AVPlayer的使用+简单的播放器Demo

Posted 2021-02-18 chenprice

学习内容

先上项目地址，一个简单的AVPlayerDemo: https://github.com/practiceqian/QCAVPlayerDemo

AVPlayer学习

1. 几个播放器相关的类

   • AVPlayer、AVURLAsset、AVPlayerItem、AVPlayerLayer

     //控制播放器的播放、暂停、播放速度
     @property (nonatomic,strong) AVPlayer * player;
     //管理资源对象，提供播放数据源
     @property (nonatomic,strong) AVPlayerItem* playItem;
     //负责显示视频，如果没有添加该类，只有声音没有画面
     @property (nonatomic,strong) AVPlayerLayer* playerLayer;
     

2. 构建一个简单的播放器

   • //一个UIImageView，构建播放器的显示区域
     self.playerView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height/3)];
     [self.view addSubview:self.playerView];
     
     //播放资源
     NSURL* playUrl = [NSURL URLWithString:@"http://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4"];
     self.playItem = [AVPlayerItem playerItemWithURL:playUrl];
     //播放器实例
     self.player = [AVPlayer playerWithPlayerItem:self.playItem];
     //显示区域
     self.playerLayer = [AVPlayerLayer playerLayerWithPlayer:self.player];
     self.playerLayer.frame = self.playerView.bounds;
     //将显示区域添加到UIImageView上
     [self.playerView.layer addSublayer:self.playerLayer];
     //开始播放
     [self.player play];
     

   • 效果如图

     

     • 可以在UIImageView的容器中看到画面，但是此时依然不能控制播放的进度等

3. 使用AVPlayer控制播放行为

   • //播放
     [self.player play];
     //暂停
     [self.player pause];
     //控制播放速度
     self.player.rate = 2.0
     

4. 使用AVPlayerItem控制播放状态

   • //三种播放状态
     typedef NS_ENUM(NSInteger, AVPlayerItemStatus) {
     	AVPlayerItemStatusUnknown = 0,	//未知
     	AVPlayerItemStatusReadyToPlay = 1,	//准备播放
     	AVPlayerItemStatusFailed = 2	//播放失败
     };
     
     

   • 使用KVO进行监听播放状态

     //对status进行监听
     [self.playItem addObserver:self forKeyPath:@"status" options:NSKeyValueObservingOptionNew context:nil];
     //监听的回调
     - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context{
         if ([object isKindOfClass:[AVPlayerItem class]]) {
             if ([keyPath isEqualToString:@"status"]) {
               //根据播放的三种状态进行处理
                 switch (self.playItem.status) {
                     case AVPlayerItemStatusUnknown:
                         NSLog(@"播放状态未知");
                         break;
                     case AVPlayerItemStatusReadyToPlay:
                         NSLog(@"准备播放");
                         break;
                     case AVPlayerItemStatusFailed:
                         NSLog(@"播放失败");
                         break;;
                     default:
                         break;
                 }
             }
         }
     }
     

   • 获取播放时间

     • //CMTime是以分数的形式表示时间，value表示分子，timescale表示分母，flags是位掩码，表示时间的指定状态。
       typedef struct{
           CMTimeValue    value;     // 帧数
           CMTimeScale    timescale;  // 帧率（影片每秒有几帧）
           CMTimeFlags    flags;        
           CMTimeEpoch    epoch;    
       } CMTime;
       

     • //获取当前的播放时间
       float currentTime = self.playItem.currentTime.value/self.playItem.currentTime.timescale;
       //获取视频的总时间(一般在准备播放状态时获取)
       float totalTime = CMTimeGetSeconds(self.playItem.duration);
       

   • 监听播放的进度

     • __weak typeof(self) weakSelf = self;
       //CMTimeMake(1,1),一秒钟监听一次
       [self.player addPeriodicTimeObserverForInterval:CMTimeMake(1, 1) queue:nil usingBlock:^(CMTime time) {
         AVPlayerItem* item = weakSelf.playItem;
         float curTime = item.currentTime.value/item.currentTime.timescale;
         NSLog(@"当前时间:%.0f",curTime);
       }];
       

   • 监听缓冲的进度

     [self.playItem addObserver:self forKeyPath:@"loadedTimeRanges" options:NSKeyValueObservingOptionNew context:nil];
     ---------------------------------------------------------------
       if ([keyPath isEqualToString:@"loadedTimeRanges"]){
       NSArray *array = self.playItem.loadedTimeRanges;
       CMTimeRange timeRange = [array.firstObject CMTimeRangeValue];//本次缓冲时间范围
       float startSeconds = CMTimeGetSeconds(timeRange.start);
       float durationSeconds = CMTimeGetSeconds(timeRange.duration); NSTimeInterval totalBuffer = startSeconds + durationSeconds;//缓冲总长度
       NSLog(@"当前已缓冲时间：%f",totalBuffer);
     }
     

   • 监听已缓存时间充足/不足

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

   • 最后的demo

最后欢迎关注我的ios学习总结——每天学一点iOS：https://github.com/practiceqian/one-day-one-iOS-summary