如何将视频裁剪为特定大小？

Question

我已按照此链接裁剪和调整视频大小：

Swift: Crop and Export Video

我想裁剪视频并将其大小调整为 612*612。 我的代码如下：

 let outputPath : NSString = NSString(format: "%@%@", NSTemporaryDirectory(), "output.mov")

    let outputURL : NSURL = NSURL(fileURLWithPath: outputPath as String)!

    let fileManager : NSFileManager = NSFileManager.defaultManager()

    if(fileManager.fileExistsAtPath(outputPath as String))
    {
        let asset : AVURLAsset = AVURLAsset(URL: outputURL, options: nil)
        if let clipVideoTrack: AVAssetTrack = asset.tracksWithMediaType(AVMediaTypeVideo)[0] as? AVAssetTrack
        {

            var videoComposition: AVMutableVideoComposition = AVMutableVideoComposition()
            videoComposition.frameDuration = CMTimeMake(1, 60)

            print(clipVideoTrack.naturalSize.height)

            videoComposition.renderSize = CGSizeMake(612,612)

            var instruction: AVMutableVideoCompositionInstruction = AVMutableVideoCompositionInstruction()
            instruction.timeRange = CMTimeRangeMake(kCMTimeZero, CMTimeMakeWithSeconds(60, 30))
            var transformer: AVMutableVideoCompositionLayerInstruction =
            AVMutableVideoCompositionLayerInstruction(assetTrack: clipVideoTrack)

            var t1: CGAffineTransform = CGAffineTransformMakeTranslation(clipVideoTrack.naturalSize.height, 0)

            var t2: CGAffineTransform = CGAffineTransformRotate(t1, CGFloat(M_PI_2))

            var finalTransform: CGAffineTransform = t2

             transformer.setTransform(finalTransform, atTime: kCMTimeZero)
            instruction.layerInstructions = NSArray(object: transformer) as [AnyObject]

            videoComposition.instructions = NSArray(object: instruction) as [AnyObject]


            let exportPath : NSString = NSString(format: "%@%@", NSTemporaryDirectory(), "output2.mov")

            var exportUrl: NSURL = NSURL.fileURLWithPath(exportPath as! String)!
            if(fileManager.fileExistsAtPath(exportPath as String))
            {
                var error:NSError? = nil
                if(fileManager.removeItemAtPath(exportPath as String, error: &error))
                {
                    //Error - handle if requried
                }
            }

            var exporter = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetHighestQuality)
            exporter.videoComposition = videoComposition
            exporter.outputFileType = AVFileTypeQuickTimeMovie
            exporter.outputURL = exportUrl
            exporter.exportAsynchronouslyWithCompletionHandler({ () -> Void in

                dispatch_async(dispatch_get_main_queue()) {
                    () -> Void in
                    let outputURL:NSURL = exporter.outputURL;
                    self.videoURL = outputURL
                    let asset:AVURLAsset = AVURLAsset(URL: outputURL, options: nil)

                }

            })

        }


    }

我的视频尺寸为 612*612，但内容很奇怪。可能是什么问题？

Answer 1

解决方法： 我已将 AVCaptureSession 的值设置为 AVCaptureSessionPresetiFrame960x540 我将其值更改为 AVCaptureSessionPreset1280x720 解决了我的问题。