What is a Digital
Video Recorder (DVR)?
. 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)
What features should
I look for in a CCTV Digital Video Recorder (DVR)?
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 $140(AB-M2104A) for a basic 4 camera
input DVR up to $799 for a 16 camera input real time DVR(Such as AB-H8016AL)with
a terabyte of hard drive storage!
What is frames per
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.
How big a hard drive
do I need?
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.
What is the difference
between a PC-based DVR and an Embedded DVR?
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.
How does a CCTV digital
video recorder work?
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
Are security digital
video recorders hard to install?
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
What comes with the
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.
How do I see pictures
from a remote site?
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).
What about email
Email tech support at
. Emails are normally answered within
12 hours and it may be faster to email than to call. This way we can
send you a link or any software that you may need.