ios - 如何将 YUV 帧(从 OTVideoFrame)转换为 CVPixelBuffer

Question

我需要将 YUV 帧转换为从 OTVideoFrame 获得的 CVPixelBuffer类

此类提供视频帧中的平面数组，其中包含 y,u,v 帧的三个元素，每个元素位于索引 0,1,2。

@property (nonatomic, retain) NSPointerArray *planes

和format视频帧数

@property (nonatomic, retain) OTVideoFormat *format

包含框架的宽度、高度、bytesPerRow 等属性

我需要为以 OTVideoFrame 形式收到的图像添加过滤器，我已经尝试过这些答案:

• How to convert from YUV to CIImage for iOS
• Create CVPixelBuffer from YUV with IOSurface backed

这两个链接在 Objective-C 中有解决方案，但我想快速完成。第二个链接中的答案之一是快速的，但它缺少有关答案引用的 YUVFrame 结构的一些信息。

我收到的格式是NV12

这是我到目前为止一直在尝试做的事情，但我不知道下一步该怎么做:-

 /**
 * Calcualte the size of each plane from OTVideoFrame.
 *
 * @param frame The frame to render.
 * @return tuple containing three elements for size of each plane
 */
fileprivate func calculatePlaneSize(forFrame frame: OTVideoFrame)
        -> (ySize: Int, uSize: Int, vSize: Int){
            guard let frameFormat = frame.format
                else {
                    return (0, 0 ,0)
            }
            let baseSize = Int(frameFormat.imageWidth * frameFormat.imageHeight) * MemoryLayout<GLubyte>.size
            return (baseSize, baseSize / 4, baseSize / 4)
    }

/**
 * Renders a frame to the video renderer.
 *
 * @param frame The frame to render.
 */
func renderVideoFrame(_ frame: OTVideoFrame) {


    let planeSize = calculatePlaneSize(forFrame: frame)
    let yPlane = UnsafeMutablePointer<GLubyte>.allocate(capacity: planeSize.ySize)
    let uPlane = UnsafeMutablePointer<GLubyte>.allocate(capacity: planeSize.uSize)
    let vPlane = UnsafeMutablePointer<GLubyte>.allocate(capacity: planeSize.vSize)

    memcpy(yPlane, frame.planes?.pointer(at: 0), planeSize.ySize)
    memcpy(uPlane, frame.planes?.pointer(at: 1), planeSize.uSize)
    memcpy(vPlane, frame.planes?.pointer(at: 2), planeSize.vSize)

    let yStride = frame.format!.bytesPerRow.object(at: 0) as! Int
    // multiply chroma strides by 2 as bytesPerRow represents 2x2 subsample
    let uStride = frame.format!.bytesPerRow.object(at: 1) as! Int
    let vStride = frame.format!.bytesPerRow.object(at: 2) as! Int

    let width = frame.format!.imageWidth
    let height = frame.format!.imageHeight

    var pixelBuffer: CVPixelBuffer? = nil
    var err: CVReturn;


    err = CVPixelBufferCreate(kCFAllocatorDefault, Int(width), Int(height), kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange, nil, &pixelBuffer)
    if (err != 0) {
        NSLog("Error at CVPixelBufferCreate %d", err)
        fatalError()
    }

}

根据这两个链接的指导，我尝试创建 Pixel 缓冲区，但每次都卡在这一点上，因为此后 Objective-C 代码的转换与我们在 Swift 3 中的不相似。

Answer 1

对于那些正在寻找快速解决方案的人，我使用了 swift Accelerate 使用 vImageConvert_AnyToAny(_:_:_:_:_:) 函数。

import Foundation
import Accelerate
import UIKit
import OpenTok
class Accelerater{


    var infoYpCbCrToARGB = vImage_YpCbCrToARGB()
    init() {
        _ = configureYpCbCrToARGBInfo()
    }

    func configureYpCbCrToARGBInfo() -> vImage_Error {
        print("Configuring")
        var pixelRange = vImage_YpCbCrPixelRange(Yp_bias: 0,
                                                 CbCr_bias: 128,
                                                 YpRangeMax: 255,
                                                 CbCrRangeMax: 255,
                                                 YpMax: 255,
                                                 YpMin: 1,
                                                 CbCrMax: 255,
                                                 CbCrMin: 0)

        let error = vImageConvert_YpCbCrToARGB_GenerateConversion(
            kvImage_YpCbCrToARGBMatrix_ITU_R_601_4!,
            &pixelRange,
            &infoYpCbCrToARGB,
            kvImage420Yp8_Cb8_Cr8,
            kvImageARGB8888,
            vImage_Flags(kvImagePrintDiagnosticsToConsole))



        print("Configration done \(error)")
        return error
    }

    public func convertFrameVImageYUV(toUIImage frame: OTVideoFrame, flag: Bool) -> UIImage {

        var result: UIImage? = nil
        let width = frame.format?.imageWidth ?? 0
        let height = frame.format?.imageHeight ?? 0
        var pixelBuffer: CVPixelBuffer? = nil
        _ = CVPixelBufferCreate(kCFAllocatorDefault, Int(width), Int(height), kCVPixelFormatType_32BGRA, nil, &pixelBuffer)

        _ = convertFrameVImageYUV(frame, to: pixelBuffer)
        var ciImage: CIImage? = nil
        if let pixelBuffer = pixelBuffer {
            ciImage = CIImage(cvPixelBuffer: pixelBuffer)
        }

        let temporaryContext = CIContext(options: nil)
        var uiImage: CGImage? = nil
        if let ciImage = ciImage {
            uiImage = temporaryContext.createCGImage(ciImage, from: CGRect(x: 0, y: 0, width: CVPixelBufferGetWidth(pixelBuffer!), height: CVPixelBufferGetHeight(pixelBuffer!)))
        }

        if let uiImage = uiImage {
            result = UIImage(cgImage: uiImage)
        }
        CVPixelBufferUnlockBaseAddress(pixelBuffer!, [])
        return result!

    }

    func convertFrameVImageYUV(_ frame: OTVideoFrame, to pixelBufferRef: CVPixelBuffer?) -> vImage_Error{
        let start  = CFAbsoluteTimeGetCurrent()
        if pixelBufferRef == nil {
            print("No PixelBuffer refrance found")
            return vImage_Error(kvImageInvalidParameter)
        }

        let width = frame.format?.imageWidth ?? 0
        let height = frame.format?.imageHeight ?? 0
        let subsampledWidth = frame.format!.imageWidth/2
        let subsampledHeight = frame.format!.imageHeight/2
        print("subsample height \(subsampledHeight) \(subsampledWidth)")
        let planeSize = calculatePlaneSize(forFrame: frame)

        print("ysize : \(planeSize.ySize) \(planeSize.uSize) \(planeSize.vSize)")
        let yPlane = UnsafeMutablePointer<GLubyte>.allocate(capacity: planeSize.ySize)
        let uPlane = UnsafeMutablePointer<GLubyte>.allocate(capacity: planeSize.uSize)
        let vPlane = UnsafeMutablePointer<GLubyte>.allocate(capacity: planeSize.vSize)

        memcpy(yPlane, frame.planes?.pointer(at: 0), planeSize.ySize)
        memcpy(uPlane, frame.planes?.pointer(at: 1), planeSize.uSize)
        memcpy(vPlane, frame.planes?.pointer(at: 2), planeSize.vSize)

        let yStride = frame.format!.bytesPerRow.object(at: 0) as! Int
        // multiply chroma strides by 2 as bytesPerRow represents 2x2 subsample
        let uStride = frame.format!.bytesPerRow.object(at: 1) as! Int
        let vStride = frame.format!.bytesPerRow.object(at: 2) as! Int

        var yPlaneBuffer = vImage_Buffer(data: yPlane, height: vImagePixelCount(height), width: vImagePixelCount(width), rowBytes: yStride)

        var uPlaneBuffer = vImage_Buffer(data: uPlane, height: vImagePixelCount(subsampledHeight), width: vImagePixelCount(subsampledWidth), rowBytes: uStride)




        var vPlaneBuffer = vImage_Buffer(data: vPlane, height: vImagePixelCount(subsampledHeight), width: vImagePixelCount(subsampledWidth), rowBytes: vStride)
        CVPixelBufferLockBaseAddress(pixelBufferRef!, .readOnly)
        let pixelBufferData = CVPixelBufferGetBaseAddress(pixelBufferRef!)
        let rowBytes = CVPixelBufferGetBytesPerRow(pixelBufferRef!)
        var destinationImageBuffer = vImage_Buffer()
        destinationImageBuffer.data = pixelBufferData
        destinationImageBuffer.height = vImagePixelCount(height)
        destinationImageBuffer.width = vImagePixelCount(width)
        destinationImageBuffer.rowBytes = rowBytes

        var permuteMap: [UInt8] = [3, 2, 1, 0] // BGRA
        let convertError = vImageConvert_420Yp8_Cb8_Cr8ToARGB8888(&yPlaneBuffer, &uPlaneBuffer, &vPlaneBuffer, &destinationImageBuffer, &infoYpCbCrToARGB, &permuteMap, 255, vImage_Flags(kvImagePrintDiagnosticsToConsole))

        CVPixelBufferUnlockBaseAddress(pixelBufferRef!, [])


        yPlane.deallocate()
        uPlane.deallocate()
        vPlane.deallocate()
        let end = CFAbsoluteTimeGetCurrent()
        print("Decoding time \((end-start)*1000)")
        return convertError

    }
    fileprivate func calculatePlaneSize(forFrame frame: OTVideoFrame)
        -> (ySize: Int, uSize: Int, vSize: Int)
    {
        guard let frameFormat = frame.format
            else {
                return (0, 0 ,0)
        }
        let baseSize = Int(frameFormat.imageWidth * frameFormat.imageHeight) * MemoryLayout<GLubyte>.size
        return (baseSize, baseSize / 4, baseSize / 4)
    }

}

在iPhone7上进行性能测试，一帧转换不到一毫秒。