Video stream and scene requirements for the Tampering detector

Image requirements for the Tampering detector

To create the detection tool, do the following:

  1. Go to the Detection Tools tab.

  2. Below the required camera, click Create… → Category: Service → Tampering Detection.

By default, the detection tool is enabled and set to respond to all types of video analysis.

If necessary, you can change the detection tool parameters. The list of parameters is given in the table:

ParameterValueDescription
Object features
Video streamMain streamIf the camera supports multistreaming, select the stream for which detection is needed. Selecting a low-quality video stream reduces the load on the Server
Other
EnableYesBy default, the detection tool is enabled. To disable, select the No value
No
NameTampering DetectionEnter the detection tool name or leave the default name
Decode key frames

Yes

By default, the Decode key frames parameter is enabled. In this case only key frames are decoded. To disable the parameter, select the No value.
This parameter reduces the load on the Server, but at the same time the detection quality decreases. We recommend enabling this parameter for "blind" (without video image display) Servers, on which you want to perform detection.
For the MJPEG codec decoding isn’t relevant, as each frame is considered a key frame.

The Number of frames processed per second and Decode key frames parameters are interrelated.

If a local Client isn’t connected to the Server, the following rules work for remote Clients:

  • If the key frame rate is less than the value specified in the Number of frames processed per second field, the detection tool will work by key frames.
  • If the key frame rate is greater than the value specified in the Number of frames processed per second field, the detection will be performed according to the set period.

If a local Client is connected to the Server, the detection tool will always work according to the set period. After disconnecting the local Client, the above rules will be relevant again.

 
No
Decoder modeAutoSelect a processing resource for decoding video. When you select a GPU, a stand-alone graphics card takes priority (when decoding with Nvidia NVDEC chips). If there is no appropriate GPU, the decoding will use the Intel Quick Sync Video technology. Otherwise, CPU resources will be used for decoding
CPU
GPU
HuaweiNPU
Number of frames processed per second25Specify the number of frames for the detection tool to process per second. The value must be in the range [0.016; 100]
TypeTampering DetectionName of the detection tool type (non-editable field)
Advanced settings
Blurred image analysisYes


Functions of the Tampering detector

By default, all types of analysis are applied to the video image. Select the No value for unnecessary types of analysis.

If you select Compression artifacts analysis, Image noise analysis and Blurred image analysis, you must specify the values for the Event duration to trigger detection (sec), Sensitivity parameters.


No
Compression artifacts analysisYes
No
Image noise analysisYes
No
Quality degradation analysisYes
No
Scene change analysisYes
No
Basic settings
Event duration to trigger detection (sec)20

Specify the maximum time of event duration for the response in seconds, after which the detection tool generates an event. The value must be in the range [5, 1200].

  • If the algorithm definetely detects a defect in the frame, the response from the detection tool comes before the specified time.
  • If after the specified time, the defect hasn't been detected, you must increase the Sensitivity of the detection tool
Sensitivity 50Specify the sensitivity of the detection tool as a percentage. The higher the sensitivity, the smaller change in the frame is detected. The value must be in the range [0, 100]

To save the parameters of the detection tool, click the Apply  button. To cancel the changes, click the Cancel  button.