在GPUImage中应用视频过滤器时播放音频

Question

我用谷歌搜索了这个问题,但没有找到任何解决方案.

所以,我的问题是,我正在将视频滤镜GPUImage应用于视频文件.同时,该视频的声音没有播放.我知道在GPUImage应用过滤器时不支持声音播放.

那么,我该如何实现呢？

Answer 1

您可以通过添加这样的支持来实现声音播放AVPlayer.

1. 在GPUImageMovie.h,

   @property(readwrite, nonatomic) BOOL playSound;

2. 在GPUImageMovie.m,@interface GPUImageMovie ()像这样更新.

   @interface GPUImageMovie() <AVPlayerItemOutputPullDelegate> 
   {
       // Add this
       BOOL hasAudioTrack;
   
       .........
       ........
   
      // Add all below three lines
      AVPlayer *theAudioPlayer;
      CFAbsoluteTime startActualFrameTime;
      CGFloat currentVideoTime;
   }
   

3. 之后,在-(void)startProcessing方法中,添加以下行.

   - (void)startProcessing
   {
      // Add this
      currentVideoTime = 0.0f;
   
      .....
      .....
   
      // Add this
      if (self.playSound)
      {
          [self setupSound];
      }
   
      GPUImageMovie __block *blockSelf = self;
   
      [inputAsset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:@"tracks"] completionHandler: ^{
       runSynchronouslyOnVideoProcessingQueue(^{
   
               .........
               .........
   
               // Add this
               startActualFrameTime = CFAbsoluteTimeGetCurrent() - currentVideoTime;
   
               .......
               .......
           });
      }];
   }
   

4. 再次,在-(AVAssetReader*)createAssetReader更新它,

   - (AVAssetReader*)createAssetReader
   {
       .......
       .......  
       BOOL shouldRecordAudioTrack = (([audioTracks count] > 0) &&  (self.audioEncodingTarget != nil));
   
       // Add this
       hasAudioTrack = ([audioTracks count] > 0);
   
       .........
   }
   

5. 在- (void)processAsset,

   - (void)processAsset
   {
   
      .......
      .......
   
      if ([reader startReading] == NO)
      {
         NSLog(@"Error reading from file at URL: %@", self.url);
         return;
      }
   
      // Add this
      if (self.playSound && hasAudioTrack)
      {
         [theAudioPlayer seekToTime:kCMTimeZero];
         [theAudioPlayer play];
      }
   
      .........
      .........
   }
   

6. 在-(void)endProcessing,

   - (void)endProcessing
   {
      .........
      .........
   
      if (self.playerItem && (displayLink != nil))
      {
         [displayLink invalidate]; // remove from all run loops
         displayLink = nil;
      } 
   
      // Add this
      if (theAudioPlayer != nil)
      {
         [theAudioPlayer pause];
         [theAudioPlayer seekToTime:kCMTimeZero];
      }
   
      .........
      .........
   }
   

7. -(void)setupSound最后添加新方法,

   // Add this
   - (void)setupSound
   {
      if (theAudioPlayer != nil)
      {
          [theAudioPlayer pause];
          [theAudioPlayer seekToTime:kCMTimeZero];
          theAudioPlayer = nil;
      }
   
      theAudioPlayer = [[AVPlayer alloc] initWithURL:self.url];
   }
   

8. 最后,当您创建GPUImageMovie对象时,不要忘记将playSound标志设置为YES.

   像这样 : movieFile.playSound = YES;

   希望这可以帮助.