用C＃预览视频文件（简略）

我的IR项目里要对视频文件进行预览，目前还没有解决，以下的方法是一个尝试。

在system32下，有一个qedit.dll文件，这是DirectShow的一个COM组件（DS大部份都是COM组件），就是说我们可以直接以COM的形式引用到C＃项目里。

我做了一个简单测试项目。先把qedit.dll找到，然后以COM注册到项目中。对MediaDet类进行了一个简单的封装，然后运行一个测试项目：
运行结果（从AVI中提取第10桢的内容）：

部份代码：仅供参考：

MediaDetector类

using System;

using System.IO;

using DexterLib;

using System.Drawing;

using System.Drawing.Imaging;

namespace PublicLibrary

{

/// <summary>

/// Summary description for MediaDetector.

/// </summary>

public class MediaDetector

{

//fields

protected MediaDetClass _MediaDet;

protected Image.GetThumbnailImageAbort _ImageCallback;

//events

public event ErrorHandler OnError;

//properties

protected MediaDetClass MediaDecteor

{

get

{

if(this._MediaDet==null)

{

try

{

this._MediaDet = new MediaDetClass();

}

catch(Exception ex)

{

this.FileErrorEvent(ex);

}

return _MediaDet;

}

protected Image.GetThumbnailImageAbort ImageCallback

{

get

{

if(this._ImageCallback == null)

{

this._ImageCallback = new Image.GetThumbnailImageAbort(ThumbnailCallback);

}

return this._ImageCallback;

}

//methods

private void FileErrorEvent(Exception i_ex)

{

if(this.OnError!=null)

{

try

{

this.OnError(this,i_ex);

}

catch(Exception ex)

{

System.Diagnostics.Trace.WriteLine(ex.Message);

}

/// <summary>

/// Method to get thumbinal image from media file.

/// </summary>

/// <param name="i_MediaFile">Media file full path and name.</param>

/// <param name="i_Size">Image size.</param>

/// <param name="i_type">Media type</param>

/// <param name="i_Stream">If the media type is video, this parameter is the video's stream to grab and create image.</param>

/// <returns></returns>

public Image GetThumbnail(string i_MediaFile,Size i_Size,MediaTypes i_type,int i_Stream)

{

switch(i_type)

{

default:

case MediaTypes.Unknow:

this.FileErrorEvent(new Exception("Unknow media type."));

return null;

case MediaTypes.Audio:

this.FileErrorEvent(new Exception("This media type has not implemented to create an image."));

return null;

case MediaTypes.Image:

return this.GetThumbnailFromImage(i_MediaFile,i_Size);

case MediaTypes.Video:

return this.GetThumbnailFromVideo(i_MediaFile,i_Size,i_Stream);

}

public Image GetThumbnailFromImage(string i_MediaFile,Size i_Size)

{

try

{

Image m_image = Image.FromFile(i_MediaFile);

return m_image.GetThumbnailImage(i_Size.Width,i_Size.Height,this.ImageCallback,IntPtr.Zero);

}

catch(Exception ex)

{

this.FileErrorEvent(ex);

return null;

}

public Image GetThumbnailFromVideo(string i_MediaFile,Size i_Size,int i_Stream)

{

this.MediaDecteor.Filename = i_MediaFile;

this.MediaDecteor.CurrentStream = 0;

//int m_ImageSize = (int)this.MediaDecteor.StreamLength;

try

{

this.MediaDecteor.WriteBitmapBits(i_Stream,i_Size.Width,i_Size.Height,"Temp.bmp");

Stream m_stream = File.Open("Temp.bmp",FileMode.Open,FileAccess.Read,FileShare.None);

byte[] m_bytes = new byte[m_stream.Length];

m_stream.Read(m_bytes,0,m_bytes.Length);

m_stream.Close();

File.Delete("Temp.bmp");

MemoryStream m_MemoStream = new MemoryStream(m_bytes.Length);

m_MemoStream.Write(m_bytes,0,m_bytes.Length);

return Image.FromStream(m_MemoStream);

}

catch(Exception ex)

{

this.FileErrorEvent(ex);

return null;

}

private bool ThumbnailCallback()

{

return false;

}

//ctor

public MediaDetector()

{

}

public class MediaHelper

public delegate void ErrorHandler(object i_Sender,Exception i_ex);

public enum MediaTypes

{

Image = 1,

Video = 2,

Audio = 3,

Unknow = 0,

}

测试Form代码：

Form类

using System;

using System.Drawing;

using System.Collections;

using System.ComponentModel;

using System.Windows.Forms;

using PublicLibrary;

namespace Country.Study

{

/// <summary>

/// Summary description for Thumbinal.

/// </summary>

public class Thumbnail : System.Windows.Forms.Form

{

private MediaDetector _MediaDetector;

private MediaDetector MediaDetector

{

get

{

return this._MediaDetector;

}

private System.Windows.Forms.StatusBar statusBar1;

private System.Windows.Forms.Panel panel1;

private System.Windows.Forms.TextBox C_Path;

private System.Windows.Forms.Button C_Browse;

private System.Windows.Forms.Panel panel2;

private System.Windows.Forms.Label C_LabWidth;

private System.Windows.Forms.TextBox C_Width;

private System.Windows.Forms.Label C_LabHeight;

private System.Windows.Forms.TextBox C_Height;

private System.Windows.Forms.Label C_LabType;

private System.Windows.Forms.ComboBox C_MediaTypes;

private System.Windows.Forms.Label C_LabStream;

private System.Windows.Forms.Button C_Create;

private System.Windows.Forms.OpenFileDialog C_OpenFileDialog;

private System.Windows.Forms.TextBox C_Stream;

private System.Windows.Forms.PictureBox C_PicBox;

/// <summary>

/// Required designer variable.

/// </summary>

private System.ComponentModel.Container components = null;

public Thumbnail()

{

// Required for Windows Form Designer support

InitializeComponent();

// TODO: Add any constructor code after InitializeComponent call

this._MediaDetector = new MediaDetector();

this._MediaDetector.OnError += new ErrorHandler(MediaDetector_OnError);

}

/// <summary>

/// Clean up any resources being used.

/// </summary>

protected override void Dispose( bool disposing )

{

if(this._MediaDetector!=null)

{

this._MediaDetector.OnError -= new ErrorHandler(MediaDetector_OnError);

this._MediaDetector = null;

}

if( disposing )

{

if(components != null)

{

components.Dispose();

}

base.Dispose( disposing );

}

Windows Form Designer generated code#region Windows Form Designer generated code

/// <summary>

/// Required method for Designer support - do not modify

/// the contents of this method with the code editor.

/// </summary>

private void InitializeComponent()

{

this.statusBar1 = new System.Windows.Forms.StatusBar();

this.panel1 = new System.Windows.Forms.Panel();

this.C_Browse = new System.Windows.Forms.Button();

this.C_Path = new System.Windows.Forms.TextBox();

this.panel2 = new System.Windows.Forms.Panel();

this.C_Create = new System.Windows.Forms.Button();

this.C_Stream = new System.Windows.Forms.TextBox();

this.C_LabStream = new System.Windows.Forms.Label();

this.C_MediaTypes = new System.Windows.Forms.ComboBox();

this.C_LabType = new System.Windows.Forms.Label();

this.C_Height = new System.Windows.Forms.TextBox();

this.C_LabHeight = new System.Windows.Forms.Label();

this.C_LabWidth = new System.Windows.Forms.Label();

this.C_Width = new System.Windows.Forms.TextBox();

this.C_PicBox = new System.Windows.Forms.PictureBox();

this.C_OpenFileDialog = new System.Windows.Forms.OpenFileDialog();

this.panel1.SuspendLayout();

this.panel2.SuspendLayout();

this.SuspendLayout();

// statusBar1

this.statusBar1.Location = new System.Drawing.Point(0, 391);

this.statusBar1.Name = "statusBar1";

this.statusBar1.Size = new System.Drawing.Size(568, 22);

this.statusBar1.TabIndex = 0;

this.statusBar1.Text = "statusBar1";

// panel1

this.panel1.Controls.Add(this.C_Browse);

this.panel1.Controls.Add(this.C_Path);

this.panel1.Dock = System.Windows.Forms.DockStyle.Top;

this.panel1.Location = new System.Drawing.Point(0, 0);

this.panel1.Name = "panel1";

this.panel1.Size = new System.Drawing.Size(568, 40);

this.panel1.TabIndex = 1;

// C_Browse

this.C_Browse.Location = new System.Drawing.Point(480, 8);

this.C_Browse.Name = "C_Browse";

this.C_Browse.TabIndex = 1;

this.C_Browse.Text = "Browse

this.C_Browse.Click += new System.EventHandler(this.C_Browse_Click);

// C_Path

this.C_Path.Location = new System.Drawing.Point(8, 8);

this.C_Path.Name = "C_Path";

this.C_Path.ReadOnly = true;

this.C_Path.Size = new System.Drawing.Size(464, 20);

this.C_Path.TabIndex = 0;

this.C_Path.Text = "textBox1";

// panel2

this.panel2.Controls.Add(this.C_Create);

this.panel2.Controls.Add(this.C_Stream);

this.panel2.Controls.Add(this.C_LabStream);

this.panel2.Controls.Add(this.C_MediaTypes);

this.panel2.Controls.Add(this.C_LabType);

this.panel2.Controls.Add(this.C_Height);

this.panel2.Controls.Add(this.C_LabHeight);

this.panel2.Controls.Add(this.C_LabWidth);

this.panel2.Controls.Add(this.C_Width);

this.panel2.Dock = System.Windows.Forms.DockStyle.Left;

this.panel2.Location = new System.Drawing.Point(0, 40);

this.panel2.Name = "panel2";

this.panel2.Size = new System.Drawing.Size(176, 351);

this.panel2.TabIndex = 2;

// C_Create

this.C_Create.Location = new System.Drawing.Point(8, 136);

this.C_Create.Name = "C_Create";

this.C_Create.Size = new System.Drawing.Size(152, 23);

this.C_Create.TabIndex = 10;

this.C_Create.Text = "Create Thumbnail Image";

this.C_Create.Click += new System.EventHandler(this.C_Create_Click);

// C_Stream

this.C_Stream.Location = new System.Drawing.Point(64, 104);

this.C_Stream.Name = "C_Stream";

this.C_Stream.TabIndex = 9;

this.C_Stream.Text = "1";

// C_LabStream

this.C_LabStream.Location = new System.Drawing.Point(8, 104);

this.C_LabStream.Name = "C_LabStream";

this.C_LabStream.Size = new System.Drawing.Size(56, 16);

this.C_LabStream.TabIndex = 8;

this.C_LabStream.Text = "Stream";

// C_MediaTypes

this.C_MediaTypes.Items.AddRange(new object[] {

"Unknow",

"Image",

"Audio",

"Video"});

this.C_MediaTypes.Location = new System.Drawing.Point(64, 72);

this.C_MediaTypes.Name = "C_MediaTypes";

this.C_MediaTypes.Size = new System.Drawing.Size(104, 21);

this.C_MediaTypes.TabIndex = 7;

// C_LabType

this.C_LabType.Location = new System.Drawing.Point(8, 72);

this.C_LabType.Name = "C_LabType";

this.C_LabType.Size = new System.Drawing.Size(56, 16);

this.C_LabType.TabIndex = 6;

this.C_LabType.Text = "Type";

// C_Height

this.C_Height.Location = new System.Drawing.Point(64, 40);

this.C_Height.Name = "C_Height";

this.C_Height.TabIndex = 5;

this.C_Height.Text = "300";

// C_LabHeight

this.C_LabHeight.Location = new System.Drawing.Point(8, 40);

this.C_LabHeight.Name = "C_LabHeight";

this.C_LabHeight.Size = new System.Drawing.Size(56, 16);

this.C_LabHeight.TabIndex = 4;

this.C_LabHeight.Text = "Height";

// C_LabWidth

this.C_LabWidth.Location = new System.Drawing.Point(8, 8);

this.C_LabWidth.Name = "C_LabWidth";

this.C_LabWidth.Size = new System.Drawing.Size(56, 16);

this.C_LabWidth.TabIndex = 3;

this.C_LabWidth.Text = "Width";

// C_Width

this.C_Width.Location = new System.Drawing.Point(64, 8);

this.C_Width.Name = "C_Width";

this.C_Width.TabIndex = 3;

this.C_Width.Text = "300";

// C_PicBox

this.C_PicBox.Location = new System.Drawing.Point(176, 40);

this.C_PicBox.Name = "C_PicBox";

this.C_PicBox.Size = new System.Drawing.Size(392, 351);

this.C_PicBox.SizeMode = System.Windows.Forms.PictureBoxSizeMode.StretchImage;

this.C_PicBox.TabIndex = 3;

this.C_PicBox.TabStop = false;

// Thumbnail

this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);

this.ClientSize = new System.Drawing.Size(568, 413);

this.Controls.Add(this.C_PicBox);

this.Controls.Add(this.panel2);

this.Controls.Add(this.panel1);

this.Controls.Add(this.statusBar1);

this.Name = "Thumbnail";

this.Text = "Thumbinal";

this.panel1.ResumeLayout(false);

this.panel2.ResumeLayout(false);

this.ResumeLayout(false);

}

#endregion

private void C_Create_Click(object sender, System.EventArgs e)

{

try

{

int m_width = Convert.ToInt32(this.C_Width.Text);

int m_height = Convert.ToInt32(this.C_Height.Text);

int m_stream = Convert.ToInt32(this.C_Stream.Text);

MediaTypes m_MediaType = MediaHelper.ConvertToMediaType(this.C_MediaTypes.SelectedItem.ToString());

Image m_image = this.MediaDetector.GetThumbnail(this.C_Path.Text,new Size(m_width,m_height),m_MediaType,m_stream);

this.C_PicBox.Image = m_image;

this.C_PicBox.Width = m_width;

this.C_PicBox.Height = m_height;

this.C_PicBox.Refresh();

}

catch(Exception ex)

{

MessageBox.Show(string.Format("Error:{0}",ex.Message));

}

private void MediaDetector_OnError(object i_Sender, Exception i_ex)

{

MessageBox.Show(this,string.Format("Create thumbnail image error. Message:{0}",i_ex.Message));

}

private void C_Browse_Click(object sender, System.EventArgs e)

{

if(this.C_OpenFileDialog.ShowDialog(this)==DialogResult.OK)

{

this.C_Path.Text = this.C_OpenFileDialog.FileName;

}

仅做参考！