AVPlayer 不在 iOS 文档目录中播放 MP3 音频文件

Posted 2023-03-07

【中文标题】AVPlayer 不在 iOS 文档目录中播放 MP3 音频文件

【英文标题】：AVPlayer not playing MP3 audio file in documents directory iOS

【发布时间】：2012-08-28 08:00:16

【问题描述】：

我正在使用 AVPlayer 播放位于文档目录中的 MP3（文件已确认在其中）-我加载 AVPlayerItem 等待 AVPlayerItemStatusReadyToPlay 然后用该项目实例化 AVPlayer 并播放.

确实调用了AVPlayerItemStatusReadyToPlay，但实际上没有播放音频，有人知道为什么吗？

- (void)checkFileExists 
    if (![[NSFileManager defaultManager] fileExistsAtPath:[self.urlForEightBarAudioFile path]]) 
        [self beginEightBarDownload];
     else 
        // set up audio
        [self setupAudio];

        //NSLog(@"file %@ already exists", [self.urlForEightBarAudioFile path]);
    



- (void)setupAudio

    AVAsset *eightBarAsset = [AVAsset assetWithURL:self.urlForEightBarAudioFile];
    self.eightBarsPlayerItem = [[AVPlayerItem alloc] initWithAsset:eightBarAsset];
    [self.eightBarsPlayerItem addObserver:self forKeyPath:@"status" options:0 context:nil];


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

    if ([object isKindOfClass:[AVPlayerItem class]])
    
        AVPlayerItem *item = (AVPlayerItem *)object;

        if ([keyPath isEqualToString:@"status"])
        
            switch(item.status)
            
                case AVPlayerItemStatusFailed:
                    break;
                case AVPlayerItemStatusReadyToPlay:
                    self.player = [[AVPlayer alloc] initWithPlayerItem:self.eightBarsPlayerItem];
                    [self.player play];
                    NSLog(@"player item status is ready to play");
                    break;
                case AVPlayerItemStatusUnknown:
                    NSLog(@"player item status is unknown");
                    break;
            
        
        else if ([keyPath isEqualToString:@"playbackBufferEmpty"])
        
            if (item.playbackBufferEmpty)
            
                NSLog(@"player item playback buffer is empty");
            
        
    

【参考方案1】：

这样做：

- (void)setupAudio

 if([NSFileManager defaultManager] fileExistsAtPath:[self.urlForEightBarAudioFile absoluteString]])
 
   AVAsset *eightBarAsset = [AVAsset assetWithURL:self.urlForEightBarAudioFile];
   self.eightBarsPlayerItem = [[AVPlayerItem alloc] initWithAsset:eightBarAsset];
   self.eightBarsPlayer = [AVPlayer playerWithPlayerItem:self.eightBarsPlayerItem]; //forgot this line
   [self.eightBarsPlayer addObserver:self forKeyPath:@"status" options:0 context:nil]; // add observer for player not item
 

参考avplayer-and-local-files链接

【讨论】：

谢谢，但我已经检查了文件是否存在，我已经编辑了我的帖子以显示这一点。

嗯，对了，如果你从本地播放，那么你必须观察播放器，但如果你从远程播放，那么你观察播放器项目？我这样想对吗？你的回答很完美，谢谢。

【参考方案2】：

迅速

func setupAudio() 
 if NSFileManager.defaultManager().fileExistsAtPath(self.urlForEightBarAudioFile.absoluteString) 
   self.eightBarsPlayerItem = AVPlayerItem(asset: AVAsset(URL: self.urlForEightBarAudioFile))
   self.eightBarsPlayer = AVPlayer(playerItem: self.eightBarsPlayerItem)
 

【参考方案3】：

- (void)setupAudio

  dispatch_async(dispatch_get_main_queue(), ^ 
  AVAsset *eightBarAsset = [AVAsset   assetWithURL:self.urlForEightBarAudioFile];
  self.eightBarsPlayerItem = [[AVPlayerItem alloc] initWithAsset:eightBarAsset];
  self.eightBarsPlayer = [AVPlayer  playerWithPlayerItem:self.eightBarsPlayerItem]; //forgot this line
  [self.eightBarsPlayer addObserver:self forKeyPath:@"status" options:0 context:nil]; // add observer for player not item
);