如何获取 AVPlayer 的视频帧？

Posted 2023-02-23

【中文标题】如何获取 AVPlayer 的视频帧？

【英文标题】：How to get video frame of the AVPlayer?

【发布时间】：2012-08-23 12:12:15

【问题描述】：

我有用于显示 AVPlayer 播放的 PlayerView 类。来自documentation的代码。

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>

@interface PlayerView : UIView
@property (nonatomic) AVPlayer *player;
@end

@implementation PlayerView
+ (Class)layerClass 
    return [AVPlayerLayer class];

- (AVPlayer*)player 
    return [(AVPlayerLayer *)[self layer] player];

- (void)setPlayer:(AVPlayer *)player 
    [(AVPlayerLayer *)[self layer] setPlayer:player];

@end

我在此 PlayerView（frame.size.width = 100，frame.size.height = 100）中设置了我的 AVPlayer（包含大小为 320x240 的视频资产），并且调整了我的视频大小。在 PlayerView 中添加后如何获取视频大小？

【参考方案1】：

在 iOS 7.0 中添加了新功能：

AVPlayerLayer 具有属性 videoRect。

【讨论】：

对我来说，videoRect 只是返回 CGRectZero，即使我可以在屏幕上看到视频。我正在使用 ios 8

等待currentItem.status为== AVPlayerStatusReadyToPlay，然后就可以拿到frame了

这行不通，甚至我已经添加了KVO等待状态为AVPlayerStatusReadyToPlay。 videoRect 仍然返回全零

再试一次，成功了。所以你需要对 AVPlayerItem 进行 KVO，而不是 AVPlayer，并且要检查的状态是 AVPlayerItemStatus.ReadyToPlay，而不是 AVPlayerStatusReadyToPlay。这种做法是正确的，但@Yocoh 的评论有点误导。

这适用于方面fit，但不适用于方面fill。根据docs，这是“视频图像的显示矩形在层边界内”

【参考方案2】：

这对我有用。当您没有 AVPLayerLayer 时。

- (CGRect)videoRect 
    // @see http://***.com/a/6565988/1545158

    AVAssetTrack *track = [[self.player.currentItem.asset tracksWithMediaType:AVMediaTypeVideo] firstObject];
    if (!track) 
        return CGRectZero;
    

    CGSize trackSize = [track naturalSize];
    CGSize videoViewSize = self.videoView.bounds.size;

    CGFloat trackRatio = trackSize.width / trackSize.height;
    CGFloat videoViewRatio = videoViewSize.width / videoViewSize.height;

    CGSize newSize;

    if (videoViewRatio > trackRatio) 
        newSize = CGSizeMake(trackSize.width * videoViewSize.height / trackSize.height, videoViewSize.height);
     else 
        newSize = CGSizeMake(videoViewSize.width, trackSize.height * videoViewSize.width / trackSize.width);
    

    CGFloat newX = (videoViewSize.width - newSize.width) / 2;
    CGFloat newY = (videoViewSize.height - newSize.height) / 2;

    return CGRectMake(newX, newY, newSize.width, newSize.height);

【讨论】：

很好的解决方案！

【参考方案3】：

找到解决办法：

添加到 PlayerView 类：

- (CGRect)videoContentFrame 
    AVPlayerLayer *avLayer = (AVPlayerLayer *)[self layer];
    // AVPlayerLayerContentLayer
    CALayer *layer = (CALayer *)[[avLayer sublayers] objectAtIndex:0];
    CGRect transformedBounds = CGRectApplyAffineTransform(layer.bounds, CATransform3DGetAffineTransform(layer.sublayerTransform));
    return transformedBounds;

【讨论】：

它在 Xcode4.5、iOS6 sdk、构建目标 4.3 中对我不起作用。获取大小（0,0）。它现在还为你工作吗？

【参考方案4】：

这是对我有用的解决方案，它考虑了 AVPlayer 在视图中的定位。我刚刚将它添加到 PlayerView 自定义类中。我必须解决这个问题，因为 videoRect 在 10.7 中似乎没有工作。

- (NSRect) videoRect 
    NSRect theVideoRect = NSMakeRect(0,0,0,0);
    NSRect theLayerRect = self.playerLayer.frame;

    NSSize theNaturalSize = NSSizeFromCGSize([[[self.movie asset] tracksWithMediaType:AVMediaTypeVideo][0] naturalSize]);
    float movieAspectRatio = theNaturalSize.width/theNaturalSize.height;
    float viewAspectRatio = theLayerRect.size.width/theLayerRect.size.height;
    if (viewAspectRatio < movieAspectRatio) 
        theVideoRect.size.width = theLayerRect.size.width;
        theVideoRect.size.height = theLayerRect.size.width/movieAspectRatio;
        theVideoRect.origin.x = 0;
        theVideoRect.origin.y = (theLayerRect.size.height/2) - (theVideoRect.size.height/2);

    else if (viewAspectRatio > movieAspectRatio) 

        theVideoRect.size.width = movieAspectRatio * theLayerRect.size.height;
        theVideoRect.size.height = theLayerRect.size.height;
        theVideoRect.origin.x = (theLayerRect.size.width/2) - (theVideoRect.size.width/2);
        theVideoRect.origin.y = 0;
    
    return theVideoRect;

【讨论】：

videoRect 在 iOS 13 中无法使用，但谢谢！

【参考方案5】：

这是移植到 iOS 的Eric Badros' answer。我还添加了preferredTransform 处理。这假设_player 是AVPlayer

- (CGRect) videoRect 
    CGRect theVideoRect = CGRectZero;

    // Replace this with whatever frame your AVPlayer is playing inside of:
    CGRect theLayerRect = self.playerLayer.frame;

    AVAssetTrack *track = [_player.currentItem.asset tracksWithMediaType:AVMediaTypeVideo][0];
    CGSize theNaturalSize = [track naturalSize];
    theNaturalSize = CGSizeApplyAffineTransform(theNaturalSize, track.preferredTransform);
    theNaturalSize.width = fabs(theNaturalSize.width);
    theNaturalSize.height = fabs(theNaturalSize.height);

    CGFloat movieAspectRatio = theNaturalSize.width / theNaturalSize.height;
    CGFloat viewAspectRatio = theLayerRect.size.width / theLayerRect.size.height;

    // Note change this *greater than* to a *less than* if your video will play in aspect fit mode (as opposed to aspect fill mode)
    if (viewAspectRatio > movieAspectRatio) 
        theVideoRect.size.width = theLayerRect.size.width;
        theVideoRect.size.height = theLayerRect.size.width / movieAspectRatio;
        theVideoRect.origin.x = 0;
        theVideoRect.origin.y = (theLayerRect.size.height - theVideoRect.size.height) / 2;
     else if (viewAspectRatio < movieAspectRatio) 
        theVideoRect.size.width = movieAspectRatio * theLayerRect.size.height;
        theVideoRect.size.height = theLayerRect.size.height;
        theVideoRect.origin.x = (theLayerRect.size.width - theVideoRect.size.width) / 2;
        theVideoRect.origin.y = 0;
    
    return theVideoRect;

【讨论】：

谢谢@tettoffensive

【参考方案6】：

这是一个基于 Andrey Banshchikov's answer 的 Swift 解决方案。当您无法访问AVPLayerLayer 时，他的解决方案特别有用。

func currentVideoFrameSize(playerView: AVPlayerView, player: AVPlayer) -> CGSize 
    // See https://***.com/a/40164496/1877617
    let track = player.currentItem?.asset.tracks(withMediaType: .video).first
    if let track = track 
        let trackSize      = track.naturalSize
        let videoViewSize  = playerView.bounds.size
        let trackRatio     = trackSize.width / trackSize.height
        let videoViewRatio = videoViewSize.width / videoViewSize.height
        
        var newSize: CGSize

        if videoViewRatio > trackRatio 
            newSize = CGSize(width: trackSize.width * videoViewSize.height / trackSize.height, height: videoViewSize.height)
         else 
            newSize = CGSize(width: videoViewSize.width, height: trackSize.height * videoViewSize.width / trackSize.width)
        
        
        return newSize
    
    return CGSize.zero