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CHAPTER 8 HARD DISK DRIVE
8.2 CALCULATING THE RECORDING CAPACITY OF A
HARD DISK DRIVE
While the physical data capacity of a hard drive is fixed, how much video you can record upon
it depends on your recording configurations. Higher quality recordings will take up more space
on the drive and setting the DVR to record for more frequently will fill it up more rapidly.
To determine the optimal capacity for your purposes, the chart below to estimate the size of
hard drive that you’ll need.
VIDEO
FORMAT
RESOLUTION FRAME
RATE
(FPS)
VIDEO
QUALITY
BIT
RATE
(kbps)
SPACE
USED
(MB/h)
NTSC CIF 30 Highest 1M 465
Higher 768k 297
Medium 512k 230
Low 384k 173
Lower 256k 115
Lowest 128k 56
D1 Highest 2M 910
Higher 1.5M 712
Medium 1M 468
Lower 768K 297
Lowest 512K 241
PAL CIF 25 Highest 1M 466
Higher 768k 295
Medium 512k 235
Low 384k 175
Lower 256k 112
Lowest 128k 56.4
D1 Highest 2M 915
Higher 1.5M 700
Medium 1M 465
Lower 768K 297
Lowest 512K 241
The formula for calculating the required disk space is:
Total Recording Capacity = Used space per hour (MB/h) x Recording time (hour) x
number of channels
Example: A customer is using the NTSC format (30 frames per second), CIF resolution
with video quality set to Lowest and a total of 16 Channels. He wants the unit to record
continuously for a month. Therefore, the calculation will look like this:
56(MB/h), x 24 (hours/day) x 30 (days) x 16 (channels) = 645,120MB or 650GB
Installing a 750GB SATA hard drive should provide enough space for one month’s continuous
recording time at those settings.
PICTURE 8-7 PICTURE 8-9
STEP 8. Place the HDD with the HDD
cover back into the slot being
careful not to pinch or bend the
cables inside. Firmly tighten both
thumbscrews.
STEP 9. Re-insert the key into the hole
and then press. Turn the key counter
clockwise 90 degrees to lock the
panel in place.