獲取語音設備并創建Interface
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??? DirectSound開發中常常需要獲取系統當前可用的語音設備列表，在SDK Samples中最先介紹了它。DirectX將它封裝成函數DirectSoundEnumerate/DirectSoundCaptureEnumerate，我們所要做的只是以DSEnumCallback作為接口模板，添加一個自定義的回調函數，然后簡單的調用一下即可。
??? 獲取設備列表后，創建DirectSound環境使用函數DirectSoundCreate8/DirectSoundCaptureCreate8。

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下面是示例源代碼：

/*----------------------------------------------------------------------------------
*? File: EnumDevices.cpp
*
*? Desc: This sample shows how to enumerate DirectSound sound and capture devices.
*
*? Copyright (c) Microsoft Corp. All rights reserved.
*
*
*? DirectSoundEnumerate
*? DirectSoundCaptureEnumerate
*? DirectSoundCreate8
*? DirectSoundCaptureCreate8
*? DXTRACE_ERR_MSGBOX : 在DEBUG模式下用來顯示錯誤信息
*? DSEnumCallback???? : 用來枚舉設備的回調函數
*-----------------------------------------------------------------------------------*/

#include <windows.h>
#include <dxerr9.h>
#include <dsound.h>
#include "resource.h"

#pragma comment( lib,"Dsound.lib" )
#ifdef _DEBUG
??? #pragma comment( lib,"dxerr9.lib" )
#endif

INT_PTR CALLBACK MainDlgProc( HWND,UINT,WPARAM,LPARAM );
INT_PTR CALLBACK DSoundEnumCallback( GUID*,LPSTR, LPSTR,VOID* );
HRESULT OnInitDialog( HWND );
HRESULT InitDirectSound( HWND );
HRESULT FreeDirectSound();

#define SAFE_DELETE(p)? { if(p) { delete (p);???? (p)=NULL; } }
#define SAFE_RELEASE(p) { if(p) { (p)->Release(); (p)=NULL; } }

LPDIRECTSOUND8??????? g_pDS??????? = NULL; //用來存放IDirectSound8 interface地址
LPDIRECTSOUNDCAPTURE8 g_pDSCapture = NULL; //用來存放IDirectSoundCapture8 interface地址

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR pszCmdLine, int iCmdShow)
{
??? //初始化COM, 可參考DirectX開發文檔中創建COM對象部分(Creating a COM Object)
??? CoInitialize( NULL );

??? // Display the main dialog box.
??? DialogBox( hInstance, MAKEINTRESOURCE(IDD_MAIN), NULL, MainDlgProc );

??? //釋放COM
??? CoUninitialize();

??? return TRUE;
}

//主窗口回調函數
INT_PTR CALLBACK MainDlgProc( HWND hDlg, UINT msg, WPARAM wParam, LPARAM lParam )
{
??? HRESULT hr;

??? switch( msg )
??? {
??????? case WM_INITDIALOG:
??????????? if( FAILED( hr = OnInitDialog( hDlg ) ) )
??????????? {
??????????????? DXTRACE_ERR_MSGBOX( TEXT("OnInitDialog"), hr );
??????????????? MessageBox( hDlg, "枚舉DirectSound設備錯誤,程序退出.", "EnumDevices", MB_OK | MB_ICONERROR );
??????????????? EndDialog( hDlg, IDABORT );
??????????? }
??????????? break;

??????? case WM_COMMAND:
??????????? switch( LOWORD(wParam) )
??????????? {
??????????????? case IDC_BUTTON_CREATE:
??????????????????? //嘗試創建
??????????????????? if( SUCCEEDED( hr = InitDirectSound( hDlg ) ) )
??????????????????????? MessageBox( hDlg, TEXT("創建DirectSound interface成功."), TEXT("EnumDevices"), MB_OK );
??????????????????? else
??????????????????? {
??????????????????????? DXTRACE_ERR_MSGBOX( TEXT("InitDirectSound"), hr );
??????????????????????? MessageBox( hDlg, TEXT("創建DirectSound interface失敗."), TEXT("EnumDevices"), MB_OK | MB_ICONERROR );
??????????????????? }
??????????????????? break;

??????????????? case IDOK:
??????????????????? EndDialog( hDlg, IDCANCEL );
??????????????????? break;

??????????????? default:
??????????????????? return FALSE;
??????????? }
??????????? break;

??????? case WM_DESTROY:
??????????? FreeDirectSound(); //不要忘記釋放設備
??????????? break;

??????? default:
??????????? return FALSE;
??? }
??? return TRUE;
}

//初始化窗體
HRESULT OnInitDialog( HWND hDlg )
{
??? HRESULT hr;

??? //枚舉sound devices并添加到組合框中
??? HWND hSoundDeviceCombo = GetDlgItem( hDlg, IDC_COMBO_SOUND_DEVICE );
??? if( FAILED( hr = DirectSoundEnumerate( (LPDSENUMCALLBACK)DSoundEnumCallback, (VOID*)hSoundDeviceCombo ) ) )
??????? return DXTRACE_ERR_MSGBOX( TEXT("DirectSoundEnumerate"), hr );

??? //枚舉capture devices并添加到組合框中
??? HWND hCaptureDeviceCombo = GetDlgItem( hDlg, IDC_COMBO_CAPTURE_DEVICE );
??? if( FAILED( hr = DirectSoundCaptureEnumerate( (LPDSENUMCALLBACK)DSoundEnumCallback, (VOID*)hCaptureDeviceCombo ) ) )
??????? return DXTRACE_ERR_MSGBOX( TEXT("DirectSoundCaptureEnumerate"), hr );

??? //選中組合框中的第一個設備
??? SendMessage( hSoundDeviceCombo,?? CB_SETCURSEL, 0, 0 );
??? SendMessage( hCaptureDeviceCombo, CB_SETCURSEL, 0, 0 );

??? return S_OK;
}

//供枚舉函數使用的回調函數
INT_PTR CALLBACK DSoundEnumCallback( GUID* pGUID, LPSTR strDesc, LPSTR strDrvName, VOID* pContext )
{
??? //注意定義為靜態變量
??? static GUID? AudioDriverGUIDs[20]; //預留20個設備的存儲空間
??? static DWORD dwAudioDriverIndex = 0;

??? GUID* pTemp? = NULL;

??? if( pGUID )
??? {
??????? if( dwAudioDriverIndex >= 20 )
??????????? return TRUE;

??????? pTemp = &AudioDriverGUIDs[dwAudioDriverIndex++];
??????? memcpy( pTemp, pGUID, sizeof(GUID) );
??? }

??? HWND hSoundDeviceCombo = (HWND)pContext;

??? //把設備名稱添加到組合框中
??? SendMessage( hSoundDeviceCombo, CB_ADDSTRING, 0, (LPARAM)(LPCTSTR)strDesc );

??? //獲取當前設備名稱在組合框中的索引值
??? int nIndex = (int)SendMessage( hSoundDeviceCombo, CB_FINDSTRING, 0, (LPARAM) (LPCTSTR) strDesc );

??? //將存儲在AudioDriverGUIDs設備數組中的GUID保存到對應項中
??? SendMessage( hSoundDeviceCombo, CB_SETITEMDATA, nIndex, (LPARAM) pTemp );

??? return TRUE;
}

//創建IDirectSound
HRESULT InitDirectSound( HWND hDlg )
{
??? HRESULT hr;

??? //首先釋放當前可能使用的DirectSound對象
??? FreeDirectSound();

??? HWND hSoundDeviceCombo?? = GetDlgItem( hDlg, IDC_COMBO_SOUND_DEVICE );
??? HWND hCaptureDeviceCombo = GetDlgItem( hDlg, IDC_COMBO_CAPTURE_DEVICE );

??? int nSoundIndex?? = (int)SendMessage( hSoundDeviceCombo,?? CB_GETCURSEL, 0, 0 );
??? int nCaptureIndex = (int)SendMessage( hCaptureDeviceCombo, CB_GETCURSEL, 0, 0 );

??? //獲取當前選擇項所對應的GUID數據
??? GUID* pSoundGUID?? = (GUID*) SendMessage( hSoundDeviceCombo, CB_GETITEMDATA, nSoundIndex, 0 );
??? GUID* pCaptureGUID = (GUID*) SendMessage( hCaptureDeviceCombo, CB_GETITEMDATA, nCaptureIndex, 0 );

??? //使用所選設備創建IDirectSound
??? if( FAILED( hr = DirectSoundCreate8( pSoundGUID, &g_pDS, NULL ) ) )
??????? return DXTRACE_ERR_MSGBOX( TEXT("DirectSoundCreate"), hr );

??? //作為一個示例,我們嘗試創建后馬上釋放掉.
??? SAFE_RELEASE( g_pDS );

??? //使用所選設備創建IDirectSoundCapture
??? if( FAILED( hr = DirectSoundCaptureCreate8( pCaptureGUID, &g_pDSCapture, NULL ) ) )
??????? return DXTRACE_ERR_MSGBOX( TEXT("DirectSoundCaptureCreate"), hr );

??? //釋放
??? SAFE_RELEASE( g_pDSCapture );

??? return S_OK;
}

//釋放對象
HRESULT FreeDirectSound()
{
??? SAFE_RELEASE( g_pDSCapture );
??? SAFE_RELEASE( g_pDS );

??? return S_OK;

?
?}

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