/// <summary>
/// Updates the background model
/// </summary>
/// <param name="frame">Next video frame.</param>
/// <param name="fgmask">The output forground mask</param>
/// <param name="learningRate">The learning rate, use -1.0f for default value.</param>
/// <param name="stream">Use a Stream to call the function asynchronously (non-blocking) or null to call the function synchronously (blocking).</param>
public void Update(IInputArray frame, IOutputArray fgmask, double learningRate, Stream stream = null)
{
using (InputArray iaFrame = frame.GetInputArray())
using (OutputArray oaForgroundMask = fgmask.GetOutputArray())
CudaInvoke.cudaBackgroundSubtractorMOG2Apply(_ptr, iaFrame, oaForgroundMask, learningRate, stream);
}