在目标C中正确定位视频

Question

我希望在从相机录制和合并后以正确的方向导出视频。但视频处于横向模式。不知道为什么这是景观。如何解决这个问题。这是https://github.com/mkoehnke/MKOVideoMerge

的方法

+ (void)mergeVideoFiles:(NSArray *)fileURLs
         completion:(void(^)(NSURL *mergedVideoFile, NSError *error))completion {
NSLog(@"%@fileURLs", fileURLs);
NSLog(@"Start merging video files ...");

AVMutableComposition *composition = [[AVMutableComposition alloc] init];
AVMutableCompositionTrack *videoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
AVMutableCompositionTrack *audioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
NSMutableArray *instructions = [NSMutableArray new];

__block BOOL errorOccurred = NO;
__block CMTime currentTime = kCMTimeZero;
__block CGSize size = CGSizeZero;
__block int32_t highestFrameRate = 0;

[fileURLs enumerateObjectsUsingBlock:^(NSURL *fileURL, NSUInteger idx, BOOL *stop) {
    #pragma unused(idx)

    NSDictionary *options = @{AVURLAssetPreferPreciseDurationAndTimingKey:@YES};
    AVURLAsset *sourceAsset = [AVURLAsset URLAssetWithURL:fileURL options:options];
    AVAssetTrack *videoAsset = [[sourceAsset tracksWithMediaType:AVMediaTypeVideo] firstObject];
    AVAssetTrack *audioAsset = [[sourceAsset tracksWithMediaType:AVMediaTypeAudio] firstObject];
    if (CGSizeEqualToSize(size, CGSizeZero)) { size = videoAsset.naturalSize; }

    int32_t currentFrameRate = (int)roundf(videoAsset.nominalFrameRate);
    highestFrameRate = (currentFrameRate > highestFrameRate) ? currentFrameRate : highestFrameRate;
    NSLog(@"* %@ (%dfps)", [fileURL lastPathComponent], currentFrameRate);

    // According to Apple placing multiple video segments on the same composition track can potentially lead to dropping frames
    // at the transitions between video segments. Therefore we trim the first and last frame of each video.
    // https://developer.apple.com/library/ios/documentation/AudioVideo/Conceptual/AVFoundationPG/Articles/03_Editing.html
    CMTime trimmingTime = CMTimeMake(lround(videoAsset.naturalTimeScale / videoAsset.nominalFrameRate), videoAsset.naturalTimeScale);
    CMTimeRange timeRange = CMTimeRangeMake(trimmingTime, CMTimeSubtract(videoAsset.timeRange.duration, trimmingTime));

    NSError *videoError;
    BOOL videoResult = [videoTrack insertTimeRange:timeRange ofTrack:videoAsset atTime:currentTime error:&videoError];

    NSError *audioError;
    BOOL audioResult = [audioTrack insertTimeRange:timeRange ofTrack:audioAsset atTime:currentTime error:&audioError];

    if(!videoResult || !audioResult || videoError || audioError) {
        if (completion) completion(nil, videoError? : audioError);
        errorOccurred = YES;
        *stop = YES;
    } else {
        AVMutableVideoCompositionInstruction *videoCompositionInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
        videoCompositionInstruction.timeRange = CMTimeRangeMake(currentTime, timeRange.duration);

        videoCompositionInstruction.layerInstructions = @[[AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack]];
        [instructions addObject:videoCompositionInstruction];
        currentTime = CMTimeAdd(currentTime, timeRange.duration);

    }
}];

if (errorOccurred == NO) {
    AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:composition presetName:AVAssetExportPresetHighestQuality];
    NSString *fileName = [MKOVideoMerge generateFileName];
    NSString *filePath = [MKOVideoMerge documentsPathWithFilePath:fileName];
    exportSession.outputURL = [NSURL fileURLWithPath:filePath];
    exportSession.outputFileType = AVFileTypeMPEG4;
    exportSession.shouldOptimizeForNetworkUse = YES;

    AVMutableVideoComposition *mutableVideoComposition = [AVMutableVideoComposition videoComposition];
     mutableVideoComposition.instructions = instructions;
     mutableVideoComposition.frameDuration = CMTimeMake(1, highestFrameRate);
     mutableVideoComposition.renderSize = size;

    exportSession.videoComposition = mutableVideoComposition;

    NSLog(@"Composition Duration: %ld seconds", lround(CMTimeGetSeconds(composition.duration)));
    NSLog(@"Composition Framerate: %d fps", highestFrameRate);

    void(^exportCompletion)(void) = ^{
        dispatch_async(dispatch_get_main_queue(), ^{
            if (completion) completion(exportSession.outputURL, exportSession.error);
        });
    };

    [exportSession exportAsynchronouslyWithCompletionHandler:^{
        switch (exportSession.status) {
            case AVAssetExportSessionStatusFailed:{
                exportCompletion();
                break;
            }
            case AVAssetExportSessionStatusCancelled:{
                exportCompletion();
                break;
            }
            case AVAssetExportSessionStatusCompleted: {
                NSLog(@"Successfully merged video files into: %@", fileName);
                exportCompletion();
                break;
            }
            case AVAssetExportSessionStatusUnknown: {
                NSLog(@"Export Status: Unknown");
            }
            case AVAssetExportSessionStatusExporting : {
                NSLog(@"Export Status: Exporting");
            }
            case AVAssetExportSessionStatusWaiting: {
                NSLog(@"Export Status: Wating");
            }
        };
    }];
  }
}