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A Digital Video Recorder or DVR is a generic term for a device that is similar to a VCR but records television data in digital format as opposed to the VCR ¯s analog format. VCRs utilize analog tapes to record and play programs broadcast over television, but Digital Video Recorders (DVR) encode video data in MPEG-2 or MPEG-4(Include H.264) formats and store the data in a hard drive. DVRs have all of the same functionality of VCRs (recording, playback, fast forwarding, rewinding, pausing).
A DVR is essentially made up of two elements: the device that stores the hard disk drive and power supply, and some type of Electronic Programming Guide (EPG) that allows the user to program recordings.
A DVR is also referred to as a hard disk recorder (HDR) or a personal video recorder (PVR)
All DVRs are definitely not made equal! There are several factors that are critical to consider when purchasing a DVR, especially when comparing price. The most important factors to look at are the number of cameras supported, frames per second (fps), compression technology, hard drive space, network connection/ remote viewing capability, motion detection, scheduling, and ability to save video and audio to a CD or flash drive. You should also look for easy and comprehensive search capabilities (check out our ‘Smart Search’ technology) and audio support. The setup and user interface should be intuitive and easy to operate. The price range varies from as little as $35(HK-S1008E) for a basic 4 camera input DVR up to $2599 for a 16 camera input real time DVR(Such as HK-S8616F)with a terabyte of hard drive storage
The frames per second (fps) relates to how many pictures the DVR will record in a second. Real time recording is about 30 fps on each camera. To calculate the fps per camera take the total fps in the system and divide it by the number of video inputs. For example, a 60 fps digital video recorder with 4 video inputs would result in about 15 fps per camera. The technology has finally gotten to the point now where real time recording is affordable. If you are recording cash registers or something similar then you should definitely invest in real time recording.
The amount of hard drive space is very important because it will limit how many days of recording you can store before the system has to start recording over the oldest video. Each DVR will have its storage capacity listed in the specifications. But this calculation is just a rough estimate as there are many factors that affect hard drive use. The most critical factor being the compression format used by the DVR (for more info on compression formats click here). But also the type of cameras that are connected to the DVR make a difference (specifically the chip size and resolution) and also the features that are selected on the DVR. If you use the scheduling or motion detection features or tune down the frame rate that will extend the storage capacity of the unit. Even the field of view (what you are recording) will affect the storage capacity – the more complex the image, the more hard drive space it will take to capture the complexity.
A PC-based digital video recorder is basically a personal computer that has been modified with hardware and software to work as a DVR. An embedded digital video recorder is a machine that has been manufactured specifically to work as a DVR. In embedded DVRs there is typically one circuit board with software burned into the chip. There used to be significant differences in features between the PC-based and the embedded machines. But with recent advancements in the embedded DVR technologies the differences are becoming less. The advantages of an embedded digital video recorder is that they are extremely stable and reliable since they contain fewer parts. The software is often written in basic machine code or Linux code which tends to be more stable than Windows software. The advantages of the PC-based digital video recorders is that they are easier to interact with because you use the on-screen menus and a mouse (as opposed to embedded which you interact with more like a VCR – via buttons). And you tend to have more features and options on the PC-based machines.
A CCTV digital video recorder (or °DVR ± for short) is essentially a computer that saves security video images to a hard drive. Most security cameras in use today capture an analog picture. The DVR converts the analog signal to digital and then compresses it.
Many cameras can be connected to one DVR. DVRs generally come with 4, 8, 16, or 32 camera inputs. The DVR will allow you to view all of these images at once or one at a time, and all of the video is saved to the hard drive. Additional switches, quads, or multiplexors are not required.
Not at all. You simply plug the cameras into the back of the unit. For the PC-based: Plug in the power, monitor, keyboard and mouse – just like a regular computer. You will receive instructions on how to set up the machine with your shipment.
Most of our PC Based-DVRs come standard with an 200 gig hard drive (unless otherwise noted). They also include the software (for setup, local, and remote viewing), power cord, and documentation. PC-based machines also come with the mouse and keyboard. You just need to add the cameras, whatever cable you need, and a monitor. For embedded machines you can use a TV set or security monitor. For PC-based machines you need a standard computer monitor. Also, we have on-site technical support available at no additional cost.
You can view the camera video over the internet using a modem which is slow but can display 1 or 2 frames every 5 seconds. Better is a DSL or cable modem connection which can generally display 1 frame per second. When viewing remotely, the refresh rate is restricted by the communications medium (your internet connection speed). When viewing or playing back locally, the display is dependent of the unit’s frame rate (fps). You will need a static ip address available to assign to the DVR (more about this in your documentation).
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Kingwood Liu
Kingwood Liu
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Finny Liu
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Serena Li
Cindy Li
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