ios - CFBasicAnimation 中带有自定义键的动画在导出视频时不起作用

Question

我有一个 FrameChangeAnimation 类，它需要多个 spritesheet 和持续时间。所以假设我有 3 个 spritesheet，每个 spritesheet 包含 16 个字符 block ，然后我给出“3”秒作为持续时间。将 FrameChangeAnimation 实例作为 CALayer 返回后，我将其附加到屏幕并流畅播放 [16 帧/秒]

现在我想将此动画导出为视频。问题是，当我这次附加 CABasicAnimation 时。 “持续时间”参数不起作用，所有帧都在一秒钟内播放。

    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

根据 AVVideoCompositionCoreAnimationTool 类的文档，

“任何动画都将在视频的时间轴上进行解释，而不是实时的，因此您应该:

将动画的 beginTime 属性设置为 1e-100 而不是 0(CoreAnimation 将其替换为 CACurrentMediaTime)；