qt+directshow usb摄像头及音频设备录制视频

最近来了个项目，有一块功能是usb摄像头录制视频并且录音的实现，网上的东西七七八八什么技术都有，先用opencv打了半天环境不能录音频，后来用ffmpeg，原谅我太菜，视频编码和格式让人头疼，不懂怎么移植到自己的程序中，后来用的directshow，希望大家少走些弯路。

#include "PreviewController.h"


std::string TCHAR2STRING(const TCHAR *STR)
{
int iLen = WideCharToMultiByte(CP_ACP, 0,STR, -1, NULL, 0, NULL, NULL);
char* chRtn =new char[iLen*sizeof(char)];
WideCharToMultiByte(CP_ACP, 0, STR, -1, chRtn, iLen, NULL, NULL);
std::string str(chRtn);
return str;
}


PreviewController::~PreviewController()
{
IVideoWindowPtr pVW = m_pSourceGraph;
if (pVW != NULL)
{
pVW->put_Visible(OAFALSE);
pVW->put_Owner(NULL);
}
StopCapture();
m_pCaptureGraph = NULL;
IMediaControlPtr pMC = m_pSourceGraph;
if (pMC != NULL)
{
pMC->Stop();
pMC = NULL;
}
m_pSourceGraph = NULL;
}


HRESULT 
PreviewController::SelectDevice(const TCHAR* pVideo, const TCHAR* pAudio, HWND hwnd, RECT* prc)
{
// create a new device
m_pSourceGraph = NULL;
m_pBridge = NULL;
m_pCapOutput = NULL;


HRESULT hr = m_pBridge.CreateInstance(__uuidof(GMFBridgeController));


if (FAILED(hr))
{
return hr;
}


// init to video-only, in discard mode (ie when source graph
// is running but not connected, buffers are discarded at the bridge)
hr = m_pBridge->AddStream(true, eMuxInputs, true);


m_bAudio = false;
_bstr_t strAudio = pAudio;
IBaseFilterPtr pfAudio;
if (SUCCEEDED(hr) && (strAudio.length() > 0))
{
m_bAudio = true;
hr = m_pBridge->AddStream(false, eMuxInputs, true);
if (SUCCEEDED(hr))
{
hr = LocateFilter(pAudio, CLSID_AudioInputDeviceCategory, &pfAudio);
}
}


if (FAILED(hr))
{
return hr;
}


// locate the requested filter
IBaseFilterPtr pfDevice;
hr = LocateFilter(pVideo, CLSID_VideoInputDeviceCategory, &pfDevice);
if (FAILED(hr))
{
return hr;
}


// create source graph and add sink filter
hr = m_pSourceGraph.CreateInstance(CLSID_FilterGraph);
if (FAILED(hr))
{
return hr;
}
_bstr_t strName = pVideo;
m_pSourceGraph->AddFilter(pfDevice, strName);


if (m_bAudio)
{
m_pSourceGraph->AddFilter(pfAudio, strAudio);
}


IUnknownPtr punkSink;
hr = m_pBridge->InsertSinkFilter(m_pSourceGraph, &punkSink);
if (FAILED(hr))
{
return hr;
}
IBaseFilterPtr pfSink = punkSink;


// use capture graph builder to render preview
ICaptureGraphBuilder2Ptr pBuilder;
hr = pBuilder.CreateInstance(CLSID_CaptureGraphBuilder2);
if (SUCCEEDED(hr))
{
pBuilder->SetFiltergraph(m_pSourceGraph);
hr = pBuilder->RenderStream(
                                    &PIN_CATEGORY_PREVIEW, 
                                    &MEDIATYPE_Video,
                                    pfDevice,
                                    NULL,
                                    NULL);

if (SUCCEEDED(hr))
{
// connect capture output to the pseudo-sink filter,
// where it will be discarded until required
hr = pBuilder->RenderStream(
                                &PIN_CATEGORY_CAPTURE,
                                &MEDIATYPE_Video,
                                pfDevice,
                                NULL,
                                pfSink);


if (SUCCEEDED(hr))
{
// turn off capture stream if possible except when capturing
HRESULT hrCtl = pBuilder->FindPin(
pfDevice,
PINDIR_OUTPUT,
&PIN_CATEGORY_CAPTURE,
&MEDIATYPE_Video,
false,
0,
&m_pCapOutput);
if (SUCCEEDED(hrCtl))
{
IAMStreamControlPtr pSC = m_pCapOutput;
if (pSC != NULL)
{
REFERENCE_TIME tNever = MAXLONGLONG;
pSC->StartAt(&tNever, 0);
}
}
}
}
if (SUCCEEDED(hr) && m_bAudio)
{
hr = pBuilder->RenderStream(
&PIN_CATEGORY_CAPTURE,
&MEDIATYPE_Audio,
pfAudio,
NULL,
pfSink);
}
pBuilder->SetFiltergraph(NULL);
}
if (SUCCEEDED(hr) && IsWindow(hwnd))
{
// adjust rect to maintain something like aspect ratio
IBasicVideoPtr pBV = m_pSourceGraph;
long cx, cy;
pBV->GetVideoSize(&cx, &cy);
RECT rc = *prc;
long cxRect = rc.right - rc.left;
long cyRect = rc.bottom - rc.top;
if ((cx > cxRect) ||
(cy > cyRect))
{
if ((cxRect * cy/cx) <= cyRect)
{
cy = cxRect * cy / cx;
cx = cxRect;
} else {
cx = cyRect * cx / cy;
cy = cyRect;
}
}


// centre video inside requested rect
rc.left = rc.left + ((cxRect - cx) / 2);
rc.right = rc.left + cx;
rc.top = rc.top + ((cyRect - cy)/2);
rc.bottom = rc.top + cy;


// reparent playback window
IVideoWindowPtr pVW = m_pSourceGraph;
if (pVW != NULL)
{
long style;
pVW->get_WindowStyle(&style);
style &= ~WS_OVERLAPPEDWINDOW;
style |= WS_CHILD;
pVW->put_WindowStyle(style);
pVW->put_Owner((OAHWND)hwnd);
pVW->SetWindowPosition(rc.left, rc.top, rc.right - rc.left, rc.bottom - rc.top);
}
IMediaControlPtr pMC = m_pSourceGraph;
hr = pMC->Run();
if (hr == S_FALSE)
{
// this is just background state change
hr = S_OK;
}
}
m_pSourceGraphSinkFilter = punkSink;
pfSink = NULL;
return hr;
}


HRESULT 
PreviewController::SetNextFilename(const TCHAR* pFile)
{
if (m_pSourceGraph == NULL)
{
return VFW_E_WRONG_STATE;
}


HRESULT hr = m_pCaptureGraph.CreateInstance(CLSID_FilterGraph);
if (FAILED(hr))
{
return hr;
}
    IUnknownPtr punkSource;
hr = m_pBridge->InsertSourceFilter(m_pSourceGraphSinkFilter, m_pCaptureGraph, &punkSource);
if (FAILED(hr))
{
return hr;
}
IBaseFilterPtr pfSource = punkSource;


// use capture graph builder to create mux/writer stage
ICaptureGraphBuilder2Ptr pBuilder;
hr = pBuilder.CreateInstance(CLSID_CaptureGraphBuilder2);
if (FAILED(hr))
{
return hr;
}
pBuilder->SetFiltergraph(m_pCaptureGraph);


// create the mux/writer
_bstr_t bstrFile = pFile;
IBaseFilterPtr pfMux;
hr = pBuilder->SetOutputFileName(&MEDIASUBTYPE_Avi, bstrFile, &pfMux, NULL);
if (SUCCEEDED(hr))
{
// render source output to mux
hr = pBuilder->RenderStream(NULL, &MEDIATYPE_Video, punkSource, NULL, pfMux);
if (SUCCEEDED(hr) && m_bAudio)
{
hr = pBuilder->RenderStream(NULL, &MEDIATYPE_Audio, punkSource, NULL, pfMux);
}


}


if (SUCCEEDED(hr))
{
m_strFile = TCHAR2STRING(pFile);
}
m_pCaptureGraphSourceFilter = punkSource;
return hr;
}


HRESULT 
PreviewController::StartCapture()
{
// re-enable capture stream
IAMStreamControlPtr pSC = m_pCapOutput;
if (pSC != NULL)
{
// immediately!
pSC->StartAt(NULL, 0);
}


// start capture graph
IMediaControlPtr pMC = m_pCaptureGraph;
if (pMC == NULL)
{
return E_INVALIDARG;
}
pMC->Run();


// connect the two segments
return m_pBridge->BridgeGraphs(m_pSourceGraphSinkFilter, m_pCaptureGraphSourceFilter);
}


HRESULT 
PreviewController::StopCapture()
{
HRESULT hr = S_OK;
if (m_pBridge)
{
// disconnect segments
hr = m_pBridge->BridgeGraphs(NULL, NULL);


// stop capture graph
IMediaControlPtr pMC = m_pCaptureGraph;
if (pMC)
{
pMC->Stop();
}
}
// disable capture stream (to save resources)
IAMStreamControlPtr pSC = m_pCapOutput;
if (pSC != NULL)
{
REFERENCE_TIME tNever = MAXLONGLONG;
pSC->StartAt(&tNever, 0);
}
return hr;
}


HRESULT 
PreviewController::Pause()
{
HRESULT hr = S_OK;
if (m_pBridge)
{
// disconnect segments
hr = m_pBridge->BridgeGraphs(NULL, NULL);


// pause capture graph
IMediaControlPtr pMC = m_pCaptureGraph;
if (pMC)
{
pMC->Pause();
}
}
// disable capture stream (to save resources)
IAMStreamControlPtr pSC = m_pCapOutput;
if (pSC != NULL)
{
REFERENCE_TIME tNever = MAXLONGLONG;
pSC->StartAt(&tNever, 0);
}
return hr;
}


HRESULT 
PreviewController::Resume()
{
return StartCapture();
}




HRESULT
PreviewController::LocateFilter(const TCHAR* pName, REFIID catid, IBaseFilter** ppFilter)
{
_bstr_t strRequested = pName;
    ICreateDevEnumPtr pCreate(CLSID_SystemDeviceEnum);
IEnumMonikerPtr pEnum;
    HRESULT hr = pCreate->CreateClassEnumerator(catid, &pEnum, 0);
    if (hr != S_OK) {
   // hr == S_FALSE means pEnum == NULL because category empty
        return E_INVALIDARG;
    }


if (pEnum != NULL) {
        IMonikerPtr pMoniker;
        while(pEnum->Next(1, &pMoniker, NULL) == S_OK) {
IPropertyBagPtr pBag;
hr = pMoniker->BindToStorage(0, 0, IID_IPropertyBag, (void**)&pBag);


if (SUCCEEDED(hr)) {
_variant_t var;
var.vt = VT_BSTR;
hr = pBag->Read(L"FriendlyName", &var, NULL);
if (SUCCEEDED(hr)) {
_bstr_t str = var;
if (str == strRequested)
{
       hr = pMoniker->BindToObject(0, 0, IID_IBaseFilter, (void**)ppFilter);
if (FAILED(hr))
{
return hr;
}
break;
}
}
}
}
}
if (*ppFilter == NULL)
{
return E_INVALIDARG;
}
return S_OK;
}


HRESULT PreviewController::Stop()
{
    HRESULT hr;
    IMediaControlPtr pMC = m_pSourceGraph;
if (pMC != NULL)
{
hr = pMC->Stop();
pMC = NULL;
}
    return hr;

}

源码地址：https://download.csdn.net/download/qq_39805297/10282010