AVPlayer未呈现到其AVPlayerLayer [英] AVPlayer not rendering to its AVPlayerLayer

问题描述

我有一个AVPlayerLayer(CALayer的子类)，我需要进入一种可以传递给QCRenderer的图像类型(QCRenderer接受NSImages和CIImages.)，我可以将CALayer转换为CGImageRef，然后转换为CGImageRef.NSImage，但是内容总是很清楚.

I have a AVPlayerLayer (subclass of CALayer) and I need to get in into a image type that can be passed to a QCRenderer (QCRenderer accepts NSImages and CIImages.) I can convert the CALayer to a CGImageRef, and that to an NSImage, but the contents is always clear.

我将其范围缩小为以下两个原因之一:

I've narrowed it down to one of two reasons:

1. 我没有正确创建NSImage.
2. AVPlayer未呈现到AVPlayerLayer.

我没有收到任何错误，并且找到了一些有关转换CALayers的文档.另外，我将AVPlayerLayer添加到NSView，该视图仍然为空，因此我相信2是问题所在.

I am not receiving any errors, and have found some documentation on converting CALayers. Also, I added the AVPlayerLayer to an NSView, which remains empty so I believe 2 is the problem.

我正在使用Apple的AVPlayerDemo的AVPlayerDemoPlaybackViewController的修改版本.因为将所有接口代码都剥离了，所以我将其变成了NSObject.

I'm using a modified version of Apple's AVPlayerDemo's AVPlayerDemoPlaybackViewController. I turned it into an NSObject since I stripped all of the interface code out of it.

创建AVPlayer时，我在(void)prepareToPlayAsset:withKeys:方法中创建了AVPlayerLayer :(我只是将图层添加到NSView中以测试其是否正常工作.)

I create the AVPlayerLayer in the (void)prepareToPlayAsset:withKeys: method when I create the AVPlayer: (I'm only adding the layer to a NSView to test if it is working.)

 if (![self player])
{
    /* Get a new AVPlayer initialized to play the specified player item. */
    [self setPlayer:[AVPlayer playerWithPlayerItem:self.mPlayerItem]];  

    /* Observe the AVPlayer "currentItem" property to find out when any 
     AVPlayer replaceCurrentItemWithPlayerItem: replacement will/did 
     occur.*/
    [self.player addObserver:self 
                  forKeyPath:kCurrentItemKey 
                     options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew
                     context:AVPlayerDemoPlaybackViewControllerCurrentItemObservationContext];
    mPlaybackView = [AVPlayerLayer playerLayerWithPlayer:self.player];
    [self.theView setWantsLayer:YES];
    [mPlaybackView setFrame:self.theView.layer.bounds];
    [self.theView.layer addSublayer:mPlaybackView];
}

然后我创建一个NSRunLoop来每秒抓取30次AVPlayerLayer的帧:

I then create a NSRunLoop to grab a frame of the AVPlayerLayer 30 times per second:

framegrabTimer = [NSTimer timerWithTimeInterval:(1/30) target:self selector:@selector(grabFrameFromMovie) userInfo:nil repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:framegrabTimer forMode:NSDefaultRunLoopMode];

这是我用来抓取框架并将其传递给处理QCRenderer的类的代码:

Here is the code I use to grab the frame and pass it to the class that handles the QCRenderer:

-(void)grabFrameFromMovie {
CGColorSpaceRef colorSpace = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);
CGContextRef theContext = CGBitmapContextCreate(NULL, mPlaybackView.frame.size.width, mPlaybackView.frame.size.height, 8, 4*mPlaybackView.frame.size.width, colorSpace, kCGImageAlphaPremultipliedLast);
[mPlaybackView renderInContext:theContext];
CGImageRef CGImage = CGBitmapContextCreateImage(theContext);
NSImage *image = [[NSImage alloc] initWithCGImage:CGImage size:NSMakeSize(mPlaybackView.frame.size.width, mPlaybackView.frame.size.height)];
[[NSNotificationCenter defaultCenter] postNotificationName:@"AVPlayerLoadedNewFrame" object:[image copy]];
CGContextRelease(theContext);
CGColorSpaceRelease(colorSpace);
CGImageRelease(CGImage); }

我不知道为什么我只会变得很清楚.对此的任何帮助将不胜感激，因为没有足够的AVFoundation文档可用于OS X.

I can't figure out why I'm only getting clear. Any help with this is greatly appreciated, as there is not enough AVFoundation documentation for OS X.

推荐答案

对我有用:

AVAssetImageGenerator *gen = [[AVAssetImageGenerator alloc] initWithAsset:[[[self player] currentItem] asset]];
CGImageRef capture = [gen copyCGImageAtTime:self.player.currentTime actualTime:NULL error:NULL];
NSImage *img = [[NSImage alloc] initWithCGImage:capture size:self.playerView.frame.size];

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