一、界面布局

两个Button
一个PictureBox
一个BackgroundWorker cameraWorker

二、功能实现

2.1 打开视频文件

打开文件夹
选择视频文件
判断文件是否打开，否：提示并退出

文件后台任务fileWorker开始运行

private void openFileBtn_Click(object sender, EventArgs e)

    { 
        if (fileWorker.IsBusy)
        { 
            closeFile();
        }
        else
        { 
            openFile();
        }
    }
    private void openFile()
    { 
        OpenFileDialog openfiledialog = new OpenFileDialog();
        //openfiledialog.Title = "打开文本文件";
        openfiledialog.Filter = "All Files(*.*)|*.*|mp4 Files(*.mp4)|*.mp4";
        openfiledialog.FilterIndex = 2;//根据文件类型索引设置文件过滤类型
        openfiledialog.RestoreDirectory = true;//设置对话框是否记忆之前打开的目录
        if (openfiledialog.ShowDialog() == DialogResult.OK)
        { 
            Console.WriteLine(openfiledialog.FileName);
            capture.Open(openfiledialog.FileName, VideoCaptureAPIs.ANY);
            if (!capture.IsOpened())
            { 
                Close();
                MessageBox.Show("打开视频文件失败");
                return;
            }
            openFileBtn.Text = "关闭视频文件";
            fileWorker.RunWorkerAsync();
        }
    }
    private void closeFile()
    { 
        openFileBtn.Text = "打开视频文件";
        fileWorker.CancelAsync();
        capture.Release();
        pictureBox1.Image = null;
    }

2.2 运行文件后台任务

while死循环
获取文件frameMat
判断frameMat是否为空，是：则跳出循环
转换成Bitmap

复制给pictureBox1

private void fileWorker_DoWork(object sender, DoWorkEventArgs e)
{

int sleepTime = (int)Math.Round(1000 / capture.Fps);
var bgWorker = (BackgroundWorker)sender;
while (!bgWorker.CancellationPending)
{ 
    using (var frameMat = capture.RetrieveMat())
    { 
        if (frameMat.Empty())
            break;
        var frameBitmap = BitmapConverter.ToBitmap(frameMat);
        bgWorker.ReportProgress(0, frameBitmap);
    }
    Thread.Sleep(sleepTime);
}
Console.WriteLine("fileWorker_DoWork end");

}

private void fileWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{

var frameBitmap = (Bitmap)e.UserState;
pictureBox1.Image?.Dispose();
pictureBox1.Image = frameBitmap;

}

private void fileWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{

Console.WriteLine("fileWorker_RunWorkerCompleted");
openFileBtn.Text = "打开视频文件";

}

三、异常报错

System.TypeInitializationException:““OpenCvSharp.Internal.NativeMethods”的类型初始值设定项引发异常。”
内部异常
DllNotFoundException: 无法加载 DLL“OpenCvSharpExtern”: 找不到指定的模块。 (异常来自 HRESULT:0x8007007E)。