AVPlayer设置iOS的初始播放时间

Question

当以queuePlayer作为AVPlayer播放视频时，添加了KVO功能。

[self.queuePlayer addObserver:self forKeyPath:@"status" options:0 context:NULL];

观察者模式的方法:

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
  if ([keyPath isEqualToString:@"status"]) {
    if (self.queuePlayer.status == AVPlayerStatusReadyToPlay) {

        NSInteger step = (NSInteger)(startTimeForVideo/0.04);
        [self.queuePlayer.currentItem stepByCount:step];

        //CMTime seekTime = CMTimeMake(startTimeForVideo*timeScale,timeScale);
        //if (CMTIME_IS_VALID(seekTime)) 
        //  [self.queuePlayer seekToTime:seekTime toleranceBefore:kCMTimePositiveInfinity toleranceAfter:kCMTimePositiveInfinity];
        //else
        //  NSLog(@"In valid time");

        [self.queuePlayer play];
    } else if (self.queuePlayer.status == AVPlayerStatusFailed) {
        /* An error was encountered */
    }
}

这里的 startTimeForVideo 是视频的初始播放时间。 seekToTime 和 stepByCount 都无法正常工作。 编辑： 在方法中使用的 object 的 values 是正确的，尽管没有成功。

- Paresh Navadiya

Answer 1

KVO方法在queuePlayer作为AVPlayer时发生了变化:

if (self.queuePlayer.status == AVPlayerStatusReadyToPlay) 
{
  //firstly make cmtime as here startTimeForVideo is Float64 value in seconds
  //get video's time scale as CMTime has it. 
  int32_t timeScale = self.queuePlayer.currentItem.asset.duration.timescale
  CMTime seektime=CMTimeMakeWithSeconds(startTimeForVideo, timeScale);
  //use this cmtime for seekToTime. 
  [self.queuePlayer seekToTime:seektime toleranceBefore:kCMTimeZero toleranceAfter:kCMTimeZero];
}
............

编辑：在seekToTime:toleranceBefore:toleranceAfter:方法中，对于exact location的tolerance field，都应设为kCMTimeZero。

- Paresh Navadiya