AVPlayer播放时检测

Question

如何检测AVPlayer何时播放？在调用play()函数和实际播放视频之间似乎有一点点延迟。

Answer 1

据我所知，我同意你的看法，有从调用play()函数到视频实际播放（换句话说，视频的第一帧被渲染的时间）之间有轻微的延迟。延迟取决于一些标准，例如视频类型（视频点播或直播），网络状况......但幸运的是，无论何时呈现视频的第一帧，我的意思是视频实际播放的时间。

通过观察当前AVPlayerItem的status，并且每当它是AVPlayerItemStatusReadyToPlay时，应该是第一帧已经被渲染。

[self.playerItem addObserver:self forKeyPath:@"status" options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew context:NULL]; 

-(void)observeValueForKeyPath:(NSString*)path ofObject:(id)object change:(NSDictionary*)change context:(void*) context { 

    if([self.playerItem status] == AVPlayerStatusReadyToPlay){ 
     NSLog(@"The video actually plays") 
    } 
} 

顺便提一下，还有另一种解决方案，我们观察到的AVPlayerLayerreadyForDisplay状态，这也表明，每当视频呈现。然而，这种解决方案具有苹果文件

/*! 
    @property  readyForDisplay 
    @abstract  Boolean indicating that the first video frame has been made ready for display for the current item of the associated AVPlayer. 
    @discusssion Use this property as an indicator of when best to show or animate-in an AVPlayerLayer into view. 
        An AVPlayerLayer may be displayed, or made visible, while this propoerty is NO, however the layer will not have any 
        user-visible content until the value becomes YES. 
        This property remains NO for an AVPlayer currentItem whose AVAsset contains no enabled video tracks. 
*/ 
@property(nonatomic, readonly, getter=isReadyForDisplay) BOOL readyForDisplay; 

这里提到一个缺点是示例代码

self.playerLayer = [AVPlayerLayer playerLayerWithPlayer:self.player]; 
[self.playerLayer addObserver:self forKeyPath:@"readyForDisplay" options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew context:NULL]; 

-(void)observeValueForKeyPath:(NSString*)path ofObject:(id)object change:(NSDictionary*)change context:(void*) context { 
    if([self.playerLayer isReadyForDisplay]){ 
     NSLog(@"Ready to display"); 
    } 
} 

Thereotically，[self.playerLayer isReadyForDisplay]然而，应该返回YES，作为文档，它不guaranted。

我希望这会有所帮助。

Answer 2

对于视频：

AVPlayer有一个名为rate (Float)的说法，如果rate大于0.0，那里正在播放的视频。

您可以检查是否rate为!=0：（速度可以为负，如果玩家会倒流）

if vidPlayer != nil && vidPlayer.rate != 0 { 
    println("playing") 
} 

AVPlayer class reference