Video grabbing now works for VfW even without visible preview window

videodev-vfw.cc

@@ -113,6 +113,24 @@ int VideoDev_VFW::CreateClass() {
   return 1;
 }
 
+/*
+ * Print driver capabilities.
+ */
+void VideoDev_VFW::GetCapabilities() {
+  
+    CAPDRIVERCAPS caps;
+    if(!capDriverGetCaps(cap, &caps, sizeof(caps))) {
+      printf ("%s:%d %s Unable to get driver capabilities\n", __FILE__, __LINE__, __FUNCTION__);
+    }
+    else {
+      printf ("%s:%d %s Id: %d\n", __FILE__, __LINE__, __FUNCTION__, caps.wDeviceIndex);
+      printf ("%s:%d %s Overlay: %d\n", __FILE__, __LINE__, __FUNCTION__, caps.fHasOverlay);
+      printf ("%s:%d %s VideoSource Dialog: %d\n", __FILE__, __LINE__, __FUNCTION__, caps.fHasDlgVideoSource);
+      printf ("%s:%d %s VideoFormat Dialog: %d\n", __FILE__, __LINE__, __FUNCTION__, caps.fHasDlgVideoFormat);
+      printf ("%s:%d %s VideoDisplay Dialog: %d\n", __FILE__, __LINE__, __FUNCTION__, caps.fHasDlgVideoDisplay);
+    }
+}  
+
 /*
  * The callback is run when an error in the capture driver occurred.
  */
@@ -129,7 +147,7 @@ LRESULT VFW_status_callback (HWND h, int nID, LPCSTR lpsz) {
   return TRUE;
 }
 
-#define USE_PREVIEW 1
+#define USE_PREVIEW 0
 
 /*
  * Opens the device.
@@ -155,18 +173,33 @@ int VideoDev_VFW::Open() {
   // - the WS_POPUPWINDOW removes window decorations
   // - it does not need a parent window
   // - the window MUST be visible, otherwise video grabbing does not work (no callbacks run)
+#if USE_PREVIEW
   hwnd = CreateWindowEx(0, classNameVfW, "CameraPreview", WS_POPUPWINDOW|WS_VISIBLE, 0, 0, 3, 3, NULL, NULL, hinst, NULL);
+#else
+  hwnd = CreateWindowEx(0, classNameVfW, "CameraPreview", WS_POPUPWINDOW|WS_VISIBLE, 0, 0, 0, 0, NULL, NULL, hinst, NULL);
+#endif
   if (!hwnd) {
     printf ("%s:%d %s Could not create window (%ld)\n", __FILE__, __LINE__, __FUNCTION__, GetLastError());
     return VDEV_STATUS_ERROR;
   }
+#if USE_PREVIEW
   if(!ShowWindow(hwnd, SW_SHOW)) {
     printf ("%s:%d %s Could not show window (%ld)\n", __FILE__, __LINE__, __FUNCTION__, GetLastError());
     return VDEV_STATUS_ERROR;
   }
+#else
+  if(!ShowWindow(hwnd, SW_HIDE)) {
+    printf ("%s:%d %s Could not hide window (%ld)\n", __FILE__, __LINE__, __FUNCTION__, GetLastError());
+    return VDEV_STATUS_ERROR;
+  }
+#endif
 
   // create capture driver window handle, also here minim size is 1x1
+#if USE_PREVIEW
   cap = capCreateCaptureWindow("VFW", WS_CHILD|WS_VISIBLE, 0, 0, 1, 1, hwnd, camid);
+#else
+  cap = capCreateCaptureWindow("VFW", WS_CHILD, 0, 0, 0, 0, hwnd, camid);
+#endif  
   if(!cap) {
     printf ("%s:%d %s Could not open VFW id %d window\n", __FILE__, __LINE__, __FUNCTION__, camid);
     return VDEV_STATUS_ERROR;
@@ -186,6 +219,9 @@ int VideoDev_VFW::Open() {
     return VDEV_STATUS_ERROR;
   }
 
+  // check capabilities
+  GetCapabilities();
+
   // let the callbacks know this class pointer
   capSetUserData(cap, this);
 
@@ -198,9 +234,9 @@ int VideoDev_VFW::Open() {
     printf ("%s:%d %s Could not get VFW capture setup\n", __FILE__, __LINE__, __FUNCTION__);
     return VDEV_STATUS_ERROR;
   }
-  cp.dwRequestMicroSecPerFrame = 33333;
+  cp.dwRequestMicroSecPerFrame = 10000; // rate in us
   cp.fMakeUserHitOKToCapture = 0;
-  cp.wPercentDropForError = 90;
+  cp.wPercentDropForError = 10;
   cp.fYield = TRUE;
   cp.wNumVideoRequested = 1;
   cp.fCaptureAudio = 0;
@@ -292,7 +328,9 @@ int VideoDev_VFW::Close() {
 LRESULT CALLBACK VFW_frame_callback (HWND h, LPVIDEOHDR v) {
   VideoDev_VFW * obj = (VideoDev_VFW *)capGetUserData(h);
   obj->SetFrameBufferSize(v->dwBytesUsed);
+  if (obj->GetFrameBuffer()) {
     memcpy(obj->GetFrameBuffer(), v->lpData, obj->GetFrameBufferSize());
+  }
   return TRUE;
 }
 
@@ -312,6 +350,18 @@ int VideoDev_VFW::CaptureStart() {
 
 	pixelformat = inframe_pixfmt;
 
+#if USE_PREVIEW
+	if(!capSetCallbackOnFrame(cap, VFW_frame_callback)) {
+	  printf ("%s:%d %s Could not set frame callback to VFW id %d (%ld)\n", __FILE__, __LINE__, __FUNCTION__, camid, GetLastError());
+	  return VDEV_STATUS_ERROR;
+	}
+#else
+	if(!capSetCallbackOnVideoStream(cap, VFW_frame_callback)) {
+	  printf ("%s:%d %s Could not set videostream callback to VFW id %d (%ld)\n", __FILE__, __LINE__, __FUNCTION__, camid, GetLastError());
+	  return VDEV_STATUS_ERROR;
+	}
+#endif
+
     // disable overlay
     capOverlay(cap, FALSE);
 
@@ -328,21 +378,6 @@ int VideoDev_VFW::CaptureStart() {
     }
 #endif
 
-	if(!capSetCallbackOnFrame(cap, VFW_frame_callback)) {
-	  printf ("%s:%d %s Could not set frame callback to VFW id %d (%ld)\n", __FILE__, __LINE__, __FUNCTION__, camid, GetLastError());
-	  return VDEV_STATUS_ERROR;
-	}
-
-	if(!capSetCallbackOnVideoStream(cap, VFW_frame_callback)) {
-	  printf ("%s:%d %s Could not set videostream callback to VFW id %d (%ld)\n", __FILE__, __LINE__, __FUNCTION__, camid, GetLastError());
-	  //return VDEV_STATUS_ERROR;
-	}
-
-	if(!capSetCallbackOnYield(cap, VFW_frame_callback)) {
-	  printf ("%s:%d %s Could not set yield callback to VFW id %d (%ld)\n", __FILE__, __LINE__, __FUNCTION__, camid, GetLastError());
-	  //return VDEV_STATUS_ERROR;
-	}
-
 	return VDEV_STATUS_OK;
 };
 
@@ -356,10 +391,10 @@ int VideoDev_VFW::CaptureStop() {
 	printf ("%s:%d %s\n", __FILE__, __LINE__, __FUNCTION__);
     
 	capCaptureAbort(cap);
-	capSetCallbackOnError(cap, NULL);
 	capSetCallbackOnFrame(cap, NULL);
 	capSetCallbackOnVideoStream(cap, NULL);
-	capSetCallbackOnYield(cap, NULL);
+	capSetCallbackOnStatus(cap, NULL);
+	capSetCallbackOnError(cap, NULL);
 
 	// free inframe memory
 	if (inframe) {
@@ -397,6 +432,7 @@ int VideoDev_VFW::Grab(VideoFrameRaw *vf) {
 	if (GetFrameBufferSize() > 0) {
 	  LockMutex();
 	  vf->CopyFrom(inframe_pixfmt, inframe_w, inframe_h, GetFrameBufferSize(), inframe);
+      SetFrameBufferSize(0);
 	  UnLockMutex();
 	}
     else {

videodev-vfw.h

@@ -28,6 +28,7 @@ private:
     int CreateClass();
     int DestroyClass();
     void HandleMessages();
+    void GetCapabilities();
 
 	void print_error(int err);
 public: