NULLNULL.CPP

//==========================================================================; 
// 
//  THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY 
//  KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE 
//  IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR 
//  PURPOSE. 
// 
//  Copyright (c) 1992 - 1997  Microsoft Corporation.  All Rights Reserved. 
// 
//--------------------------------------------------------------------------; 
 
 
//     What This Sample Illustrates 
// 
// What is the minimum necessary in a filter. 
// 
//     Summary 
// 
// A filter which does nothing except pass the data through. 
// 
//     Demonstration instructions 
// 
// First build the sample and get it registered (see nullnull.reg) 
// Start GRAPHEDT available in the ActiveMovie SDK tools. Drag and drop into 
// the tool any WAV file or any MPEG, AVI or MOV file. 
// A graph will be built to render the file.  From the Graph menu select 
// Insert filters and insert NullNull.  (If it is not on the list then you 
// failed to register it properly.  If it fails to load then you either 
// didn't build it properly or the registration does not correctly point to 
// the path where nullnull.ax is now found.) 
// In the graph displayed, pick on a connection.  Disconnect it (click on 
// the incoming arrow and then press the Delete key). 
// Create a connection between the same two filters.  (Drag the mouse along 
// the same path as the arrow follwed from tail to head). 
// If the nullnull filter is not now included, try it with a different 
// connection.  (Connections between source filters and parsers normally 
// do not work, others normally do.  Why is another story). 
// 
// 
//     Implementation 
// 
// Does everything possible with the base classes.  That which cannot be so 
// done (e.g. creating this filter) is done here. 
// The filter has one input pin, one output pin and does its transform 
// in-place (i.e. without copying the data) on the push thread (i.e. it 
// is called with a buffer, which it "transforms" and gives to the next 
// filter downstream.  It is then blocked until that filter returns. 
// It then returns to its own caller).  This filter in fact does the null 
// transform it merely passes the data on unchanged. 
// 
// 
//    Known problems ("features NOT illustrated by this sample"): 
// 
// Almost everything!  This is a truly minimal filter. 
// 
// 
//      Files 
// 
// nullnull.cpp  The entire implementation 
// nullnull.def  Lists exports and imports (part of build process) 
// nullnull.rc   Contains some "boiler-plate" 
// nullnull.reg  Allows REGEDIT to register this filter.  (Not strictly necessary). 
// 
//     Base classes used (refer to docs for diagram of what they inherit): 
// 
// CTransInPlaceFilter 
 
 
 
#include <streams.h>     // Active Movie (includes windows.h) 
#include <initguid.h>    // declares DEFINE_GUID to declare an EXTERN_C const. 
 
// The CLSID used by the minimal, in-place, null filter 
// DO NOT REUSE IT.  Run uuidgen.exe to create a new one. 
// {08af6540-4f21-11cf-aacb-0020af0b99a3} 
DEFINE_GUID(CLSID_NullNull, 
0x08af6540, 0x4f21, 0x11cf, 0xaa, 0xcb, 0x00, 0x20, 0xaf, 0x0b, 0x99, 0xa3); 
 
 
// setup data - allows the self-registration to work. 
 
const AMOVIESETUP_MEDIATYPE sudPinTypes = 
{ &MEDIATYPE_NULL        // clsMajorType 
, &MEDIASUBTYPE_NULL };  // clsMinorType 
 
const AMOVIESETUP_PIN psudPins[] = 
{ { L"Input"            // strName 
  , FALSE               // bRendered 
  , FALSE               // bOutput 
  , FALSE               // bZero 
  , FALSE               // bMany 
  , &CLSID_NULL         // clsConnectsToFilter 
  , L""                 // strConnectsToPin 
  , 1                   // nTypes 
  , &sudPinTypes        // lpTypes 
  } 
, { L"Output"           // strName 
  , FALSE               // bRendered 
  , TRUE                // bOutput 
  , FALSE               // bZero 
  , FALSE               // bMany 
  , &CLSID_NULL         // clsConnectsToFilter 
  , L""                 // strConnectsToPin 
  , 1                   // nTypes 
  , &sudPinTypes        // lpTypes 
  } 
}; 
 
 
const AMOVIESETUP_FILTER sudNullNull = 
{ &CLSID_NullNull                  // clsID 
, L"Minimal Null"                 // strName 
, MERIT_DO_NOT_USE                // dwMerit 
, 2                               // nPins 
, psudPins };                     // lpPin 
 
// CNullNull 
// 
class CNullNull 
    : public CTransInPlaceFilter 
{ 
 
public: 
 
    static CUnknown *WINAPI CreateInstance(LPUNKNOWN punk, HRESULT *phr); 
 
    DECLARE_IUNKNOWN; 
 
private: 
 
    // Constructor - just calls the base class constructor 
    CNullNull(TCHAR *tszName, LPUNKNOWN punk, HRESULT *phr) 
        : CTransInPlaceFilter (tszName, punk, CLSID_NullNull, phr) 
    { } 
 
    // Overrides the PURE virtual Transform of CTransInPlaceFilter base class 
    // This is where the "real work" is done by altering *pSample. 
    // We do the Null transform by leaving it alone. 
    HRESULT Transform(IMediaSample *pSample){ return NOERROR; } 
 
    // We accept any input type.  We'd return S_FALSE for any we didn't like. 
    HRESULT CheckInputType(const CMediaType* mtIn) { return S_OK; } 
}; 
 
 
 
// Needed for the CreateInstance mechanism 
CFactoryTemplate g_Templates[]= 
    {   { L"Minimal Null" 
        , &CLSID_NullNull 
        , CNullNull::CreateInstance 
        , NULL 
        , &sudNullNull } 
    }; 
int g_cTemplates = sizeof(g_Templates)/sizeof(g_Templates[0]); 
 
 
// 
// CreateInstance 
// 
// Provide the way for COM to create a CNullNull object 
CUnknown * WINAPI CNullNull::CreateInstance(LPUNKNOWN punk, HRESULT *phr) { 
 
    CNullNull *pNewObject = new CNullNull(NAME("Minimal, in-place, null filter"), punk, phr ); 
    if (pNewObject == NULL) { 
        *phr = E_OUTOFMEMORY; 
    } 
 
    return pNewObject; 
} // CreateInstance 
 
 
/******************************Public*Routine******************************\ 
* exported entry points for registration and 
* unregistration (in this case they only call 
* through to default implmentations). 
* 
* 
* 
* History: 
* 
\**************************************************************************/ 
STDAPI 
DllRegisterServer() 
{ 
  return AMovieDllRegisterServer2( TRUE ); 
} 
 
STDAPI 
DllUnregisterServer() 
{ 
  return AMovieDllRegisterServer2( FALSE ); 
} 
 
// Microsoft C Compiler will give hundreds of warnings about 
// unused inline functions in header files.  Try to disable them. 
#pragma warning( disable:4514)