One of the reasons we've always worried about using the open Ogg and WebM formats on iPhones and iPads is that we don't get to make use of the hardware MP4/H.264 codec... using the main CPU cores is presumed to drain the battery faster.I've done a first-pass test measuring energy usage of native-code WebM/Ogg playback using the new energy reporting in the Xcode 7 / iOS 9 beta: