Glossary

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.

Lens format is the focal plane size of the lens. You can use 1/2" format lens for smaller image sensors, such as 1/2.7" or 1/3" or 1/4", but not the other way around. Or else, you will end up seeing part of the lens barrel shadows at the corners of the image especially in wide angle mode.

Optics play a very important role in cameras. And good lenses are critical to build a good surveillance system. When we talk about resolutions, we often talk about image sensor resolutions but not the one for the lenses. Your image is going to be only as good and sharp as the capability of the lens that you use in your camera. Mega pixel lenses can "resolve" mega pixel resolutions on its focal plane.
You can use analog camera lenses on mega pixel cameras. You will see the images, but they will never be mega pixel sharp, but blurry no matter how hard you want to focus it because the lens you are using can not resolve more than about D1 resolution, not mega pixel resolutions.

Infrared LEDs are used to illuminate low light scenes. Typically they are 850nm (visible to most human), and non visible 920nm.

If you are using IR illumination in your scene, make sure you use an IR corrected lens on your camera, if not you will experience focus drift if your lens is not IR corrected and when only the IR LED lights are used. IR corrected lens allows the IR lights to focus on the same focal plane as the visible lights.

Instead of ICR, it uses a IR pass filter which passes the visible spectrum of lights as well. It works great in artificial light conditions, such as indoor applications, but when you have light sources that emits IR spectrum, such as incandescent light blurs, halogen or sun light, the color can be slightly distorted.
Because it is less complex to build the camera without ICR, it is more affordable than True Day and Night cameras.

Infrared Cut-filter Removal is a mechanism used in True Day and Night cameras. Camera sensors are sensitive to a wider spectrum of lights the spectrum of visible lights. So it can see what you can not see. During the day time, it puts the IR cut filter between the lens and the image sensor in True Day and Night cameras. Without this filter, the sensors will see the non visible lights, and may distort the colors on the scene or blur the scene. Also, Frequently Infrared LED lighting is used to assist to low light conditions. So the IR cut filter is removed during the night time so that the IR LED light source can be used to sense the scene in IR spectrum. Because human eyes can not see the IR, the scene is rendered in black and white.

Some light sources are flickering lights, such as fluorescent lights. Human eyes may not notice it but cameras can notice it. It may cause flickering or rolling artifacts on the video. Use anti-flickering option to match the lighting condition of the scene to avoid these artifacts.

Camera is an imaging sensor that collects the light and converts the light signals into images. And different light sources have different light spectrum, which changes the reflected lights on the object. So the same object may look like it has different colors depending on its light source. In most cases, automatic white balance works good enough. But if it does not, use the white balance to match the light profile closest to the light condition. Sometimes it is called color temperature adjustment.

External SATA (eSATA) connector is used to connect additional external storage to the NVR. Mega pixel requires more storage, and you can never have enough storage. eSATA storage boxes come in different fashions and configurations. Sometimes it comes with RAID or mirroring option, where you need to pre-configure the eSATA storage box before you connect to the NVR. Not all eSATA storage controller chipsets are compatible with NVR. Please refer to the approved eSATA storage boxes, and IDIS provides an rack mountable eSATA storage for the NVR.

eSATA is hotpluggable, but it ls always advised to shutdown the NVR before you turn off or unplug the eSATA storages.

[Recording]

It monitors if the NVR has been recording at least once during the specified duration. If not, you can have your NVR notifiy you of the condition. Maybe the recording schedule has changed, and it is not recording properly as you intended it.

[Alarm input]

It monitors if an alarm input has been triggered at least once during the specified duration. If it is a door, it is safe to assume that the door will be open at least once a day. If this was not detected, maybe the sensor is bad or sensor wiring is bad. You can have your NVR notify this condition so that you can send a technician to take a look.

Self-Monitoring, Analysis and Reporting Technology. HDD it does have a brain. It keeps monitoring its operating condition and gathers statistics. NVR can read this information such as highest temperatures the HDD reached. This information can be used to adjust the installation environment to a more friendly one for the operation of NVR.