The recommendations in this section must be followed for proper operation of the motion detector.

Camera recommendations

• Resolution: no less than 320×240 pixels and no more than 800×600 (a higher resolution stream will inefficiently load the CPU);
• Number of frames per second: 8-10;
• Codec: H.264, H.265;
• Protocol: TCP/RTSP;
• Camera shake should not cause image shifts exceeding 1% of the frame size.
• Битрейт: CBR;
• Bitrate: CBR
• I-frame interval: 15  
  • Use a smaller GOP (e.g., 1 I-frame every 1-2 seconds).
  • Make sure that the frequency of I-frames corresponds to the speed of movement of objects in the frame.

GOP (Group of Pictures) is a group of frames in a video stream that defines the coding structure of a video stream.

Each GOP includes three types of frames:

• I-frames (Intra) — key frames containing complete information about the image and independent of other frames;
• P-frames (Predictive) — contains data on changes from the previous frame;
• B-frames (Bi-directional) — use information from both the previous frame and the next frame.

This structure allows to significantly reduce the video size by storing the complete information only in the I-frames and in the rest only the differences between them. The influence of GOP parameters on motion detectors is significant and depends on several factors:

I-frame rate

Motion detectors usually operate based on analyzing changes between frames. If the interval between I-frames is too long, P-frames may contain insufficient information to accurately analyze changes, which may result in false alarms or missed events.

• • Small GOP: The more frequently I-frames appear, the more accurately algorithms can analyze changes in the video, since each I-frame contains complete information.
  • Large GOP: If the interval between I-frames is large, important motion details may be lost, especially if the motion occurs between I-frames.

Example: if an object moves quickly through a scene and the interval between I-frames takes a few seconds, the system may not capture its movement because P-frames depend on the previous state and may not convey the full picture.

Lighting recommendations

• Moderate illumination. In conditions of insufficient (night) or excessive (backlight) illumination, the performance of the motion detector may be degraded.
• Absence of abrupt changes in illumination.

Recommendations for scene and camera angle

• The background is mostly static and does not change dramatically.
• The motion detector may not work properly when there are sharp shadows from moving objects.
• The motion detector may not work correctly on long, monotone objects.
• The motion detector may not respond correctly to objects moving at high speed.