来自AVMutableComposition的音频和视频AVPlayer不会播放

Question

我试图从视频和音频的合成中显示视频。不过，我似乎有一个问题，一旦视频状态永远达不到AVPlayerStatusReadyToPlay。

如果我将视频资产或音频资产直接包含到播放器项目中，它将起作用。因此，我知道资产没有问题。

这是我的代码：

 - (void) loadPlayer { 
      NSURL *videoURL = **; 
      AVURLAsset *videoAsset = [AVURLAsset URLAssetWithURL:videoURL options:nil]; 

      NSURL *audioURL = **; 
      AVURLAsset *audioAsset = [AVURLAsset URLAssetWithURL:audioURL options:nil]; 


      NSArray *keys = [NSArray arrayWithObject:@"duration"]; 
      [videoAsset loadValuesAsynchronouslyForKeys:keys completionHandler:^() { 

       NSError *error = nil; 
       AVKeyValueStatus durationStatus = [videoAsset statusOfValueForKey:@"duration" error:&error]; 

       switch (durationStatus) { 
        case AVKeyValueStatusLoaded:; 
         _videoDuration = videoAsset.duration; 
         if (_audioDuration.flags == kCMTimeFlags_Valid) { 
          [self loadPlayWithVideoAsset:videoAsset withDuration:_videoDuration andAudioAsset:audioAsset withDuration:_audioDuration]; 
         } 
         break; 
       } 
      }]; 

      [audioAsset loadValuesAsynchronouslyForKeys:keys completionHandler:^() { 

       NSError *error = nil; 
       AVKeyValueStatus durationStatus = [audioAsset statusOfValueForKey:@"duration" error:&error]; 

       switch (durationStatus) { 
        case AVKeyValueStatusLoaded:; 
         _audioDuration = audioAsset.duration; 
         if (_videoDuration.flags == kCMTimeFlags_Valid) { 
          [self loadPlayWithVideoAsset:videoAsset withDuration:_videoDuration andAudioAsset:audioAsset withDuration:_audioDuration]; 
         } 
         break; 
       } 
      }]; 
     } 

     - (void) loadPlayWithVideoAsset:(AVURLAsset *)videoAsset withDuration:(CMTime)videoDuration andAudioAsset:(AVURLAsset *)audioAsset withDuration:(CMTime)audioDuration { 


     AVMutableComposition *composition = [AVMutableComposition composition]; 

     //Video 
     AVMutableCompositionTrack *compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid]; 
     AVAssetTrack *videoTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] lastObject]; 
     NSError *videoError = nil; 
     if (![compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero,videoDuration) 
              ofTrack:videoTrack 
              atTime:kCMTimeZero 
               error:&videoError]) { 
      NSLog(@"videoError: %@",videoError); 
     } 



     //Audio 
     AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid]; 
     AVAssetTrack *audioTrack = [[audioAsset tracksWithMediaType:AVMediaTypeAudio] lastObject]; 
     NSError *audioError = nil; 
     if (![compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero,audioDuration) 
              ofTrack:audioTrack 
              atTime:kCMTimeZero 
               error:&audioError]) { 
      NSLog(@"audioError: %@",audioError); 
     } 


     NSInteger compare = CMTimeCompare(videoDuration, audioDuration); 

     if (compare == 1) { 
      //The video is larger 
      CMTime timeDiff = CMTimeSubtract(videoDuration, audioDuration); 
      [compositionAudioTrack insertEmptyTimeRange:CMTimeRangeMake(audioDuration, timeDiff)]; 
     } 
     else { 
      CMTime timeDiff = CMTimeSubtract(audioDuration, videoDuration); 
      [compositionVideoTrack insertEmptyTimeRange:CMTimeRangeMake(videoDuration, timeDiff)]; 
     } 
     AVPlayerItem * playerItem = [AVPlayerItem playerItemWithAsset:composition]; 
     self.mPlayer = [AVPlayer playerWithPlayerItem:playerItem]; 
     self.mPlaybackView = [[AVPlayerPlaybackView alloc] initWithFrame:CGRectZero]; 
     [self.view addSubview:self.mPlaybackView]; 
     [self.mPlayer addObserver:self forKeyPath:@"status" options:0 context:AVPlayerPlaybackViewControllerStatusObservationContext]; 
} 
- (void)observeValueForKeyPath:(NSString*) path ofObject:(id)object change:(NSDictionary*)change context:(void*)context 
{ 
    if (self.mPlayer.status == AVPlayerStatusReadyToPlay) { 
     [self.mPlaybackView setPlayer:self.mPlayer]; 
     isReadyToPlay = YES; 
     _playVideoBtn.hidden = NO; 
    } 
} 
- (void) playVideo { 
    if (YES || isReadyToPlay) { 
     [self.mPlayer play]; 
    } 
} 

Answer 1

从我的经验，AVPlayer可与AVMutableComposition只有当资源/视频捆绑的应用程序。如果视频资源位于网络上，AVPlayer将不会播放AVMUtableComposition，尽管AVPlayerItem和AVPlayer报告状态为“准备播放”。