Preferably something I can mute so that I can leave it running overnight. My battery life on the iPhone 4S has been really bad (it seems) ... but I want to try a calibration. Presently, my phone is either charging at home or in the car ... so I haven't had a chance to really have it die on me yet. Don't want to wait too long. I thought of leaving a video running on repeat all night. Would that work or would the phone turn off? Can you repeat a single video, or a podcast, with it on mute?