Added some more documentation. Larger previews, e.g. 1280x720 seem possible.

videodev-vfw.cc

@@ -1,5 +1,6 @@
 /*
- * module to read video data from vfw.
+ * Module to grab video data from VfW interface.  The interface is
+ * poorly documented for which some odd comments maybe found here.
  */
 
 #include "config.h"
@@ -15,26 +16,36 @@
 #include "convert.h"
 #include "videodev-vfw.h"
 
+static char classNameVfW[] = "VFW-Class";
+
+/*
+ * Constructor
+ */
 VideoDev_VFW::VideoDev_VFW() {
-	printf ("%s:%d %s\n", __FILE__, __LINE__, __FUNCTION__);
+  printf ("%s:%d %s\n", __FILE__, __LINE__, __FUNCTION__);
-	hwnd = cap = NULL;
+  hwnd = cap = NULL;
-	camid = -1;
+  camid = -1;
-	inframe_pixfmt = 0x0;
+  inframe_pixfmt = 0x0;
-	inframe_w = -1;
+  inframe_w = -1;
-	inframe_h = -1;
+  inframe_h = -1;
-	inframe = NULL;
+  inframe = NULL;
-	inframe_size = 0;
+  inframe_size = 0;
-	vfw_size = 0;
+  vfw_size = 0;
+  hclass = NULL;
+  hinst = NULL;
 };
 
-
+/*
+ * Destructor
+ */
 VideoDev_VFW::~VideoDev_VFW() {
-	printf ("%s:%d %s\n", __FILE__, __LINE__, __FUNCTION__);
+  printf ("%s:%d %s\n", __FILE__, __LINE__, __FUNCTION__);
-	if (running > 0) 	CaptureStop();
+  if (running > 0)
+ 	CaptureStop();
 }
 
 /*
- * check for connected devices and return the result in a list.
+ * Check for connected devices and returns the result in a list.
  */
 int VideoDev_VFW::GetDeviceList(std::list<std::string> *list) {
 
@@ -43,9 +54,11 @@ int VideoDev_VFW::GetDeviceList(std::list<std::string> *list) {
     
   printf ("%s:%d %s\n", __FILE__, __LINE__, __FUNCTION__);
   if (list == NULL) return VDEV_STATUS_ERROR;
-	
+
+  // go through a list of 10 (maximum number defined by VfW)
   for(int i=0; i < 10; i++)
     if(capGetDriverDescription(i, name, sizeof(name), desc, sizeof(desc))) {
+      // create a driver for the return list
       std::string device;
       device = "VFW " + to_string(i) + " " + (string)name + " [" + (string)desc + "]";
       printf ("%s:%d %s Found device '%s'\n", __FILE__, __LINE__, __FUNCTION__, device.c_str());
@@ -56,57 +69,118 @@ int VideoDev_VFW::GetDeviceList(std::list<std::string> *list) {
 }
 
 /*
- * Open Device
+ * Destroy and unregister window class.
- * prepare the buffer
  */
-int VideoDev_VFW::Open() {
+int VideoDev_VFW::DestroyClass() {
+  printf ("%s:%d %s\n", __FILE__, __LINE__, __FUNCTION__);
+  if (hclass) {
+    if(!UnregisterClass(classNameVfW, hinst)) {
+      printf ("%s:%d %s Could not unregister VFW class\n", __FILE__, __LINE__, __FUNCTION__);
+      return 0;
+    }
+    free (hclass);
+    hclass = NULL;
+  }
+  return 1;
+}
+
+/*
+ * Create and register window class.
+ */
+int VideoDev_VFW::CreateClass() {
+
+  printf ("%s:%d %s\n", __FILE__, __LINE__, __FUNCTION__);
+  if (hclass) return 1;
+  
+  hclass = (WNDCLASSEX *)malloc(sizeof(WNDCLASSEX));
+  hclass->hInstance = hinst;
+  hclass->lpszClassName = classNameVfW;
+  hclass->lpfnWndProc = DefWindowProc;
+  hclass->style = CS_DBLCLKS;
+  hclass->cbSize = sizeof(WNDCLASSEX);
+  hclass->hIcon = LoadIcon(NULL,IDI_APPLICATION);
+  hclass->hIconSm = LoadIcon(NULL,IDI_APPLICATION);
+  hclass->hCursor = LoadCursor(NULL,IDC_ARROW);
+  hclass->lpszMenuName = NULL;
+  hclass->cbClsExtra = 0;
+  hclass->cbWndExtra = 0;
+  hclass->hbrBackground = (HBRUSH)COLOR_BACKGROUND;
+
+  if(!RegisterClassEx (hclass)) {
+    printf ("%s:%d %s Could not register VFW class\n", __FILE__, __LINE__, __FUNCTION__);
+    return 0;
+  }
+  return 1;
+}
+
+/*
+ * The callback is run when an error in the capture driver occurred.
+ */
+LRESULT VFW_error_callback (HWND h, int nID, LPCSTR lpsz) {
+  printf("%s:%d %s id=%d (%s)\n", __FILE__, __LINE__, __FUNCTION__, nID, lpsz);
+  return TRUE;
+}
 
-  static int first = 1;
+/*
+ * The callback is run when a status update in the capture driver occurred.
+ */
+LRESULT VFW_status_callback (HWND h, int nID, LPCSTR lpsz) {
+  printf("%s:%d %s id=%d (%s)\n", __FILE__, __LINE__, __FUNCTION__, nID, lpsz);
+  return TRUE;
+}
+
+#define USE_PREVIEW 1
+
+/*
+ * Opens the device.
+ */
+int VideoDev_VFW::Open() {
 
   printf ("%s:%d %s\n", __FILE__, __LINE__, __FUNCTION__);
 
+  // extract camera id from device name
   camid = atoi (conf_device.c_str());
   printf ("%s:%d %s Opening VFW id %d\n", __FILE__, __LINE__, __FUNCTION__, camid);
 
-  // create parent window
+  // find application instance handle for later use
-  //HWND main_hwnd = (HWND)GDK_WINDOW_HWND (gtk_widget_get_window (GTK_WIDGET(main_window)));
+  hinst = GetModuleHandle(NULL);
-  HINSTANCE hinst = GetModuleHandle(NULL);
+
-  char classNameVfW[] = "VFW-Class";
+  // create and register window class
-
+  if (!CreateClass())
-  if (first) {
+    return VDEV_STATUS_ERROR;
-    WNDCLASSEX hclass;
+
-    hclass.hInstance=hinst;
+  // now create the parent window for capture devicey
-    hclass.lpszClassName=classNameVfW;
+  // some notes:
-    hclass.lpfnWndProc=DefWindowProc;
+  // - the minimum possible size of 3x3
-    hclass.style=CS_DBLCLKS;
+  // - the WS_POPUPWINDOW removes window decorations
-    hclass.cbSize=sizeof(WNDCLASSEX);
+  // - it does not need a parent window
-    hclass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
+  // - the window MUST be visible, otherwise video grabbing does not work (no callbacks run)
-    hclass.hIconSm=LoadIcon(NULL,IDI_APPLICATION);
-    hclass.hCursor=LoadCursor(NULL,IDC_ARROW);
-    hclass.lpszMenuName=NULL;
-    hclass.cbClsExtra=0;
-    hclass.cbWndExtra=0;
-    hclass.hbrBackground=(HBRUSH)COLOR_BACKGROUND;
-
-    if(!RegisterClassEx(&hclass)) {
-      printf ("%s:%d %s Could not register VFW class\n", __FILE__, __LINE__, __FUNCTION__);
-      return VDEV_STATUS_ERROR;
-    }
-    first = 0;
-  }
   hwnd = CreateWindowEx(0, classNameVfW, "CameraPreview", WS_POPUPWINDOW|WS_VISIBLE, 0, 0, 3, 3, NULL, NULL, hinst, NULL);
-  if (hwnd == NULL) {
+  if (!hwnd) {
     printf ("%s:%d %s Could not create window (%ld)\n", __FILE__, __LINE__, __FUNCTION__, GetLastError());
     return VDEV_STATUS_ERROR;
   }
-  ShowWindow(hwnd, SW_SHOW);
+  if(!ShowWindow(hwnd, SW_SHOW)) {
-	
+    printf ("%s:%d %s Could not show window (%ld)\n", __FILE__, __LINE__, __FUNCTION__, GetLastError());
-  // connect to driver
+    return VDEV_STATUS_ERROR;
+  }
+
+  // create capture driver window handle, also here minim size is 1x1
   cap = capCreateCaptureWindow("VFW", WS_CHILD|WS_VISIBLE, 0, 0, 1, 1, hwnd, camid);
   if(!cap) {
     printf ("%s:%d %s Could not open VFW id %d window\n", __FILE__, __LINE__, __FUNCTION__, camid);
     return VDEV_STATUS_ERROR;
   }
+  if(!capSetCallbackOnStatus(cap, VFW_status_callback)) {
+    printf ("%s:%d %s Could not set status callback to VFW id %d (%ld)\n", __FILE__, __LINE__, __FUNCTION__, camid, GetLastError());
+    return VDEV_STATUS_ERROR;
+  }
+  if(!capSetCallbackOnError(cap, VFW_error_callback)) {
+    printf ("%s:%d %s Could not set error callback to VFW id %d (%ld)\n", __FILE__, __LINE__, __FUNCTION__, camid, GetLastError());
+    return VDEV_STATUS_ERROR;
+  }
+
+  // connect to driver
   if(!capDriverConnect(cap, camid)) {
     printf ("%s:%d %s Could not connect to VFW id %d\n", __FILE__, __LINE__, __FUNCTION__, camid);
     return VDEV_STATUS_ERROR;
@@ -115,9 +189,13 @@ int VideoDev_VFW::Open() {
   // let the callbacks know this class pointer
   capSetUserData(cap, this);
 
+  // set video source, capture format and size
+  capDlgVideoSource(cap);
+  capDlgVideoFormat(cap);
+
   CAPTUREPARMS cp;
   if(!capCaptureGetSetup(cap, &cp, sizeof(cp))) {
-    printf ("%s:%d %s Could not get VFW setup\n", __FILE__, __LINE__, __FUNCTION__);
+    printf ("%s:%d %s Could not get VFW capture setup\n", __FILE__, __LINE__, __FUNCTION__);
     return VDEV_STATUS_ERROR;
   }
   cp.dwRequestMicroSecPerFrame = 33333;
@@ -131,20 +209,10 @@ int VideoDev_VFW::Open() {
   cp.fAbortRightMouse = 0;
   cp.fLimitEnabled = 0;
   if(!capCaptureSetSetup(cap, &cp, sizeof(cp))) {
-    printf ("%s:%d %s Could not set VFW setup\n", __FILE__, __LINE__, __FUNCTION__);
+    printf ("%s:%d %s Could not set VFW capture setup\n", __FILE__, __LINE__, __FUNCTION__);
     return VDEV_STATUS_ERROR;
   }
 
-  capOverlay(cap, 0);
-  capPreviewRate(cap, 10); // rate in ms
-  capPreviewScale(cap, 0);
-  capPreview(cap, TRUE);
-  //capCaptureSequenceNoFile(cap);
-
-  // set video source, capture format and size
-  capDlgVideoSource(cap);
-  capDlgVideoFormat(cap);
-
   // get current valid width/height
   BITMAPINFO bi;
   int i = 0;
@@ -158,14 +226,15 @@ int VideoDev_VFW::Open() {
 
   // try to set the configured width/height
   if(conf_width != -1) {
-    bi.bmiHeader.biWidth = conf_width;
+    inframe_w = bi.bmiHeader.biWidth = conf_width;
-    bi.bmiHeader.biHeight = conf_height;
+    inframe_h = bi.bmiHeader.biHeight = conf_height;
     bi.bmiHeader.biCompression = inframe_pixfmt;
     if(!capSetVideoFormat(cap, &bi, sizeof(BITMAPINFO))) {
       printf ("%s:%d %s Could not set capture size %dx%d (%s)\n", __FILE__, __LINE__, __FUNCTION__, conf_width, conf_height, conf_format.c_str());
       return VDEV_STATUS_ERROR;
     }
   }
+  
   // find out maximum resolution
   else {
     int sizes[][2] = {{320, 240}, {640, 480}, {800, 600}, {1024, 768}, {1280, 720}, {1280, 1024}, {1920, 1080}, {-1, -1}};
@@ -175,18 +244,18 @@ int VideoDev_VFW::Open() {
       inframe_h = bi.bmiHeader.biHeight = sizes[i][1];
       bi.bmiHeader.biCompression = inframe_pixfmt;
       if(capSetVideoFormat(cap, &bi, sizeof(BITMAPINFO))) {
-	printf ("%s:%d %s Resolution %dx%d (%s) works\n", __FILE__, __LINE__, __FUNCTION__, inframe_w, inframe_h, conf_format.c_str());
+        printf ("%s:%d %s Resolution %dx%d (%s) works\n", __FILE__, __LINE__, __FUNCTION__, inframe_w, inframe_h, conf_format.c_str());
-	if (inframe_w >= conf_width && inframe_h >= conf_height) {
+        if (inframe_w >= conf_width && inframe_h >= conf_height) {
-	  conf_width = inframe_w;
+          conf_width = inframe_w;
-	  conf_height = inframe_h;
+          conf_height = inframe_h;
-	}
+        }
       }
       i++;
     }
   }
 
   // translate this special format to what our convert functions can work with
-  if(inframe_pixfmt == V4L2_PIX_FMT_YUY2) {
+  if (inframe_pixfmt == V4L2_PIX_FMT_YUY2) {
     inframe_pixfmt = V4L2_PIX_FMT_YUYV;
   }
   
@@ -195,8 +264,7 @@ int VideoDev_VFW::Open() {
 
 
 /*
- * Close Device
+ * Close the device.
- * Free videobuffer
  */
 int VideoDev_VFW::Close() {
 
@@ -207,6 +275,7 @@ int VideoDev_VFW::Close() {
 	  DestroyWindow(hwnd);
 	  hwnd = cap = NULL;
 	}
+    DestroyClass();
 	return VDEV_STATUS_OK;
 };
 
@@ -216,22 +285,21 @@ int VideoDev_VFW::Close() {
  * VideoGrabbing
  */
 
-LRESULT CALLBACK VFW_frame_callback(HWND h, LPVIDEOHDR v) {
+/*
+ * The callback is run when a new frame is available.  It copies the
+ * available data into the framebuffer of the class instance.
+ */
+LRESULT CALLBACK VFW_frame_callback (HWND h, LPVIDEOHDR v) {
   VideoDev_VFW * obj = (VideoDev_VFW *)capGetUserData(h);
   obj->SetFrameBufferSize(v->dwBytesUsed);
   memcpy(obj->GetFrameBuffer(), v->lpData, obj->GetFrameBufferSize());
   return TRUE;
 }
 
-LRESULT VFW_error_callback(HWND h, int nID, LPCSTR lpsz) {
-  printf("%s:%d %s id=%d (%s)\n", __FILE__, __LINE__, __FUNCTION__, nID, lpsz);
-  return TRUE;
-}
-
 /*
- * prepare inframe for raw picture data, will hold a video frame with 16bit per channel or BGR32/BGR24
+ * Prepare inframe for raw picture data, will hold a video frame with
- * inframe size = 4*W*H
+ * maximum size of inframe size = 4*W*H.  Setup capture
- * send the start capture signal to the cam
+ * callbacks. Then send the start capture signal to the camera.
  */
 int VideoDev_VFW::CaptureStart() {
 
@@ -240,41 +308,53 @@ int VideoDev_VFW::CaptureStart() {
 	// allocate memory for frame data
 	if (inframe != NULL) free (inframe);
 	inframe_size = 4 * inframe_w * inframe_h;
-	inframe = (unsigned char*) malloc(inframe_size);
+	inframe = (unsigned char *) malloc(inframe_size);
 
 	pixelformat = inframe_pixfmt;
 
-	if(!capSetCallbackOnError(cap, VFW_error_callback)) {
+    // disable overlay
-	  printf ("%s:%d %s Could not set error callback to VFW id %d\n", __FILE__, __LINE__, __FUNCTION__, camid);
+    capOverlay(cap, FALSE);
+
+#if USE_PREVIEW
+    // use preview window for grabbing
+    capPreviewRate (cap, 10); // rate in ms
+    capPreviewScale (cap, FALSE);
+    capPreview (cap, TRUE);
+#else
+    // otherwise use other capture
+    capPreview (cap, FALSE);
+    if(!capCaptureSequenceNoFile (cap)) {
+      printf ("%s:%d %s Could not start capture (%ld)\n", __FILE__, __LINE__, __FUNCTION__, GetLastError());
+    }
+#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\n", __FILE__, __LINE__, __FUNCTION__, camid);
+	  printf ("%s:%d %s Could not set videostream callback to VFW id %d (%ld)\n", __FILE__, __LINE__, __FUNCTION__, camid, GetLastError());
-	  return VDEV_STATUS_ERROR;
+	  //return VDEV_STATUS_ERROR;
 	}
-	
+
 	if(!capSetCallbackOnYield(cap, VFW_frame_callback)) {
-	  printf ("%s:%d %s Cmould not set yield callback to VFW id %d\n", __FILE__, __LINE__, __FUNCTION__, camid);
+	  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_ERROR;
 	}
-	
+
-	if(!capSetCallbackOnFrame(cap, VFW_frame_callback)) {
-	  printf ("%s:%d %s Could not set frame callback to VFW id %d\n", __FILE__, __LINE__, __FUNCTION__, camid);
-	  return VDEV_STATUS_ERROR;
-	}
-	
 	return VDEV_STATUS_OK;
 };
 
 
 
 /*
- * free inbuffer
+ * Stop capture and free framebuffer.
  */
 int VideoDev_VFW::CaptureStop() {
 
 	printf ("%s:%d %s\n", __FILE__, __LINE__, __FUNCTION__);
+    
 	capCaptureAbort(cap);
 	capSetCallbackOnError(cap, NULL);
 	capSetCallbackOnFrame(cap, NULL);
@@ -292,35 +372,47 @@ int VideoDev_VFW::CaptureStop() {
 };
 
 /*
- * try to grab one frame and convert it into RGB32.
+ * This function needed to continue running the capture window.
- * If something goes wrong return an error code.
- * Return code VDEV_STATUS_AGAIN is not an error. There was no video image ready to read.
  */
-// FIXME: SVBGetVideoData needs to be outside of Lock/UnLockMutex - using inside thread inbuffer
+void VideoDev_VFW::HandleMessages() {
-int VideoDev_VFW::Grab(VideoFrameRaw *vf) {
+  MSG msg;
+  while(PeekMessage(&msg,NULL,0,0,PM_REMOVE)) {
+    TranslateMessage(&msg);
+    DispatchMessage(&msg);
+  }
+}
 
-	MSG msg;
-	while(PeekMessage(&msg,NULL,0,0,PM_REMOVE)) {
-	  TranslateMessage(&msg);
-	  DispatchMessage(&msg);
-	}
 
-        if (inframe == NULL) return VDEV_STATUS_ERROR;
+/*
+ * Try to grab one frame and copy it into raw video buffer.  If
+ * something goes wrong return an error code.  Return code
+ * VDEV_STATUS_AGAIN is not an error. There was no video image ready
+ * to read.
+ */
+int VideoDev_VFW::Grab(VideoFrameRaw *vf) {
+
+    HandleMessages();
+    if (inframe == NULL) return VDEV_STATUS_ERROR;
 
 	if (GetFrameBufferSize() > 0) {
 	  LockMutex();
 	  vf->CopyFrom(inframe_pixfmt, inframe_w, inframe_h, GetFrameBufferSize(), inframe);
 	  UnLockMutex();
 	}
+    else {
+      return VDEV_STATUS_AGAIN;
+    }
 	
 	return VDEV_STATUS_OK;
 }
 
-
+/*
+ * For VfW this seems difficult / impossible to obtain the supported
+ * video formats, but they must be selected via capDlgVideoFormat().
+ */
 int VideoDev_VFW::GetDeviceFormats(string device, std::list<string> *formats) {
 
 	printf ("%s:%d %s\n", __FILE__, __LINE__, __FUNCTION__);
-
 	return VDEV_STATUS_OK;
 }
 
@@ -334,7 +426,6 @@ int VideoDev_VFW::GetDeviceFormats(string device, std::list<string> *formats) {
  * set video control identified by id
  */
 int VideoDev_VFW::SetDevCtrl(unsigned int id, int value) {
-
 	return VDEV_STATUS_OK;
 };
 

videodev-vfw.h

@@ -7,14 +7,16 @@
 class VideoDev_VFW: public VideoDev {
 private:
 	unsigned char *inframe;
-        int inframe_size;
+    int inframe_size;
 	int inframe_w, inframe_h;
 	int inframe_pixfmt;
-        int vfw_size;
+    int vfw_size;
 
 	ConvertData cdata;
 	int camid;
-        HWND cap, hwnd;
+    HWND cap, hwnd;
+    WNDCLASSEX * hclass;
+    HINSTANCE hinst;
 
 	int Grab(VideoFrameRaw *vf);
 	int Open();
@@ -23,6 +25,9 @@ private:
 	int CaptureStop();
 	int SetDevCtrl(unsigned int id, int value);
 	int GetDevCtrl(unsigned int id, int *value);
+    int CreateClass();
+    int DestroyClass();
+    void HandleMessages();
 
 	void print_error(int err);
 public: