DirectX 9 Video Capture

DirectX 9
Video Capture
: http://debut.cis.nctu.edu.tw/~ching

About Video Capture
• describes any application where video is
received from a hardware device
• Cameras, TV tuner cards, video tape
recorders
• the concepts
• Graph Builder
• Video Capture Devices
• DirectShow Video Capture Filters

Writing a DirectShow Application
• Three tasks must be performed
1 2 3
立 Filter Graph Manager
利 Filter Graph Manager
立 filter graph
利 Filter Graph Manager
filter graph
When processing is completed,
the application releases the Filter Graph Manager and all of the filters

About the Capture Graph Builder
• A Filter graph that perform video & audio
capture
• ICaptureGraphBuilder2 interface
• Building & controlling a capture graph

CaptureGraphBuilder2
1
1
Create new instances
1. Capture Graph Builder
2. Filter Graph Manager
2
2
立 連
利 ICaptureGraphBuilder2::SetFiltergraph
Filter Graph Manager
Capture Graph Builder

Create new instances
HRESULT InitCaptureGraphBuilder(
IGraphBuilder **ppGraph, //
ICaptureGraphBuilder2 **ppBuild //
) {
IGraphBuilder *pGraph = NULL;
ICaptureGraphBuilder2 *pBuild = NULL;
1 立 Class ID
// 立 Capture Graph Builder.
HRESULT hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL,
CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2,
(void**)&pBuild);
DLL
process
行
Interface
Interface
NULL

SetFiltergraph
更
2
if (SUCCEEDED(hr)) {
// 立 Filter Graph Manager
hr = CoCreateInstance(CLSID_FilterGraph, 0, CLSCTX_INPROC_SERVER,
IID_IGraphBuilder, (void**)&pGraph);
if (SUCCEEDED(hr)) {
pBuild->SetFiltergraph(pGraph);
: SDK
pBuilder 理
Filter Graph Manager
}
*ppBuild = pBuild;
*ppGraph = pGraph;
return S_OK;
}
else
pBuild->Release();
}
return hr; // Failed
料

Capture Filters
• Pin Categories
• 2 更 料 output pins
• Pins 類 , GUID 來 Identify
• Preview Pins & Capture Pins
• Preview Pins render video to the screen
• drop frame
• PIN_CATEGORY_PREVIEW
• Capture Pins video
• frame time-stamped
• PIN_CATEGORY_CAPTURE
Pin Category
Pin Category

Capture Filters
• Video Port Pins
• a hardware connection ( video card video
device)
• video device 料 graph
card, hardware overlay
video memory, CPU
•
• overlay surface
• Frame Flipping .
• Pin category: PIN_CATEGORY_VIDEOPORT

Selecting a Capture Device
• 料 , 料
Step 1
利
System Device Enumerator
料 列
Step 1
IMoniker
Step 2
Step 2
利 列 IMoniker 料
* BindToStorage method : 讀
* BindToObject method : 立 Filter

例 說
#include // for ATL 7.0 串
#include // for DirectShow header file
#pragma comment( lib, "Strmiids.lib" ) // for DirectShow library file
#include // for printf
void EnumerateVideoInputDevice();
int main() {
// Step 1: initial COM
CoInitialize(NULL);
// Step 2: 列 ( 見 )
EnumerateVideoInputDevice();
}
// COM must be uninitialized
CoUninitialize();
return 0;
Video Capture Device

void EnumerateVideoInputDevice(){
ICreateDevEnum *pDevEnum = NULL;
列
// Step 1: 立 System Device Enumerator
Moniker 立 CLSID ( GUID)
HRESULT hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL,
CLSCTX_INPROC_SERVER,
IID_ICreateDevEnum,
reinterpret_cast(&pDevEnum));
IEnumMoniker *pEnum = NULL;
if (SUCCEEDED(hr)){
Non-aggregation
立
Moniker 列
// Step 2: 立 Video capture 列 ( 列 Video Input Filter)
hr = pDevEnum->CreateClassEnumerator( \
CLSID_VideoInputDeviceCategory,\
&pEnum, 0);
}
* CLSID: A globally unique identifier (GUID) associated with an OLE class object. VideoInputDevice
•aggregation: 立 , Interface exposed.
* Filter Categories 更 Filter

Step 3: 利 列 Next method Moniker ,
IMoniker *pMoniker = NULL;
while (pEnum->Next (1, &pMoniker, NULL) == S_OK) {
IPropertyBag *pPropBag;
hr = pMoniker->BindToStorage(0, 0, IID_IPropertyBag,
(void**)(&pPropBag));
if (FAILED(hr)){
pMoniker->Release();
continue;
}
// Step 4: 讀
VARIANT varName;
VariantInit(&varName);
}
hr = pPropBag->Read (L"FriendlyName", &varName, 0);
if (SUCCEEDED(hr)) {
// OLE 串 TCHAR 串
COLE2T strName(varName.bstrVal);
printf(" = %s \n",strName);
VariantClear(&varName);
}
pPropBag->Release();
pMoniker->Release();
} // end of while
利 Moniker
讀 來
列
料

立 Capture Device Filter
利 Moniker 立
IBaseFilter 來
IBaseFilter *pCap = NULL;
hr = pMoniker->BindToObject (0, 0, IID_IBaseFilter, (void**)&pCap);
Binding
串 Moniker,
left ()
NULL
, Graph Filter
hr = m_pGraph->AddFilter(pCap, L"Capture Filter");

Previewing Video
Step 1: initial COM
Step 2: 立
Graph Manager
Build help Ojbect
Step 3:
Video Capture Device Filter
Step 4: 立 Graph Filter
Graph
Step 5: 行 Graph Filter

VideoRender(this->m_hWnd);
Clear()
Video Previewing

VideoRender
// 數 便 理
IGraphBuilder *pGraph; // Graph
ICaptureGraphBuilder2 *pBuild; // Capture Graph Builder
IBaseFilter *pCap; // Capture Filter
IMediaControl *pControl; // Graph Controller
int VideoRender(HWND hwnd) {
// Step 1: initial COM
CoInitialize(NULL);
// Step 2: 立 Graph Manager Build help Ojbect
InitCaptureGraphBuilder(&pGraph,&pBuild);
// Step 3: Video Capture Device
EnumerateVideoInputDevice(&pCap);
pGraph->AddFilter(pCap,L"Capture Filter");

Step 4: Graph Builder 立 graph filter
HRESULT hr = pBuild->RenderStream(&PIN_CATEGORY_PREVIEW ,
&MEDIATYPE_Video,
連 pCap Render
pCap, NULL, NULL);
source
Render
// Step 5: 立 來 行 graph filter
hr = pGraph->QueryInterface(IID_IMediaControl, (void **)&pControl);
pControl->Run();
return 0;
}
sink
pCap preview
類 pin 料
pCap
Video
// Release everything
void Clear(){
pGraph->Release();
pCap->Release();
pBuild->Release();
pControl->Release();
filter
}
// COM must be uninitialized
CoUninitialize();

Media File 讀 frame
• 利 Media Detector object (MediaDet)
media file frame
• 利 helper object
• file seekable,
• 不 Filter Manager 立 filter graph,
Media Detector
• Media Detector 利 Sample Grabber
Filter. 料

利 Media Detector
流
Step 1:
利 ATL Smart Pointer
理 IMediaDet
Step 2: 立 MediaDet
// 1.
CComPtr pDet;
Media
Media
Detector
Detector
Object
Object
// 2.
hr = pDet.CoCreateInstance(__uuidof(MediaDet));
if (FAILED(hr)) return hr;
// 3.
CComBSTR bstrFilename(pszFileName);
hr = pDet->put_Filename(bstrFilename);
if (FAILED(hr)) return hr;
media file
Step 3: source file

Stream
了
Source File 了 ,
stream
Step 4:
Media file
stream 數 量
Step 5:
Video stream
stream 數 量
long lStreams;
bool bFound = false;
hr = pDet->get_OutputStreams(&lStreams);
if (FAILED(hr)) return hr;
for (long i = 0; i < lStreams; i++) {
stream
GUID major_type;
hr = pDet->put_CurrentStream(i); 2
if (SUCCEEDED(hr)){
hr = pDet->get_StreamType(&major_type);
}
if (FAILED(hr)) break;
if (major_type == MEDIATYPE_Video) {
bFound = true;
break;
}
}
if (!bFound)
return VFW_E_INVALIDMEDIATYPE;
1
3
stream
Video Stream

裡 DirectShow 料
( 料 Video frame Audio)
stream
• DirectShow AM_MEDIA_TYPE
filter graph digital media formats
Sample 類 , : video audio
類 , : RGB24 RGB 32 YUV
size (TRUE)
frames key frame (TRUE)
Sample . frame sample size (byte)
不
Sample 類 不 , 不
format
Format
Sample Format
參 : DirectX SDK: About Media Types

stream
Step 6:
frame
long width = 0, height = 0;
AM_MEDIA_TYPE mt;
hr = pDet->get_StreamMediaType(&mt);
if (SUCCEEDED(hr)) {
Sample
MEDIATYPE_Video,
MEDIATYPE_Video,
VIDEOINFOHEADER
VIDEOINFOHEADER
VIDEOINFOHEADER *pVih = (VIDEOINFOHEADER*)(mt.pbFormat);
width = pVih->bmiHeader.biWidth;
height = pVih->bmiHeader.biHeight;
sample
sample
Format
Format
}
// frame 度 (top-down DIB = , bottom-up DIB =)
if (height < 0) height *= -1;

frame 料
Step 7:
long size;
int second=15;
()
料
hr = pDet->GetBitmapBits (second, &size, NULL, width, height);
if (SUCCEEDED(hr)) {
char *pBuffer = new char[size]; //
if (!pBuffer) return E_OUTOFMEMORY;
try {
Frame size
hr = pDet->GetBitmapBits(second, NULL, pBuffer, width,height);
if (SUCCEEDED(hr)) {
// Delete the old image, if any.
if (*ppbmih) delete[] (*ppbmih);
(*ppbmih) = (BITMAPINFOHEADER*) pBuffer;
}
else {
delete [] pBuffer; // frame , buffer
}
}
catch (...) { // 若 exception
delete [] pBuffer;
return E_OUTOFMEMORY;
}
Step 8:
frame bitmap 料
利
料

來
1 frame
來
Grabing_a_Post_Frame

錄 : Header file
// --------- Direct Show Header File & library -------------
#include
#include // for IMediaDet Interface
#pragma comment( lib, "Strmiids.lib" )
// F:\Program Files\DX9\Samples\C++\DirectShow\BaseClasses
// VC : BaseClass header file 錄
// F:\Program Files\DX9\Samples\C++\DirectShow\BaseClasses
#include
#pragma comment(lib, "F:\\Program
Files\\DX9\\Samples\\C++\\DirectShow\\BaseClasses\\Debug\\Strmbasd.lib" ) // debug
build
// BaseClass Windows Multimedia library , 行
#pragma comment(lib, "Winmm.lib" )
// --------- ATL Smart Pointer
// Active Template Libary (ATL): 列 c++ template classes, 立
// Common Object Model (COM)
#include
#include // for
2
Direct X
錄
1

mk:@MSITStore:F:\Program%20Files\DX9\Documentation\DirectX9\DirectX9_c.chm::/directX/htm/usingthesystemdeviceenumerator.ht
錄 :
System Device Enumerator
DirectShow Filter Category

• Windows Media Downloads
• http://msdn.microsoft.com/library/default.asp
url=/downloads/list/winmedia.asp