Usually football trasmissions have identifiable elements in the screen, such as the score, the match title, etc... and those are fixed elements that do not appear in ads. For example: https://i.imgur.com/blebca8.png
Or the title bar below. You could do some basic OCR on a Pi, when the team names are readable, keep the volume up, when they are not, disable it.
Or the title bar below. You could do some basic OCR on a Pi, when the team names are readable, keep the volume up, when they are not, disable it.