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slide-detector/README.md

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slide-detector

Detect and extract slides in a video.

Slides are frames in the video that stay the same for several frames in a row. They are dumped into the current directory with filenames of the form static_at_MM:SS.jpg where MM:SS is the timestamp of the first frame showing the slide.

Usage:
    ./slide-detector.py VIDEO [x y w h] [slide_time_millis]

VIDEO is the video file. If you want to crop the video before analysis, the next four arguments are the (x, y) coordinates of the top-left of the crop rectangle and the (w, h) of its size (width and height). slide_time_millis is how long a slide has to be on the screen for it to count as a slide (default is 3000 = 3 seconds).

There's no command-line option for it, but at the top of the file, there's a UI = False option. When False the analysis is run at full speed. When True, the video is shown (in multiple windows showing the different stages of the analysis) at approximately 1x and the following keyboard commands are available which can help figure out the proper crop values and test:

  • q: quit
  • z/x: rewind/fast-forward by 100 frames (usually ~3 seconds).
  • w/a/s/d: move the top-left corner by 10px and print the new x/y value.
  • W/A/S/D: move the top-left corner by 1px and print the new x/y value.
  • i/j/k/l: move the bottom-right corner by 10px and print the new w/h value.
  • I/J/K/L: move the bottom-right corner by 1px and print the new w/h value.