Question

我正在AVCaptureVideoDataOutput中从GLKView绘制一个相机输出，但是相机是4：3，这与GLKView的宽高比不匹配（这是全屏）。我正试图获得一个方面填充，但相机输出似乎被压扁，以便它不会越过视图的边缘。如何在不弄乱纵横比的情况下使用GLKView获取全屏摄像机视图？

初始化视图：

videoDisplayView = GLKView(frame: superview.bounds, context: EAGLContext(api: .openGLES2))
videoDisplayView.transform = CGAffineTransform(rotationAngle: CGFloat(M_PI_2))
videoDisplayView.frame = superview.bounds
superview.addSubview(videoDisplayView)
superview.sendSubview(toBack: videoDisplayView)

renderContext = CIContext(eaglContext: videoDisplayView.context)
sessionQueue = DispatchQueue(label: "AVSessionQueue", attributes: [])

videoDisplayView.bindDrawable()
videoDisplayViewBounds = CGRect(x: 0, y: 0, width: videoDisplayView.drawableWidth, height: videoDisplayView.drawableHeight)

初始化视频输出：

let videoOutput = AVCaptureVideoDataOutput()
videoOutput.setSampleBufferDelegate(self, queue: sessionQueue)
if captureSession.canAddOutput(videoOutput) {
    captureSession.addOutput(videoOutput)
}

渲染输出：

func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!) {

    // Need to shimmy this through type-hell
    let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)
    // Force the type change - pass through opaque buffer
    let opaqueBuffer = Unmanaged<CVImageBuffer>.passUnretained(imageBuffer!).toOpaque()
    let pixelBuffer = Unmanaged<CVPixelBuffer>.fromOpaque(opaqueBuffer).takeUnretainedValue()

    let sourceImage = CIImage(cvPixelBuffer: pixelBuffer, options: nil)

    // Do some detection on the image
    let detectionResult = applyFilter?(sourceImage)
    var outputImage = sourceImage
    if detectionResult != nil {
        outputImage = detectionResult!
    }

    if videoDisplayView.context != EAGLContext.current() {
        EAGLContext.setCurrent(videoDisplayView.context)
    }
    videoDisplayView.bindDrawable()

    // clear eagl view to grey
    glClearColor(0.5, 0.5, 0.5, 1.0);
    glClear(0x00004000)

    // set the blend mode to "source over" so that CI will use that
    glEnable(0x0BE2);
    glBlendFunc(1, 0x0303);

    renderContext.draw(outputImage, in: videoDisplayViewBounds, from: outputImage.extent)

    videoDisplayView.display()
}

我尝试过的事情：

// Results in 4:3 stream leaving a gap at the bottom
renderContext.draw(outputImage, in: outputImage.extent, from: outputImage.extent)

// Results in same 4:3 stream
let rect = CGRect(x: 0, y: 0, width: outputImage.extent.width, height: videoDisplayViewBounds.height)
renderContext.draw(outputImage, in: rect, from: outputImage.extent)

Answer 1

我实际上最终不得不将输出裁剪为我正在显示输出的视图的大小。

func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!) {

    // Need to shimmy this through type-hell
    let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)
    // Force the type change - pass through opaque buffer
    let opaqueBuffer = Unmanaged<CVImageBuffer>.passUnretained(imageBuffer!).toOpaque()
    let pixelBuffer = Unmanaged<CVPixelBuffer>.fromOpaque(opaqueBuffer).takeUnretainedValue()

    let sourceImage = CIImage(cvPixelBuffer: pixelBuffer, options: nil)

    // Make a rect to crop to that's the size of the view we want to display the image in
    let cropRect = AVMakeRect(aspectRatio: CGSize(width: videoDisplayViewBounds.width, height: videoDisplayViewBounds.height), insideRect: sourceImage.extent)
    // Crop
    let croppedImage = sourceImage.cropping(to: cropRect)
    // Cropping changes the origin coordinates of the cropped image, so move it back to 0
    let translatedImage = croppedImage.applying(CGAffineTransform(translationX: 0, y: -croppedImage.extent.origin.y))

    // Do some detection on the image
    let detectionResult = applyFilter?(translatedImage)
    var outputImage = translatedImage
    if detectionResult != nil {
        outputImage = detectionResult!
    }

    if videoDisplayView.context != EAGLContext.current() {
        EAGLContext.setCurrent(videoDisplayView.context)
    }
    videoDisplayView.bindDrawable()

    // clear eagl view to grey
    glClearColor(0.5, 0.5, 0.5, 1.0)
    glClear(0x00004000)

    // set the blend mode to "source over" so that CI will use that
    glEnable(0x0BE2);
    glBlendFunc(1, 0x0303)

    renderContext.draw(outputImage, in: videoDisplayViewBounds, from: outputImage.extent)

    videoDisplayView.display()
}

使用CIContext在GLKView中绘制时，Aspect填充AVCaptureVideoDataOutput

1 个答案: