From the Product Manager's POV
- By Steve Surfaro
- Oct 02, 2007
New technologies are taking the world by storm. That means the security industry is in the midst of change and
product rebirth. The same holds true for recording devices. DVRs are cost-effective, and NVRs are state-of-theart.
Not sure which to choose? Read what Panasonic group manager Steve Surfaro has to say and then decide.
Q.Can a DVR, rather than an NVR,
be the right choice for an IPbased
system?
A.It would depend on the physical
size and geographic scope of the
system. Since surveillance cameras are
cabled directly into DVRs, distance
becomes an issue, because it is impractical
to run hundreds of yards of cable and
because image quality can degrade as the
signal travels over distance. There also is a
limit to the number of control inputs and
outputs for interfacing and integrating to
various systems and devices. When a DVR
unit’s video inputs are full, another unit
must be added, typically with groups of
eight, 16 or 32 video input capacities.
Still, for smaller applications, DVRs
are a cost-effective way to record and
archive video, and with today’s more
advanced DVRs like the Panasonic WJRT416,
it is possible to build a networked
surveillance system with the ability to
view real-time video over the Internet.
A
DSL or cable modem connection will typically
display 1 fps. When viewing
remotely, the refresh rate is determined by
the Internet connection speed. When viewing
or playing back locally, the display is
dependent on the unit’s frame rate.
Q.Knowing that there are different
compression formats out there,
what are the advantages of MPEG-4
compression, specifically?
A.MPEG-4 dramatically advances
video compression, enabling the distribution
of content from low bandwidths to
high-definition quality across broadcast,
broadband, wireless and packaged media.
MPEG-4 uses object-oriented compression,
meaning that individual objects within a
scene are tracked separately and compressed.
This object-based compression has
the benefit, among other things, of enabling
interactivity. MPEG-4’s goal is to attain a
high image quality at a very low bit rate. Its
efficiency and range in bit rate management
has made it popular for most of today’s
Internet and recording applications.
Most wireless applications are using
MPEG-4 because of its flexibility. It is
becoming the standard compression for
security applications due to the balance of
high compression and high-quality video.
MPEG-4 also gives developers flexibility
in managing bit stream data.
Until now,
networks were at the mercy of the data they
were moving, which often led to bottlenecks.
With MPEG-4, video applications
can adjust to network loads. These are the
reasons we incorporated MPEG-4 recording
in the WJ-RT416 DVR series.
Q.Many products are loaded with
features today. How important
are frame rate and resolution?
A.These are issues that relate directly
to the ability to identify objects and
individuals within recorded images, so
they are crucial for security applications.
Frame rate refers to the number of images,
or frames, that can be recorded per second.
The higher the frame rate, the smoother the
picture in real time.
Resolution refers to the clarity of the
image. The higher the resolution, the
sharper and clearer the picture. The WJRT416
DVR delivers 480 ips over 16
channels (30 ips per channel) with 704 x
240 pixels at full-field resolution, capturing
critical details that lead to accurate
identification.
Q.Liability has become a much bigger
issue in recent years, and
archived video surveillance images have
accordingly become much more important.
What is the best way to archive
images?
A.There are several options for archiving
video surveillance images, and
the need should always determine the
method. If the need is to create a file of
individual events relating to a specific individual
or incident, these images can be isolated
and backed up to a CD or DVD. If the
user needs to back up the entire surveillance
file for long-term storage, the best
option would probably be a removable
hard drive.
Backup to network storage and USB
flash memory are other storage options to
consider. The most typical need is simply
to maintain an archive of all recorded video
for a period of time, after which it may be
written over. This system allows for
extended archiving of video using MPEG-
4 compression and on-board storage from
500 GB to 3 TB, therefore it allows for
extended archiving of video, and it is ideal
for both standalone and systems-based
platforms.
Q.People are always concerned with
wanting more storage. What can
users do to optimize storage on their
DVRs?
A.A number of factors influence harddrive
capacity on a DVR, beginning
with the type of cameras being used to
input surveillance video. High-resolution
cameras produce high-resolution images,
which require more storage space. If optimal
image quality is not a primary concern
for a given location, using a camera with
lower resolution will help optimize the
storage space available on the DVR. The
same is true of field of view and the selected
frame rate of the cameras—the more
information being recorded, the more
space is needed.
Using a DVR that permits scheduled
recording for specific limited time frames
helps save space on the hard disk.
Similarly, video analytics that initiate
recording only when motion or other
advanced triggers—unattended luggage or
loitering, for example—are detected will
help further limit the quantity of video
being recorded and stored.
The compression format used by the
DVR also can help save hard-drive storage
space. Video data takes up an enormous
amount of space on a hard drive, so information
must be compressed to reduce the
size of the files and make it feasible to
record and store large amounts of video
data. The WJ-RT416 uses MPEG-4 compression,
a growing standard for surveillance
video.
Q.Today, consumers want information
instantaneously. What are
some of the advantages of real-time
recording?
A.Real-time recording on DVRs is
considered to be approximately 30
fps. Capturing critical event details in real
time substantially enhances security
because it helps to ensure accurate identification.
The frames per second relate to
how many images the DVR will record in
one second. To calculate the frames per
second per camera, take the total frames
per second in the system and divide it by
the number of video inputs. For example, a
60 fps DVR with four video inputs would
result in about 15 fps per camera. Video
surveillance technology has reached the
point now where real-time recording can
be cost-effective.
Q.Are there feasible hybrid configurations
combining DVRs and
NVRs for users that are in the IP transition
phase?
A.Many users with legacy analog systems
would like to introduce networked
functionality while expanding or
updating their systems. Using a combination
of DVRs and NVRs integrated
together via software can produce a seamless
solution.