经常在CSDN.NET 得到知识以及广大同胞的帮助,在此深表感谢！在很多时候都希望自己也可以为大家做点，只是....呵呵，本菜鸟实在是墨水有限，说不上什么东东。
下面是我在学习Directshow编程写的一个示例程序，结构简单，贴之。望可以为一些初学者提供一个感性的认识。
相关的技术文章建议看看陆其明写的文章，嘿嘿，我就是看看他的文章开始学习Directshow编程的。
//代码如下
//Layer3Decoder.h
#ifndef LAYER3DECODER__H__
#define LAYER3DECODER__H__
#include <atlbase.h>
#include <dshow.h>
#pragma comment(lib,"strmiids.lib")
#define S_RELEASE(x) if((x)){(x)->Release();(x)=NULL;}
class CComInit //初始化Com环境
{
public:
CComInit();
~CComInit();
};
class CLayer3Decoder //Mp3 -> wav
{
public:
CLayer3Decoder();
~CLayer3Decoder();
public:
static HRESULT GetPin(IBaseFilter *pFilter, PIN_DIRECTION PinDir, IPin **ppPin);
static HRESULT ConnectFilters(IGraphBuilder *pGraph, IBaseFilter *pFirst, IBaseFilter *pSecond);
public:
void Decoder(LPCTSTR lpszSrc,LPCTSTR lpszDest);
private:
void Release(void);
private:
IGraphBuilder * m_pGraphBuilder;
IMediaControl * m_pMediaControl;
IBaseFilter * m_pFileSource;
IBaseFilter * m_pFileDest;
IBaseFilter * m_pStreamSplitter;
IBaseFilter * m_pLayer3Decoder;
IBaseFilter * m_pWaveDest;
};
#endif //LAYER3DECODER__H__
//////////////////////
//Layer3Decoder.cpp
//#include "stdafx.h"
#include <tchar.h>
//#include <atlbase.h>
//#include <dshow.h>
#include "Layer3Decoder.h"
//WavDest.ax
//这个filter是DirectShow SDK Example 中的一个例子
//编译后注册一下就可以了
// {3C78B8E2-6C4D-11d1-ADE2-0000F8754B99}
static const GUID CLSID_WavDest =
{ 0x3c78b8e2, 0x6c4d, 0x11d1, { 0xad, 0xe2, 0x0, 0x0, 0xf8, 0x75, 0x4b, 0x99 } };
//{38BE3000-DBF4-11D0-860E-00A024CFEF6D}
static const GUID CLSID_Layer3Decoder =
{ 0x38BE3000, 0xDBF4, 0x11D0, { 0x86, 0x0e, 0x0, 0xa0, 0x24, 0xcf, 0xef, 0x6d}};
CComInit::CComInit()
{
::CoInitialize(NULL);
}
CComInit::~CComInit()
{
::CoUninitialize();
}
const CComInit comInit = CComInit();//自动初始化Com环境
CLayer3Decoder::CLayer3Decoder()
{
m_pGraphBuilder = NULL;
m_pMediaControl = NULL;
m_pFileSource = NULL;
m_pFileDest = NULL;
m_pStreamSplitter = NULL;
m_pLayer3Decoder = NULL;
m_pWaveDest = NULL;
}
CLayer3Decoder::~CLayer3Decoder()
{
Release();
}
void CLayer3Decoder::Release()
{
S_RELEASE(m_pGraphBuilder);
S_RELEASE(m_pMediaControl);
S_RELEASE(m_pFileSource);
S_RELEASE(m_pFileDest);
S_RELEASE(m_pStreamSplitter);
S_RELEASE(m_pLayer3Decoder);
S_RELEASE(m_pWaveDest);
}
HRESULT CLayer3Decoder::GetPin(IBaseFilter *pFilter, PIN_DIRECTION PinDir, IPin **ppPin)
{
IEnumPins *pEnum;
IPin *pPin;
pFilter->EnumPins(&pEnum);
while(pEnum->Next(1, &pPin, 0) == S_OK)
{
PIN_DIRECTION PinDirThis;
pPin->QueryDirection(&PinDirThis);
if (PinDir == PinDirThis)
{
pEnum->Release();
*ppPin = pPin;
return S_OK;
}
pPin->Release();
}
pEnum->Release();
return E_FAIL;
}
HRESULT CLayer3Decoder::ConnectFilters(IGraphBuilder *pGraph, IBaseFilter *pFirst, IBaseFilter *pSecond)
{
IPin *pOut = NULL, *pIn = NULL;
HRESULT hr = GetPin(pFirst, PINDIR_OUTPUT, &pOut);
if (FAILED(hr)) return hr;
hr = GetPin(pSecond, PINDIR_INPUT, &pIn);
if (FAILED(hr))
{
pOut->Release();
return E_FAIL;
}
hr = pGraph->Connect(pOut, pIn);
pIn->Release();
pOut->Release();
return hr;
}
void CLayer3Decoder::Decoder(LPCTSTR lpszSrc,LPCTSTR lpszDest)
{
HRESULT hr = S_OK;
WCHAR wFileSrc[MAX_PATH];
WCHAR wFileDes[MAX_PATH];
USES_CONVERSION;
wcsncpy(wFileSrc, T2W(lpszSrc),MAX_PATH);
wcsncpy(wFileDes,T2W(lpszDest),MAX_PATH);
///////////////////////////////////////////
//
hr = ::CoCreateInstance(CLSID_FilterGraph,NULL,CLSCTX_ALL,IID_IGraphBuilder,(void**)&m_pGraphBuilder);
if(hr!=S_OK)
{
TRACE("Crate Graph Builder => Failsed\n");
Release();
return;
}
////////////////////////////////////////////////
//
hr = m_pGraphBuilder->QueryInterface(IID_IMediaControl,(void**)&m_pMediaControl);
if(hr!=S_OK)
{
TRACE("Create MediaControl => Failsed\n");
Release();
return;
}
/////////////////////////////////////////
//建立文件读入
hr = ::CoCreateInstance(CLSID_AsyncReader,NULL,CLSCTX_ALL,IID_IBaseFilter,(void**)&m_pFileSource);
if(hr!=S_OK)
{
TRACE("Create File Async Reader => Failsed\n");
Release();
return;
}
IFileSourceFilter * psrc = NULL;
hr = m_pFileSource->QueryInterface(IID_IFileSourceFilter,(void**)&psrc);
if(hr!=S_OK)
{
TRACE("Create File Source Load's Filter => Failsed\n");
S_RELEASE(psrc);
Release();
return;
}
hr = psrc->Load(wFileSrc,NULL);//读入文件
if(hr!=S_OK)
{
TRACE("Load Source File => Failsed\n");
S_RELEASE(psrc);
Release();
return;
}
S_RELEASE(psrc);//释放文件读入
////////////////////////////////////////////////////
//建立文件写入
hr = ::CoCreateInstance(CLSID_FileWriter,NULL,CLSCTX_ALL,IID_IBaseFilter,(void**)&m_pFileDest);
if(hr!=S_OK)
{
TRACE("Create File Write => Failsed\n");
Release();
return;
}
IFileSinkFilter * pdes = NULL;
hr = m_pFileDest->QueryInterface(IID_IFileSinkFilter,(void**)&pdes);
if(hr!=S_OK)
{
TRACE("Create File Write Interface => Failsed\n");
S_RELEASE(pdes);
Release();
return;
}
hr = pdes->SetFileName(wFileDes,NULL);
if(hr!=S_OK)
{
TRACE("Set File Write => Failsed\n");
S_RELEASE(pdes);
Release();
return;
}
S_RELEASE(pdes);
////////////////////////////////////////////////////////
//Steam splitter
hr = ::CoCreateInstance(CLSID_MPEG1Splitter,NULL,CLSCTX_ALL,IID_IBaseFilter,(void**)&m_pStreamSplitter);
if(hr!=S_OK)
{
TRACE("Create Stream Splitter => Failsed\n");
Release();
return;
}
////////////////////////////////////////////////////////
//Layer 3 Decoder
hr = ::CoCreateInstance(CLSID_Layer3Decoder,NULL,CLSCTX_ALL,IID_IBaseFilter,(void**)&m_pLayer3Decoder);
if(hr!=S_OK)
{
TRACE("Create Layer3 Decoder => Failsed\n");
Release();
return;
}
//////////////////////////////////////////////////////////
//Wave Dest
hr = ::CoCreateInstance(CLSID_WavDest,NULL,CLSCTX_ALL,IID_IBaseFilter,(void**)&m_pWaveDest);
if(hr!=S_OK)
{
TRACE("create wave dest => Failsed\n");
Release();
return;
}
///////////////////////////////////////////////////////////
// add filter into GraphBuilder
hr = m_pGraphBuilder->AddFilter(m_pFileSource,L"Source File");
hr = m_pGraphBuilder->AddFilter(m_pFileDest,L"Dest File");
hr = m_pGraphBuilder->AddFilter(m_pStreamSplitter,L"Stream Splitter");
hr = m_pGraphBuilder->AddFilter(m_pLayer3Decoder,L"Layer3 Decoder");
hr = m_pGraphBuilder->AddFilter(m_pWaveDest,L"Wave Dest");
/////////////////////////////////////////////////////////////
//connection filter
hr = ConnectFilters(m_pGraphBuilder,m_pFileSource,m_pStreamSplitter);
hr = ConnectFilters(m_pGraphBuilder,m_pStreamSplitter,m_pLayer3Decoder);
hr = ConnectFilters(m_pGraphBuilder,m_pLayer3Decoder,m_pWaveDest);
hr = ConnectFilters(m_pGraphBuilder,m_pWaveDest,m_pFileDest);
//////////////////////////////////////////////////////////////
//run
m_pMediaControl->Run();
}
//the end 
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