斯威夫特视频调整器 AVAsset.

Question

我有这段代码，可以将视频大小从 1280 x 720 调整为 640 x 360但是我想要一个没有裁剪的大小调整。

有没有办法完全调整不裁剪的大小？

这是代码

class func resizer(inputURL : NSURL , completion: (outPutURL : NSURL?) -> Void ){
        let videoAsset = AVAsset(URL: inputURL) as AVAsset
        let clipVideoTrack = videoAsset.tracksWithMediaType(AVMediaTypeVideo).first! as AVAssetTrack
        let composition = AVMutableComposition()
        composition.addMutableTrackWithMediaType(AVMediaTypeVideo, preferredTrackID: CMPersistentTrackID())
        let videoComposition = AVMutableVideoComposition()
        videoComposition.renderSize = CGSizeMake(360,640)
        videoComposition.frameDuration = CMTimeMake(1, 30)
        let instruction = AVMutableVideoCompositionInstruction()
        instruction.timeRange = CMTimeRangeMake(kCMTimeZero, CMTimeMakeWithSeconds(180, 30))
        let transformer : AVMutableVideoCompositionLayerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: clipVideoTrack)
        let t1 = CGAffineTransformMakeTranslation(360, 0)
        let t2 = CGAffineTransformRotate(t1, CGFloat(M_PI_2))
//        let t2 = CGAffineTransformMakeRotation(CGFloat(M_PI_2))
        transformer.setTransform(t2, atTime: kCMTimeZero)
        instruction.layerInstructions = [transformer]
        videoComposition.instructions = [instruction]

        let formatter = NSDateFormatter()
        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss'Z'"
        let date = NSDate()
        let tempDir = NSTemporaryDirectory().stringByAppendingString(formatter.stringFromDate(date))
        let d = "(tempDir).mp4"
        let outputURL = NSURL(fileURLWithPath: d)
        let exporter = AVAssetExportSession(asset: videoAsset, presetName: AVAssetExportPresetHighestQuality)
        exporter!.videoComposition = videoComposition
        exporter!.outputURL = outputURL
        exporter!.outputFileType = AVFileTypeQuickTimeMovie
        exporter?.exportAsynchronouslyWithCompletionHandler({ () -> Void in
            dispatch_async(dispatch_get_main_queue(), {
                completion(outPutURL: outputURL)
            })
        })
    }

Answer 1

我认为您正在寻找的(调整大小而不裁剪(也是缩放视频。 尝试使用CGAffineTransformScale/MakeScale。

https://developer.apple.com/library/ios/documentation/GraphicsImaging/Reference/CGAffineTransform/#//apple_ref/c/func/CGAffineTransformMakeScale

假设您的比率为 0.5 (1280/640(，您可以尝试以下方法：

let t3 = CGAffineTransformScale(t2, 0.5, 0.5)
transformer.setTransform(t3, atTime: kCMTimeZero)

如果看起来不正确，您可能还需要按比例调整平移。

Answer 2

In Swift 4

let playerLayer = AVPlayerLayer(player: player)
let transform = CGAffineTransform.init(scaleX: 0.5, y: 0.5)
playerLayer.setAffineTransform(transform)

医生