如何从CVPixelBuffer中读取单个像素

// 获取CVPixelBuffer的基本信息
let width = CVPixelBufferGetWidth(pixelBuffer)
let height = CVPixelBufferGetHeight(pixelBuffer)
let bytesPerRow = CVPixelBufferGetBytesPerRow(pixelBuffer)

// 锁定CVPixelBuffer
CVPixelBufferLockBaseAddress(pixelBuffer, .readOnly)

// 获取数据指针
guard let baseAddress = CVPixelBufferGetBaseAddress(pixelBuffer) else {
    return
}

// 计算偏移量
let pixelOffset = 4 * (x + y * width)

// 读取像素值
let bufferPointer = baseAddress.assumingMemoryBound(to: UInt8.self)
let red = bufferPointer[pixelOffset]
let green = bufferPointer[pixelOffset + 1]
let blue = bufferPointer[pixelOffset + 2]
let alpha = bufferPointer[pixelOffset + 3]

// 解锁CVPixelBuffer
CVPixelBufferUnlockBaseAddress(pixelBuffer, .readOnly)

// 输出RGBA值
print("Red: \(red), Green: \(green), Blue: \(blue), Alpha: \(alpha)")