Creating video from scratch in iOS

I've got an app where the user shoots some video, enters a title for it, and picks a music track. I've got the music dubbing working with AVMutableComposition, but the titling is a bad hack -- just a view overlaid on the MPMoviePlayerViewController. And while the user can upload the dubbed video to YouTube, the title of course isn't included.

Are there iOS APIs that will let me access or create raw vid开发者_运维百科eo frames, so I can either overlay the title on the video, or splice in new frames with the title before the start of the video proper?

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For anyone coming along later: see, e.g., How do I export UIImage array as a movie?