title: Nested AVMutableComposition
body: <p>I'm trying to use AVMutableComposition in a nested hierarchy. Therefor I have to put a composition into an other composition. Doing so results into the following error message:</p>
  
  <blockquote>
    <p>AVCompositionTest[45347:10703] comp2 >>> The operation could not be completed</p>
  </blockquote>
  
  <p>I used the following code snipped.</p>
  
  <pre><code>AVAsset *audioAsset = [AVAsset assetWithURL:[NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"02 Undefined" ofType:@"mp3"]]];
  
  AVMutableComposition *comp1 = [AVMutableComposition composition];
  
  BOOL success = YES;
  NSError *error = nil;
  
  success = [comp1 insertTimeRange:CMTimeRangeMake(kCMTimeZero, audioAsset.duration)
                           ofAsset:audioAsset
                            atTime:kCMTimeZero
                             error:&amp;error];
  
  if (!success) {
      NSLog(@"comp1 &gt;&gt;&gt; %@", [error localizedDescription]);
  }
  
  AVMutableComposition *comp2 = [AVMutableComposition composition];
  
  success = [comp2 insertTimeRange:CMTimeRangeMake(kCMTimeZero, audioAsset.duration)
                           ofAsset:comp1
                            atTime:kCMTimeZero
                             error:&amp;error];
  
  if (!success) {
      NSLog(@"comp2 &gt;&gt;&gt; %@", [error localizedDescription]);
  }
  </code></pre>
  
  <p>Is it possible to nest compositions?</p>