问题
I need to access a video returned by the UIImagePickerController and know if it was recorded portrait or landscape. I've seen references to mov_read_tkhd but I'm not sure if that will do the job, or indeed how to include the necessary libraries.
回答1:
On iOS 4 and above, with 3GS/3rd gen iTouch or better, you can use the new AVFoundation libraries.
Something like:
NSURL *url = // url to the video returned by the picker
AVAssetTrack *videoTrack = [[url tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
videoTrack.preferredTransform; // CGAffineTransform that tells you whether the video is rotated from original orientation
videoTrack.naturalSize; // CGSize that tells you the current dimensions of the video
来源：https://stackoverflow.com/questions/2814626/programmatically-access-orientation-of-an-iphone-video