DIrectshow function is blocked at system bootup - c++

Question

I have an Directshow based mediaplayer application . It works very well without any issues during normal playabck . But occasionally i am facing one issue when the Mediaplayer started just after system boot .
HRESULT CSDirectShow::RenderOutputPins (IBaseFilter* pFilter)
{
const char* funcName = "CSDirectShow::RenderOutputPins()";
HRESULT hr = S_OK;
// Enumerate all pins on the source filter,
// looking for the output pins so that I can call Render() on them
//
CComPtr< IEnumPins > pEnumPin;
if (!FAILED (pFilter->EnumPins (&pEnumPin)))
{
while (true)
{
// get the next pin
//
CComPtr< IPin > pPin;
if (pEnumPin->Next (1L, &pPin, NULL) != S_OK) break;
// I'm not interested in connected pins
// if this pin is an unconnected output pin, then render it.
//
CComPtr< IPin > pConnectedPin;
if (pPin->ConnectedTo (&pConnectedPin) == VFW_E_NOT_CONNECTED)
{
PIN_DIRECTION pinDirection;
PIN_INFO pinInfo;
//Get the information of the pin
if (pPin->QueryDirection (&pinDirection) == S_OK
&& pinDirection == PINDIR_OUTPUT
&& pPin->QueryPinInfo(&pinInfo) == S_OK
&& strstr((char*)pinInfo.achName,"~")==NULL)
{
if (FAILED (hr = m_pGB->Render (pPin)))
{
SafeRelease(&pinInfo.pFilter);
return hr;
}
}
SafeRelease(&pinInfo.pFilter);
}
}
}
TraceMsg ("%s: exit",funcName);
return S_OK;
}
When m_pGB->Render (pPin) is called ,This function never returns and it is blocked inside .I confirmed using logs .This issue happens only when i start my application immediately after bootup . When issues occures if I close and restart my application it works like a charm .Since application is designed to start automatically after system bootup this behaviour has become a bigger concern .Kindly help

Answer 1

IGraphBuilder.Render call does a lot internally, and specifically it goes over enumeration of potentially suitable filter, which in turn attempts to load additional DLLs registered with DirectShow environment. Such file could have missing dependencies, or dependencies on remote or temporarily inaccessible drivers (just one example).
If you experience a deadlock, you can troubleshoot it further (debug it) and get details on locked state, and on activity during Render call.
If the problem is caused by third party filters (esp. codec packs registering a collection of filters at once without thinking too much on compatibility) registered with the system in a not so good way, perhaps you could identify them and uninstall.
If you want to improve the player on your side, you should avoid Render call, and build your filter graph with smaller increments - adding specific filter and connecting pins, without leaving big tasks at mercy of Intelligent Connect, which works well in general but is sensitive to compatibility problems as mentioned above.