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如何直接从ciimage而不是swift中的uiimage生成cvPixelBuffer?

cvpixelbuffer ciimage avassetwriter uiimage swift

1

Chewie The Chorkie · 技术社区 · 6 年前

我正在通过iPhone摄像头录制过滤后的视频,并且在录制时将ciimage实时转换为uiimage时,CPU使用率会大幅增加。我的buffer函数使cvPixelBuffer使用uiImage,到目前为止,这需要我进行这个转换。我想做一个缓冲函数,如果可能的话,它将获取一个ciimage,这样我可以跳过从uiimage到ciimage的转换。我在想,这将给我在录制视频时的性能一个巨大的提升,因为CPU和GPU之间不会有任何交接。

这就是我现在拥有的。在captureoutput函数中,我从ciimage创建一个uiimage,它是过滤后的图像。我使用uiimage从buffer函数创建cvPixelBuffer,并将其附加到AssetWriter的PixelBuffer输入:

let imageUI = UIImage(ciImage: ciImage)

let filteredBuffer:CVPixelBuffer? = buffer(from: imageUI)

let success = self.assetWriterPixelBufferInput?.append(filteredBuffer!, withPresentationTime: self.currentSampleTime!)

使用uiimage的缓冲区函数:

func buffer(from image: UIImage) -> CVPixelBuffer? {
    let attrs = [kCVPixelBufferCGImageCompatibilityKey: kCFBooleanTrue, kCVPixelBufferCGBitmapContextCompatibilityKey: kCFBooleanTrue] as CFDictionary
    var pixelBuffer : CVPixelBuffer?
    let status = CVPixelBufferCreate(kCFAllocatorDefault, Int(image.size.width), Int(image.size.height), kCVPixelFormatType_32ARGB, attrs, &pixelBuffer)

    guard (status == kCVReturnSuccess) else {
        return nil
    }

    CVPixelBufferLockBaseAddress(pixelBuffer!, CVPixelBufferLockFlags(rawValue: 0))
    let pixelData = CVPixelBufferGetBaseAddress(pixelBuffer!)

    let videoRecContext = CGContext(data: pixelData,
                            width: Int(image.size.width),
                            height: Int(image.size.height),
                            bitsPerComponent: 8,
                            bytesPerRow: videoRecBytesPerRow,
                            space: (MTLCaptureView?.colorSpace)!, // It's getting the current colorspace from a MTKView
                            bitmapInfo: CGImageAlphaInfo.noneSkipFirst.rawValue)

    videoRecContext?.translateBy(x: 0, y: image.size.height)
    videoRecContext?.scaleBy(x: 1.0, y: -1.0)

    UIGraphicsPushContext(videoRecContext!)
    image.draw(in: CGRect(x: 0, y: 0, width: image.size.width, height: image.size.height))
    UIGraphicsPopContext()
    CVPixelBufferUnlockBaseAddress(pixelBuffer!, CVPixelBufferLockFlags(rawValue: 0))

    return pixelBuffer
}

2 回复 | 直到 6 年前

1

2

rob mayoff 6 年前

创建一个 CIContext 用它来渲染 CIImage 直接到您的 CVPixelBuffer 使用 CIContext.render(_: CIImage, to buffer: CVPixelBuffer) .

2

1

Chewie The Chorkie 6 年前

为了扩展我从Rob Mayoff那里得到的答案,我将在下面显示我所做的更改:

在captureoutput函数中,我将代码更改为:

let filteredBuffer : CVPixelBuffer? = buffer(from: ciImage)

filterContext?.render(_:ciImage, to:filteredBuffer!)

let success = self.assetWriterPixelBufferInput?.append(filteredBuffer!, withPresentationTime: self.currentSampleTime!)

注意,buffer函数传递一个ciimage。我对缓冲区函数进行了格式化,以传递ciimage,并能够清除其中的许多内容:

func buffer(from image: CIImage) -> CVPixelBuffer? {
    let attrs = [kCVPixelBufferCGImageCompatibilityKey: kCFBooleanTrue, kCVPixelBufferCGBitmapContextCompatibilityKey: kCFBooleanTrue] as CFDictionary
    var pixelBuffer : CVPixelBuffer?
    let status = CVPixelBufferCreate(kCFAllocatorDefault, Int(image.extent.width), Int(image.extent.height), kCVPixelFormatType_32ARGB, attrs, &pixelBuffer)

    guard (status == kCVReturnSuccess) else {
        return nil
    }

    return pixelBuffer
}