iPhone AVErrorInvalidVideo Errore di posizione durante l'overlay di immagini su video?

Question

Ho combinato i 2 blocchi di codice trovati here in un unico blocco solido (e ho verificato il processo con un file di esercitazione Xcode per Apple Developer). Quando lo eseguo, tuttavia, ottengo un errore. Dice: "L'operazione non può essere completata (. Errore AVFoundationErrorDomain -11.841)"

errore di dominio = AVFoundationErrorDomain Codice = -11841

Qualsiasi idea del perché si genera un errore AVErrorInvalidVideoComposition? Grazie! (Sono nuovo qui quindi per favore fatemi sapere se avete bisogno di maggiori informazioni.)

NSURL *videoURL = [info valueForKey:UIImagePickerControllerMediaURL]; 

/// UIImage into CALayer 
UIImage *myImage = [UIImage imageNamed:@"Test.png"]; 
CALayer *aLayer = [CALayer layer]; 
aLayer.contents = (id)myImage.CGImage; 

AVURLAsset* url = [AVURLAsset URLAssetWithURL:videoURL options:nil]; 
AVMutableComposition *videoComposition = [[AVMutableComposition alloc] init]; 
NSError *error; 
NSFileManager *fileManager = [NSFileManager defaultManager]; 

AVMutableCompositionTrack *compositionVideoTrack = [videoComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid]; 
AVAssetTrack *clipVideoTrack = [[url tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0]; 
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [url duration]) ofTrack:clipVideoTrack atTime:kCMTimeZero error:&error]; 

AVMutableVideoComposition* videoComp = [[AVMutableVideoComposition alloc] init]; 
videoComp.renderSize = CGSizeMake(640, 480); 
videoComp.frameDuration = CMTimeMake(1, 30); 
CALayer *parentLayer = [CALayer layer]; 
CALayer *videoLayer = [CALayer layer]; 
parentLayer.frame = CGRectMake(0, 0, videoComp.renderSize.width, videoComp.renderSize.height); 
videoLayer.frame = CGRectMake(0, 0, videoComp.renderSize.width, videoComp.renderSize.height); 
[parentLayer addSublayer:videoLayer]; 
[parentLayer addSublayer:aLayer]; 
videoComp.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer]; 


/// instruction 
AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction]; 
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, CMTimeMakeWithSeconds(60, 30)); 
AVMutableVideoCompositionLayerInstruction* layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:clipVideoTrack]; 
instruction.layerInstructions = [NSArray arrayWithObject:layerInstruction]; 
videoComp.instructions = [NSArray arrayWithObject: instruction]; 

/// outputs 
NSString *filePath = nil; 
filePath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0]; 
filePath = [filePath stringByAppendingPathComponent:@"temp.mov"]; 
NSLog(@"exporting to: %@", filePath); 
if ([fileManager fileExistsAtPath:filePath]) 
{ 
    BOOL success = [fileManager removeItemAtPath:filePath error:&error]; 
    if (!success) NSLog(@"FM error: %@", [error localizedDescription]); 
} 

/// exporting 
AVAssetExportSession *exporter; 
exporter = [[AVAssetExportSession alloc] initWithAsset:videoComposition presetName:AVAssetExportPresetHighestQuality] ; 
exporter.videoComposition = videoComp; 
exporter.outputURL=[NSURL fileURLWithPath:filePath]; 
exporter.outputFileType=AVFileTypeQuickTimeMovie; 


[exporter exportAsynchronouslyWithCompletionHandler:^(void){ 
    switch (exporter.status) { 
     case AVAssetExportSessionStatusFailed: 
      NSLog(@"exporting failed:%@",exporter.error); 
      break; 
     case AVAssetExportSessionStatusCompleted: 
      NSLog(@"exporting completed"); 
      UISaveVideoAtPathToSavedPhotosAlbum(filePath, self, @selector(video:didFinishSavingWithError:contextInfo:), NULL); 
      break; 
     case AVAssetExportSessionStatusCancelled: 
      NSLog(@"export cancelled"); 
      break; 
    } 
}]; 

Answer 1

Un problema comune con le composizioni non valide è il tempo.

Se le varie risorse che si stanno combinando non hanno la stessa lunghezza, assicurarsi che la composizione creata copra l'intero segmento.

Verificare che il valore di tempo di AVMutableVideoCompositionInstruction sia corretto.