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9
Appendix A HDD Capacity Calculation
Calculate total capacity needed by each device according to video recording (video recording type
and video file storage time).
Step 1: According to Formula (1) to calculate storage capacity
i
q
that is the capacity of each
channel needed for each hour, unit Mbyte.
1024
3600
8
÷
×
÷
=
i
i
d
q
(1)
In the formula:
i
d
means the bit rate, unit Kbit/s
Step 2: After video time requirement is confirmed, according to Formula (2) to calculate the
storage capacity
i
m
, which is storage of each channel needed unit Mbyte.
i
m
=
i
q
×
i
h
×
i
D
(2)
In the formula:
i
h
means the recording time for each day (hour)
i
D
means number of days for which the video shall be kept
Step 3: According to Formula (3) to calculate total capacity (accumulation)
T
q
that is needed for
all channels in the device during
scheduled video recording
.
∑
=
=
c
i
i
T
m
q
1
(3)
In the formula:
c
means total number of channels in one device
Step 4: According to Formula (4) to calculate total capacity (accumulation)
T
q
that is needed for
all channels in device during
alarm video recording (including motion detection)
.
∑
=
=
c
i
i
T
m
q
1
×
a%
(4)
In the formula
：
a%
means alarm occurrence rate
