We realize
this may be confusing. Here's some info which could be useful.
ANALOG
VCR or DIGITAL DVR?
Please
click here
to see our DVR FAQ Answer Page for additional information
1.
What is the difference between digital and
analog video / audio recording?
2. What are advantages and disadvantages
of each?
3. What is the difference between realtime
and time lapse recording?
4. What is alarm recording?
5. What is "video motion detection"
and its pros and cons?
6. What's the difference between your DVR
units and a Tivo type digital recorder?
Q1:
What is the difference between digital and analog recording?
A1:
For all practical purposes, analog
recording is what we generally think of when using our vcr
or audio cassette recorders. Analog recording consists of heads
writing or reading signals directly onto a medium (like a tape)
with a magnetic encoding. Digital,
on the other hand - also reads/writes data but encodes the signals
into a numeric string of digits. There are a couple different
ways in which we generally use digital video/ audio
recording:
1. Directly onto a computer's magnetic
hard drive through a variety of compression
formats- such as in PC (Windows) based systems and embedded OS
/ Linux based systems such as our DVR-N4,
or;
2. Onto a magnetic tape cassette, as used with mini decks (Sony's
GVD-200 and GVD-800) and new digital camcorders. The major tape
formats found in new digital camcorders are Sony's 'Digital 8'
or the more common 'Mini-DV' . No analog equipment will record
or playback digital media, but some digital units (GVD-200/ 800)
do have the ability to playback analog format(s). 8mm, Hi-8 and
VHS-C are the standard tape formats for today's analog camcorders.
*Mini decks and camcorders are used in limited covert and mobile
uses for short-term recording, but are generally not considered
part of the security / surveillance industry. Please click
here to see a terrific miniature digital video recorder made
for portable use.
Digital technology has become much more stable and reliable in
the last 2 or 3 years and is quickly replacing analog video recording
to the point of impending extinction. If you didn't rush into
anything- and are still clinging to your worn out old timelapse
VCR- there's no better time than NOW to upgrade it. Prices have
finally become AFFORDABLE for a product which is actually both
reliable AND user friendly.
One KEY advantage to DIGITAL is its higher resolution
ability. Depending on features of individual unit, you may be
able to achieve 480+ horizontal
lines recording with digital recorders vs. 300 lines color
(350 bw) with the highest quality analog units (such as our high
band/ high density Sanyo models). Most analog recorders permit
only about 280 lines for black and white and 240 lines for color.
Analog recording can still be argued to be little reliable due
to the fact that a videotape (mechanical) drive system is not
likely to "crash" like a computer hard
drive or operating system might, risking some or all data
to irretrievable loss. And many security professionals are using
redundancy systems with a digital recorder as the primary system-
backed up by a high density/ high resolution analog VCR. Back
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Q2: What are advantages
and disadvantages of each?
A2:
Digital
is certainly the way ALL video recording will be done in the future
(and likely the very near future). However, it does still have
some drawbacks to consider. Many systems have low frame speed
ability per camera when recording multiple cameras at once. Analog
recording is still generally considered a little more reliable
due to the fact that a videotape (mechanical) drive system is
not likely to "crash" like a computer hard
drive or operating
system might, risking some or all data to irretrievable loss.
Most PROFESSIONAL security people will employ BOTH nowadays- generally
a digital
recorder connected to a (high bandwidth/ high resolution)
VCR
as a redundant 'backup' system.
DVRs must really be separated into 2 main categories: PC-based
and Linux-based operating systems (OS). Think about it... how
many times has your PC 'crashed' due to a glitch or flaw in Windows
systems or programs?! Don't you want potentially life-saving evidence
to be recorded into a stable and re-accessible format? We waited,
watched and learned while a lot of our competition jumped right
into advertising their own PC based systems. Most quickly found
that they. *Even though we are highly impressed with the new Linux
systems, there are great strides being currently made to bypass
an operating system altogether by compressing the video through
on-board hardware logic rather than any kind of software. Stay
tuned but please don't let this hold you back from upgrading right
now to a stable Linux-based embedded OS system.
One KEY advantage to DIGITAL is its higher resolution
ability. Depending on features of individual unit, you may be
able to achieve 480+ horizontal
lines of color recording with digital vs. 300 lines color
(350 black
& white) with the highest quality analog units (such as
our high band/ high density models). *Little known fact- most
analog VCR video recorders permit only about 280 lines BW and
240 lines of color recording- no kidding! Even for expensive consumer
and security '4-head' systems. Why are there separate resolution
abilities for color and black & white? Because color requires
more bandwidth
as it is encoding and decoding more data at one time. Audio
(especially mono) requires very little bandwidth at all in comparison
to video, even BW/ monochrome.
Please SEE our newest 4 camera digital recorder (#DVR-N4)
for a really DYNAMITE unit! It has all the features of several
separate and advanced units all in one. Back
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Q3: What is the difference
between 'realtime' and time lapse recording?
A3:
Time
lapse vcrs
use specially engineered recording heads which slow down the video
tape to allow intervals of media to be recorded over a longer
period of time (generally seen as 960 hours, or 40 days. Unlike
realtime
VCRs (read below), which feature a smooth flow to the video action,
timelapse units essentially take a snapshot of what video camera(s)
sees every few seconds. For this reason, it appears jittery and
often captures very little video data during the time you may
need it most! Think of bank robbery footage you may have seen
on television- you oftentimes see suspect(s) cover 20 feet or
more in 3 or 4 consecutive frames. Due to the advent of reliable
realtime analog and better digital recording, the obvious drawbacks
of timelapse recording are quickly making the technology obsolete
in today's marketplace- and only recommended for limited or specialized
applications. We only offer one time lapse vcr (VCR-5),
which features selectable speeds including 24-40 hours of real
time recording- which can be extended to over 1000 hours in the
slowest time lapse mode.
Realtime VCRs also use specially engineered recording heads which
slow down the video tape to allow more media to be recorded onto
the tape.
Unlike time lapse vcrs which essentially take snapshots every
few seconds- appearing jittery and capturing very little video
data- real time units feature a smooth flow to the video. Note:
ALL real time analog video recorder decks (VCR) require 8 hour
T-160 tapes, ratherthan the more common T-120 to achieve advertised
recording times. T-160 VHS video tapes are now widely available
for under $5 each. However, we even carry the hard-to-find T-200
(10 hour) tapes as well- though they are a little pricier.
Important to note that digital recording DVR systems can also
be classified as realtime or timelapse as well- with a couple
of minor variables. Rather than physically slowing down the tape
heads- it records similar snapshots from each camera onto the
hard drive. Many DVR systems offer the ability to manipulate frame
speed. Back
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Q4: What is alarm recording?
A4:
Alarm
recording is considered as any video recording which is prompted
by a signal. Generally speaking, alarm recording is achieved when
an alarm signal from a dedicated switch (such as a passive infrared,
or "PIR"
motion sensor) after the device is triggered. Alarm VCRs
and DVRs
with alarm IN ports are capable of being programmed to record
ONLY after such a signal has been received. It should also be
noted that video motion detection (built into the software of
the recorder or processor rather than) could also be considered
an alarm signal. Back
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Q5: What is "video
motion detection" and its pros and cons?
A5:
Video
motion detection is a relatively new technology which attempts
to replace external motion sensors and physical switches to achieve
'alarm'
(or action-only) recording. It is generally found in three versions-
those which use tiny sensor "markers" which you place
on the screen. These little dots create an internal alarm in the
device when the video underneath them changes (figured as motion).
The other kind uses a basic light adjustment feature. The main
reported problems with the marker type are that- by the time a
subject passes the area in which marker has been installed, more
than half of the desired video will never have been recorded.
The somwhat newer light sensitive type has been reported to create
a lot of false alarms in light changing environments- such as
slight movements in the sun or clouds when conducting outdoor
surveillance!
The third is the newest and, by far- the MOST desirable. Found
in all Eyespyvideo.com DVR
units, the technology is called digital pixelation motion detect
circuitry (or PMD for short). Finally, a more reliable way has
arrived to activate motion recording. However, it must be said
that there are a range of quality factors within this technology
as well. The ability to mask (or to bypass the function in certain
areas onscreen such as for passing cars) and. Furthermore, our
DVR systems also have easy to use inputs for external alarm devices
in case you want to use physical sensors such as PIRs,
bypassing the video motion detection option. They also feature
ethernet
ports and are TCP/IP addressable so you can connect them to a
network
and even view
over the internet. Back
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Q6: What's the difference
between your DVR units and a Tivo type digital video recorder?
A6:
Actually, very little! Tivo-type systems also encode/ decode and
store video data. The main difference is that Tivo is designed
for primarily single channel recreational/ entertainment recording
of programs- not for security applications. So it's not really
appropriate for multiple camera uses- especially where most want
video
motion detection and time/ date stamping, etc.. Back
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