Question

I create a composition with several video clips, i also add some empty ranges where I show title screens with CoreAnimation.

|--Video1--|--NoVideo(AVsyncLayer)--|--Video2--|

Etc… Which all works fine, the problem comes when I start using:
AVMutableVideoComposition, AVMutableVideoCompositionInstruction and AVMutableVideoCompositionLayerInstruction which I have to do to rotate videos properly.

|--Video1--|--NoVideo(AVsyncLayer)--|

Works fine in my AVPlayer, but if I instead do:

|--NoVideo(AVsyncLayer)--|--Video1--|

The application crashes the next time I push a new view controller, or pop the current view controller in my Navigation Controller stack. Sometimes with a memory warning sometimes without it, but according to instruments I only allocated 1.5Mb.

I’ve watched the Working With Media in AVFoundation from last years WWDC several times, and the only thing I can think of is that the comment

AVMutableVideoCompositionInstruction must not overlap or contain gaps.

Which it really doesn’t. I have instructions for the full duration of the composition. But there are gaps in the AVMutableCompositionTrack (my video track) where I don’t plan to show video, but only the CoreAnimation layer.

Have anyone else experienced similar issues?

Answer 1

insert empty time range works in some cases, but we found it wasn’t good enough as it broke when we let the user rewind/fast-forward and change on the time bar. To solve this we added a black video clip when nothing else was showing.