色域转换

[taontech]

先看效果

// https://user-images.githubusercontent.com/990488/164454078-0c6e6366-c34c-4da0-ade5-5113de4b8569.mov

转换过程中几个关键节点

CVPixelBuffer的创建

    func buffer(from ciimage:CIImage) -> CVPixelBuffer?{
        let attrs = [kCVPixelBufferCGImageCompatibilityKey: kCFBooleanTrue, kCVPixelBufferCGBitmapContextCompatibilityKey: kCFBooleanTrue] as CFDictionary
        var pixelBuffer : CVPixelBuffer?
        let status = CVPixelBufferCreate(kCFAllocatorDefault, Int(ciimage.extent.width), Int(ciimage.extent.height), kCVPixelFormatType_420YpCbCr10BiPlanarVideoRange, attrs, &pixelBuffer)
        guard (status == kCVReturnSuccess) else {
            return nil
        }
        let context = CIContext()
        let cs = context.workingColorSpace
        print(cs)
        context.render(ciimage, to: pixelBuffer!, bounds: ciimage.extent, colorSpace: CGColorSpace(name: CGColorSpace.itur_2100_HLG ))
        return pixelBuffer
    }

OutputSetting的设置

        let outputSize = (self.imageView?.image?.size)!
        let outputSettings = [
            AVVideoCodecKey: AVVideoCodecType.hevc,
            AVVideoWidthKey : NSNumber(value: Float(outputSize.width)),
            AVVideoHeightKey : NSNumber(value: Float(outputSize.height)),
            AVVideoColorPropertiesKey : [AVVideoTransferFunctionKey: AVVideoTransferFunction_ITU_R_2100_HLG,
                                        AVVideoColorPrimariesKey: AVVideoColorPrimaries_ITU_R_2020,
                                        AVVideoYCbCrMatrixKey: AVVideoYCbCrMatrix_ITU_R_2020
                                         ],
            AVVideoCompressionPropertiesKey: [AVVideoProfileLevelKey:kVTProfileLevel_HEVC_Main10_AutoLevel/*,AVVideoAverageBitRateKey:NSNumber(value: Float(3000000))*/ ,AVVideoQualityKey:NSNumber(value: Float(0.85)),AVVideoMaxKeyFrameIntervalKey:NSNumber(value: Float(250)),AVVideoMaxKeyFrameIntervalDurationKey:NSNumber(value: Float(10))]

        ] as [String:Any]
        guard videoWriter.canApply(outputSettings: outputSettings, forMediaType: .video) else {
            fatalError("输出设定不支持")
        }