问OpenCvSharp VideoWriter写一个空视频

EN

using System;
using System.Drawing;
using System.Windows.Forms;
using OpenCvSharp;
using OpenCvSharp.Extensions;

namespace VideoProcessing
{
    public class Player
    {
        private VideoCapture capture;
        private VideoWriter writer;

        private Mat matInternal;
        public Bitmap bmInternal;

        private bool bIsPlaying = false;
        public Timer MyTimer    = new Timer();

        const string outname = "output.avi";
        OpenCvSharp.Size dsize = new OpenCvSharp.Size(640, 480);   

        public void InitPlayer(string videoName)
        {
            capture = new VideoCapture(videoName);
            writer  = new VideoWriter(outname, FourCC.MJPG, capture.Fps, dsize);

            matInternal = Mat.Zeros(dsize, MatType.CV_8UC3);
            bmInternal = matInternal.ToBitmap();

            var delay = 1000 / (int)capture.Fps;

            MyTimer.Interval = delay;
            MyTimer.Tick += new EventHandler(mk_onTick());
            MyTimer.Start();
        }

        private Action<object, EventArgs>
        mk_onTick()
        {
            return (object sender, EventArgs e) =>
            {
                capture.Read(matInternal);
                if (matInternal.Empty())
                {
                    Console.WriteLine("Empty frame!");
                }
                else
                {
                    matInternal.Resize(dsize);
                    bmInternal = matInternal.ToBitmap();
                    writer.Write(matInternal);
                }
            };
        }

        public void Dispose()
        {
            capture.Dispose();
            writer.Dispose();
        }
        
    }
}

using System;
using System.Drawing;
using OpenCvSharp;
using OpenCvSharp.Extensions;

namespace VideoProcessing
{
    internal class Program
    {

        private static void Main(string[] args)
        {
            var videoName = "input.mp4";

            var pl = new Player();

            pl.InitPlayer(videoName);

            // Some other code that executes in the meantime

            pl.Dispose();
        }

    }
}