mpmovieercontroller取消AVAudioPlayer中的硬件静音

I've set my phone to muted state by switching vibrate/sound hardware button. In whole application some background music is playing unless the device is in muted state. So in this case, my music is playing but muted. Now in some point I want to present video (which is without sound but this shouldn't matter), however the video in MPMoviePlayerController turns music from AVAudioPlayer on even though the device is is 'muted' state. The AVAudioPlayer continues to play loudly even when i quit MPMoviePlayerController.I've set my phone to muted state by switching v