在IOS中使用AVPlayer去播放在线音频文件，并设置音量

在这里给AVPlayer播放在线音频文件作个记号

1.在H文件中初始：

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AVPlayer *mp3Player;

AVPlayerItem *mp3PlayerItem;

id audioMix;

id volumeMixInput;

2.在MM文件中：

//作品播放

    NSURL * songUrl = [ NSURL URLWithString: userInfo. songUrl];

    AVURLAsset *movieAsset    = [[[ AVURLAsset alloc] initWithURL:songUrl  options: nil] autorelease];

      self. mp3PlayerItem = [ AVPlayerItem playerItemWithAsset:movieAsset];

     [ self .  mp3PlayerItem addObserver : self forKeyPath : @"status" options : 0 context : NULL ];

      self .  mp3Player = [ AVPlayer playerWithPlayerItem : self .  mp3PlayerItem];

      AVPlayerLayer *playerLayer = [ AVPlayerLayer playerLayerWithPlayer: self. mp3Player];

      playerLayer. frame = self. view. layer. bounds;

      playerLayer.videoGravity = AVLayerVideoGravityResizeAspect ;

      [ self. view. layer addSublayer:playerLayer];

       [ self .  mp3Player setAllowsExternalPlayback : YES ];

    

3.实现代理方法：

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

{

    if ([keyPath isEqualToString: @"status"])

    {

        if (AVPlayerItemStatusReadyToPlay == self .  mp3Player. currentItem . status )

        {

            [ self. mp3Player  play];

        }

    }

}

4.现实音量调整

-( void) setVolume:( float)volume{

    // 作品音量控制

    NSMutableArray *allAudioParams = [NSMutableArray array ];

    AVMutableAudioMixInputParameters *audioInputParams =[AVMutableAudioMixInputParameters audioMixInputParameters ];

    [audioInputParams setVolume:volume atTime: kCMTimeZero];

    [audioInputParams setTrackID: 1];

    [allAudioParams addObject:audioInputParams];

    audioMix = [AVMutableAudioMix audioMix ];

    [ audioMix setInputParameters:allAudioParams];

    [ self .  mp3PlayerItem  setAudioMix :audioMix ]; // Mute the player item

    

    [ avAudioPlayer setVolume:volume];

}

5.取得播放时间

- ( NSTimeInterval) playableDuration

{

    AVPlayerItem * item = self . worksPlayer .currentItem ;

    if (item. status == AVPlayerItemStatusReadyToPlay ) {

        return CMTimeGetSeconds ( self . worksPlayer .currentItem .duration );

    }

    else

    {

        return (CMTimeGetSeconds ( kCMTimeInvalid ));

    }

}

- ( NSTimeInterval) playableCurrentTime

{

    AVPlayerItem * item = self . worksPlayer .currentItem ;

    

    if (item. status == AVPlayerItemStatusReadyToPlay ) {

        NSLog ( @"%f\n" ,CMTimeGetSeconds ( self . worksPlayer . currentItem .currentTime ));

        if (! playBeginState &&CMTimeGetSeconds ( self . worksPlayer . currentItem .currentTime )==CMTimeGetSeconds ( self . worksPlayer . currentItem . duration )) {

            [ streamer stop];

        }

        playBeginState = NO ;

        return CMTimeGetSeconds ( self . worksPlayer . currentItem .currentTime );

    }

    else

    {

        return (CMTimeGetSeconds ( kCMTimeInvalid ));

    }

}