我可以在AVFoundation中合并两个视频，一个带前凸轮，另一个带后凸轮

Question

当我尝试将两个视频与前置摄像头和另一个带有后置摄像头合并时，其中一个视频的方向存在问题，我使用此代码：

- （void）combineMultibleVideoSegments {     NSError *错误;

AVMutableComposition *composition = [AVMutableComposition composition];
AVMutableCompositionTrack *compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];

AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];

AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoComposition];
videoComposition.frameDuration = CMTimeMake(1,30);
videoComposition.renderScale = 1.0;
AVMutableVideoCompositionLayerInstruction *layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:compositionVideoTrack];
CMTime currentTime = kCMTimeZero;
CGFloat videoTrackY = 0.0;
CGFloat videoTrackWidth=0.0;
for (int i = 0; i<videosPathsArray.count; i++)
{
    NSURL *videoURL = [NSURL fileURLWithPath:[videosPathsArray objectAtIndex:i]];
    AVURLAsset* sourceAsset = [[AVURLAsset alloc]initWithURL:videoURL options:nil];

    NSLog(@"path = %@" , [videosPathsArray objectAtIndex:i]);

    NSError *error = nil;
    BOOL ok = NO;

    AVAssetTrack *sourceVideoTrack = [[sourceAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
    AVAssetTrack *sourceAudioTrack = [[sourceAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
    videoTrackY = sourceVideoTrack.naturalSize.height;
    videoTrackWidth = sourceVideoTrack.naturalSize.width;

    if ([[VideosReocrdCamera objectAtIndex:i] isEqual:@"Yes"])
    {
        CGAffineTransform rotationTransform = CGAffineTransformMakeRotation(M_PI/2);
        CGAffineTransform rotateTranslate = CGAffineTransformTranslate(rotationTransform,320,0);

        [compositionVideoTrack setPreferredTransform:sourceVideoTrack.preferredTransform];
        [layerInstruction setTransform:rotateTranslate atTime:kCMTimeZero];
    }
    else
    {
        CGAffineTransform rotationTransform = CGAffineTransformMakeRotation(0.0);
        CGAffineTransform rotateTranslate = CGAffineTransformTranslate(rotationTransform,320,0);

        [compositionVideoTrack setPreferredTransform:rotationTransform];
        [layerInstruction setTransform:rotateTranslate atTime:kCMTimeZero];
    }

    [compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [sourceAsset duration]) ofTrack:sourceAudioTrack atTime:currentTime error:&error];
    ok = [compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [sourceAsset duration]) ofTrack:sourceVideoTrack atTime:currentTime error:&error];
    currentTime = CMTimeAdd(currentTime, [sourceAsset duration]);
    if (!ok) {
        // Deal with the error.
        NSLog(@"something went wrong");
    }
    NSLog(@"\n source asset duration is %f \n source vid track timerange is %f %f \n composition duration is %f \n composition vid track time range is %f %f",CMTimeGetSeconds([sourceAsset duration]), CMTimeGetSeconds(sourceVideoTrack.timeRange.start),CMTimeGetSeconds(sourceVideoTrack.timeRange.duration),CMTimeGetSeconds([composition duration]), CMTimeGetSeconds(compositionVideoTrack.timeRange.start),CMTimeGetSeconds(compositionVideoTrack.timeRange.duration));
}

所以任何人都可以告诉我如何解决这个问题