Axis IP-Surveillance system Design Manual page 37

External devices such as a door contact, a glass break detector or a passive infrared detector (PIR) that
are connected to the input or output ports of a camera/video encoder can also be used as triggers by
AXIS Camera Station. In addition, other intelligent video functionalities—for example, active camera
tampering—that are supported in a network camera/video encoder can be used by AXIS Camera Station
if they are first configured (through the network video product's web interface) to trigger the output
port of the network video product.
Event/alarm responses include initiating recordings from selected cameras, raising an alarm, showing a
live image from a selected camera, setting an external output device such as sounding a siren, and send-
ing e-mail notifications.
5.5.
Calculating your hard disk requirements
Network video products utilize network bandwidth based on their configuration. Bandwidth usage de-
pends on five criteria:
1) Image resolution (the higher the resolution, the more bandwidth is required)
2) Compression type (H.264 requires much less bandwidth than MPEG-4 and Motion JPEG)
3) Compression ratio (the higher the compression, the lower the bandwidth usage)
4) Frame rate (the higher the frame rate, the higher the bandwidth usage)
5) Image complexity (the more motion or scene changes, the higher the bandwidth usage)
The above criteria can be set either in the AXIS Camera Station software or in the network camera or
video encoder itself. A simulation-based calculation tool called the AXIS Design Tool is available at
www.axis.com/products/video/design_tool/ (or on a DVD) and helps provide guidance on a network
video product's bandwidth and storage requirements based on the five criteria mentioned earlier.
Figure 5.5.a. AXIS Design Tool user interface
You can reduce the use of bandwidth and storage space if you record only when motion or alarm is de-
tected compared with continuous recording and if you use the H.264 or MPEG-4 compression format.
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