我正在制作一个迅速的视频应用程序。
在我的应用程序中，我需要进行裁剪和水平翻转cvpixelbuffer并返回结果，哪种类型也是cvpixelbuffer。
我尝试了几件事。
首先，我使用了'cvpixelbuffercreatewithbytes'
func resizePixelBuffer(_ pixelBuffer: CVPixelBuffer, destSize: CGSize)
-> CVPixelBuffer?
{
CVPixelBufferLockAddress(pixelBuffer, CVPixelBufferLockFlags(rawValue: O))
let baseAddress = CVPixelBufferGetBaseAddress(pixelBuffer)
let bytesPerRow = CVPixelBufferGetBytesPerRow(pixelBuffer)
let pixelFormat = CVPixelBufferGetPixelFormatType(pixelBuffer)
let width = CVPixelBufferGetWidth(pixelBuffer)
let height = CVPixelBufferGetHeight(pixelBuffer)
var destPixelBuffer: CVPixelBuffer?
let topMargin = (height - destsize.height) / 2
let leftMargin = (width - destsize.width) / 2 * 4 // bytesPerPixel
let offset = topMargin * bytesPerRow + leftMargin
CVPixelBufferCreateWithBytes(kCFAllocatorDefault,
destSize.width,
destSize.height,
pixelFormat,
baseAddress.advanced(by: offset),
bytesPerRow,
nil, nil, nil,
&destPixelBuffer)
CVPixelBufferUnlockBaseAddress(pixelBuffer, CVPixelBufferLockFlags(rawValue: O))
return destPixelBuffer
)
使用此代码，我可以直接裁剪cvpixelbuffer并返回cvpixelbuffer。但是，我不知道如何水平翻转cvplxelbuffer。
所以我尝试了其他解决方案。
秒，我将cvpixelbuffer转换为ciimage，然后返回到cvpixelbuffer
func resizePixelBuffer(_ pixelBuffer, destSize: CGSize)
-> CVPixelBuffer?
{
let bufferWidth = CVPixelBufferGetWidth(pixelBuffer)
let bufferHeight = CVPixelBufferGetHeight(pixelBuffer)
let ciImage = CIImage(cvPixelBuffer: pixelBuffer)
let rect = CGRect(x: (bufferWidth - destSize.width)/2, y: (bufferHeight - destSize.height)/2, width: destSize.width, height: destSize.height)
let croppedImage = ciImage.cropped(to: rect)
croppedImage.transformed(by: CGAffineTransform(translateX: -1, y: 0))
var destPixelBuffer: CVPixelBuffer?
CVPixelBufferCreate(kCFAllocatorDefault, destSize.width, destSize.height,
CVPixelBufferGetPixelFormatType(pixelBuffer), nil,
&destPixelBuffer)
CIContext().render(croppedImage, to: destPixelBuffer!, bounds: croppedImage.extent, croppedImage.colorSpace)
return destPixelBuffer
}
，但结果不是我所期望的。图像的某些部分是黑色的，我认为cgaffinetransform不起作用。
最后，我尝试转换为cgimage
func resizePixelBuffer(_ pixelBuffer: CVPixelBuffer, destSize: CGSize)
-> CVPixelBuffer?
{
let ciImage = CIImage(cvPixelBuffer: pixelBuffer)
let cgImage = CIContext().createCGImage(ciImage, from: ciImage.extent)
let rect = CGRect(x: (bufferWidth - destSize.width)/2, y: (bufferHeight - destSize.height)/2, width: destSize.width, height: destSize.height)
let croppedImage = cgImage.cropping(to: rect)
let width = croppedImage.width
let height = croppedImage.height
let pixelFormat = CVPixelBufferGetPixelFormatType(pixelBuffer)
var destPixelBuffer: CVPixelBuffer?
CVPixelBufferCreate(kCFAllocatorDefault, width, height, pixelFormat, &destPixelBuffer)
CVPixelBufferLockBaseAddress(destPixelBuffer, CVPixelBufferLockFlags(rawValue: 0))
let destBaseAddress = CVPixelBufferGetBaseAddress(destPixelBuffer)
let destBytesPerRow = CVPixelBufferGetBytesPerRow(destPixelBuffer)
let context = CGContext(data: destBaseAddress,
width: width,
height: height,
bitsPerComponent: 8,
bytesPerRow: destBytesPerRow,
space: croppedImage.colorSpace,
bitmapInfo: CGImageAlphaInfo.premultipliedFirst.rawValue | CGBitmapInfo.byteOrder32Little.rawValue)
context?.concatenate(__CGAffineTransformMake( 1, 0, 0, -1, 0, CGFloat(height)))
context?.draw(croppedCgImage, in: CGRect(x: 0, y: 0, width: CGFloat(width), height: CGFloat(height)))
CVPixelBufferUnlockBaseAddress(srcPixelBuffer, CVPixelBufferLockFlags(rawValue: 0))
return destPixelBuffer
}
此时，输出pixelbuffer是完全黑色的。
我不知道如何裁剪和翻转cvpixelbuffer并返回cvpixelbuffer。
我认为转换CIIMAGE或CGIMAGE是更好的方法，因为我可以使用这些格式来处理很多事情。
，但我不知道如何掩盖这些格式回到cvpixelbuffer。
请让我知道该怎么做。
这是使用vImage中的CVPixelBuffer流。
- 检查iOS-缩放和裁剪CMMAMPLEBUFFERREF/CVIMAGEBUFFERREF农作物如何用于缓冲液
- 检查https://developer.apple.com/documentation/accelerate/reading_from_and_writing_to_core_core_video_pixel_buffers in Vimage上的基本用法。基本上，您需要创建源和目标缓冲区并在其上应用转换。
- vimageBuffer从https://github.com/tensorflow/tensorflow/examples/blob/master/lite/lite/lite/examplection/object_detection/objection/objectdetection/extection/extentection/extensions/cvpppppixelbufferextension.swift
import Cocoa import Accelerate extension CVPixelBuffer { func crop(to rect: CGRect) -> CVPixelBuffer? { CVPixelBufferLockBaseAddress(self, .readOnly) defer { CVPixelBufferUnlockBaseAddress(self, .readOnly) } guard let baseAddress = CVPixelBufferGetBaseAddress(self) else { return nil } let inputImageRowBytes = CVPixelBufferGetBytesPerRow(self) let imageChannels = 4 let startPos = Int(rect.origin.y) * inputImageRowBytes + imageChannels * Int(rect.origin.x) let outWidth = UInt(rect.width) let outHeight = UInt(rect.height) let croppedImageRowBytes = Int(outWidth) * imageChannels var inBuffer = vImage_Buffer() inBuffer.height = outHeight inBuffer.width = outWidth inBuffer.rowBytes = inputImageRowBytes inBuffer.data = baseAddress + UnsafeMutableRawPointer.Stride(startPos) guard let croppedImageBytes = malloc(Int(outHeight) * croppedImageRowBytes) else { return nil } var outBuffer = vImage_Buffer(data: croppedImageBytes, height: outHeight, width: outWidth, rowBytes: croppedImageRowBytes) let scaleError = vImageScale_ARGB8888(&inBuffer, &outBuffer, nil, vImage_Flags(0)) guard scaleError == kvImageNoError else { free(croppedImageBytes) return nil } return croppedImageBytes.toCVPixelBuffer(pixelBuffer: self, targetWith: Int(outWidth), targetHeight: Int(outHeight), targetImageRowBytes: croppedImageRowBytes) } func flip() -> CVPixelBuffer? { CVPixelBufferLockBaseAddress(self, .readOnly) defer { CVPixelBufferUnlockBaseAddress(self, .readOnly) } guard let baseAddress = CVPixelBufferGetBaseAddress(self) else { return nil } let width = UInt(CVPixelBufferGetWidth(self)) let height = UInt(CVPixelBufferGetHeight(self)) let inputImageRowBytes = CVPixelBufferGetBytesPerRow(self) let outputImageRowBytes = inputImageRowBytes var inBuffer = vImage_Buffer( data: baseAddress, height: height, width: width, rowBytes: inputImageRowBytes) guard let targetImageBytes = malloc(Int(height) * outputImageRowBytes) else { return nil } var outBuffer = vImage_Buffer(data: targetImageBytes, height: height, width: width, rowBytes: outputImageRowBytes) // See https://developer.apple.com/documentation/accelerate/vimage/vimage_operations/image_reflection for other transformations let reflectError = vImageHorizontalReflect_ARGB8888(&inBuffer, &outBuffer, vImage_Flags(0)) // let reflectError = vImageVerticalReflect_ARGB8888(&inBuffer, &outBuffer, vImage_Flags(0)) guard reflectError == kvImageNoError else { free(targetImageBytes) return nil } return targetImageBytes.toCVPixelBuffer(pixelBuffer: self, targetWith: Int(width), targetHeight: Int(height), targetImageRowBytes: outputImageRowBytes) } } extension UnsafeMutableRawPointer { // Converts the vImage buffer to CVPixelBuffer func toCVPixelBuffer(pixelBuffer: CVPixelBuffer, targetWith: Int, targetHeight: Int, targetImageRowBytes: Int) -> CVPixelBuffer? { let pixelBufferType = CVPixelBufferGetPixelFormatType(pixelBuffer) let releaseCallBack: CVPixelBufferReleaseBytesCallback = {mutablePointer, pointer in if let pointer = pointer { free(UnsafeMutableRawPointer(mutating: pointer)) } } var targetPixelBuffer: CVPixelBuffer? let conversionStatus = CVPixelBufferCreateWithBytes(nil, targetWith, targetHeight, pixelBufferType, self, targetImageRowBytes, releaseCallBack, nil, nil, &targetPixelBuffer) guard conversionStatus == kCVReturnSuccess else { free(self) return nil } return targetPixelBuffer } } // Change this to your input pixelBuffer var pixelBuffer: CVPixelBuffer? // The result would be stored in resultPixelBuffer let resultPixelBuffer = pixelBuffer?.crop(to: CGRect(x: 50, y: 50, width: 100, height: 100))?.flip()