Is there any foolproof way of detecting if some video or audio is a commercial or not? A TV tuner that just replaces commercials with a placeholder image and a

Is there any foolproof way of detecting if some video or audio is a commercial or not? A TV tuner that just replaces commercials with a placeholder image and a countdown to when the break is over would make broadcast TV just about tolerable for me. (time-shift, and skipping past commercials is a better solution, but there's some things you want to see live)