Setting AVMutableComposition's frameDuration

Question

I\'m playing with the AVEditDemo project, from Apple\'s WWDC 2010 sample pack, and I\'m trying to change the frame rate of the exported video. The

Answer 1

The client can set sourceTrackIDForFrameTiming to kCMPersistentTrackID_Invalid and frameDuration to an appropriate value in order to specify the maximum output frame rate independent of the source track timing.

videoComposition.sourceTrackIDForFrameTiming = kCMPersistentTrackID_Invalid;
videoComposition.frameDuration = CMTimeMake(1, 30);