videoio: give chance for all enabled backends

"Eat" unexpected backend exceptions

diff --git a/modules/videoio/src/cap.cpp b/modules/videoio/src/cap.cpp
index 40682ab..46cbf42 100644 (file)
--- a/modules/videoio/src/cap.cpp
+++ b/modules/videoio/src/cap.cpp
@@ -117,6 +117,36 @@ CV_IMPL int cvGetCaptureDomain( CvCapture* capture)
     return capture ? capture->getCaptureDomain() : 0;
 }
 
+static bool get_capture_debug_flag()
+{
+    static bool initialized = false;
+    static bool flag = false;
+    if (!initialized)
+    {
+#ifndef NO_GETENV
+        flag = getenv("OPENCV_VIDEOCAPTURE_DEBUG") ? true : false; // TODO Use getBoolParameter
+#endif
+        initialized = true;
+    }
+    return flag;
+}
+
+#define TRY_OPEN(capture, backend_func) \
+{ \
+    if (!capture) \
+        try { \
+            if (get_capture_debug_flag()) fprintf(stderr, "VIDEOIO(%s): trying ...\n", #backend_func); \
+            capture = backend_func; \
+            if (get_capture_debug_flag()) fprintf(stderr, "VIDEOIO(%s): result=%p ...\n", #backend_func, capture); \
+        } catch (const cv::Exception& e) { \
+            fprintf(stderr, "VIDEOIO(%s): raised OpenCV exception:\n\n%s\n", #backend_func, e.what()); \
+        } catch (const std::exception& e) { \
+            fprintf(stderr, "VIDEOIO(%s): raised C++ exception:\n\n%s\n", #backend_func, e.what()); \
+        } catch (...) { \
+            fprintf(stderr, "VIDEOIO(%s): raised unknown C++ exception!\n\n", #backend_func); \
+        } \
+}
+
 
 /**
  * Camera dispatching method: index is the camera number.
@@ -144,120 +174,101 @@ CV_IMPL CvCapture * cvCreateCameraCapture (int index)
 
 #ifdef HAVE_MSMF
     case CV_CAP_MSMF:
-        if (!capture)
-            capture = cvCreateCameraCapture_MSMF(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_MSMF(index))
         if (pref) break;
 #endif
 #ifdef HAVE_TYZX
     case CV_CAP_STEREO:
-        if (!capture)
-            capture = cvCreateCameraCapture_TYZX(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_TYZX(index))
         if (pref) break;
 #endif
     case CV_CAP_VFW:
 #ifdef HAVE_VFW
-        if (!capture)
-            capture = cvCreateCameraCapture_VFW(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_VFW(index))
 #endif
+        if (pref) break; // CV_CAP_VFW
+
 #if defined HAVE_LIBV4L || defined HAVE_CAMV4L || defined HAVE_CAMV4L2 || defined HAVE_VIDEOIO
-        if (!capture)
-            capture = cvCreateCameraCapture_V4L(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_V4L(index))
 #endif
 
 #ifdef HAVE_GSTREAMER
-        if (!capture)
-            capture = cvCreateCapture_GStreamer(CV_CAP_GSTREAMER_V4L2,
-                                                reinterpret_cast<char *>(index));
+        TRY_OPEN(capture, cvCreateCapture_GStreamer(CV_CAP_GSTREAMER_V4L2, reinterpret_cast<char *>(index)))
 
-        if (!capture)
-            capture = cvCreateCapture_GStreamer(CV_CAP_GSTREAMER_V4L,
-                                                reinterpret_cast<char *>(index));
+        TRY_OPEN(capture, cvCreateCapture_GStreamer(CV_CAP_GSTREAMER_V4L, reinterpret_cast<char *>(index)))
 #endif
-        if (pref) break; // CV_CAP_VFW
 
     case CV_CAP_FIREWIRE:
 #ifdef HAVE_DC1394_2
-        if (!capture)
-            capture = cvCreateCameraCapture_DC1394_2(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_DC1394_2(index))
 #endif
 
 #ifdef HAVE_DC1394
-        if (!capture)
-            capture = cvCreateCameraCapture_DC1394(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_DC1394(index))
 #endif
 
 #ifdef HAVE_CMU1394
-        if (!capture)
-            capture = cvCreateCameraCapture_CMU(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_CMU(index))
 #endif
 
 #if defined(HAVE_GSTREAMER) && 0
         // Re-enable again when gstreamer 1394 support will land in the backend code
-        if (!capture)
-            capture = cvCreateCapture_GStreamer(CV_CAP_GSTREAMER_1394, 0);
+        TRY_OPEN(capture, cvCreateCapture_GStreamer(CV_CAP_GSTREAMER_1394, 0))
 #endif
+
         if (pref) break; // CV_CAP_FIREWIRE
 
 #ifdef HAVE_MIL
     case CV_CAP_MIL:
-        if (!capture)
-            capture = cvCreateCameraCapture_MIL(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_MIL(index))
         if (pref) break;
 #endif
 
 #if defined(HAVE_QUICKTIME) || defined(HAVE_QTKIT)
     case CV_CAP_QT:
-        if (!capture)
-            capture = cvCreateCameraCapture_QT(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_QT(index))
         if (pref) break;
 #endif
 
 #ifdef HAVE_UNICAP
     case CV_CAP_UNICAP:
-        if (!capture)
-            capture = cvCreateCameraCapture_Unicap(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_Unicap(index))
         if (pref) break;
 #endif
 
 #ifdef HAVE_PVAPI
     case CV_CAP_PVAPI:
-        if (!capture)
-            capture = cvCreateCameraCapture_PvAPI(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_PvAPI(index))
         if (pref) break;
 #endif
 
 #ifdef HAVE_OPENNI
     case CV_CAP_OPENNI:
-        if (!capture)
-            capture = cvCreateCameraCapture_OpenNI(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_OpenNI(index))
         if (pref) break;
 #endif
 
 #ifdef HAVE_OPENNI2
     case CV_CAP_OPENNI2:
-        if (!capture)
-            capture = cvCreateCameraCapture_OpenNI2(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_OpenNI2(index))
         if (pref) break;
 #endif
 
 #ifdef HAVE_XIMEA
     case CV_CAP_XIAPI:
-        if (!capture)
-            capture = cvCreateCameraCapture_XIMEA(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_XIMEA(index))
         if (pref) break;
 #endif
 
 #ifdef HAVE_AVFOUNDATION
     case CV_CAP_AVFOUNDATION:
-        if (!capture)
-            capture = cvCreateCameraCapture_AVFoundation(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_AVFoundation(index))
         if (pref) break;
 #endif
 
 #ifdef HAVE_GIGE_API
     case CV_CAP_GIGANETIX:
-        if (!capture)
-            capture = cvCreateCameraCapture_Giganetix(index);
+        TRY_OPEN(capture, cvCreateCameraCapture_Giganetix(index))
         if (pref) break; // CV_CAP_GIGANETIX
 #endif
     }
@@ -281,66 +292,56 @@ CV_IMPL CvCapture * cvCreateFileCaptureWithPreference (const char * filename, in
 
 #ifdef HAVE_FFMPEG
     case CV_CAP_FFMPEG:
-        if (! result)
-            result = cvCreateFileCapture_FFMPEG_proxy (filename);
+        TRY_OPEN(result, cvCreateFileCapture_FFMPEG_proxy (filename))
         if (apiPreference) break;
 #endif
 
 #ifdef HAVE_VFW
     case CV_CAP_VFW:
-        if (! result)
-            result = cvCreateFileCapture_VFW (filename);
+        TRY_OPEN(result, cvCreateFileCapture_VFW (filename))
         if (apiPreference) break;
 #endif
 #if defined HAVE_LIBV4L || defined HAVE_CAMV4L || defined HAVE_CAMV4L2 || defined HAVE_VIDEOIO
-        if (!result)
-            result = cvCreateCameraCapture_V4L(filename);
+        TRY_OPEN(result, cvCreateCameraCapture_V4L(filename))
         if (apiPreference) break;
 #endif
 
     case CV_CAP_MSMF:
 #ifdef HAVE_MSMF
-        if (! result)
-            result = cvCreateFileCapture_MSMF (filename);
+        TRY_OPEN(result, cvCreateFileCapture_MSMF (filename))
 #endif
 
 #ifdef HAVE_XINE
-        if (! result)
-            result = cvCreateFileCapture_XINE (filename);
+        TRY_OPEN(result, cvCreateFileCapture_XINE (filename))
 #endif
         if (apiPreference) break;
 
 #ifdef HAVE_GSTREAMER
     case CV_CAP_GSTREAMER:
-        if (! result)
-            result = cvCreateCapture_GStreamer (CV_CAP_GSTREAMER_FILE, filename);
+        TRY_OPEN(result, cvCreateCapture_GStreamer (CV_CAP_GSTREAMER_FILE, filename))
         if (apiPreference) break;
 #endif
 
 #if defined(HAVE_QUICKTIME) || defined(HAVE_QTKIT)
     case CV_CAP_QT:
-        if (! result)
-            result = cvCreateFileCapture_QT (filename);
+        TRY_OPEN(result, cvCreateFileCapture_QT (filename))
         if (apiPreference) break;
 #endif
 
 #ifdef HAVE_AVFOUNDATION
     case CV_CAP_AVFOUNDATION:
-        if (! result)
-            result = cvCreateFileCapture_AVFoundation (filename);
+        TRY_OPEN(result, cvCreateFileCapture_AVFoundation (filename))
         if (apiPreference) break;
 #endif
 
 #ifdef HAVE_OPENNI
     case CV_CAP_OPENNI:
-        if (! result)
-            result = cvCreateFileCapture_OpenNI (filename);
+        TRY_OPEN(result, cvCreateFileCapture_OpenNI (filename))
         if (apiPreference) break;
 #endif
 
     case CV_CAP_IMAGES:
-        if (! result)
-            result = cvCreateFileCapture_Images (filename);
+        TRY_OPEN(result, cvCreateFileCapture_Images (filename))
     }
 
     return result;
@@ -358,63 +359,47 @@ CV_IMPL CvCapture * cvCreateFileCapture (const char * filename)
 CV_IMPL CvVideoWriter* cvCreateVideoWriter( const char* filename, int fourcc,
                                             double fps, CvSize frameSize, int is_color )
 {
+    // If none of the writers is used
+    // these statements suppress 'unused parameter' warnings.
+    CV_UNUSED(frameSize);
+    CV_UNUSED(is_color);
+
     //CV_FUNCNAME( "cvCreateVideoWriter" );
 
     CvVideoWriter *result = 0;
 
     if(!fourcc || !fps)
-        result = cvCreateVideoWriter_Images(filename);
+        TRY_OPEN(result, cvCreateVideoWriter_Images(filename))
 
 #ifdef HAVE_FFMPEG
-    if(!result)
-        result = cvCreateVideoWriter_FFMPEG_proxy (filename, fourcc, fps, frameSize, is_color);
+    TRY_OPEN(result, cvCreateVideoWriter_FFMPEG_proxy (filename, fourcc, fps, frameSize, is_color))
 #endif
 
 #ifdef HAVE_VFW
-    if(!result)
-        result = cvCreateVideoWriter_VFW(filename, fourcc, fps, frameSize, is_color);
+    TRY_OPEN(result, cvCreateVideoWriter_VFW(filename, fourcc, fps, frameSize, is_color))
 #endif
 
 #ifdef HAVE_MSMF
-    if (!result)
-        result = cvCreateVideoWriter_MSMF(filename, fourcc, fps, frameSize, is_color);
+    TRY_OPEN(result, cvCreateVideoWriter_MSMF(filename, fourcc, fps, frameSize, is_color))
 #endif
 
 /*  #ifdef HAVE_XINE
-    if(!result)
-        result = cvCreateVideoWriter_XINE(filename, fourcc, fps, frameSize, is_color);
+    TRY_OPEN(result, cvCreateVideoWriter_XINE(filename, fourcc, fps, frameSize, is_color))
     #endif
 */
 #ifdef HAVE_AVFOUNDATION
-    if (! result)
-        result = cvCreateVideoWriter_AVFoundation(filename, fourcc, fps, frameSize, is_color);
+    TRY_OPEN(result, cvCreateVideoWriter_AVFoundation(filename, fourcc, fps, frameSize, is_color))
 #endif
 
 #if defined(HAVE_QUICKTIME) || defined(HAVE_QTKIT)
-    if(!result)
-        result = cvCreateVideoWriter_QT(filename, fourcc, fps, frameSize, is_color);
+    TRY_OPEN(result, cvCreateVideoWriter_QT(filename, fourcc, fps, frameSize, is_color))
 #endif
 
 #ifdef HAVE_GSTREAMER
-    if (! result)
-        result = cvCreateVideoWriter_GStreamer(filename, fourcc, fps, frameSize, is_color);
-#endif
-
-#if !defined(HAVE_FFMPEG) && \
-    !defined(HAVE_VFW) && \
-    !defined(HAVE_MSMF) && \
-    !defined(HAVE_AVFOUNDATION) && \
-    !defined(HAVE_QUICKTIME) && \
-    !defined(HAVE_QTKIT) && \
-    !defined(HAVE_GSTREAMER)
-// If none of the writers is used
-// these statements suppress 'unused parameter' warnings.
-    (void)frameSize;
-    (void)is_color;
+    TRY_OPEN(result, cvCreateVideoWriter_GStreamer(filename, fourcc, fps, frameSize, is_color))
 #endif
 
-    if(!result)
-        result = cvCreateVideoWriter_Images(filename);
+    TRY_OPEN(result, cvCreateVideoWriter_Images(filename))
 
     return result;
 }