OpenCVSharp入门教程基础篇④——从本地视频文件获取媒体流

柔情只为你懂 2023-01-23 09:54 28阅读 0赞

### 文章目录 ###

*  一、界面布局
 *  二、功能实现
 *   *  2.1 打开视频文件
     *  2.2 运行文件后台任务
 *  三、异常报错
 *  四、运行
 *  五、Demo源码

# 一、界面布局 #

*  两个`Button`
 *  一个`PictureBox`
 *  一个`BackgroundWorker cameraWorker`  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70]

# 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)。

因为还少了一点dll

*  点击下载[OpenCVSharp dll.zip][]
 *  放到`\bin\Debug\下面`  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 1]

# 四、运行 #

*  堪称完美

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 2]

# 五、Demo源码 #

[OpenCVSharpDemo工程源码点击下载][OpenCVSharpDemo]

***觉得好，就一键三连呗（点赞+收藏+关注）***

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[OpenCVSharp dll.zip]: https://download.csdn.net/download/kangweijian/20247973
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2thbmd3ZWlqaWFu_size_16_color_FFFFFF_t_70 1]: /images/20221004/9ca07d1103af44dcb4704edd55d18c1c.png
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[OpenCVSharpDemo]: https://download.csdn.net/download/kangweijian/20259433