Video recorded from EAGLView is flipped when uploaded to youtube

Question

In my ios app, I am trying to record video of the content of EAGLView(There is no Camera involvement). I have no problem recording the video. After recording I have to add few sound tracks to the video and then have to share this video to Youtube and facebook. My problem is that the video is okay when I play it on iphone or on mac but when I upload this video to youtube (using Youtube Data Api v3), the video is vertically inverted or upside down.

I guess I need to rotate the frame in video before uploading but I don't know how to do that.

Any help will be highly appreciated.

The code I am using to add audio tracks to the video is below:

-(void)prepareVideoForPath:(NSString *)videoPath usingAudio:(NSArray *)audioArray andOutputPath:(NSString *)exportPath{


NSDictionary *optionsDictionary = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:AVURLAssetPreferPreciseDurationAndTimingKey];

NSURL *videoUrl=[NSURL fileURLWithPath:videoPath];

AVURLAsset* videoAsset = [AVURLAsset URLAssetWithURL:videoUrl options:optionsDictionary];

AVAssetTrack *FirstAssetTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
CGAffineTransform firstTransform = FirstAssetTrack.preferredTransform;
AVMutableComposition* mixComposition = [AVMutableComposition composition];


//VideoTrack

AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:FirstAssetTrack atTime:kCMTimeZero error:nil];
[compositionVideoTrack setPreferredTransform:firstTransform];


//Audio Track

AVMutableCompositionTrack *audioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];

CMTime audioStartTime = kCMTimeZero;
for (NSURL *audioURL in audioArray) {
    AVURLAsset *audioAsset = [AVURLAsset URLAssetWithURL:audioURL options:optionsDictionary];
    [audioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, audioAsset.duration) ofTrack:[[audioAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:audioStartTime error:nil];
    audioStartTime = CMTimeAdd(audioStartTime, audioAsset.duration);
}


AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetPassthrough];


NSURL *exportUrl = [NSURL fileURLWithPath:exportPath];

_assetExport.outputFileType = AVFileTypeQuickTimeMovie;

NSLog(@"file type %@",_assetExport.outputFileType);

_assetExport.outputURL = exportUrl;

_assetExport.shouldOptimizeForNetworkUse = YES;

[_assetExport exportAsynchronouslyWithCompletionHandler:

 ^(void ) {

     // your completion code here

     dispatch_async(dispatch_get_main_queue(), ^{
         NSLog(@"Mixing complete");

     });

 }

 ];

}

Answer 1

Ok I found it how to rotate a video.

Here is the code:

-(void)fixVideoOrientationForURL:(NSURL *)videoURL andOutputPath:(NSString *)exportPath{


    AVURLAsset *asset = [AVURLAsset URLAssetWithURL:videoURL options:@{ AVURLAssetPreferPreciseDurationAndTimingKey:@YES }];

    AVMutableVideoCompositionInstruction *instruction = nil;
    AVMutableVideoCompositionLayerInstruction *layerInstruction = nil;

    CGAffineTransform transform;

AVAssetTrack *assetVideoTrack = nil;
AVAssetTrack *assetAudioTrack = nil;
// Check if the asset contains video and audio tracks
if ([[asset tracksWithMediaType:AVMediaTypeVideo] count] != 0) {
    assetVideoTrack = [asset tracksWithMediaType:AVMediaTypeVideo][0];
}
if ([[asset tracksWithMediaType:AVMediaTypeAudio] count] != 0) {
    assetAudioTrack = [asset tracksWithMediaType:AVMediaTypeAudio][0];
}

CMTime insertionPoint = kCMTimeZero;
NSError *error = nil;


// Step 1
// Create a composition with the given asset and insert audio and video tracks into it from the asset

AVMutableComposition *mutableComposition = [AVMutableComposition composition];

    // Insert the video and audio tracks from AVAsset
    if (assetVideoTrack != nil) {
        AVMutableCompositionTrack *compositionVideoTrack = [mutableComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
        [compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [asset duration]) ofTrack:assetVideoTrack atTime:insertionPoint error:&error];
    }
    if (assetAudioTrack != nil) {
        AVMutableCompositionTrack *compositionAudioTrack = [mutableComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
        [compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [asset duration]) ofTrack:assetAudioTrack atTime:insertionPoint error:&error];
    }

// Step 2
// Translate the composition to compensate the movement caused by rotation (since rotation would cause it to move out of frame)
// Rotate transformation
    transform = CGAffineTransformMake(1, 0, 0, -1, 0, assetVideoTrack.naturalSize.height);

// Step 3
// Set the appropriate render sizes and rotational transforms


    // Create a new video composition
    AVMutableVideoComposition *mutableVideoComposition = [AVMutableVideoComposition videoComposition];
    mutableVideoComposition.renderSize = CGSizeMake(assetVideoTrack.naturalSize.width,assetVideoTrack.naturalSize.height);
    mutableVideoComposition.frameDuration = CMTimeMake(1, 30);

    // The rotate transform is set on a layer instruction
    instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
    instruction.timeRange = CMTimeRangeMake(kCMTimeZero, [mutableComposition duration]);
    layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:(mutableComposition.tracks)[0]];
    [layerInstruction setTransform:t2 atTime:kCMTimeZero];

// Step 4
// Add the transform instructions to the video composition
instruction.layerInstructions = @[layerInstruction];
mutableVideoComposition.instructions = @[instruction];


    AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:[mutableComposition copy] presetName:AVAssetExportPresetHighestQuality];

exportSession.videoComposition = mutableVideoComposition;
exportSession.outputURL = [NSURL fileURLWithPath:exportPath];
exportSession.outputFileType=AVFileTypeQuickTimeMovie;
exportSession.shouldOptimizeForNetworkUse = YES;

[exportSession exportAsynchronouslyWithCompletionHandler:^(void){

        dispatch_async(dispatch_get_main_queue(), ^{
            switch (exportSession.status) {
                case AVAssetExportSessionStatusCompleted:
                    NSLog(@"writing complete");


                    break;
                case AVAssetExportSessionStatusFailed:
                    NSLog(@"Failed:%@",exportSession.error);
                    break;
                case AVAssetExportSessionStatusCancelled:
                    NSLog(@"Canceled:%@",exportSession.error);
                    break;
                default:
                    break;
            }
        });

}];
}