AVCaptureVideoDataOutputのCMSampleBufferからCVPixelBufferにアクセスするときのお作法

CVPixelBufferを取得する場合はCVPixelBufferLockBaseAddressでロックを確保してpixelBufferにアクセス、終わったらCVPixelBufferUnlockBaseAddressでアンロックする

Detecting Human Body Poses in an Image より

// Attempt to lock the image buffer to gain access to its memory.
guard CVPixelBufferLockBaseAddress(pixelBuffer, .readOnly) == kCVReturnSuccess
    else {
        return
}

// Create Core Graphics image placeholder.
var image: CGImage?

// Create a Core Graphics bitmap image from the pixel buffer.
VTCreateCGImageFromCVPixelBuffer(pixelBuffer, options: nil, imageOut: &image)

// Release the image buffer.
CVPixelBufferUnlockBaseAddress(pixelBuffer, .readOnly)

DispatchQueue.main.sync {
    delegate.videoCapture(self, didCaptureFrame: image)
}

captureOutput(_:didOutput:from:) | Apple Developer Documentation