设置AVSynchonizedLayer [英] Setting up AVSynchonizedLayer

问题描述

我一直在试图制造一个概念证明与动画对象（基本上，我在对位用户选择的位图到特定​​位置罐头视频）连接摄像。看着这一切关于核心动画（WWDC10等）和AVSync..Layer（苹果WWDC10样本code，文档样本$​​ C $ C）可用苹果材料之后，我们确实没有一个足够清晰的隔离code为例，得出如何正确地实施这种播放模式。

I've been trying to produce a proof of concept that connects a video with an animation object (essentially, I am "rotoscoping" a user-selected-bitmap onto a canned video at specific locations). After watching all the available Apple material regarding Core Animation (WWDC10, etc.) and the AVSync..Layer (Apple WWDC10 sample code, doc sample code), there simply isn't a clear enough isolated code example to derive how to implemented this playback mode correctly.

使用CA，我有被装入的CALayer视频资源，并且其连接到一个位图，然后连接到另一个的CALayer动画。我已经创建了一个AVSynchronizedLayer并添加两个对象的子层。

Using CA, I have a video asset which is loaded into a CALayer, and an animation which is attached to a bitmap, and then connected to another CALayer. I have created an AVSynchronizedLayer and added both objects as sublayers.

在此树被添加到了UIView的层属性我期待动画的播放，以与视频同步运行。相反，我只看到了视频播放和动画从未执行 - 在这里是我的code的相关作品，所有存在于单个视图控制器（称为内viewDidLoad中）

When this Tree is added to the UIView's layer property I was expecting the playback of the animation to run in sync with the video. Instead, I only see the video playing, and the animation never executes - here are the relevant pieces of my code which all resides within a single View Controller (called within ViewDidLoad).

Video101.m4v =简单M4V视频，
gerald.png =位图

Video101.m4v = simple m4v video, gerald.png = bitmap

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, 0, 1024, 768);
playerLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;

CALayer *gerald = [CALayer layer];
gerald.frame = CGRectMake(0, 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, 406.0)],
               [NSValue valueWithCGPoint:CGPointMake(310.0, 400.0)],
               [NSValue valueWithCGPoint:CGPointMake(320.0, 406.0)],
               [NSValue valueWithCGPoint:CGPointMake(310.0, 400.0)],
               [NSValue valueWithCGPoint:CGPointMake(480.0, 206.0)],
               [NSValue valueWithCGPoint:CGPointMake(310.0, 400.0)],
               [NSValue valueWithCGPoint:CGPointMake(320.0, 406.0)],
               [NSValue valueWithCGPoint:CGPointMake(320.0, 406.0)],
               [NSValue valueWithCGPoint:CGPointMake(310.0, 400.0)],
               [NSValue valueWithCGPoint:CGPointMake(320.0, 406.0)],
               [NSValue valueWithCGPoint:CGPointMake(10.0, 760.0)],
               [NSValue valueWithCGPoint:CGPointMake(320.0, 406.0)],
               [NSValue valueWithCGPoint:CGPointMake(310.0, 400.0)],
               [NSValue valueWithCGPoint:CGPointMake(320.0, 406.0)],
               [NSValue valueWithCGPoint:CGPointMake(310.0, 400.0)], 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来实现AVSynchronizedLayer，这样既动画和视频播放在一起吗？

What is the correct format or manner to implement AVSynchronizedLayer, so that both animation and video playback together?

推荐答案

您有 CAKeyframeAnimation 设置正确，除了一个位：
按照WWDC与AV基金会编辑媒体的讲座，你需要动画的 BEGINTIME 属性设置为一个非零值。

You have the CAKeyframeAnimation set up correctly except for one bit: According to the WWDC "Editing Media with AV Foundation" lecture, you need to set the beginTime property of your animation to a non-zero value.

零BEGINTIME被自动转换为CACurrentMediaTime（）。使用小型非零数字：例如，1E-100或-1e-100（AVCoreAnimationBeginTimeAtZero）

Zero beginTime is automatically translated to CACurrentMediaTime(). Use a small nonzero number: e.g., 1e-100 or -1e-100 (AVCoreAnimationBeginTimeAtZero)

我觉得如果你添加 anim.beginTime = AVCoreAnimationBeginTimeAtZero; 你会发现在动画开始权当视频开始播放

I think if you add anim.beginTime = AVCoreAnimationBeginTimeAtZero; you'll find the animation begins right when the video starts playing.

这篇关于设置AVSynchonizedLayer的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！