Question

好的，这个让我完成了难过。如果您需要，我很乐意发布其他代码，但我认为这已经足够了。我不能为我的生活弄清楚为什么事情出错了。我正在使用AVVideoCompositionCoreAnimationTool将包含图像的CALayers添加到合成中。我创建了一个所有注释的NSArray（请参阅下面的界面）我想要添加，然后使用枚举器将它们添加到动画层。无论多少，据我所知，注释都在数组中，唯一最终出现在输出视频中的是最后一个循环添加的注释。有人能发现我错过的东西吗？

这是注释的界面

@interface Annotation : NSObject// <NSCoding>

@property float time;
@property AnnotationType type;
@property CALayer *startLayer;
@property CALayer *typeLayer;
@property CALayer *detailLayer;

+ (Annotation *)annotationAtTime:(float)time ofType:(AnnotationType)type;

- (NSString *)annotationString;

@end

这是用动画创建视频合成的消息。

- (AVMutableVideoComposition *)createCompositionForMovie:(AVAsset *)movie fromAnnotations:(NSArray *)annotations {
 AVMutableVideoComposition *videoComposition = nil;

if (annotations){
//CALayer *imageLayer = [self layerOfImageNamed:@"Ring.png"];
//imageLayer.opacity = 0.0;
//[imageLayer setMasksToBounds:YES];

Annotation *ann;
NSEnumerator *enumerator = [annotations objectEnumerator];

CALayer *animationLayer = [CALayer layer];
animationLayer.frame = CGRectMake(0, 0, movie.naturalSize.width, movie.naturalSize.height);

CALayer *videoLayer = [CALayer layer];
videoLayer.frame = CGRectMake(0, 0, movie.naturalSize.width, movie.naturalSize.height);

[animationLayer addSublayer:videoLayer];

// TODO: Consider amalgamating this message and scaleVideoTrackTime:fromAnnotations
// Single loop instead of two and sharing of othe offset variables

while (ann = (Annotation *)[enumerator nextObject]) {
  CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"opacity"];
  animation.duration = 3; // TODO: Three seconds is the currently hard-coded display length for an annotation, should this be a configurable option after the demo?
  animation.repeatCount = 0;
  animation.autoreverses = NO;
  animation.removedOnCompletion = NO;
  animation.fromValue = [NSNumber numberWithFloat:1.0];
  animation.toValue = [NSNumber numberWithFloat:1.0];
  animation.beginTime = time;
  //  animation.beginTime = AVCoreAnimationBeginTimeAtZero;

  ann.startLayer.opacity = 0.0;
  ann.startLayer.masksToBounds = YES;
  [ann.startLayer addAnimation:animation forKey:@"animateOpacity"];
  [animationLayer addSublayer:ann.startLayer];

  ann.typeLayer.opacity = 0.0;
  ann.typeLayer.masksToBounds = YES;
  [ann.typeLayer addAnimation:animation forKey:@"animateOpacity"];
  [animationLayer addSublayer:ann.typeLayer];

  ann.detailLayer.opacity = 0.0;
  ann.detailLayer.masksToBounds = YES;
  [ann.detailLayer addAnimation:animation forKey:@"animateOpacity"];
  [animationLayer addSublayer:ann.detailLayer];

}

  videoComposition = [AVMutableVideoComposition videoCompositionWithPropertiesOfAsset:movie];

  videoComposition.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:animationLayer];
}

  return videoComposition;
}

我想强调视频输出正确，我确实在正确的时间出现了图层，而不是所有图层。很困惑，非常感谢你的帮助。

Answer 1

所以我正在摆弄试图找出可能导致这种情况的原因，结果发现它是由图层隐藏属性设置为YES引起的。通过将其设置为NO，所有图层都会出现，但之后它们永远不会消失。所以我不得不将动画的autoreverses属性更改为YES并将持续时间减半。

所以我把代码更改为：

while (ann = (Annotation *)[enumerator nextObject]){
  CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"opacity"];
  animation.duration = 1.5; // TODO: Three seconds is the currently hard-coded display length for an annotation, should this be a configurable option after the demo?
  animation.repeatCount = 0;
  animation.autoreverses = YES; // This causes the animation to run forwards then backwards, thus doubling the duration, that's why a 3-second period is using 1.5 as duration
  animation.removedOnCompletion = NO;
  animation.fromValue = [NSNumber numberWithFloat:1.0];
  animation.toValue = [NSNumber numberWithFloat:1.0];
  animation.beginTime = time;
  //  animation.beginTime = AVCoreAnimationBeginTimeAtZero;

  ann.startLayer.hidden = NO;
  ann.startLayer.opacity = 0.0;
  ann.startLayer.masksToBounds = YES;
  [ann.startLayer addAnimation:animation forKey:@"animateOpacity"];
  [animationLayer addSublayer:ann.startLayer];

  ann.typeLayer.hidden = NO;
  ann.typeLayer.opacity = 0.0;
  ann.typeLayer.masksToBounds = YES;
  [ann.typeLayer addAnimation:animation forKey:@"animateOpacity"];
  [animationLayer addSublayer:ann.typeLayer];

  ann.detailLayer.hidden = NO;
  ann.detailLayer.opacity = 0.0;
  ann.detailLayer.masksToBounds = YES;
  [ann.detailLayer addAnimation:animation forKey:@"animateOpacity"];
  [animationLayer addSublayer:ann.detailLayer];
}

AVVideoCompositionCoreAnimationTool不添加所有CALayers

1 个答案: