The Harry Potter moving newspaper is like a video overlay on a static background. Here is an example:. the video starting from 1min, 17sec. HOWTO crop only the video part? I have an image to show what i mean by the moving newspaper and what area does the video locate and what is the static background part. Please refer to the image. The area I draw by pink is where i mean by real video and any area except the video, is the static part. I understand if the frame size of the video does not change, I can specify the w, h, x, y to crop. But what if the frame size changes? Is there a way to autodetect the static part and only crop the real video part? like ffmpeg cropdetect for letterboxing. I tried cropdetect but failed. Any suggestion is welcome and I prefer using ffmpeg but any other softwares are welcome!