Question

I have FrameChangeAnimation class which takes multiple spritesheets and duration. So lets say I have 3 spritesheet each containing 16 blocks of characters then I give ‘3’ seconds as duration. Upon return of FrameChangeAnimation instance as CALayer I attach it to screen and it plays smoothly [16 frames/second]

Now I want to export this animation as video. Problem is that when I attach CABasicAnimation this time with duration. ‘Duration’ parameter doesn’t work and all frames are played in a single second.

    GTAnimation *an = [[GTAnimation alloc] initWithFrame:CGRectMake(0, 0, videoSize.width, videoSize.height) withFileName:@"Host_Angry_" withSeconds:3.5];

    CALayer *animationLayer = [CALayer layer];
    animationLayer.bounds = CGRectMake(0, 0, videoSize.width, videoSize.height);
    [animationLayer addSublayer:an.animLayer];

    CABasicAnimation *fadeAnimation = [CABasicAnimation animationWithKeyPath:@"currentFrame"];
    fadeAnimation.fromValue = [NSNumber numberWithFloat:1.0];
    fadeAnimation.toValue = [NSNumber numberWithFloat:45.0];
    fadeAnimation.additive = NO;
    fadeAnimation.removedOnCompletion = NO;
    fadeAnimation.beginTime = 0.0;
    fadeAnimation.duration = 3.5;
    fadeAnimation.repeatCount = HUGE_VAL;
    fadeAnimation.fillMode = kCAFillModeBoth;
    [an.animLayer addAnimation:fadeAnimation forKey:@"currentFrame"];

    CALayer *parentLayer = [CALayer layer];
    CALayer *videoLayer = [CALayer layer];

    videoLayer.bounds = CGRectMake(0, 0, videoSize.width, videoSize.height);
    [parentLayer addSublayer:videoLayer];
    [parentLayer addSublayer:animationLayer];
    videoLayer.anchorPoint =  CGPointMake(0.5, 0.5);
    videoLayer.position = CGPointMake(CGRectGetMidX(parentLayer.bounds), CGRectGetMidY(parentLayer.bounds));
    animationLayer.anchorPoint =  CGPointMake(0.5, 0.5);
    animationLayer.position = CGPointMake(CGRectGetMidX(parentLayer.bounds), CGRectGetMidY(parentLayer.bounds));
    videoComposition.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];

Answer 1

According to the docs for the AVVideoCompositionCoreAnimationTool class,

“Any animations will be interpreted on the video’s timeline, not real-time, so you should:

Set animations’ beginTime property to 1e-100 rather than 0 (which CoreAnimation replaces with CACurrentMediaTime);