What is a DVR?
Surely everyone in life had cases when, in the absence of witnesses to any incident, he could not prove his case or not being involved in what had happened. In such cases, only the DVR can help - a device for recording and processing digital video, with the possibility of its replay. These technical devices have long ceased to be a wonder in the electronics market, but many still do not know what a DVR is and what it is for.
Types of DVRs
Although there is no universally accepted classification of DVRs by any particular criterion, some devices still took shape in separate groups:
- Network Video Recorders (NVRs) are devices for recording, storing, and playing video that receive signals directly from an IP camera and archives data for further storage.
- Hybrid DVRs (Hybrid Digital Video Recorders) - devices for recording, storing and playing video from both analog and IP cameras.
- Video recorders based on PC (PC-based Digital Video Recorders) can operate in multitasking mode using the power of the computer.
- Car DVRs (Car Digital Video Recorders) are used to record traffic from the inside of a car, truck, boat and other vehicles. They are also sometimes called mobile, in contrast to other stationary recorders.
However, there are other classifications. For example, by the number of channels for recording a signal, DVRs can be single-channel, two-channel, four-channel, six-channel and eight-channel.
DVR Functions and Uses
A full DVR has the following features:
- FullHD recording is the most high-quality recording format currently (1920x1080 pixels).
- GPS-receiver - an indispensable thing in an emergency. Indicates the recording coordinates and speed of movement.
- G-sensor - a sensor that is able to accurately determine which side was hit. Sensor data can be used in court as evidence.
- IR illumination - guarantees full recording, even in the dark.
- Zoom - the ability of the recorder to increase a fragment of a video or image.
Depending on the purpose for which the DVR is intended, some functions of the device may be absent or be realized in a lower quality (for example, the recording format may be VGA, and the Zoom - only double or absent).
So, DVRs can be used not only in cars, but also:
- in video surveillance systems of private houses, office premises and various public buildings for security purposes;
- in cafes, snack bars, restaurants and shops to monitor the activities of staff. Video surveillance allows, for example, to identify the cause of the discrepancy between cash on hand and data from point-of-sale terminals;
- at various checkpoints and in organizations equipped with security stations, to account for visitors and vehicles arriving in the reporting territory;
- at large enterprises and in various centers, where control is needed over all processes that take place simultaneously in such a large area, etc.
The principle of operation of the DVR
The most common work of the DVR can be described as follows:
- A camera designed to perform a particular task, records what is happening with a certain time interval specified by the settings, and transmits the video signal to the DVR via cable.
- The device processes the received signal taking into account the indication of the date, time and duration of the video.
- A special codec archives or compresses the received data and saves it to the built-in memory or memory card.
Depending on the model of the DVR, up to 8 analog or ip-cameras can be connected to it simultaneously. Additionally, you can connect a microphone, while the video will be superimposed also audio. The shelf life of video recordings on the recorder mainly depends on the amount of hard disk memory to which it is connected.
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