User manual

85XX Series Network DVR User Manual……………………………………………………………………….V1.0
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The output of the tamper detection algorithm is displayed as red blocks on the image. The red area is where
the algorithm has detected that the image has changed from its reference image. Once enough of the image
has changed and remained so for a certain length of time, a tamper alarm is triggered.
Note: In order to see the output of the tamper detection on the image, Tamper Debug metadata must be
enabled on the VCA -> Advanced page. Please refer to Advanced Settings for more information.
Advanced Tamper Detection Settings
In the advanced tamper detection settings it is possible to change the thresholds for the area of the image
which must be changed and the length of time it must be changed for before the alarm is triggered.
 Tampered Duration until Alarm: The length of time that the image must be persistently changed
before the alarm is triggered.
 Tampered Screen Area: Percentage area of the image which must be changed for tampering to be
triggered.
If false alarms are a problem the duration and/or area should be increased so that large transient changes
such as a close object temporarily obscuring the camera do not cause false alarms.
4.4.5 Suppress alarm on lights on/off:
Large fast changes to the image lighting such as switching on/off indoor lighting can cause false tamper alarms.
Enable this option if this is likely to be a problem in the area where the camera is installed. However, this option
will reduce sensitivity to genuine alarms so it is not recommended if fast light changes are not likely to be a
problem.
4.4.6 Burnt-in Annotation
The Burnt-in Annotation setting allows the VCA annotation to be burnt in to the raw video stream. The
annotation can include tracked objects, counters and system messages. The Burnt-in Annotation can be
enabled for compressed video streams or the analogue video output, if supported.