Specifies whether to apply the track matrix (or matrices) when extracting an image from the asset.
The default is?NO AVAssetImageGenerator?only supports rotation by 90, 180, or 270 degrees. This property is ignored if you set a value for the videoComposition?property. ——developer.apple.com
To?fix?the thumbnail orientation set?appliesPreferredTrackTransform?to?YES?in the?AVAssetImageGenerator?instance. If you add your own video composition, you’ll need to include the right transform to rotate the video as wanted. ——http://stackoverflow.com/ ?djromero
1)?CMTimeMake(1,10)?actually means a value of 1 and a timescale of 10. They are a numerator and denominator, so it is 1/10 of a second, not 1 second. 2) The result will be like?CMTimeMake(2, 10), which is 2/10ths of a second. ——http://stackoverflow.com/?Peter DeWeese