dewarping software do dewarp the video on the fly.

DirectIP cameras talk to DirecIP NVRs using DirectIP protocol. They can discover each other on the same subnet automatically. This is called auto scanning. No IP address, subnet mask, gate way information settings are required for each IP cameras, which is a big time saving during the installation.

Bit rate is a little bit controversial. the codec engine is the game of using less bit rate for the equal or better video image quality. given the same codec profile, the bit rate roughly translates into the amount of information about the video image quality allowed to reconstruct the video image.
A reasonable and optimized bit rate is used in most IP camera codec engines. but sometimes, you meet an application that requires a lot higher fidelity. You can tackle it with higher mega pixel cameras, or you can tackle it with higher bit rates.

In DirectIP product, we use basic~very high quality that use bit rates optimized for most video surveillance applications. And 12Mbps@1080p@30IPS is one of the best that you will find.

codec comes in different capabilities. a profile is a collection of techniques used in a codec engine. the more sophisticated  techniques are used, the higher compression efficiency, and the better codec profile with different bit rate. in H.264, typically base profile is used in lower cost codec engines, and main profile or high profile is used for more high end IP cameras.

IP camera can compress video images in more than one codec, such as H.264 and MJPEG.

IP camera provides multiple video streams, probably, in multiple video profile.

IP video stream that NVR can subscribe to do live watching or recording

Codec specification of the video: resolution, ips(image per second) and bit rate.