C# 实现Windows Media Encoder音视频捕捉

我的博客中讲述过WMS9，可以实现流媒体服务器，但没有WME（windows media encoder）的支持，总觉得缺少点什么，这里就讲述一下如何通过.net实现WME获取设备视频音频流，并推送到远程（本地当然可以）流媒体广播发布点。

一.下载了wme9的SDK，安装完毕：这一步主要体验一下WME能够实现那些功能。

读者可以自行安装试试。

二.创建.net winform Application，添加引用

using  WMEncoderLib;

WMEncoderLib是一个assemble，通过它，我们可以方便实现WME的操作。

三.获取本地屏幕，并转换为视频信号

IWMEncSource SrcAud  =  SrcGrp.AddSource(WMENC_SOURCE_TYPE.WMENC_AUDIO);
                IWMEncSource SrcVid  =  SrcGrp.AddSource(WMENC_SOURCE_TYPE.WMENC_VIDEO);
                SrcAud.SetInput( " Default_Audio_Device " ,  " Device " ,  "" );
                SrcVid.SetInput( " ScreenCapture1 " ,  " ScreenCap " ,  "" );

四.启动Encoder，推送到远程WMS服务器

                 // Set up the push broadcast.
                IWMEncPushDistribution PushDist  =  (IWMEncPushDistribution)Encoder.Broadcast;
                 string  strServerName  =   this .TB_ServerName.Text.Trim()  +   " : "   +   this .TB_Port.Text.Trim();
                 string  strPubPoint  =   " TmpBroadCastPubPoint " ;
                 //  Remove the publishing point when the broadcast is over.
                PushDist.AutoRemovePublishingPoint  =   true ;
                 //  Set the push distribution variables.
                PushDist.ServerName  =  strServerName;        
                PushDist.PublishingPoint  =  strPubPoint;
                 //  PushDist.Template = strPubTemplate;
                 //  Initialize the encoding process.
                Encoder.PrepareToEncode( true );

注意：在这里，直接推送到远程服务器，如果服务器不在同一域内，或在不可信任区域，推送时应该会需要验证用户名和密码。因此我们需要创建一个委托：

Encoder.OnAcquireCredentials  +=   new  _IWMEncoderEvents_OnAcquireCredentialsEventHandler(OnUserAuth);

public   void  OnUserAuth( string  bstrRealm,  string  bstrSite,  ref   object  pvarUser,  ref   object  pvarPassword,  ref   object  plFlags)
         ... {
            pvarUser = "administrator";
            pvarPassword = "622316";
            plFlags = 4;
        }

五.到这里就差不多了，完整代码贴出来：

using  System;
using  System.Collections.Generic;
using  System.ComponentModel;
using  System.Data;
using  System.Drawing;
using  System.Text;
using  System.Windows.Forms;
using  WMEncoderLib;

namespace  Project2
... {
    public partial class Form1 : Form
    ...{
        static bool bDone;
        private WMEncoder Encoder;
        public Form1()
        ...{
            InitializeComponent();
            Encoder = new WMEncoder();
            Encoder.OnStateChange += new _IWMEncoderEvents_OnStateChangeEventHandler(OnWmeStatusChange);
            Encoder.OnError += new _IWMEncoderEvents_OnErrorEventHandler(Encoder_OnError);
            Encoder.OnAcquireCredentials += new _IWMEncoderEvents_OnAcquireCredentialsEventHandler(OnUserAuth);
        }

        private void Btn_Start_Click(object sender, EventArgs e)
        ...{
            this.StartBroadCast();
        }

        private void Btn_Close_Click(object sender, EventArgs e)
        ...{
            this.StopBroadCast();
        }

        /**//// 

        /// 停止广播服务
        /// 

        public void StopBroadCast()
        ...{
            this.Encoder.Stop();
        }

        /**//// 

        /// 启动广播服务
        /// 

        public void StartBroadCast()
        ...{
            if (Encoder != null)
            ...{         
                
                
                // Retrieve the source group collection.
                IWMEncSourceGroupCollection SrcGrpColl = Encoder.SourceGroupCollection;

                // Add a source group to the collection.
                IWMEncSourceGroup SrcGrp = SrcGrpColl.Add("SG_2");
                
                IWMEncSource SrcAud = SrcGrp.AddSource(WMENC_SOURCE_TYPE.WMENC_AUDIO);
                IWMEncSource SrcVid = SrcGrp.AddSource(WMENC_SOURCE_TYPE.WMENC_VIDEO);
                SrcAud.SetInput("Default_Audio_Device", "Device", "");
                SrcVid.SetInput("ScreenCapture1", "ScreenCap", "");


                // Choose a profile from the collection.
                IWMEncProfileCollection ProColl = Encoder.ProfileCollection;
                IWMEncProfile Pro;
                for (int i = 0; i < ProColl.Count; i++)
                ...{
                    Pro = ProColl.Item(i);
                    if (Pro.Name == "Windows Media Video 8 for Local Area Network (384 Kbps)")
                    ...{
                        SrcGrp.set_Profile(Pro);
                        break;
                    }
                }

                //Set up the push broadcast.
                IWMEncPushDistribution PushDist = (IWMEncPushDistribution)Encoder.Broadcast;

                // Specify the push distribution variables, including the Windows Media
                // server name, publishing point, and announcement files.
                string strServerName = this.TB_ServerName.Text.Trim() + ":" + this.TB_Port.Text.Trim();
                string strPubPoint = "TmpBroadCastPubPoint";
                //string strPubTemplate = "AnotherPubPoint";
                //string MyNSCFile = "//localhost/test/MyPubPoint.nsc";
                //string MyNSCURL = "//localhost/MyPubPoint.nsc";
                //string MyASXFile = @"C:InetpubwwwrootMyPubPoint.asx";

                // Remove the publishing point when the broadcast is over.
                PushDist.AutoRemovePublishingPoint = true;
                // Set the push distribution variables.
                PushDist.ServerName = strServerName;
               
                PushDist.PublishingPoint = strPubPoint;
                // PushDist.Template = strPubTemplate;
                // Initialize the encoding process.
                

                Encoder.PrepareToEncode(true);
                
                // Generate the announcement file.
                //PushDist.GenerateMulticastInfoFile(MyNSCFile);
                //PushDist.GenerateAnnouncementFile(MyNSCURL, MyASXFile);

                // Start the encoding process.
                Encoder.Start();
                // wmp.openPlayer("mms://LIH-M/test");
                this.wmp.URL = "mms://192.168.1.108/TmpBroadCastPubPoint";
            }
        }

        public void OnUserAuth(string bstrRealm, string bstrSite, ref object pvarUser, ref object pvarPassword, ref object plFlags)
        ...{
            pvarUser = "administrator";
            pvarPassword = "622316";
            plFlags = 4;
        }

        public void Encoder_OnError(int Result)
        ...{
            this.RTB_Error.Text = "运行状态：出错代码 " + Result + " 【" + Encoder.ErrorState.ToString() + "】";
        }

        public void OnWmeStatusChange(WMENC_ENCODER_STATE enumState)
        ...{

            switch (enumState)
            ...{
                case WMENC_ENCODER_STATE.WMENC_ENCODER_RUNNING:
                    RTB_Error.Text += " 运行状态：Encoder正在运行";
                    break;

                case WMENC_ENCODER_STATE.WMENC_ENCODER_STOPPED:
                    // TODO: Handle stopped state.
                    bDone = true;
                    RTB_Error.Text += " 运行状态：Encoder已经停止";
                    break;

                case WMENC_ENCODER_STATE.WMENC_ENCODER_STARTING:
                    RTB_Error.Text += " 运行状态：Encoder正在启动";
                    break;

                case WMENC_ENCODER_STATE.WMENC_ENCODER_PAUSING:
                    // TODO: Handle pausing state.
                    RTB_Error.Text += " 运行状态：Encoder正在暂停";
                    break;

                case WMENC_ENCODER_STATE.WMENC_ENCODER_STOPPING:
                    // TODO: Handle stopping state.
                    RTB_Error.Text += " 运行状态：Encoder正在停止";
                    break;

                case WMENC_ENCODER_STATE.WMENC_ENCODER_PAUSED:
                    // TODO: Handle paused state.
                    RTB_Error.Text += " 运行状态：Encoder已暂停";
                    break;

                case WMENC_ENCODER_STATE.WMENC_ENCODER_END_PREPROCESS:
                    // TODO: Handle end preprocess state.
                    RTB_Error.Text += " 运行状态：Encoder正在处理结束前操作";
                    break;
            }

        }
    }
}

WME可以捕捉机器音频和视频等设备，如：摄像头，桌面，光驱，声卡，电视卡等等。因此我们可以通过它实现网上电视直播，视频、音频捕捉等等功能。有兴趣的话可以研究一下。