从C＃中的Windows媒体播放器上播放视频拍摄图像

Question

在我的Windows应用程序中，我使用Windows Media Player dll播放视频。

在我的表格中，我有一个按钮来拍摄当前视频帧。

我做了很多测试和代码检查，但我无法找出为什么拍摄当前帧的图片失败。

我尝试了这段代码，但结果图片是黑色的：

private Graphics g = null;

private void btnTakePicture_Click(object sender, EventArgs e)
{
    if (!string.IsNullOrEmpty(axWMVMovie.URL))
    {
        axWMVMovie.Ctlcontrols.pause();
        if (saveFileDialog1.ShowDialog() == DialogResult.OK)
        {
            System.Drawing.Image ret = null;
            try
            {
                Bitmap bitmap = new Bitmap(axWMVMovie.Width, axWMVMovie.Height);
                {
                    g = Graphics.FromImage(bitmap);
                    {
                        Graphics gg = axWMVMovie.CreateGraphics();
                        {
                            timerTakePicFromVideo.Start();
                        }
                    }

                    using (MemoryStream ms = new MemoryStream())
                    {
                        bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
                        ret = System.Drawing.Image.FromStream(ms);
                        ret.Save(saveFileDialog1.FileName);
                    }
                }
            }
            catch
            {
            }
        }
    }
}

private void timerTakePicFromVideo_Tick(object sender, EventArgs e)
{
    timerTakePicFromVideo.Stop();

    g.CopyFromScreen(axWMVMovie.PointToScreen(new System.Drawing.Point()).X, 

    axWMVMovie.PointToScreen(new System.Drawing.Point()).Y, 0, 0,

    new System.Drawing.Size(axWMVMovie.Width, axWMVMovie.Height));
}

我使用Timer因为当用户选择保存路径时，函数会从save file dialog中指定的文件用户获取图像。视频格式为WMV。

Answer 1

我带了你的代码和修改了它。我把代码放到一点点捕获照片，现在它的工作原理。我在saveFileDialog弹出之前创建图片 ，所以你真的只能得到图片而不是你图片中的saveFileDialog。

if (!string.IsNullOrEmpty(axWindowsMediaPlayer1.URL))
{
    axWindowsMediaPlayer1.Ctlcontrols.pause();

    System.Drawing.Image ret = null;
    try
    {
        // take picture BEFORE saveFileDialog pops up!!
        Bitmap bitmap = new Bitmap(axWindowsMediaPlayer1.Width, axWindowsMediaPlayer1.Height);
        {
            Graphics g = Graphics.FromImage(bitmap);
            {
                Graphics gg = axWindowsMediaPlayer1.CreateGraphics();
                {
                    //timerTakePicFromVideo.Start();
                    this.BringToFront();
                    g.CopyFromScreen(
                        axWindowsMediaPlayer1.PointToScreen(
                            new System.Drawing.Point()).X,
                        axWindowsMediaPlayer1.PointToScreen(
                            new System.Drawing.Point()).Y,
                        0, 0,
                        new System.Drawing.Size(
                            axWindowsMediaPlayer1.Width,
                            axWindowsMediaPlayer1.Height)
                        );
                }
            }
            // afterwards save bitmap file if user wants to
            if (saveFileDialog1.ShowDialog() == DialogResult.OK)
            {
                using (MemoryStream ms = new MemoryStream())
                {
                    bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
                    ret = System.Drawing.Image.FromStream(ms);
                    ret.Save(saveFileDialog1.FileName);
                }
            }
        }
    }
    catch (Exception ex)
    {
        Debug.WriteLine(ex.Message);
    }
}

Answer 2

对于先前的回答，避免获取捕获控件的一个技巧是在捕获之前执行此操作：

string uimode_previus = axWindowsMediaPlayer2.uiMode;
axWindowsMediaPlayer2.uiMode = "none";

然后在完成捕获后像这样将uimode设置回previous：

axWindowsMediaPlayer2.uiMode = uimode_previus ;

那样，您只能从当前帧获得实际拍摄。 这是一个小解决方法，但是可以完成工作。

这是可行的例子

private void button8_Click_1(object sender, EventArgs e)
{
  string uimode_previus = axWindowsMediaPlayer2.uiMode;
  axWindowsMediaPlayer2.uiMode = "none";

  if (!string.IsNullOrEmpty(axWindowsMediaPlayer2.URL))
  {
    ret = null;
    try
    {
      // take picture BEFORE saveFileDialog pops up!!
      Bitmap bitmap = new Bitmap(axWindowsMediaPlayer2.Width, axWindowsMediaPlayer2.Height);
      {
        Graphics g = Graphics.FromImage(bitmap);
        {
          Graphics gg = axWindowsMediaPlayer2.CreateGraphics();
          {
            //timerTakePicFromVideo.Start();
            this.BringToFront();
            g.CopyFromScreen(axWindowsMediaPlayer2.PointToScreen(
                             new System.Drawing.Point()).X,
                             axWindowsMediaPlayer2.PointToScreen(
                             new System.Drawing.Point()).Y,
                             0, 0,
                             new System.Drawing.Size(
                             axWindowsMediaPlayer2.Width - 0,
                             axWindowsMediaPlayer2.Height - 0)
                            );
          }
        }
        // afterwards save bitmap file if user wants to
        try
        {
          using (MemoryStream ms = new MemoryStream())
          {
            string rute = axWindowsMediaPlayer2.URL.ToString().Replace(".", "Review_."); // 
            bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
            ret = new Bitmap(System.Drawing.Image.FromStream(ms));
            ret.Save(rute.Replace(".mp4", ".Png"));
          }

          // open captured frame in new form
          TeamEasy.ShowPictureForm spf = new ShowPictureForm();
          spf.ImagePictureBox.Image = ret;
          spf.ShowDialog();
        }
        catch (Exception ex)
        {
          Debug.WriteLine(ex.Message);
        }
      }
    }
    catch (Exception ex)
    {
      Debug.WriteLine(ex.Message);
    }
  }

  axWindowsMediaPlayer2.uiMode = uimode_previus;
  // restore the UImode of player
}