我已按照此链接裁剪和调整视频大小：

我想裁剪视频并将其调整为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)

}

})

}

}

我将尺寸视频尺寸设为612 * 612,但内容很奇怪.可能是什么问题？