如何知道AVPlayerItem何时播放

Question

我AVPlayerItem和他有问题AVQueuePlayer.目前我有很多1-2秒长的音乐文件和一个按顺序播放它们的队列播放器.

我想要的是知道音乐文件何时刚刚开始播放而不是在播放完毕后(通过AVPlayerItemDidPlayToEndTimeNotification).

这是因为我想在加载和播放新文件时运行一个函数.

我的代码:

 for (NSUInteger i = 0; i < [matchedAddr count]; i++)
{
    NSString *firstVideoPath = [[NSBundle mainBundle] pathForResource:[matchedAddr objectAtIndex:i] ofType:@"wav"];
    //NSLog(@"file %@",firstVideoPath);
    avitem=[AVPlayerItem playerItemWithURL:[NSURL fileURLWithPath:firstVideoPath]];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(currentItemIs:)
                                                 name:AVPlayerItemDidPlayToEndTimeNotification
                                               object:avitem];

    [filelist addObject:avitem];
}
 player = [AVQueuePlayer queuePlayerWithItems:filelist];
[player play];


- (void)currentItemIs:(NSNotification *)notification
{
    NSString *asd=[seqArray objectAtIndex:currentColor];
    currentColor=currentColor+1;
    AVPlayerItem *p = [notification object];
    [p seekToTime:kCMTimeZero];

    if([asd isEqual:@"1"])
    {
        [UIView animateWithDuration:0.01 animations:^{
           one.alpha = 0;
        } completion:^(BOOL finished) {

            [UIView animateWithDuration:0.01 animations:^{
               one.alpha = 1;
            }];
        }];
    }
}

正如您所看到的,currentItemIsvoid被调用,但是当轨道完成播放时它会运行.我希望在轨道开始时调用它.

编辑: Winston的代码片段的更新版本:

NSString * const kStatusKey         = @"status";

        [avitem addObserver:self
                              forKeyPath:kStatusKey
                                 options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew
                                 context:@"AVPlayerStatus"];
- (void)observeValueForKeyPath:(NSString *)path
                      ofObject:(id)object
                        change:(NSDictionary *)change
                       context:(void *)context {

    if (context == @"AVPlayerStatus") {

        AVPlayerStatus status = [[change objectForKey:NSKeyValueChangeNewKey] integerValue];
        switch (status) {
            case AVPlayerStatusUnknown: {

            }
                break;

            case AVPlayerStatusReadyToPlay: {
                // audio will begin to play now.
                NSLog(@"PLAU");
                [self playa];
            }
                break;
        }
    }
}

Answer 1

首先,您需要注册您AVPlayerItem的观察员:

[self.yourPlayerItem addObserver:self
                      forKeyPath:kStatus
                         options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew
                         context:AVPlayerStatus];

然后在您的播放器Key Value Observer方法中,您需要检查AVPlayerStatusReadyToPlay 状态,如下所示:

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

     if (context == AVPlayerStatus) {

        AVPlayerStatus status = [[change objectForKey:NSKeyValueChangeNewKey] integerValue];
        switch (status) {
            case AVPlayerStatusUnknown: {

            }
            break;

            case AVPlayerStatusReadyToPlay: {
                // audio will begin to play now.
            }
            break;
   }
}