Comparison Xiaomi Smart Doorbell 3 vs IMILAB Smart Wireless Video Doorbell

— Street (universal). Call panels that can be used outdoors. Even in a fairly mild climate, "street" devices are constantly exposed to various adverse effects: precipitation, temperature changes, ultraviolet radiation; in addition, they can be a very attractive target for hooligans and vandals. All this requires the use of durable and sustainable materials. At the same time, nothing prevents the installation of such panels in the premises (hence the name "universal").

— Premises. Call panels designed for installation inside buildings. Such placement assumes quite favorable conditions (lack of moisture, almost constant temperature, etc.), as well as a minimal risk of vandalism. Therefore, "internal" devices do not have such a margin of safety and reliability as external ones; this has a positive effect on the cost, but does not allow the use of outdoor panels of this type outdoors.

A card reader is a device for working with removable memory cards. Such media are used to record data, which allows you to save events occurring in front of the calling panel at the right time.

Type of matrix installed in the camera of the video panel (see "Type").

— CMOS. She is CMOP. Relatively inexpensive matrices, which, nevertheless, provide good image processing speed with low power consumption, and also take up little space (which is very important for miniature cameras). Their main disadvantage is the increased tendency to the appearance of noise in the image, which is why the quality of this image is somewhat inferior to CMOS CCD.

— CCD. The Russian equivalent of the name is "PZS". Such sensors are somewhat more expensive than CMOS, due to the complexity of the design, and their size is somewhat larger. At the same time, they have more uniform characteristics and are not as prone to heat during operation, which reduces noise and has a positive effect on image quality — especially with a small amount of light.

Diagonal size of the surveillance camera matrix. This parameter is traditionally indicated in inches and fractions of an inch.

With the same type (see above) and the number of megapixels (see below), larger sensors are considered more advanced. This is due to the fact that a large sensor size means a larger area of each individual pixel — and this, in turn, increases the amount of light falling on each pixel, has a positive effect on light sensitivity and reduces noise. Large sensors are especially important for working in low light conditions, including with IR illumination (see "Design and capabilities"). However, for calling panels, matrices are mainly limited to 1/4" and 1/3" sizes. Other options are much less common.

The number of megapixels in the camera sensor, in other words, its resolution. A megapixel is one million light-sensitive dots (pixels) that make up an image; the resolution of modern matrices is very high, so it is more convenient to use just this method of designation. However, for call panels, the values are 1 MP, 1.3 MP and 2 MP. More advanced options are extremely rare.

The higher the resolution of the matrix, the higher the video resolution can be (see below), the more detailed the image can be provided by the door panel camera. At the same time, note that as the number of megapixels increases (without changing the size of the matrix), the size of each individual pixel decreases, which increases the likelihood of noise and deterioration in the overall image quality. Therefore, high resolution in itself is not necessarily a sign of high quality — a lot depends on other things, for example, on the size of the matrix (see above).

Video compression format (codec) used by the door panel camera.

In practice, this information is important mainly for assessing compatibility with other special equipment, as well as when viewing captured video on household media players. This point is not important for interaction with a computer: most modern operating systems have extensive sets of built-in codecs, and if necessary, additional codecs can be installed separately. However, different video compression formats also have some specific features, here they are:

- H.263. The oldest of the codecs widely used in digital cameras of calling panels. It was created back in the mid-1990s for efficient video transmission over low-bandwidth channels; nowadays it is considered obsolete and is found extremely rarely in calling panels, and exclusively as an addition to the more advanced H.264 (see below).

- H.264. A codec widely used in modern video equipment, including for transmitting high-definition video. It provides a good compression ratio while maintaining quality, and is not particularly demanding on computing power, which is why it is extremely popular in our time.

- H.265. The newest and most advanced of the formats found in calling panels. It provides even higher efficiency than H.264, supports resolutions up to 8K, but has quite serious hardware requirements. As a result, support for this standard is...rarely found in calling panels.

Horizontal size of the video panel covered by the camera (see "Type"); this size is most conveniently indicated by the angle between the lines connecting the camera lens with the left and right edges of the scene being viewed.

Theoretically, the wider the viewing angle, the more space the camera is able to cover and the less likely it is that some details will remain out of the frame. At the same time, taking into account the specifics of the use of outdoor panels, it is usually not necessary to equip them with wide-angle cameras; moreover, such optics would be inconvenient due to distortion and reduction effect. Therefore, most models have horizontal viewing angles in the range of 60 – 80 ° — this is quite enough for the intended use.

The vertical size of the video panel covered by the camera (see "Type"), in other words, the angle between two lines connecting the lens with the top and bottom edges of the scene being viewed. The value of the viewing angles is described in detail above in paragraph "Viewing angles horizontally"; we only note that they are usually smaller vertically than horizontally, and in many models this parameter is not indicated at all because of its secondary importance.

This value characterizes the angle of coverage of the image diagonally, this figure is usually slightly larger than the horizontal angle, this is due to the fact that the frame that we see is already in a rectangular form, usually with an aspect ratio of 3 to 4 or 16 to 9, and part of the frame can be circumcised. This indicator, along with the horizontal and vertical viewing angles, allows you to estimate from what distance the visibility of the interlocutor will be acceptable.