CODEWITHSUNDEEP
iosios7core-animationavfoundation
Bjorn Roche
Bjorn Roche

Reputation: 11469

AVFoundation exporting with customVideoCompositorClass and animationTool

I am using AVFoundation to edit a movie with a custom video compositor, but I can't seem to get this working with core animation. It works fine for playback, but when I try to export, I get unexpected results.

My code looks like this:

AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoComposition];
videoComposition.instructions = videoInstructions;
videoComposition.frameDuration = CMTimeMake(1, videoTrackA.naturalTimeScale);
videoComposition.renderSize = size;
videoComposition.customVideoCompositorClass = self.project.videoEdits.editClass;

if( isExport )
    videoComposition.animationTool = [self createAnimationToolForSize:size];

where createAnimationToolForSize: looks like this:

-(AVVideoCompositionCoreAnimationTool *) createAnimationToolForSize:(CGSize) size
{
    CATextLayer *titleLayer = [CATextLayer layer];
    titleLayer.string = @"Text goes here";
    titleLayer.font = (__bridge CFTypeRef)(@"Helvetica");
    titleLayer.fontSize = size.height / 20;
    titleLayer.cornerRadius = size.height / 50;
    titleLayer.foregroundColor = [UIColor blackColor].CGColor;
    titleLayer.backgroundColor = [UIColor whiteColor].CGColor;
    titleLayer.frame = CGRectMake(size.width/4, size.height/4, size.width/2, size.height/2 );
    titleLayer.opacity = .5;

    //CALayer *parentLayer = [CALayer layer];
    //CALayer *videoLayer = [CALayer layer];
    //parentLayer.frame = CGRectMake(0, 0, size.width, size.height);
    //videoLayer.frame = CGRectMake(0, 0, size.width, size.height);
    //[parentLayer addSublayer:videoLayer];
    //[parentLayer addSublayer:titleLayer];

    //return [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];

    return [AVVideoCompositionCoreAnimationTool
        videoCompositionCoreAnimationToolWithAdditionalLayer:
        titleLayer
        asTrackID:2];
}

The code as written exports a video with a black background and a rounded white rectangle with no text. The original video, which should be seen in the background, around the edges, is not visible.

If I replace the last line with the commented lines, I simply get the original image with no animation.

Is it possible to get both the movie and the animation (including text)? Am I doing something wrong? Do I need to consider the animation layer in my compositor somehow or is this a bug that prevents you from using core animation with custom compositors in AVFoundation?

Upvotes: 1

Views: 1275

Answers (1)

Bjorn Roche
Bjorn Roche

Reputation: 11469

I was able to get the animation to display if I create a new track for it, but then my custom renderers need to be able to handle different numbers of tracks (n when rendering live because the animation is in a CALayer separate from the movie and n+1 when exporting because the layer now exists as a track). That is, of course, doable, even if it is complex, but it leaves some problems unsolved: eg I never figured out why my text doesn't display in my CATextLayer.

So, even if I did rewrite my code, it's not clear to me that this strategy would work.

Upvotes: 1

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