AVPlayer 项目缓冲区为空

Posted 2023-02-23

【中文标题】AVPlayer 项目缓冲区为空

【英文标题】：AVPlayer item buffer empty

【发布时间】：2013-07-30 08:42:47

【问题描述】：

我使用播放流内容的 AVPlayer。我想知道缓冲区为空的时间以及准备播放的时间。但是观察者“playbackBufferEmpty”和“playbackLikelyToKeepUp”并不是每次都按需要工作。他们有时工作，但往往不工作。我在 OSX 10.7.5 下只使用 iPad 模拟器 ios 6.1。 以下是我设置和监听观察者的方式：

- (void)playAudioStream:(NSURL *)audioStreamURL

 if(_audioPlayer && _audioPlayer.currentItem)
 
     [_audioPlayer removeObserver:self forKeyPath:StatusKey];
     [_audioPlayer.currentItem removeObserver:self forKeyPath:@"playbackBufferEmpty"];
     [_audioPlayer.currentItem removeObserver:self forKeyPath:@"playbackLikelyToKeepUp"];
 

 AVPlayerItem *playerItem = [AVPlayerItem playerItemWithURL:audioStreamURL];

 [playerItem addObserver:self forKeyPath:@"playbackBufferEmpty" options:NSKeyValueObservingOptionNew context:nil];
 [playerItem addObserver:self forKeyPath:@"playbackLikelyToKeepUp" options:NSKeyValueObservingOptionNew context:nil];

 _audioPlayer = [AVPlayer playerWithPlayerItem:playerItem];

 [_audioPlayer addObserver:self forKeyPath:StatusKey options:NSKeyValueObservingOptionNew context:nil];

 //[_audioPlayer replaceCurrentItemWithPlayerItem:playerItem];
 //_audioPlayer.actionAtItemEnd = AVPlayerActionAtItemEndNone;
 [_audioPlayer play];

...

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

 if ([keyPath isEqualToString:@"playbackBufferEmpty"] )
 
    if (_audioPlayer.currentItem.playbackBufferEmpty)
    
       ...
    

 

 if ([keyPath isEqualToString:@"playbackLikelyToKeepUp"])
 
    if (_audioPlayer.currentItem.playbackLikelyToKeepUp)
    
        ...
    
 

请帮助我获取“缓冲区空”和“缓冲区就绪”事件的正确方法（例如，当 Internet 连接中断时）。谢谢！

【参考方案1】：

添加观察者时需要使用上下文。这是给你的示例代码。

初始化上下文

static void *playbackLikelyToKeepUpKVOToken = &playbackLikelyToKeepUpKVOToken;
static void *playbackBufferEmpty = &playbackBufferEmpty;
static void *playbackBufferFull = &playbackBufferFull;

添加观察者

[self.playerItem removeObserver:self forKeyPath:@"playbackBufferEmpty" context:playbackBufferEmpty];
[self.playerItem removeObserver:self forKeyPath:@"playbackLikelyToKeepUp" context:playbackLikelyToKeepUpKVOToken];
[self.playerItem removeObserver:self forKeyPath:@"playbackBufferFull" context:playbackBufferFull];

手柄

if (context == playbackLikelyToKeepUpKVOToken)

    if (self.playerItem.playbackLikelyToKeepUp)
    
        NSLog(@"recieve playbackLikelyToKeepUp");
    


else if (context == playbackBufferEmpty)

    if (self.playerItem.playbackBufferEmpty)
    
        NSLog(@"recieve playbackBufferEmpty");
    

else if(context == playbackBufferFull)

    NSLog(@"recieve playbackBufferFull");

else

    [super observeValueForKeyPath:path ofObject:object change:change context:context];

【参考方案2】：

@Nghia Tran 的回答帮助了我。 他只是混淆了添加观察者/删除观察者（我们需要两者）

添加观察者：

[self.playerItem addObserver:self forKeyPath:@"playbackBufferEmpty" options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew  context:playbackBufferEmpty];
[self.playerItem addObserver:self forKeyPath:@"playbackLikelyToKeepUp" options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew  context:playbackLikelyToKeepUpKVOToken];
[self.playerItem addObserver:self forKeyPath:@"playbackBufferFull" options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew   context:playbackBufferFull];

移除观察者：

[self.playerItem removeObserver:self forKeyPath:@"playbackBufferEmpty" context:playbackBufferEmpty];
[self.playerItem removeObserver:self forKeyPath:@"playbackLikelyToKeepUp" context:playbackLikelyToKeepUpKVOToken];
[self.playerItem removeObserver:self forKeyPath:@"playbackBufferFull" context:playbackBufferFull];