ios swift yuv格式转rgb格式

2020-05-08 03:40:15 计算机视觉

Swift ios RGB YUV

最近做项目遇到一个问题，iOS相机视频默认输出是yuv格式，然而图像处理类算法都是以rgb为输入，所以需要将yuv格式转为rgb格式，然后我用的是swift语言，在这里记录一下

yuv是一种图片储存格式，跟RGB格式类似。yuv中，y表示亮度，单独只有y数据就可以形成一张图片，只不过这张图片是灰色的。u和v表示色差(u和v也被称为：Cb－蓝色差，Cr－红色差)， yuv比rgb数据占用字节数少，而且传输过程中可以y\u\v三种分别传输，所以最常见的是在直播推流类应用，yuv会比较常见。

多的不谈了，代码先跟上。

extension CVPixelBuffer {
    public func toBGRA() throws -> CVPixelBuffer? {
        let pixelBuffer = self

        /// Check format
        let pixelFormat = CVPixelBufferGetPixelFormatType(pixelBuffer)
        guard pixelFormat == kCVPixelFormatType_420YpCbCr8BiPlanarFullRange || pixelFormat == kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange else { return pixelBuffer }
//        guard pixelFormat == kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange else { return pixelBuffer }

        /// Split plane
        let yImage = pixelBuffer.with({ VImage(pixelBuffer: $0, plane: 0, pixelFormat: pixelFormat) })!
        let cbcrImage = pixelBuffer.with({ VImage(pixelBuffer: $0, plane: 1, pixelFormat: pixelFormat) })!

        /// Create output pixelBuffer
        let outPixelBuffer = CVPixelBuffer.make(width: yImage.width, height: yImage.height, format: kCVPixelFormatType_32BGRA)!

        /// Convert yuv to argb
        var argbImage = outPixelBuffer.with({ VImage(pixelBuffer: $0, pixelFormat: pixelFormat) })!
        try argbImage.draw(yBuffer: yImage.buffer, cbcrBuffer: cbcrImage.buffer)
        /// Convert argb to bgra
        argbImage.permute(channelMap: [3, 2, 1, 0])
//        argbImage.permute(channelMap: [0, 1, 2, 3])

        return outPixelBuffer
    }
}

struct VImage {
    let width: Int
    let height: Int
    let bytesPerRow: Int
    var buffer: vImage_Buffer
    let pixelFotmat: OSType

    init?(pixelBuffer: CVPixelBuffer, plane: Int, pixelFormat: OSType) {
        guard let rawBuffer = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, plane) else { return nil }
        self.width = CVPixelBufferGetWidthOfPlane(pixelBuffer, plane)
        self.height = CVPixelBufferGetHeightOfPlane(pixelBuffer, plane)
        self.bytesPerRow = CVPixelBufferGetBytesPerRowOfPlane(pixelBuffer, plane)
        self.buffer = vImage_Buffer(
            data: UnsafeMutableRawPointer(mutating: rawBuffer),
            height: vImagePixelCount(height),
            width: vImagePixelCount(width),
            rowBytes: bytesPerRow
        )
        self.pixelFotmat = pixelFormat
    }

    init?(pixelBuffer: CVPixelBuffer, pixelFormat: OSType) {
        guard let rawBuffer = CVPixelBufferGetBaseAddress(pixelBuffer) else { return nil }
        self.width = CVPixelBufferGetWidth(pixelBuffer)
        self.height = CVPixelBufferGetHeight(pixelBuffer)
        self.bytesPerRow = CVPixelBufferGetBytesPerRow(pixelBuffer)
        self.buffer = vImage_Buffer(
            data: UnsafeMutableRawPointer(mutating: rawBuffer),
            height: vImagePixelCount(height),
            width: vImagePixelCount(width),
            rowBytes: bytesPerRow
        )
        self.pixelFotmat = pixelFormat
    }

    mutating func draw(yBuffer: vImage_Buffer, cbcrBuffer: vImage_Buffer) throws {
        try buffer.draw(yBuffer: yBuffer, cbcrBuffer: cbcrBuffer, pixelFormat: self.pixelFotmat)
    }

    mutating func permute(channelMap: [UInt8]) {
        buffer.permute(channelMap: channelMap)
    }
}

extension CVPixelBuffer {
    func with<T>(_ closure: ((_ pixelBuffer: CVPixelBuffer) -> T)) -> T {
        CVPixelBufferLockBaseAddress(self, .readOnly)
        let result = closure(self)
        CVPixelBufferUnlockBaseAddress(self, .readOnly)
        return result
    }

    static func make(width: Int, height: Int, format: OSType) -> CVPixelBuffer? {
        var pixelBuffer: CVPixelBuffer? = nil
        CVPixelBufferCreate(kCFAllocatorDefault,
                            width,
                            height,
                            format,
                            nil,
                            &pixelBuffer)
        return pixelBuffer
    }
}

extension vImage_Buffer {
    mutating func draw(yBuffer: vImage_Buffer, cbcrBuffer: vImage_Buffer, pixelFormat: OSType) throws {
        var yBuffer = yBuffer
        var cbcrBuffer = cbcrBuffer
        var conversionMatrix: vImage_YpCbCrToARGB
        if (pixelFormat == kCVPixelFormatType_420YpCbCr8BiPlanarFullRange) {
             conversionMatrix = {
                var pixelRange = vImage_YpCbCrPixelRange(Yp_bias: 0, CbCr_bias: 128, YpRangeMax: 255, CbCrRangeMax: 255, YpMax: 255, YpMin: 1, CbCrMax: 255, CbCrMin: 0)
                var matrix = vImage_YpCbCrToARGB()
                vImageConvert_YpCbCrToARGB_GenerateConversion(kvImage_YpCbCrToARGBMatrix_ITU_R_709_2, &pixelRange, &matrix, kvImage420Yp8_CbCr8, kvImageARGB8888, UInt32(kvImageNoFlags))
                return matrix
            }()
        } else if (pixelFormat == kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange) {
            conversionMatrix = {
                var pixelRange = vImage_YpCbCrPixelRange(Yp_bias: 16, CbCr_bias: 128, YpRangeMax: 235, CbCrRangeMax: 240, YpMax: 235, YpMin: 16, CbCrMax: 240, CbCrMin: 16)
                var matrix = vImage_YpCbCrToARGB()
                vImageConvert_YpCbCrToARGB_GenerateConversion(kvImage_YpCbCrToARGBMatrix_ITU_R_709_2, &pixelRange, &matrix, kvImage420Yp8_CbCr8, kvImageARGB8888, UInt32(kvImageNoFlags))
                return matrix
            }()
        } else {
            fatalError()
        }
        let error = vImageConvert_420Yp8_CbCr8ToARGB8888(&yBuffer, &cbcrBuffer, &self, &conversionMatrix, nil, 255, UInt32(kvImageNoFlags))
        if error != kvImageNoError {
            fatalError()
        }
    }

    mutating func permute(channelMap: [UInt8]) {
        vImagePermuteChannels_ARGB8888(&self, &self, channelMap, 0)
    }
}

我这里是转的BGRA格式，用的是CVPixelBuffer，从CMSampleBuffer获取CVPixelBuffer也很简单，

let pixelBuffer: CVPixelBuffer? = CMSampleBufferGetImageBuffer(buffer)

guard let imagePixelBuffer = pixelBuffer else {
    // 异常处理
}

然后直接调用就好了

let bgraImagePixelBuffer = try? pixelBuffer.toBGRA()
guard let oPixelBuffer = bgraImagePixelBuffer else {
    // 异常处理
}

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ios swift yuv格式转rgb格式

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