一番下のプロセスで 2 番目の数値が 0.00000 になる理由
NSURL *movieURL = [NSURL URLWithString:@"s26a.mov"];
NSDictionary *opts = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:NO]
forKey:AVURLAssetPreferPreciseDurationAndTimingKey];
AVURLAsset *urlAsset = [AVURLAsset URLAssetWithURL:movieURL options:opts];
float minute = 0;
float second = 0;
second = urlAsset.duration.value / urlAsset.duration.timescale;
NSLog(@"movie duration : %f", second);