注册Filter
AX文件的一个对外接口DllRegisterServer，由外部调用，比如注册AX的时候：regsvr32 xxx.ax
通常情况下，我们的filter可能注册在”Direct Show”目录下，那么直接调用
// Creates registry entries for the DLL
STDAPIDllRegisterServer()
{
return AMovieDllRegisterServer2(TRUE);
}
AMovieDllRegisterServer2在DX的帮助文档内的说明如下：
The AMovieDllRegisterServer2 function creates registry entries for every component in the g_Templates array. However, this function has some limitations. First, it assigns every filter to the "DirectShow Filters" category (CLSID_LegacyAmFilterCategory), but not every filter belongs in this category. Capture filters and compression filters, for example, have their own categories. Second, if your filter supports a hardware device, you might need to register two additional pieces of information that AMovieDLLRegisterServer2 does not handle: the medium and the pin category. A medium defines a method of communication in a hardware device, such as a bus. The pin category defines the function of a pin. For information on mediums, see KSPIN_MEDIUM in the Microsoft Windows Driver Development Kit (DDK). For a list of pin categories, see Pin Property Set.
如果我们的引擎需要注册到DirectShow之外的目录，又该如何做？
// 注册Filter到Video Compressor
REGFILTER2 rf2FilterReg =
{
1, // Version 1 (no pin mediums or pin category).
MERIT_NORMAL, // Merit.
1, // Number of pins.
&sudPins // Pointer to pin information.
};
//Creates registry entries for the DLL
STDAPI DllRegisterServer(void)
{
HRESULT hr = E_FAIL;
IFilterMapper2 *pFM2 = NULL;
hr = AMovieDllRegisterServer2(TRUE); // 这个还是要调用的
if (FAILED(hr)) return hr;
hr = CoCreateInstance(CLSID_FilterMapper2, NULL,
CLSCTX_INPROC_SERVER,
IID_IFilterMapper2, (void **)&pFM2);
if (FAILED(hr)) return hr;
hr = pFM2->RegisterFilter(CLSID_SomeFilter, // Filter CLSID.
g_wszName, // Filter name.
NULL, // Device moniker.
&CLSID_VideoCompressorCategory, // Video compressor category.
g_wszName, // Instance data.
&rf2FilterReg // Pointer to filter information.
);
pFM2->Release();
return hr;
}
注销Filter
注销DirectShow内的引擎
// Removes registry entries for the DLL
STDAPI DllUnregisterServer()
{
return AMovieDllRegisterServer2(FALSE);
}
注销指定目录下的引擎
// 注销Video Compressor下的引擎
// Removes registry entries for the DLL
STDAPI DllUnregisterServer()
{
HRESULT hr = E_FAIL;
IFilterMapper2* pFM2 = NULL;
hr = AMovieDllRegisterServer2(FALSE);
if (FAILED(hr)) return hr;
hr = CoCreateInstance(CLSID_FilterMapper2, NULL, CLSCTX_INPROC_SERVER,
IID_IFilterMapper2, (void **)&pFM2);
if (FAILED(hr)) return hr;
hr = pFM2->UnregisterFilter(&CLSID_VideoCompressorCategory,
g_wszName, CLSID_SomeFilter);
pFM2->Release();
return hr;
}
给Filter起个名字
// Pin的type分为Major Type 和 Subtype
// 比如，Major Type = Video, Subtype = MPEG-2
const AMOVIESETUP_MEDIATYPE sudPinTypes =
{
&MEDIATYPE_NULL, // Major type
&MEDIASUBTYPE_NULL // Subtype
};
const AMOVIESETUP_PIN psudPins[] =
{
// 定义Input Pin的信息
{
L"Input", // String pin name
FALSE, // Is it rendered
FALSE, // Is it an output
FALSE, // Allowed none
FALSE, // Allowed many
&CLSID_NULL, // Connects to filter
0 // Connects to pin
1, // Number of types
&sudPinTypes
}, // The pin details
{
L"Output", // String pin name
FALSE, // Is it rendered
TRUE, // Is it an output
FALSE, // Allowed none
FALSE, // Allowed many
&CLSID_NULL, // Connects to filter
0, // Connects to pin
1, // Number of types
&sudPinTypes // The pin details
}
};
// Declare filter information
const AMOVIESETUP_FILTER sudFilter =
{
&CLSID_MPKiller, // Filter CLSID
L"HQ MP Killer", // Filter name
0x8800000, // Its merit
2, // Number of pins
psudPins // Pin details
};
// declare a global array of CFactoryTemplate class instances, named g_Templates. Each
// CFactoryTemplate class contains registry information for one filter. Several filters can
// reside in a single DLL; simply include additional CFactoryTemplate entries. You can
// also declare other COM objects, such as property pages
// 在同一个DLL或者AX内，可以有多个引擎，比如系统目录下的quartz.dll。
// 所以，如果有多个引擎，相应的数组的大小就是引擎的个数。
CFactoryTemplateg_Templates[] =
{
{
L"HQ MP Killer",
&CLSID_MPKiller,
CImplement::CreateInstance,
NULL,
&sudFilter
}
};
int g_cTemplates = sizeof(g_Templates) / sizeof(g_Templates[0]); // 有几个引擎
允许Filter应用
// CreateInstance 是CFactory的一个接口，在Filter内部实现它
CUnknown* WINAPI CImplement::CreateInstance( LPUNKNOWN pUnk,
HRESULT *pHr)
{
CImplement *pFilter = new CImplement ();
if (!pFilter)
{
*pHr = E_OUTOFMEMORY;
}
return pFilter;
}
Filter的Merit
Graph 会使用“傻子”机制联接不同的filter，这就要通过filter的merit值的高低进行“傻子”联接。
该联接要使用IFilterMapper2::EnumMatchingFilters方法。
Merit：
enum
{
MERIT_PREFERRED = 0x800000,
MERIT_NORMAL = 0x600000,
MERIT_UNLIKELY = 0x400000,
MERIT_DO_NOT_USE = 0x200000,
MERIT_SW_COMPRESSOR = 0x100000,
MERIT_HW_COMPRESSOR = 0x100050
};
<= MERIT_DO_NOT_USE的Merit的Filter，系统是不会去“傻子”联接的。当然Merit值可以是任意值，而不一定是枚举出来的。
确定Filter的用途
不同的Filter有不同的用途，可以选择不同的基类，实现不同的方法。详见DirectX 文档。Filter的种类，在内进行了详细的描述root\DirectShow\DirectShow Reference\Constants and GUIDs\Filter Categories。
添加属性页
CFactoryTemplateg_Templates[2] =
{
{
g_wszArcIPCam, // Name
&CLSID_ArcIPCam, // CLSID
CArcIPCam::CreateInstance, // Method to create an instance of MyComponent
NULL, // Initialization function
&sudArcIPCamSourceFilter // Set-up information (for filters)
},
{
// 这些数据，为属性页准备
g_wszArcIPCamProperty,
&CLSID_ArcIPCamProperty,
CArcIPCamProperty::CreateInstance
}
};
class CArcIPCam : public xxx, public IArcIPCam, public ISpecifyPropertyPages
{
private:
// Constructor is private because you have to use CreateInstance
CArcIPCam(IUnknown *pUnk, HRESULT *phr);
~CArcIPCam();
CArcIPCamPin *m_pPin;
public:
static CUnknown * WINAPI CreateInstance(IUnknown *pUnk, HRESULT *phr);
DECLARE_IUNKNOWN;
// Property Page---
STDMETHODIMP GetClassID(CLSID *pClsid);
// Basic COM - used here to reveal our property interface.
STDMETHODIMP NonDelegatingQueryInterface(REFIID riid, void ** ppv);
// return our property pages
STDMETHODIMP GetPages(CAUUID * pPages);
}
这三个函数必须实现。