Encoding for iPad 2 and effects on battery life

[kogyaru]

John Gruber of Daring Fireball, a noted blog, posted a review of the iPad 2 on March 9, 2011 stating that his battery drained faster when using a Handbrake encode compared to movies from iTunes. He says (emphasis mine):

I believe the reason The Empire Strikes Back drained more battery life than the other two is that it was a movie I’d ripped from DVD myself, using HandBrake. Movies from the iTunes Store require less CPU to decode.

http://daringfireball.net/2011/03/the_i ... 2011-03-09

Was Gruber being willfully obtuse with that statement, or is there actually an equivalence in quality between HB's encodes but a difference in CPU overhead?

Would it be useful, in the context of the above, to compare an iTunes-purchased HD movie with an HB one encoded with the iPad preset?

[Deleted User 11865]

Well, HandBrake iPad encodes use many H.264 features not found in iTunes downloads (partly because the latter must remain compatible with the original AppleTV). Theoretically it should make little difference since the iPad's H.264 decoder is hardware-accelerated, but you never know.

If you have an iPad, you can always test it. Find an HD source (with a framerate <= 25 fps), then encode is twice: once with the AppleTV preset, bumping the resolution to 1280x720 (should be you the rough equivalent of an iTunes download in terms of decoding requirements), and once with the AppleTV 2 preset. Sync both vids to the iPad and test*.

* Example: fully charge your iPad, play video 1 in a loop until the battery depletes (don't forget to measure how long it takes); repeat the procedure for video 2.