Crop video swift

Question

I am recording a video in a square UIView but when I export the video is full screen 1080x1920 now I am wondering how I can reduce the video from being full screen to being

Answer 1

Firstly you need to make use of the AVCaptureFileOutputRecordingDelegate.

You specifically use the func capture( _ captureOutput: AVCaptureFileOutput!, didFinishRecordingToOutputFileAt outputFileURL: URL!, fromConnections connections: [Any]!, error: Error! ) method to perform the cropping process, once the video has finished recording.

Here is an example of a cropping function I once implemented. You need to pass in the URL of the video that was recorded and a callback that is used to return the new URL of the cropped video once the cropping process is finished.

   func cropVideo( _ outputFileUrl: URL, callback: @escaping ( _ newUrl: URL ) -> () )
   {
       // Get input clip
       let videoAsset: AVAsset = AVAsset( url: outputFileUrl )
       let clipVideoTrack = videoAsset.tracks( withMediaType: AVMediaTypeVideo ).first! as AVAssetTrack

       // Make video to square
       let videoComposition = AVMutableVideoComposition()
       videoComposition.renderSize = CGSize( width: clipVideoTrack.naturalSize.height, height: clipVideoTrack.naturalSize.height )
       videoComposition.frameDuration = CMTimeMake( 1, self.framesPerSecond )

       // Rotate to portrait
       let transformer = AVMutableVideoCompositionLayerInstruction( assetTrack: clipVideoTrack )
       let transform1 = CGAffineTransform( translationX: clipVideoTrack.naturalSize.height, y: -( clipVideoTrack.naturalSize.width - clipVideoTrack.naturalSize.height ) / 2 )
       let transform2 = transform1.rotated(by: CGFloat( M_PI_2 ) )
       transformer.setTransform( transform2, at: kCMTimeZero)

       let instruction = AVMutableVideoCompositionInstruction()
       instruction.timeRange = CMTimeRangeMake(kCMTimeZero, CMTimeMakeWithSeconds( self.intendedVideoLength, self.framesPerSecond ) )

       instruction.layerInstructions = [transformer]
       videoComposition.instructions = [instruction]

       // Export
       let croppedOutputFileUrl = URL( fileURLWithPath: FileManager.getOutputPath( String.random() ) )
       let exporter = AVAssetExportSession(asset: videoAsset, presetName: AVAssetExportPresetHighestQuality)!
       exporter.videoComposition = videoComposition
       exporter.outputURL = croppedOutputFileUrl
       exporter.outputFileType = AVFileTypeQuickTimeMovie

       exporter.exportAsynchronously( completionHandler: { () -> Void in
           DispatchQueue.main.async(execute: {
               callback( croppedOutputFileUrl )
           })
       })
   }

Also, here is the implementation of my getOutputPath method:

func getOutputPath( _ name: String ) -> String
{
    let documentPath = NSSearchPathForDirectoriesInDomains(      .documentDirectory, .userDomainMask, true )[ 0 ] as NSString
    let outputPath = "\(documentPath)/\(name).mov"
    return outputPath
}

Hope this helps.