Estou tentando transformar um CALayer no vídeo em modo retrato (na exportação) usando um AVMutableComposition, um AVMutableVideoComposition e um AVVideoCompositionCoreAnimationTool no iOS 4.3. Tudo isso funciona na paisagem. Se eu capturar vídeo em retrato, no entanto, o AVVideoCompositionCoreAnimationTool está ignorando a transformação na trilha de vídeo. Ou seja, no vídeo em modo retrato, estou configurando AVMutableCompositionTrack.preferredTransform para o valor de preferênciaTransform da trilha de vídeo do ativo original. Desde que eu não use um AVVideoCompositionCoreAnimationTool, isso funcionará e o vídeo sairá no modo retrato. Assim que adiciono um AVVideoCompositionCoreAnimationTool e CALayer, no entanto, o arquivo sai em modo paisagem. (O CALayer aparece corretamente, mas o vídeo por trás está do lado e a proporção do arquivo está desativada). Tentei aplicar a transformação ao CALayer e definir uma transformação no ACVideoComposition. Nenhuma delas altera a orientação do arquivo produzido (ainda é 480x369, não 360x480). Existe uma maneira de renderizar vídeo em modo retrato com o AVVideoCompositionCoreAnimationTool?

Primeiro configurei um AVMutableComposition e AVMutableVideoComposition

AVMutableComposition *composition = [AVMutableComposition composition];
AVMutableCompositionTrack *compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
AVURLAsset *videoAsset = [AVURLAsset URLAssetWithURL:url options:nil];
CMTimeRange timeRange = CMTimeRangeMake(kCMTimeZero, [videoAsset duration]);
AVAssetTrack *clipVideoTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];

CGSize videoSize = CGSizeApplyAffineTransform(clipVideoTrack.naturalSize, clipVideoTrack.preferredTransform);
videoSize.width = fabs(videoSize.width);
videoSize.height = fabs(videoSize.height);

CMTime titleDuration = CMTimeMakeWithSeconds(5, 600);
CMTimeRange titleRange = CMTimeRangeMake(kCMTimeZero, titleDuration);

[compositionVideoTrack insertTimeRange:titleRange ofTrack:nil atTime:kCMTimeZero error:nil];
[compositionVideoTrack insertTimeRange:timeRange ofTrack:clipVideoTrack atTime:titleDuration error:nil];
compositionVideoTrack.preferredTransform = clipVideoTrack.preferredTransform;

AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoComposition];
AVMutableVideoCompositionInstruction *passThroughInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
passThroughInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, [composition duration]);
AVAssetTrack *videoTrack = [[composition tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
AVMutableVideoCompositionLayerInstruction *passThroughLayer = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];    
passThroughInstruction.layerInstructions = [NSArray arrayWithObject:passThroughLayer];
videoComposition.instructions = [NSArray arrayWithObject:passThroughInstruction];       
videoComposition.frameDuration = CMTimeMake(1, 30); 
videoComposition.renderSize = videoSize;
videoComposition.renderScale = 1.0;

E um CALayer com um título

CALayer *animationLayer = [CALayer layer];
animationLayer.bounds = CGRectMake(0, 0, videoSize.width, videoSize.height);

CATextLayer *titleLayer = [CATextLayer layer];
titleLayer.string = [effect valueForKey:@"title"];
titleLayer.font = [effect valueForKey:@"font"];
titleLayer.fontSize = 30;

titleLayer.alignmentMode = kCAAlignmentCenter;
titleLayer.bounds = CGRectMake(0, 0, videoSize.width, videoSize.height / 6);

[animationLayer addSublayer:titleLayer];
titleLayer.anchorPoint =  CGPointMake(0.5, 0.5);
titleLayer.position = CGPointMake(CGRectGetMidX(layer.bounds), CGRectGetMidY(layer.bounds));    

CABasicAnimation *fadeAnimation = [CABasicAnimation animationWithKeyPath:@"opacity"];
fadeAnimation.fromValue = [NSNumber numberWithFloat:1.0];
fadeAnimation.toValue = [NSNumber numberWithFloat:0.0];
fadeAnimation.additive = NO;
fadeAnimation.removedOnCompletion = NO;
fadeAnimation.beginTime = 3.5;
fadeAnimation.duration = 1.0;
fadeAnimation.fillMode = kCAFillModeBoth;
[titleLayer addAnimation:fadeAnimation forKey:nil];

Finalmente, adiciono o CALayer ao AVMutableVideoComposition

CALayer *parentLayer = [CALayer layer];
CALayer *videoLayer = [CALayer layer];

parentLayer.bounds = CGRectMake(0, 0, videoSize.width, videoSize.height);
parentLayer.anchorPoint =  CGPointMake(0, 0);
parentLayer.position = CGPointMake(0, 0);

videoLayer.bounds = CGRectMake(0, 0, videoSize.width, videoSize.height);
[parentLayer addSublayer:videoLayer];
videoLayer.anchorPoint =  CGPointMake(0.5, 0.5);
videoLayer.position = CGPointMake(CGRectGetMidX(parentLayer.bounds), CGRectGetMidY(parentLayer.bounds));
[parentLayer addSublayer:layer];    
animationLayer.anchorPoint =  CGPointMake(0.5, 0.5);
animationLayer.position = CGPointMake(CGRectGetMidX(parentLayer.bounds), CGRectGetMidY(parentLayer.bounds));
videoComposition.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];

E exportação!

AVAssetExportSession *exportSession = [[[AVAssetExportSession alloc] initWithAsset:composition presetName:AVAssetExportPresetMediumQuality] autorelease];
exportSession.videoComposition = videoComposition; 

NSURL *segmentFileURL = //some local URL
exportSession.outputFileType = @"com.apple.quicktime-movie";
exportSession.outputURL = segmentFileURL;


[exportSession exportAsynchronouslyWithCompletionHandler:^{
    switch ([exportSession status]) {
        case AVAssetExportSessionStatusFailed:
            Log(@"Export failed: %@", [exportSession error]);
            break;
        case AVAssetExportSessionStatusCancelled:
            Log(@"Export canceled");
            break;
        case AVAssetExportSessionStatusCompleted:
            Log(@"Export done");
            break;
    }
}]; 

Este código funciona no modo paisagem e também em retrato se eu remover a linhavideoComposition.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];