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 video is exported using an AVMutableComposition on which the frameDuration is set like that:
videoComposition.frameDuration = CMTimeMake(1, 30); // 30 fps
For some reason, changing the 30 to 25 does not change the framerate of the video exported with the AVAssetExportSession. Does anyone have an idea why?
It seems that the AVAssetExportSession preset takes precedence over the AVVideoComposition frameDuration. I've opened a bug report: