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Understand Digital Video
Storage
All DVRs record video images
to a hard drive. The hard drive is a data
container that has a limit to how much video
information it can hold. The bigger the hard drive
the longer it can record video before becoming
full and recording over the oldest information.
There are ways to get more days of video recording
out of a hard drive. This includes lowering the
frame rate, recording only when there is motion
and scheduling recording.
It is important to note that none of these
three methods of squeezing more video days out of
your hard drive affects the live streaming and
smooth live motion quality of watching a monitor
hooked directly into the DVR. The following
techniques only affect recorded information.
Resolution. Typical resolutions that you may encounter:
Low--160 x 120 dpi
Medium--320 x 240 dpi (compares with VHS)
High--640 x 240 dpi or greater (similar to S-VHS)
Frame Rate. POM Technologies
DVRs come with 120 frames per second (FPS) for its
4 camera DVR and 240 frames per second for all
other DVRs it sells. Think of frames as being
still picture snapshots. The more snapshots per
second the smoother the video motion. Also the
more snapshots the more information needs to be
saved on your hard drive. The number of FPS for
each camera attached to your DVR can be
individually adjusted. Reducing the number of
frames per second increases the length of time the
DVR can record. You can also adjust individual
security cameras so the most important areas have
more frames per second than other areas.
Frame rate per camera. Many systems provide a complete range of recording speeds for cameras, anywhere from one image every two seconds to thirty images per second (IPS). Systems can be grouped into three categories: low, medium and high. (These are frame rates per camera, not a total record speed to be shared amongst inputs.) Frame rates: //www.pom-tec.com/
- Low--0.2-5 IPS
- Medium--7.5-15 IPS
- High--30 IPS
Tips:
1 frame per second is the lowest frame rate recordable and 30 frames per second is the maximum which is real time
There is no real need to record in real time unless there are regulatory reasons as in case of government facilities or casinos
Recording at 1 frame per second is what traditional analog systems record
You can always rewind in high speed so the lower the frame rate the faster it is to playback an entire day
At 3 - 5 frames per second recording you will not miss any activity (remember this is per second
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