使用AVFoundation可以拍摄视频，Avplayer播放视频。如果使用Metal取处理视频的话需要把视频的每一帧去处理然后显示，
需要用到CMSampleBuffer相关处理，本篇滤镜使用了Metal的内置滤镜MetalPerformanceShaders，MPS提供了许多常用的滤镜，具体可以参考apple官方文档
一、使用Metal处理实时拍摄视频
class ViewController: UIViewController { //按钮 var captureButton:UIButton! var recodButton:UIButton! var session : AVCaptureSession = AVCaptureSession() var queue = DispatchQueue(label: "quque") var input: AVCaptureDeviceInput? lazy var previewLayer = AVCaptureVideoPreviewLayer(session: self.session) lazy var recordOutput = AVCaptureMovieFileOutput() //Metal相关 var device :MTLDevice! var mtkView : MTKView! var texture : MTLTexture? var tetureCache : CVMetalTextureCache? override func viewDidLoad() { super.viewDidLoad() view.backgroundColor = .white captureButton = UIButton(frame: CGRect(x: 10, y: view.bounds.size.height - 60, width: 150, height: 50)) captureButton.backgroundColor = .gray captureButton.setTitle("start capture", for: .normal) captureButton.addTarget(self, action: #selector(capture(btn:)), for: .touchUpInside) view.addSubview(captureButton) recodButton = UIButton(frame: CGRect(x: view.bounds.size.width - 160, y: view.bounds.size.height - 60, width: 150, height: 50)) recodButton.backgroundColor = .gray recodButton.setTitle("paly movie", for: .normal) recodButton.addTarget(self, action: #selector(recordAction(btn:)), for: .touchUpInside) view.addSubview(recodButton) } func setMetalConfig() { guard let device1 = MTLCreateSystemDefaultDevice() else{ return } self.device = device1 mtkView = MTKView(frame: view.bounds, device: device) mtkView.delegate = self mtkView.framebufferOnly = false //创建纹理缓存区 CVMetalTextureCacheCreate(nil, nil, device1, nil, &tetureCache) } @objc func recordAction(btn:UIButton){ btn.isSelected = !btn.isSelected if session.isRunning { if btn.isSelected { btn.setTitle("stop record", for: .normal) if !session.isRunning{ session.startRunning() } if session.canAddOutput(recordOutput){ session.addOutput(recordOutput) } // recordOutput. let connection = recordOutput.connection(with: .video) connection?.preferredVideoStabilizationMode = .auto guard let path = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first else { return } let url = URL(fileURLWithPath: "\(path)/test.mp4") recordOutput.startRecording(to: url, recordingDelegate: self) }else{ btn.setTitle("start record", for: .normal) recordOutput.stopRecording() } }else{ // btn.setTitle("paly movie", for: .normal) let moVC = MovieViewController() self.navigationController?.pushViewController(moVC, animated: true) } } @objc func capture(btn:UIButton){ btn.isSelected = !btn.isSelected if btn.isSelected { // recodButton.isHidden = false recodButton.setTitle("start record", for: .normal) btn.setTitle("stop capture", for: UIControl.State.normal) guard let device = getCamera(postion: .back) else{ return } guard let input = try? AVCaptureDeviceInput(device: device) else{ return } self.input = input if session.canAddInput(input) { session.addInput(input) } let output = AVCaptureVideoDataOutput() output.setSampleBufferDelegate(self, queue: queue) if session.canAddOutput(output){ session.addOutput(output) } //这里设置格式为BGRA，而不用YUV的颜色空间，避免使用Shader转换 //注意:这里必须和后面CVMetalTextureCacheCreateTextureFromImage 保存图像像素存储格式保持一致.否则视频会出现异常现象. output.videoSettings = [String(kCVPixelBufferPixelFormatTypeKey) :NSNumber(value: kCVPixelFormatType_32BGRA) ] let connection: AVCaptureConnection = output.connection(with: .video)! connection.videoOrientation = .portrait // previewLayer.frame = view.bounds // view.layer.insertSublayer(previewLayer, at: 0) setMetalConfig() view.insertSubview(mtkView, at: 0) session.startRunning() }else{ // recodButton.isHidden = true btn.setTitle("start capture", for: .normal) if recordOutput.isRecording { recordOutput.stopRecording() } recodButton.isSelected = false recodButton.setTitle("play movie", for: .normal) session.stopRunning() // previewLayer.removeFromSuperlayer() mtkView.removeFromSuperview() } } //获取相机设备 func getCamera(postion: AVCaptureDevice.Position) -> AVCaptureDevice? { var devices = [AVCaptureDevice]() if #available(iOS 10.0, *) { let discoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [AVCaptureDevice.DeviceType.builtInWideAngleCamera], mediaType: AVMediaType.video, position: AVCaptureDevice.Position.unspecified) devices = discoverySession.devices } else { devices = AVCaptureDevice.devices(for: AVMediaType.video) } for device in devices { if device.position == postion { return device } } return nil } //切换摄像头 func swapFrontAndBackCameras() { if let input = input { var newDevice: AVCaptureDevice? if input.device.position == .front { newDevice = getCamera(postion: AVCaptureDevice.Position.back) } else { newDevice = getCamera(postion: AVCaptureDevice.Position.front) } if let new = newDevice { do{ let newInput = try AVCaptureDeviceInput(device: new) session.beginConfiguration() session.removeInput(input) session.addInput(newInput) self.input = newInput session.commitConfiguration() } catch let error as NSError { print("AVCaptureDeviceInput(): \(error)") } } } } //设置横竖屏问题 func setupVideoPreviewLayerOrientation() { if let connection = previewLayer.connection, connection.isVideoOrientationSupported { if #available(iOS 13.0, *) { if let orientation = UIApplication.shared.windows.first?.windowScene?.interfaceOrientation{ switch orientation { case .portrait: connection.videoOrientation = .portrait case .landscapeLeft: connection.videoOrientation = .landscapeLeft case .landscapeRight: connection.videoOrientation = .landscapeRight case .portraitUpsideDown: connection.videoOrientation = .portraitUpsideDown default: connection.videoOrientation = .portrait } } }else{ switch UIApplication.shared.statusBarOrientation { case .portrait: connection.videoOrientation = .portrait case .landscapeRight: connection.videoOrientation = .landscapeRight case .landscapeLeft: connection.videoOrientation = .landscapeLeft case .portraitUpsideDown: connection.videoOrientation = .portraitUpsideDown default: connection.videoOrientation = .portrait } } } } } extension ViewController : AVCaptureVideoDataOutputSampleBufferDelegate,AVCaptureFileOutputRecordingDelegate,MTKViewDelegate { //mtk func draw(in view: MTKView) { guard let queue = device.makeCommandQueue() else { return } guard let buffer = queue.makeCommandBuffer() else { return } // guard let descriptor = mtkView.currentRenderPassDescriptor else{return} // guard let encode = buffer.makeRenderCommandEncoder(descriptor: descriptor) else { // return // } //metal有许多内置滤镜 MetalPerformanceShaders let blurFilter = MPSImageGaussianBlur.init(device: device, sigma: 10) guard let texture = self.texture else { return } blurFilter.encode(commandBuffer: buffer, sourceTexture: texture, destinationTexture: view.currentDrawable!.texture) buffer.present(view.currentDrawable!) buffer.commit() self.texture = nil } func mtkView(_ view: MTKView, drawableSizeWillChange size: CGSize) { } //录制完成 func fileOutput(_ output: AVCaptureFileOutput, didFinishRecordingTo outputFileURL: URL, from connections: [AVCaptureConnection], error: Error?) { } //采集结果 func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) { guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else { return } // imageBuffer.attachments[0]. var metalTexture:CVMetalTexture? let status = CVMetalTextureCacheCreateTextureFromImage(kCFAllocatorDefault, self.tetureCache!, imageBuffer, nil, MTLPixelFormat.bgra8Unorm, CVPixelBufferGetWidth(imageBuffer), CVPixelBufferGetHeight(imageBuffer), 0, &metalTexture) if status == kCVReturnSuccess { mtkView.drawableSize = CGSize(width: CVPixelBufferGetWidth(imageBuffer), height: CVPixelBufferGetHeight(imageBuffer)) self.texture = CVMetalTextureGetTexture(metalTexture!) } } func captureOutput(_ output: AVCaptureOutput, didDrop sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) { } }
二、处理已有视频
import UIKit import AVFoundation import MetalKit import MetalPerformanceShaders struct ConvertMatrix { var matrix :float3x3 var verctor :SIMD3<Float> } class MovieViewController: UIViewController { var device :MTLDevice! var mtkView : MTKView! var reader: DQAssetReader? var texture : MTLTexture? var textureUV:MTLTexture? var tetureCache : CVMetalTextureCache? var state : MTLRenderPipelineState? var commendQueue: MTLCommandQueue? var vertexbuffer :MTLBuffer? var cmatrixBuffer :MTLBuffer? var useYUV = true var timeRange : CMTimeRange? var pauseButton:UIButton! override func viewDidLoad() { super.viewDidLoad() self.title = "movie" self.view.backgroundColor = .white let path = Bundle.main.path(forResource: "123", ofType: "mp4") let url1 = URL(fileURLWithPath: path!) reader = DQAssetReader(url: url1,valueYUV: useYUV) reader?.timeRange = CMTimeRange(start: CMTime(value: 2, timescale: 1, flags: CMTimeFlags(rawValue: 1), epoch: 0), duration: CMTime(value: 0, timescale: 0, flags: CMTimeFlags(rawValue: 5), epoch: 0)) setMetalConfig() vertexData() yuvToRGBmatrix() pauseButton = UIButton(frame: CGRect(x: 0, y: view.frame.size.height - 100, width: 100, height: 50)) pauseButton.center.x = view.center.x pauseButton.setTitle("暂停", for:.normal) pauseButton.setTitle("继续", for:.selected) pauseButton.backgroundColor = .gray view.addSubview(pauseButton) pauseButton.addTarget(self, action: #selector(pauseAction(btn:)), for: .touchUpInside) } @objc func pauseAction(btn:UIButton){ btn.isSelected = !btn.isSelected if !btn.isSelected { if reader?.readBuffer() == nil { reader?.setUpAsset() pauseButton.setTitle("继续", for:.selected) } } } func setMetalConfig() { guard let device1 = MTLCreateSystemDefaultDevice() else{ return } self.device = device1 mtkView = MTKView(frame: view.bounds, device: device) mtkView.delegate = self mtkView.framebufferOnly = false //创建纹理缓存区 CVMetalTextureCacheCreate(nil, nil, device1, nil, &tetureCache) view.addSubview(mtkView) let library = device.makeDefaultLibrary() let verFunc = library?.makeFunction(name: "vertexShader") let fragFunc = library?.makeFunction(name: "samplingShader") let descriptor = MTLRenderPipelineDescriptor() descriptor.fragmentFunction = fragFunc descriptor.vertexFunction = verFunc descriptor.colorAttachments[0].pixelFormat = mtkView.colorPixelFormat state = try? device.makeRenderPipelineState(descriptor: descriptor) commendQueue = device.makeCommandQueue() } func vertexData() { var vertex:[Float] = [ 1.0, -1.0, 0.0, 1.0, 1.0, 1.0,1.0,1.0, -1.0, -1.0, 0.0, 1.0, 0.0, 1.0,1.0,1.0, -1.0, 1.0, 0.0, 1.0, 0.0, 0.0,1.0,1.0, 1.0, -1.0, 0.0, 1.0, 1.0, 1.0,1.0,1.0, -1.0, 1.0, 0.0, 1.0, 0.0, 0.0,1.0,1.0, 1.0, 1.0, 0.0, 1.0, 1.0, 0.0,1.0,1.0 ] vertexbuffer = device.makeBuffer(bytes: &vertex, length: MemoryLayout<Float>.size * vertex.count, options: MTLResourceOptions.storageModeShared) } func changeVertex(sampleBuffer:CMSampleBuffer) { var vertexs:[Float] = [ 1.0, -1.0, 0.0, 1.0, 1.0, 1.0,1.0,1.0, -1.0, -1.0, 0.0, 1.0, 0.0, 1.0,1.0,1.0, -1.0, 1.0, 0.0, 1.0, 0.0, 0.0,1.0,1.0, 1.0, -1.0, 0.0, 1.0, 1.0, 1.0,1.0,1.0, -1.0, 1.0, 0.0, 1.0, 0.0, 0.0,1.0,1.0, 1.0, 1.0, 0.0, 1.0, 1.0, 0.0,1.0,1.0 ] guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else { return } let width = CVPixelBufferGetWidth(imageBuffer) let height = CVPixelBufferGetHeight(imageBuffer) let scaleF = CGFloat(view.frame.height)/CGFloat(view.frame.width) let scaleI = CGFloat(height)/CGFloat(width) let imageScale = scaleF>scaleI ? (1,scaleI/scaleF) : (scaleF/scaleI,1) for (i,v) in vertexs.enumerated(){ if i % 8 == 0 { vertexs[i] = v * Float(imageScale.0) } if i % 8 == 1{ vertexs[i] = v * Float(imageScale.1) } } vertexbuffer = device.makeBuffer(bytes: vertexs, length: MemoryLayout<Float>.size * vertexs.count, options: MTLResourceOptions.storageModeShared) } func yuvToRGBmatrix() { /* YUV与RGB相互转化公式 传输时使用YUV节省空间大小 4:4:4 YUV全部取值。 不节省空间 4:2:2 U/V隔一个取一个。 节省1/3 4:2:0 第一行取U，第二行取V，还是隔一个取一个 节省1/2 Y = 0.299 * R + 0.587 * G + 0.114 * B U = -0.174 * R - 0.289 * G + 0.436 * B V = 0.615 * R - 0.515 * G - 0.100 * B R = Y + 1.14 V G = Y - 0.390 * U - 0.58 * V B = Y + 2.03 * U */ //1.转化矩阵 // BT.601, which is the standard for SDTV. let kColorConversion601DefaultMatrix = float3x3( SIMD3<Float>(1.164,1.164, 1.164), SIMD3<Float>(0.0, -0.392, 2.017), SIMD3<Float>(1.596, -0.813, 0.0)) // BT.601 full range let kColorConversion601FullRangeMatrix = float3x3( SIMD3<Float>(1.0, 1.0, 1.0), SIMD3<Float>(0.0, -0.343, 1.765), SIMD3<Float>(1.4, -0.711, 0.0)) // BT.709, which is the standard for HDTV. let kColorConversion709DefaultMatrix = float3x3( SIMD3<Float>(1.164, 1.164, 1.164), SIMD3<Float>(0.0, -0.213, 2.112), SIMD3<Float>(1.793, -0.533, 0.0)) // let offset = SIMD3<Float>(-(16.0/255.0), -0.5, -0.5) var cMatrix = ConvertMatrix(matrix: kColorConversion601FullRangeMatrix, verctor: offset) self.cmatrixBuffer = device.makeBuffer(bytes: &cMatrix, length: MemoryLayout<ConvertMatrix>.size, options: .storageModeShared) } } extension MovieViewController:MTKViewDelegate { func mtkView(_ view: MTKView, drawableSizeWillChange size: CGSize) { } func draw(in view: MTKView) { if pauseButton.isSelected { return } guard let commandBuffer = commendQueue?.makeCommandBuffer() else { return } //texture guard let sample = self.reader?.readBuffer() else { pauseButton.isSelected = true pauseButton.setTitle("重播", for: UIControl.State.selected) return } //encode guard let passDescriptor = view.currentRenderPassDescriptor else{return} passDescriptor.colorAttachments[0].clearColor = MTLClearColorMake(0.3, 0.1, 0.4, 1) guard let encode = commandBuffer.makeRenderCommandEncoder(descriptor: passDescriptor) else{return} guard let pipeState = self.state else {return} encode.setRenderPipelineState(pipeState) encode.setViewport(MTLViewport(originX: 0, originY: 0, width: Double(view.drawableSize.width), height: Double(view.drawableSize.height), znear: -1, zfar: 1)) changeVertex(sampleBuffer: sample) encode.setVertexBuffer(vertexbuffer, offset: 0, index: 0) encode.setFragmentBuffer(cmatrixBuffer, offset: 0, index: 0) setTextureWithEncoder(encoder: encode,sampleBuffer: sample,yuv: useYUV) if let blendTex = ImageTool.setUpImageTexture(imageName: "image.jpg", device: device) { encode.setFragmentTexture(blendTex, index: 2) } encode.drawPrimitives(type: .triangle, vertexStart: 0, vertexCount: 6) encode.endEncoding() commandBuffer.present(view.currentDrawable!) commandBuffer.commit() self.texture = nil } func setTextureWithEncoder(encoder:MTLRenderCommandEncoder,sampleBuffer:CMSampleBuffer,yuv:Bool = false) { guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else { return } func settexture(index:Int){ var pixelFormat:MTLPixelFormat = .bgra8Unorm if index == -1{ pixelFormat = .bgra8Unorm }else if index == 0{ pixelFormat = .r8Unorm }else if index == 1{ pixelFormat = .rg8Unorm } var metalTexture:CVImageBuffer? let width = CVPixelBufferGetWidthOfPlane(imageBuffer, index == -1 ? 0 : index) let hieght = CVPixelBufferGetHeightOfPlane(imageBuffer, index == -1 ? 0 : index) let status = CVMetalTextureCacheCreateTextureFromImage(kCFAllocatorDefault, self.tetureCache!, imageBuffer, nil, pixelFormat, width, hieght, index == -1 ? 0 : index, &metalTexture) if status == kCVReturnSuccess{ if index == 1 { self.textureUV = CVMetalTextureGetTexture(metalTexture!) encoder.setFragmentTexture(self.textureUV, index: 1) }else{ self.texture = CVMetalTextureGetTexture(metalTexture!) encoder.setFragmentTexture(self.texture, index: 0) } } } if yuv { settexture(index: 0) settexture(index: 1) }else{ settexture(index: -1) } } }
三、逐帧获取视频文件每帧的工具类
class DQAssetReader: NSObject { var readerVideoTrackOutput:AVAssetReaderTrackOutput? var assetReader:AVAssetReader! var lockObjc = NSObject() var videoUrl:URL var inputAsset :AVAsset! var YUV : Bool = false var timeRange:CMTimeRange? var loop: Bool = false init(url:URL,valueYUV:Bool = false) { videoUrl = url YUV = valueYUV super.init() setUpAsset() } func setUpAsset(startRead:Bool = true) { //创建AVUrlAsset，用于从本地/远程URL初始化资源 //AVURLAssetPreferPreciseDurationAndTimingKey 默认为NO,YES表示提供精确的时长 inputAsset = AVURLAsset(url: videoUrl, options: [AVURLAssetPreferPreciseDurationAndTimingKey:true]) //对资源所需的键执行标准的异步载入操作,这样就可以访问资源的tracks属性时,就不会受到阻碍. inputAsset.loadValuesAsynchronously(forKeys: ["tracks"]) {[weak self] in guard let `self` = self else{ return } //开辟子线程并发队列异步函数来处理读取的inputAsset DispatchQueue.global().async {[weak self] in guard let `self` = self else{ return } var error: NSError? let tracksStatus = self.inputAsset.statusOfValue(forKey: "tracks", error: &error) //如果状态不等于成功加载,则返回并打印错误信息 if tracksStatus != .loaded{ print(error?.description as Any) return } self.processAsset(asset: self.inputAsset,startRead: startRead) } } } func processAsset(asset:AVAsset,startRead:Bool = true) { //加锁 objc_sync_enter(lockObjc) //创建AVAssetReader guard let assetReader1 = try? AVAssetReader(asset: asset) else { return } assetReader = assetReader1 // /* 2.kCVPixelBufferPixelFormatTypeKey 像素格式. kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange : 420v(YUV) kCVPixelFormatType_32BGRA : iOS在内部进行YUV至BGRA格式转换 3. 设置readerVideoTrackOutput assetReaderTrackOutputWithTrack:(AVAssetTrack *)track outputSettings:(nullable NSDictionary<NSString *, id> *)outputSettings 参数1: 表示读取资源中什么信息 参数2: 视频参数 */ let pixelFormat = YUV ? kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange : kCVPixelFormatType_32BGRA readerVideoTrackOutput = AVAssetReaderTrackOutput(track: asset.tracks(withMediaType: .video).first!, outputSettings:[String(kCVPixelBufferPixelFormatTypeKey) :NSNumber(value: pixelFormat)]) //alwaysCopiesSampleData : 表示缓存区的数据输出之前是否会被复制.YES:输出总是从缓存区提供复制的数据,你可以自由的修改这些缓存区数据The default value is YES. readerVideoTrackOutput?.alwaysCopiesSampleData = false if assetReader.canAdd(readerVideoTrackOutput!){ assetReader.add(readerVideoTrackOutput!) } //开始读取 if startRead { if assetReader.startReading() == false { print("reading file error") } } //解锁 objc_sync_exit(lockObjc) } //读取每一帧 func readBuffer() -> CMSampleBuffer? { objc_sync_enter(lockObjc) var sampleBuffer:CMSampleBuffer? if let readerTrackout = self.readerVideoTrackOutput { sampleBuffer = readerTrackout.copyNextSampleBuffer() } //判断assetReader 并且status 是已经完成读取 则重新清空readerVideoTrackOutput/assetReader.并重新初始化它们 if assetReader != nil,assetReader.status == .completed { readerVideoTrackOutput = nil assetReader = nil if loop { self.setUpAsset() } } //时间 // print(sampleBuffer?.presentationTimeStamp.value as Any) objc_sync_exit(lockObjc) return sampleBuffer } }
四、Metal文件代码
#include <metal_stdlib> using namespace metal; //顶点数据结构 typedef struct { //顶点坐标(x,y,z,w) vector_float4 position; //纹理坐标(s,t) vector_float2 textureCoordinate; } CCVertex; //转换矩阵 typedef struct { //三维矩阵 float3x3 matrix; //偏移量 vector_float3 offset; } CCConvertMatrix; //结构体(用于顶点函数输出/片元函数输入) typedef struct { float4 clipSpacePosition [[position]]; // position的修饰符表示这个是顶点 float2 textureCoordinate; // 纹理坐标 } RasterizerData; //RasterizerData 返回数据类型->片元函数 // vertex_id是顶点shader每次处理的index，用于定位当前的顶点 // buffer表明是缓存数据，0是索引 vertex RasterizerData vertexShader(uint vertexID [[ vertex_id ]], constant CCVertex *vertexArray [[ buffer(0) ]]) { RasterizerData out; //顶点坐标 out.clipSpacePosition = vertexArray[vertexID].position; //纹理坐标 out.textureCoordinate = vertexArray[vertexID].textureCoordinate; return out; } //YUV->RGB 参考学习链接: https://mp.weixin.qq.com/s/KKfkS5QpwPAdYcEwFAN9VA // stage_in表示这个数据来自光栅化。（光栅化是顶点处理之后的步骤，业务层无法修改） // texture表明是纹理数据，CCFragmentTextureIndexTextureY是索引 // texture表明是纹理数据，CCFragmentTextureIndexTextureUV是索引 // buffer表明是缓存数据， CCFragmentInputIndexMatrix是索引 fragment float4 samplingShader(RasterizerData input [[stage_in]], texture2d<float> textureY [[ texture(0) ]], texture2d<float> textureUV [[ texture(1) ]], texture2d<float> textureBlend [[ texture(2) ]], constant CCConvertMatrix *convertMatrix [[ buffer(0) ]] ) { //1.获取纹理采样器 constexpr sampler textureSampler (mag_filter::linear, min_filter::linear); /* 2. 读取YUV 颜色值 textureY.sample(textureSampler, input.textureCoordinate).r 从textureY中的纹理采集器中读取,纹理坐标对应上的R值.(Y) textureUV.sample(textureSampler, input.textureCoordinate).rg 从textureUV中的纹理采集器中读取,纹理坐标对应上的RG值.(UV) */ float3 yuv = float3(textureY.sample(textureSampler, input.textureCoordinate).r, textureUV.sample(textureSampler, input.textureCoordinate).rg); float Y = textureY.sample(textureSampler, input.textureCoordinate).r; float3 rgb1 = float3(Y,Y,Y);//黑白的 //3.将YUV 转化为 RGB值.convertMatrix->matrix * (YUV + convertMatrix->offset) float3 rgb = convertMatrix->matrix * (yuv + convertMatrix->offset); //混合滤镜颜色 float4 blend = textureBlend.sample(textureSampler, input.textureCoordinate); return float4(rgb,1.0) * 0.4 + blend * 0.6; //4.返回颜色值(RGBA) // return float4(rgb, 1.0); }