在 C# 和 WPF 中使用 Aforge.NET 获取网络摄像头流

Question

我想使用我的摄像头捕捉网络摄像头源。为此，我使用了 2 个参考：AForge.Video.dll 和 AForge.Video.DirectShow.dll。

Here's我发现的一个sn-p：

public FilterInfoCollection CamsCollection;
public VideoCaptureDevice Cam = null;

void Cam_NewFrame(object sender, NewFrameEventArgs eventArgs)
{   
  frameholder.Source = (Bitmap)eventArgs.Frame.Clone(); 
  /* ^
   * Here it cannot convert implicitly from System.Drawing.Bitmap to
   * System.Windows.Media.ImageSource
   */

}

private void startcam_Click(object sender, RoutedEventArgs e)
{
  CamsCollection = new FilterInfoCollection(FilterCategory.VideoInputDevice);

  Cam = new VideoCaptureDevice(CamsCollection[1].MonikerString);
  Cam.NewFrame += new NewFrameEventHandler(Cam_NewFrame);
  Cam.Start();
}

private void stopcam_Click(object sender, RoutedEventArgs e)
{
  Cam.Stop();
}

}

他们使用PictureBox 来显示框架。当我在 WPF 中工作时，我使用了this

总结一下我的代码目前的样子。

public FilterInfoCollection CamsCollection;
public VideoCaptureDevice Cam = null;


void Cam_NewFrame(object sender, NewFrameEventArgs eventArgs)
{

    System.Drawing.Image imgforms = (Bitmap)eventArgs.Frame.Clone();


    BitmapImage bi = new BitmapImage();
    bi.BeginInit ();

    MemoryStream ms = new MemoryStream ();

    imgforms.Save(ms, ImageFormat.Bmp);

    ms.Seek(0, SeekOrigin.Begin);
    bi.StreamSource  = ms;
    frameholder.Source = bi; 
   /* ^ runtime error here because `bi` is occupied by another thread.
    */
    bi.EndInit();
}

private void startcam_Click(object sender, RoutedEventArgs e)
{

    CamsCollection = new FilterInfoCollection(FilterCategory.VideoInputDevice);

    Cam = new VideoCaptureDevice(CamsCollection[1].MonikerString);
    Cam.NewFrame += new NewFrameEventHandler(Cam_NewFrame);
    Cam.Start();
}

private void stopcam_Click(object sender, RoutedEventArgs e)
{
    Cam.Stop();
}

Answer 1

Edit1：查看我的blogpost关于同一主题的详细说明。

---

我使用Dispatcher 类作为互斥体修复了错误：

void Cam_NewFrame(object sender, NewFrameEventArgs eventArgs)
    {

        System.Drawing.Image imgforms = (Bitmap)eventArgs.Frame.Clone(); 

        BitmapImage bi = new BitmapImage(); 
        bi.BeginInit(); 

        MemoryStream ms = new MemoryStream(); 
        imgforms.Save(ms, ImageFormat.Bmp); 
        ms.Seek(0, SeekOrigin.Begin); 

        bi.StreamSource = ms; 
        bi.EndInit();

        //Using the freeze function to avoid cross thread operations 
        bi.Freeze();

        //Calling the UI thread using the Dispatcher to update the 'Image' WPF control         
        Dispatcher.BeginInvoke(new ThreadStart(delegate
        {
            frameholder.Source = bi; /*frameholder is the name of the 'Image' WPF control*/
        }));     

    }

现在它按预期运行，我获得了良好的性能，而 fps 没有任何下降。

Answer 2

如果您想支持 Silverlight，无论是 Web 版、独立版还是 WP7，都不应从 WPF 开始，因为 Silverlight 中缺少 WPF 的许多功能。

这是 Silverlight 4+ 教程：

http://www.silverlightshow.net/items/Capturing-the-Webcam-in-Silverlight-4.aspx