我一直在尝试制作一个将视频与动画对象连接在一起的概念验证(实质上,我将
用户选择的位图“旋转”到特定位置的罐头视频).在观看有关核心动画(WWDC10等)和AVSync..Layer(Apple WWDC10示例
代码,doc示例
代码)的所有可用的Apple材料之后,根本没有一个明确的孤立的
代码示例来导出如何实现这个播放模式正确.
使用CA,我有一个视频资产加载到CALayer,一个附加到位图的动画,然后连接到另一个CALayer.我创建了一个AVSynchronizedLayer并将这两个对象添加为子层.
当这个树被添加到UIView的图层属性中时,我期待动画的播放与视频同步运行.相反,我只看到播放视频,并且动画永远不会执行 – 这里是我的代码的相关部分,它们都驻留在一个View Controller中(在ViewDidLoad中调用).
Video101.m4v =简单的m4v视频,
gerald.png =位图
@H_
403_9@NSURL *fileURL = [[NSBundle mainBundle] URLForResource:@"Video101" withExtension:@"m4v"];
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:fileURL options:nil];
AVPlayerItem *playerItem = [AVPlayerItem playerItemWithAsset:asset];
AVPlayer *player = [[AVPlayer playerWithPlayerItem:playerItem]retain];
AVPlayerLayer *playerLayer = [AVPlayerLayer playerLayerWithPlayer:player];
playerLayer.frame = CGRectMake(0,1024,768);
playerLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
CALayer *gerald = [CALayer layer];
gerald.frame = CGRectMake(0,120,120);
gerald.contents = (id) [UIImage imageNamed:@"gerald.png"].CGImage;
[self.view.layer addSublayer:playerLayer];
[self.view.layer insertSublayer:gerald above:playerLayer];
CAKeyframeAnimation *anim = [CAKeyframeAnimation animationWithKeyPath:@"position"];
anim.duration = 18.0;
anim.values = [NSArray arrayWithObjects:
[NSValue valueWithCGPoint:CGPointMake(320.0,406.0)],[NSValue valueWithCGPoint:CGPointMake(310.0,400.0)],[NSValue valueWithCGPoint:CGPointMake(320.0,[NSValue valueWithCGPoint:CGPointMake(480.0,206.0)],[NSValue valueWithCGPoint:CGPointMake(10.0,760.0)],nil];
anim.keyTimes = [NSArray arrayWithObjects:
[NSNumber numberWithFloat:0.02],[NSNumber numberWithFloat:0.06],[NSNumber numberWithFloat:0.09],[NSNumber numberWithFloat:0.1],[NSNumber numberWithFloat:0.12],[NSNumber numberWithFloat:0.2],[NSNumber numberWithFloat:0.25],[NSNumber numberWithFloat:0.32],[NSNumber numberWithFloat:0.38],[NSNumber numberWithFloat:0.49],[NSNumber numberWithFloat:0.53],[NSNumber numberWithFloat:0.59],[NSNumber numberWithFloat:0.63],[NSNumber numberWithFloat:0.69],[NSNumber numberWithFloat:0.78],[NSNumber numberWithFloat:0.81],[NSNumber numberWithFloat:0.91],[NSNumber numberWithFloat:1.0],nil];
AVSynchronizedLayer *syncLayer = [AVSynchronizedLayer synchronizedLayerWithPlayerItem:playerItem];
[syncLayer addSublayer:gerald];
[gerald addAnimation:anim forKey:@"transform.position"];
[self.view.layer addSublayer:syncLayer];
[player play];
什么是正确的格式或方式实现AVSynchronizedLayer,使动画和视频一起播放？
您正在设置正确的CAKeyframeAnimation,除了一个位：
根据WWDC“使用AV Foundation编辑媒体”讲座,您需要将动画的beginTime
属性设置为非零值.
Zero beginTime is automatically translated to CACurrentMediaTime(). Use a small nonzero number: e.g.,1e-100 or -1e-100 (AVCoreAnimationBeginTimeAtZero)
我想如果你添加anim.beginTime = AVCoreAnimationBeginTimeAtZero;你会发现动画从视频开始播放时开始.
