HD (720)
The maximum resolution and frame rate of video recorded by the recorder in the
HD (720p) standard.
The classic resolution for this standard is 1280x720, but there are other options in DVRs — in particular, 1280x960 (4:3 aspect ratio). Anyway, HD is not outstanding, but quite a decent indicator that allows you to get a video with good detail (for example, it is usually quite possible to make out numbers on cars in close proximity to a car on it).
As for the frame rate, the
higher it is, the smoother and less blurry the video will be, the better the details on moving objects will be visible, and also the more space the footage will take up. It is worth noting here that in some inexpensive models, shooting in HD at very low speeds — 15 – 20 fps is used to reduce the cost. Such a shooting speed allows you to watch video more or less normally, but for a normal display of moving objects, a higher frame rate is still desirable — at least 25 frames / sec. It is also worth saying that, in general, for a comfortable perception by a person, a speed of 24 to 60 frames per second is considered quite sufficient, however, among the registrars there are models that can shoot HD at 120 fps. The meaning of this speed is to ensure that individual details on moving objects are as clearly visible as possible in slow motion or frame-by-frame viewing.
Field of view
The viewing angle provided by the main camera of the DVR. As a rule, it is indicated along the diagonal of the frame, less often - horizontally, because of this, models with the same numbers in the characteristics may differ somewhat in the actual field of view. So if you have doubts about this, when choosing, it does not hurt to find and watch video samples from different models.
Other things being equal, a wider viewing angle allows you to cover more space, but individual details in the frame are smaller. In addition, wide-angle lenses give geometric distortions of the image (however, DEWARP can be provided to eliminate them, see "Functions"). As for specific figures, viewing angles
up to 120° inclusive are considered relatively small for modern registrars, values of
121 - 140 ° can be called average,
141 - 160 ° are above average, and the most wide-angle models are able to cover a space
of more than 160 °.
Recording features
Among the photo and video functions used in the dashcam, we can distinguish
G-sensor,
rotating lens,
live,
HDR< /a>, WDR,
polarizing filter,
DEWARP and
Time Lapse. More about them:
— G-sensor (video saving). A sensor that monitors shocks and vibrations acting on the DVR. The main function of this sensor is to ensure the safety of video materials in the event of an accident: in the event of a strong impact, characteristic of a collision or fall, the recorder with a G-sensor automatically saves the previously recorded video to a non-volatile memory protected from overwriting. Thus, materials about an emergency are not only guaranteed to be saved, but with a high probability remain intact even if the recorder itself is damaged. In addition, the G-sensor is used in
parking mode — see "Functions" for details.
— Swivel lens. The ability to rotate the lens of the registrar horizontally or vertically, and in some cases — on both planes. This feature allows you to adjust the camera's field of view.
— Sound recording. Ability to record sound with a video recorder. First of all, we are talking about recording conversations in the cabin, which can become an add
...itional argument in disputable situations — for example, they will allow you to determine whether the driver was talking on a mobile phone at the time of an accident, whether he noticed the situation on the road, how he assessed it, etc.
— Live broadcast. Allows you to remotely connect to the DVR and monitor what is happening from the camera in real time. It is very important if there is an additional camera in the cabin, when you can track the situation, for example, in taxi services, courier delivery, etc. This function will also become important and useful when a car is stolen, when you can not only see the hijacker from the video from the camera, but also track the route of his movement.
— HDR (high dynamic range). A function that increases the dynamic range of the recorder. Dynamic range is the maximum difference between the brightest and darkest area achievable within a single frame. Initially, this range for digital matrices is small, so an image with large brightness differences (for example, a road against a sunset sky) turns out to be either strongly overexposed in bright areas or very dim in dark areas. HDR addresses this shortcoming and also improves the overall colour quality. This is implemented as follows: the camera takes several frames with different settings and from them forms the finished image. At the same time, this technology is simpler and cheaper to implement than WDR, which is similar in purpose (see below). The main disadvantage of HDR is that this type of shooting increases the blurring of fast moving objects in the frame somewhat.
— WDR (Wide Dynamic Range). A function similar in purpose to HDR described above: it is used to improve the quality of a “picture” that has strong differences in brightness. The key difference between these technologies is that WDR works at the hardware level — due to high-end matrices. This allows you to achieve the required dynamic range within a single frame and do without gluing several frames — as a result, WDR, unlike HDR, does not give a blurring effect and does not worsen the detail of moving objects in the frame. The downside of this quality is the high price.
— Polarizing filter. The presence of a polarizing filter in the main camera of the DVR. Such a filter reduces the brightness of glare arising from strong light on glass, water and other similar surfaces. This greatly improves image quality, especially when shooting in sunny weather.
— DEWARP. A technology used to correct the "picture" obtained using a wide-angle lens. Such lenses are often used in DVRs; one of their drawbacks is their propensity for the fish-eye effect, the characteristic distortion when straight lines in the frame turn into rounded ones. The DEWARP function eliminates this shortcoming — it "bends back" curved lines, correcting the geometry of objects in the frame. Note that such a correction does not always work 100% accurately, however, the picture processed by DEWARP is anyway more reliable than without this technology.
— Time Lapse. A special mode of operation in which video recording is carried out at a slow frequency, which in practice is mainly used for shooting slow processes. Thus, for example, a long journey or a long sunset can fit into a 3-minute video.
