Why is it fast-forwarding to play surveillance video?

This is a monitoring picture recorded in time-lapse photography mode.

Surveillance camera is a kind of camera used for security.

One difference between surveillance video and other videos is that it often faces a single picture. For example, the corridor at night may be empty for several hours, and the picture has not changed at all. At this time, the recorded data still occupies considerable resources. There are two main ways to solve this problem: one is intelligent discrimination, which directly skips the pictures that haven't changed for a long time without recording. This scheme is often not applicable outdoors, because trees shake and birds pass by, which will affect the judgment of the video recorder; The second scheme is to use time-lapse photography technology.

Time-lapse photography, also known as time-lapse photography, is a shooting technique that compresses time. The shooting process is shot with fewer frames than normal shooting, which requires 12 frames per second (the movie is 25 frames). When playing, human eyes see normal continuous motion, while time-delayed shooting takes a long time, shooting at the speed of one frame. During normal playback, the slow change of the scene is compressed into a very short time, presenting a fast-forward scene.

Monitoring video can set the time of each frame of image at an appropriate value. For example, at an intersection that takes at least ten seconds to pass, it is set to take an image every second. It can save resources without missing the scene. Data recorded in this way is "fast-forwarded" during playback. You can stop and play frame by frame if necessary.