AVMutableComposition y轴反转

Question

我在视频上添加水印。我设置了原始水印图层(10;10)，但导出后，水印位于左下角。如果我增加y，水印就会上移。就像y轴从下往上增加一样。

有没有人能提个建议？

NSString *path = [[NSBundle mainBundle] pathForResource:@"video" ofType:@"mov"];
NSURL *file = [NSURL fileURLWithPath:path];
AVURLAsset *videoAsset = [[AVURLAsset alloc]initWithURL:file options:nil];
self.asset = videoAsset;
AVMutableComposition *mixComposition = [AVMutableComposition composition];
AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo  preferredTrackID:kCMPersistentTrackID_Invalid];
AVMutableCompositionTrack *compositionAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio  preferredTrackID:kCMPersistentTrackID_Invalid];
AVAssetTrack *clipVideoTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] firstObject];
AVAssetTrack *clipAudioTrack = [[videoAsset tracksWithMediaType:AVMediaTypeAudio] firstObject];
if (clipAudioTrack)
{
    [compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration)
                                   ofTrack:clipAudioTrack
                                    atTime:kCMTimeZero
                                     error:nil];
}
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration)
                               ofTrack:clipVideoTrack
                                atTime:kCMTimeZero
                                 error:nil];
[compositionVideoTrack setPreferredTransform:clipVideoTrack.preferredTransform];

CGSize videoSize = [clipVideoTrack naturalSize];
CALayer *parentLayer = [CALayer layer];
CALayer *videoLayer = [CALayer layer];
parentLayer.frame = CGRectMake(0, 0, videoSize.width, videoSize.height);
videoLayer.frame = CGRectMake(0, 0, videoSize.width, videoSize.height);

UIImage *myImage = [UIImage imageNamed:@"watermark"];
CALayer *aLayer = [CALayer layer];
CGRect frame = CGRectMake(10, 10, CGImageGetWidth(myImage.CGImage), CGImageGetHeight(myImage.CGImage));
aLayer.frame = frame;
aLayer.contents = (id)myImage.CGImage;

[parentLayer addSublayer:videoLayer];
[parentLayer addSublayer:aLayer];

AVMutableVideoComposition *videoComposition=[AVMutableVideoComposition videoComposition] ;
videoComposition.frameDuration=CMTimeMake(1, 30);
videoComposition.renderSize = videoSize;
videoComposition.animationTool=[AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];

AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, [mixComposition duration]);
AVAssetTrack *videoTrack = [[mixComposition tracksWithMediaType:AVMediaTypeVideo] firstObject];
AVMutableVideoCompositionLayerInstruction* layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
instruction.layerInstructions = @[layerInstruction];
videoComposition.instructions = @[instruction];

NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"yyyy-MM-dd_HH-mm-ss"];
NSString *destinationPath = [documentsDirectory stringByAppendingFormat:@"/utput_%@.mov", [dateFormatter stringFromDate:[NSDate date]]];

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

exportSession.outputURL = [NSURL fileURLWithPath:destinationPath];
exportSession.outputFileType = AVFileTypeMPEG4;
[exportSession exportAsynchronouslyWithCompletionHandler:^{
    switch (exportSession.status)
    {
        case AVAssetExportSessionStatusCompleted:
            NSLog(@"Export OK");
            if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(destinationPath)) {
                UISaveVideoAtPathToSavedPhotosAlbum(destinationPath, self, nil, nil);
            }
            break;
        case AVAssetExportSessionStatusFailed:
            NSLog (@"AVAssetExportSessionStatusFailed: %@", exportSession.error);
            break;
        case AVAssetExportSessionStatusCancelled:
            NSLog(@"Export Cancelled");
            break;
        default:
            break;
    }
}];

Answer 1

我过去在寻找正确的锚点添加水印时遇到了很多问题。我会发布我的代码。请记住，它会生成一个右下角带有水印的视频(5像素边距)。

注意：

logoImageView.frame = CGRectMake(finalSize.width - ((logoImageView.frame.size.width/2) + 5),
                                         finalSize.height - ((logoImageView.frame.size.height/2) + 5),
                                         logoImageView.frame.size.width/2,
                                         logoImageView.frame.size.height/2)

最终代码：

final class QUWatermarkManager {

    static func watermark(video videoAsset:AVAsset, imageLayer : CALayer, saveToLibrary flag : Bool, completion : ((status : AVAssetExportSessionStatus!, session: AVAssetExportSession!, outputURL : NSURL!) -> ())?) {

        var finalSize =  CGSizeMake(imageLayer.frame.size.width, imageLayer.frame.size.width)
        var computedVideoSize = finalSize.width
        while (computedVideoSize%16>0) { // find the right resolution that can be divided by 16
            computedVideoSize++;
        }

        finalSize = CGSizeMake(computedVideoSize,computedVideoSize)

        let clipVideoTrack = videoAsset.tracksWithMediaType(AVMediaTypeVideo).first! as AVAssetTrack
        let videoSize = clipVideoTrack.naturalSize
        let scale = finalSize.width / videoSize.width

        let composition = AVMutableComposition()
        composition.addMutableTrackWithMediaType(AVMediaTypeVideo, preferredTrackID: CMPersistentTrackID())

        let videoComposition = AVMutableVideoComposition()


        videoComposition.renderSize = CGSizeMake(finalSize.width,finalSize.width)
        videoComposition.frameDuration = CMTimeMake(1, 30)

        let instruction = AVMutableVideoCompositionInstruction()
        instruction.timeRange = CMTimeRangeMake(kCMTimeZero, CMTimeMakeWithSeconds(180, 30))

        let layerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: clipVideoTrack)
        let t4 = CGAffineTransformScale(clipVideoTrack.preferredTransform, scale, scale)
        layerInstruction.setTransform(t4, atTime: kCMTimeZero)
        instruction.layerInstructions = [layerInstruction]
        videoComposition.instructions = [instruction]

        // Parent Layer
        let parentLayer = CALayer()
        parentLayer.frame = CGRectMake(0, 0, finalSize.width, finalSize.height)
        parentLayer.geometryFlipped = true

        //Video Layer
        let videoLayer = CALayer()
        videoLayer.frame = CGRectMake(0, 0, finalSize.width, finalSize.height)
        videoLayer.geometryFlipped = true

        let logoImageView = UIImageView(image: UIImage(named: "logo_nav2"))
        logoImageView.alpha = 0.5
        logoImageView.contentMode = .ScaleAspectFit
        logoImageView.frame = CGRectMake(finalSize.width - ((logoImageView.frame.size.width/2) + 5),
                                         finalSize.height - ((logoImageView.frame.size.height/2) + 5),
                                         logoImageView.frame.size.width/2,
                                         logoImageView.frame.size.height/2)

        parentLayer.addSublayer(videoLayer)
        parentLayer.addSublayer(imageLayer)
        parentLayer.addSublayer(logoImageView.layer)


        videoComposition.animationTool = AVVideoCompositionCoreAnimationTool(postProcessingAsVideoLayer: videoLayer, inLayer: parentLayer)

        // 4 - Get path
        let documentDirectory = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0]
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateStyle = .LongStyle
        dateFormatter.timeStyle = .FullStyle
        let date = dateFormatter.stringFromDate(NSDate())
        let savePath = documentDirectory.stringByAppendingPathComponent("watermarkVideo-\(date).mov")
        let url = NSURL(fileURLWithPath: savePath)

        let exporter = AVAssetExportSession(asset: videoAsset, presetName: AVAssetExportPresetHighestQuality)!
        exporter.videoComposition = videoComposition
        exporter.outputURL = url
        exporter.outputFileType = AVFileTypeMPEG4
        exporter.shouldOptimizeForNetworkUse = true
        exporter.canPerformMultiplePassesOverSourceMediaData = true

        exporter.exportAsynchronouslyWithCompletionHandler() {
            dispatch_async(dispatch_get_main_queue(), { () -> Void in
                if exporter.status == AVAssetExportSessionStatus.Completed {
                    let outputURL = exporter.outputURL
                    if flag {
                        // Save to library
                        let library = ALAssetsLibrary()
                        if library.videoAtPathIsCompatibleWithSavedPhotosAlbum(outputURL) {
                            library.writeVideoAtPathToSavedPhotosAlbum(outputURL,
                                completionBlock: { (assetURL:NSURL!, error:NSError!) -> Void in
                                    completion!(status: .Completed, session: exporter, outputURL: outputURL)
                            })
                        }
                    } else {
                        // Dont svae to library
                        completion!(status: .Completed, session: exporter, outputURL: outputURL)
                    }

                } else {
                    // Error
                    completion!(status: exporter.status, session: exporter, outputURL: exporter.outputURL)
                }
            })
        }

    }
}