Can we capture a particular area of screen by giving parameters like height, width with respect to a particular point/coordinate/element?

I have been trying to get the video playing screen of my emulator with/without using appium. I have used the image-grab option of PIL and dynamically passed the coordinates enclosing the screen. But what my issue is I cant get the screen if shift the emulator to another point. So i thought if I could get a way of capturing the required part with respect to emulator keys(buttons: power, volume etc), which will be at a particular point fixed from the screen. Or could you suggest any ways so that i can capture only the video screen of my emulator, while video is playing. I am using python 3.8 and appium version 1.15.1