quartz: Remove some interface pointer casts.

dlls/quartz/avisplit.c

@@ -690,7 +690,7 @@ static HRESULT AVISplitter_ProcessStreamList(AVISplitterImpl * This, const BYTE
 
     ZeroMemory(&amt, sizeof(amt));
     piOutput.dir = PINDIR_OUTPUT;
-    piOutput.pFilter = (IBaseFilter *)This;
+    piOutput.pFilter = &This->Parser.filter.IBaseFilter_iface;
     wsprintfW(piOutput.achName, wszStreamTemplate, This->Parser.cStreams);
     This->streams = CoTaskMemRealloc(This->streams, sizeof(StreamData) * (This->Parser.cStreams+1));
     stream = This->streams + This->Parser.cStreams;

dlls/quartz/mpegsplit.c

@@ -374,7 +374,7 @@ static HRESULT MPEGSplitter_init_audio(MPEGSplitterImpl *This, const BYTE *heade
 
     ZeroMemory(pamt, sizeof(*pamt));
     ppiOutput->dir = PINDIR_OUTPUT;
-    ppiOutput->pFilter = (IBaseFilter*)This;
+    ppiOutput->pFilter = &This->Parser.filter.IBaseFilter_iface;
     wsprintfW(ppiOutput->achName, wszAudioStream);
 
     pamt->formattype = FORMAT_WaveFormatEx;

dlls/quartz/parser.c

@@ -455,7 +455,7 @@ HRESULT Parser_AddPin(ParserImpl * This, const PIN_INFO * piOutput, ALLOCATOR_PR
         CopyMediaType(pin->pmt, amt);
         pin->dwSamplesProcessed = 0;
 
-        pin->pin.pin.pinInfo.pFilter = (LPVOID)This;
+        pin->pin.pin.pinInfo.pFilter = &This->filter.IBaseFilter_iface;
         pin->allocProps = *props;
         This->cStreams++;
         BaseFilterImpl_IncrementPinVersion(&This->filter);