ios - 使用 swift 将视频裁剪并导出为圆形

Question

我想在“圆圈”中裁剪视频并存储它。这是我到目前为止所做的。但问题是它只以矩形裁剪视频。我想把它裁剪成圆形。我该怎么做？

    func cropVideo() {

    let asset = AVAsset.init(url: URL(fileURLWithPath: Bundle.main.path(forResource: "1", ofType: "mp4")!))
    let clipVideoTrack = asset.tracks(withMediaType: AVMediaTypeVideo)[0]
    let videoComposition = AVMutableVideoComposition()
    videoComposition.frameDuration = CMTimeMake(1, 30)
    videoComposition.renderSize = CGSize(width: clipVideoTrack.naturalSize.height, height: clipVideoTrack.naturalSize.height)
    let instruction = AVMutableVideoCompositionInstruction()
    instruction.timeRange = CMTimeRangeMake(kCMTimeZero, CMTimeMakeWithSeconds(60, 30))
    let transformer = AVMutableVideoCompositionLayerInstruction.init(assetTrack: clipVideoTrack)
    let t1 = CGAffineTransform(translationX: clipVideoTrack.naturalSize.height, y: 0)
    let t2 = t1.rotated(by: CGFloat(M_PI_2))
    let finalTransform = t2
    transformer.setTransform(finalTransform, at: kCMTimeZero)
    instruction.layerInstructions = [transformer]
    videoComposition.instructions = [instruction]


    let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
    let exportPath = documentsPath.appendingFormat("/CroppedVideo.mp4")
    let exportUrl = URL(fileURLWithPath: exportPath)
    print("export url  = \(exportUrl)")


    do {
        try FileManager.default.removeItem(at: exportUrl)
    }
    catch _ {
    }

    exporter = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetHighestQuality)
    exporter.videoComposition = videoComposition
    exporter.outputURL = exportUrl
    exporter.outputFileType = AVFileTypeQuickTimeMovie
    exporter.exportAsynchronously(completionHandler: {() -> Void in
        DispatchQueue.main.async(execute: {() -> Void in
            self.exportDidFinish(self.exporter)
        })
    })
}

func exportDidFinish(_ session: AVAssetExportSession) {
    let outputURL = session.outputURL
    print("outputurl  = \(outputURL)")

}

Answer 1

假设我上面的问题是正确的，诀窍是使用 mask 和圆形图像而不是使用 CGAffineTransform。我怀疑有一种方法可以使用 CGAffineTransform 来实现，但与此同时......

• 做一张中间有透明圆圈的图片
• 将其导入您的项目并加载
• 先添加视频层，然后添加 mask 图像
• 导出

这应该可以满足您的需求。关于这个 here 有一个稍旧的教程，往下看大约一半。