     
     // MARK: - ivars
     
-    internal var _device: MTLDevice?
-    internal var _library: MTLLibrary?
-    internal var _commandQueue: MTLCommandQueue?
     
     internal var _texture: MTLTexture?
     

    internal var _bufferHeight: Int = 0
    internal var _bufferFormatType: OSType = OSType(kCVPixelFormatType_32BGRA)
    internal var _presentationFrame: CGRect = .zero
    fileprivate var _renderPassDescriptor: MTLRenderPassDescriptor = MTLRenderPassDescriptor()
    
    internal var _ciContext: CIContext?
    internal var _pixelBufferPool: CVPixelBufferPool?
    internal var _videoBufferOutput: CVPixelBuffer?
    
    #if USE_ARKIT
    internal weak var _arView: ARSCNView?

        #endif
        
        self._commandQueue = view.device?.makeCommandQueue()
    }
    #endif
    
