1、多媒體網絡通信技術大作業電信1203朱銀嘯01212093103091、題目：基于局域網的可視對講系統設計2、系統開發環境與工具：（1）、硬件環境：實驗室局域網（2）、軟件環境：WindowsXP操作系統（3）、開發工具：自己熟悉的面向對象的網絡通信編程工具與平臺，相關音頻、視頻編碼與傳輸協議類庫3、要求與評分標準：（1）要求：在以上硬軟件環境下，利用合適的開發工具，設計一套可視對講軟件，實現局域網內兩臺計算機之間的可視對講功能，要求音視頻信號連續性、實時性較好，滿足正常交流需要。（2）評分標準系統原理分析（20分）1.系統原理概述（10分）2.關鍵技術分析（10分）系統總體方案設計（30分）

2、1.按模塊化設計要求畫系統結構圖（15分）2數據流分析（15分）系統具體設計（30分）呼叫處理模塊流程圖與關鍵代碼（6分）音視頻采集與播放模塊流程圖與關鍵代碼（6分）音視頻處理（編解碼）模塊流程圖與關鍵代碼（6分）音視頻封包與解析模塊流程圖與關鍵代碼（6分）音視頻發送與接收模塊流程圖與關鍵代碼（6分）系統測試與評價（20）實現語音通信（6分）實現視頻通信（6分）實現音視頻同步（8分）代碼客戶端請求連接線程（呼叫處理）關鍵代碼如下：DWORD WINAPI ConnectThreadFunc(LPVOID pParam)CChatRoomDlg *pChatRoom = (CChatRoomDl

3、g *)pParam;ASSERT(pChatRoom ! = NULL);pChatRoom ->m_ConnectSock = socket (AF_INET ,SOCK_STREAM , IPPROTO_TCP);if ( pChatRoom->m_ConnectSock = INVALID_SOCKET) AfxMessageBox(_T("新建Socket 失敗！ ");return FALSE;CString strServIp;pChatRoom->GetDlgItemText(IDC_IP_ADDR, strServIp);int iPor

4、t = pChatRoom ->GetDlgItemInt (IDC_CONNECT_PORT);if( iPort <= 0 | iPort > 65535 ) AfxMessageBox(_T("請輸入合適的端口：1 - 65535");goto _Error_End;char szIpAddr16 = 0;USES_CONVERSION;strcpy_s(szIpAddr, 16, T2A(strServIp);sockaddr_in server;server.sin_family = AF_INET;server.sin_port = htons

5、(iPort);server.sin_addr.s_addr = inet_addr(szIpAddr);if(connect(pChatRoom->m_ConnectSock,(struct sockaddr*)&server, sizeof(struct sockaddr) = SOCKET_ERROR )AfxMessageBox(_T("連接失敗，請重試！ ");goto _Error_End;pChatRoom->ShowMsg(_T(" 系統信息： 連接服務器成功！ ");while( TRUE ) if ( SOCKET

6、_Select(pChatRoom->m_ConnectSock) ) TCHAR szBufMAX_BUF_SIZE = 0;int iRet = recv (pChatRoom->m_ConnectSock, (char*)szBuf, MAX_BUF_SIZE, 0);if ( iRet > 0 ) pChatRoom->ShowMsg(szBuf);elsepChatRoom->ShowMsg(_T("聊天服務器已停止，請重新進行連接！ ");break;Sleep(500);_Error_End:closesocket(pChatRo

7、om->m_ConnectSock);return TRUE;/捕獲窗口BOOL VideoCapture:Initialize() char devname128=0,devversion128=0; int index=0; BOOL ret = TRUE, ret1 = TRUE, ret2 = TRUE, ret3 = TRUE; TRACE("VideoCapture:Initializen"); /創建一個AVICap捕獲窗口 m_capwnd = capCreateCaptureWindow("Capture",WS_POPUP,0,

8、0,1,1,0,0);if(!m_capwnd)return FALSE;/connect callback functionsret = capSetUserData(m_capwnd,this);/Change destroy functions also. ret1 = capSetCallbackOnVideoStream(m_capwnd,OnCaptureVideo); /得到已安裝的捕獲設備的名稱及版本 ret2 = capGetDriverDescription(index,devname,100,devversion,100);/ Connect to webcam driv

9、er/使一個捕獲窗口與一個捕獲設備連接或關聯ret3 = capDriverConnect(m_capwnd,index);if(!(ret && ret1 && ret2 && ret3)/ Device may be open already or it may not have been/ closed properly last time.AfxMessageBox("Unable to open Video Capture Device");/log.WriteString("n Unable to con

10、nect driver to the window");m_capwnd=NULL;return FALSE;/ Set the capture parametersif(SetCapturePara()=FALSE)/ log.WriteString("n Setting capture parameters failed");capDriverDisconnect(m_capwnd); /使捕獲窗口與一個捕獲設備斷開return FALSE;return TRUE;下面程序為設置CAPTUREPARAMS結構的實現代碼：BOOL VideoCapture:Se

11、tCapturePara()CAPTUREPARMS CapParms=0;capCaptureGetSetup(m_capwnd,&CapParms,sizeof(CapParms);/得到當前的捕獲速度CapParms.fAbortLeftMouse = FALSE;CapParms.fAbortRightMouse = FALSE;CapParms.fYield = TRUE;CapParms.fCaptureAudio = FALSE;CapParms.wPercentDropForError = 80;if(!capCaptureSetSetup(m_capwnd,&

12、CapParms,sizeof(CapParms)/ log.WriteString("n Failed to set the capture parameters ");return FALSE;/ Set Video Format capGetVideoFormat(m_capwnd,&m_bmpinfo,sizeof(m_bmpinfo);m_bmpinfo.bmiHeader.biWidth=IMAGE_WIDTH;m_bmpinfo.bmiHeader.biHeight=IMAGE_HEIGHT;BOOL ret=capSetVideoFormat(m_c

13、apwnd,&m_bmpinfo,sizeof(m_bmpinfo);/log.WriteString("n Video parameters set properly");return ret;/終止一個捕獲任務BOOL VideoCapture:StopCapture()capCaptureStop(m_capwnd);capCaptureAbort(m_capwnd);Sleep(500);return TRUE;音視頻編碼處理就是對音視頻進行壓縮。MPEG-4編碼算法的完整源代碼如下：class CVideoEncoderX264 :public: 

14、;CVideoEncoderX264(void); CVideoEncoderX264(void); virtual bool Connect(CVideoEnDecodeNotify* pNotify, const CVideoEnDecodeItem& Item); virtual void Release(void); virtual void Encode(BYTE* pInData, int nLen, BYTE* pOutBuf, int& nOutLen, int& nKeyFrame);private: x264_

15、picture_t m_Pic; x264_t *h; x264_param_t param; void Flush(void);文件：VideoEncoderX264.cppbool CVideoEncoderX264:Connect(CVideoEnDecodeNotify* pNotify, const CVideoEnDecodeItem& Item) CBase:Connect(pNotify, Item); ParseSize(Item.m_stSize); x264_param_default( &param ); 

16、;param.i_threads = 1; param.i_frame_total = 0; param.i_width  = m_nWidth; param.i_height = m_nHeight; param.i_keyint_min = Item.m_nKeyInterval; param.i_keyint_max = Item.m_nKeyInterval * 10; param.i_fps_num = Item.m_nFps;*/ param.i_log_level = X264_LOG_NONE;if

17、( ( h = x264_encoder_open( &param ) ) = NULL ) return false;  /* Create a new pic */x264_picture_alloc( &m_Pic, X264_CSP_I420, param.i_width, param.i_height ); return true;void CVideoEncoderX264:Release(void) Flush(); x264_picture_clean( &m_Pic ); x264_encoder_cl

18、ose( h ); CBase:Release();void CVideoEncoderX264:Encode(BYTE* pInData, int nLen, BYTE* pOutBuf, int& nOutLen, int& nKeyFrame) if(nLen != param.i_width * param.i_height * 3) return; param.i_frame_total +;memcpy(m_Pic.img.plane0, pInData, param.i_width * param.i_height);mem

19、cpy(m_Pic.img.plane1, pInData + param.i_width * param.i_height, param.i_width * param.i_height / 4);memcpy(m_Pic.img.plane2, pInData + param.i_width * param.i_height * 5 / 4, param.i_width * param.i_height / 4); m_Pic.i_pts = (int64_t)param.i_frame_total * param.i_fps_den;static x264_picture_t

20、pic_out;x264_nal_t *nal = NULL;int i_nal, i;if( &m_Pic )m_Pic.i_type = X264_TYPE_AUTO;m_Pic.i_qpplus1 = 0; /TraceTime("x264_encoder_encode begin");if( x264_encoder_encode( h, &nal, &i_nal, &m_Pic, &pic_out ) < 0 )  return;/TraceTime("x264_encoder_encod

21、e   end");int nOutCanUse = nOutLen;nOutLen = 0;for( i = 0; i < i_nal; i+ )int i_size = 0;if( ( i_size = x264_nal_encode( pOutBuf + nOutLen, &nOutCanUse, 1, &nali ) ) > 0 )nOutLen += i_size;nOutCanUse -= i_size;nKeyFrame = pic_out.i_type=X264_TYPE_IDR;/ | (pic_out.i_type=

22、X264_TYPE_I && coCfg->x264_max_ref_frames=1)void CVideoEncoderX264:Flush(void)x264_picture_t pic_out;x264_nal_t *nal;int i_nal, i;int i_file = 0;if( x264_encoder_encode( h, &nal, &i_nal, NULL, &pic_out ) < 0 )不妨假設創建的線程名為sendThread，發送代碼如下：while(1)isOK=true; /準備就緒SuspendThrea

23、d(sendThread); /掛起線程isOK=false; /線程正在發送數據int length=frameLength; /待發數據長度if(length<50000) /判斷數據是否正常int n=0;int sendCount=0;while(length>0) n=send(sock,(char*)imageBuf+sendCount,length,0); /發送數據，/imageBuf是指針，指向待發數據幀if(n=SOCKET_ERROR) /網絡出現異常，則退出線程break;length-=n;sendCount+=n;接收端創建一個線程專門用來執行數據接收。不妨假設線程名為recThread，核心代碼實現如下：while(temp!=SOCKET_ERROR)if(!isStart) /幀數據是否開始，true表示開始if(endNum>3) /endNum紀錄當前接收未處理的數據endNum=0;temp=recv(clisock,(char*)(recBuf+endNum),1000,0);/從緩沖區讀取數據