how to let OpenCV save the last few seconds of analyzed video

Question

I am trying to program a python OpenCV app for my own use because I can't go to gyms for some time. I would like to do the following:

Capture frames from a video flow using OpenCV [ done ]
Have OpenCV track a yellow soccer and return the coordinate of this soccer in the frame [done]
Come up with an algorithm to detect when a soccer juggling failed, for example the soccer went out of frame and so on [ done ]

Now my question is: let's say I want to save the "10 seconds right before this event" of video into a mp4 file. How should I do it? Is there any good template that I can follow?

Thanks!

You want to do kind of clipping? Does [this](https://stackoverflow.com/questions/44461630/clipping-a-video-in-c-opencv-from-a-specified-start-and-end-point) help? — Yunus Temurlenk, May 06 '20 at 07:29

score 2 · Accepted Answer · answered May 06 '20 at 07:35

2

You may create a memory buffer worth of 10sec of video (~about 300 frames for most web-cameras), then save frames to that buffer, removing the old ones while adding the new ones.

Once your ball is out of the frame -- open a video file, and save your frames from the buffer.

answered May 06 '20 at 07:35

lenik

23,228
4
34
43

This might be an easy way to buffer say 300 frames... https://stackoverflow.com/a/5944754/2836621 – Mark Setchell May 06 '20 at 08:30
@MarkSetchell thank you very much, looks easy enough =) – lenik May 06 '20 at 09:45

how to let OpenCV save the last few seconds of analyzed video

1 Answers1