dshowsrcwrapper: avoid error when set_caps called twice

If set_caps is called in a running state, return immediately if the caps
haven't changed. If the pins are already connected, disconnect them.

https://bugzilla.gnome.org/show_bug.cgi?id=736926

sys/dshowsrcwrapper/gstdshow.cpp

@@ -413,6 +413,22 @@ gst_dshow_guid_to_gst_video_format (AM_MEDIA_TYPE *mediatype)
   return GST_VIDEO_FORMAT_UNKNOWN;
 }
 
+gboolean
+gst_dshow_is_pin_connected (IPin * pin)
+{
+  IPin *tmp_pin = NULL;
+  gboolean res;
+  HRESULT hres;
+
+  g_assert (pin);
+  hres = pin->ConnectedTo (&tmp_pin);
+  res = (hres != VFW_E_NOT_CONNECTED);
+  if (tmp_pin)
+    tmp_pin->Release ();
+
+  return res;
+}
+
 GstCaps *
 gst_dshow_new_video_caps (GstVideoFormat video_format, const gchar * name,
     GstCapturePinMediaType * pin_mediatype)

sys/dshowsrcwrapper/gstdshow.h

@@ -92,6 +92,9 @@ gboolean gst_dshow_show_propertypage (IBaseFilter * base_filter);
 /* translate GUID format to gsteamer video format */
 GstVideoFormat gst_dshow_guid_to_gst_video_format (AM_MEDIA_TYPE *mediatype);
 
+/* check if IPin is connected */
+gboolean gst_dshow_is_pin_connected (IPin *pin);
+
 /* transform a dshow video caps to a gstreamer video caps */
 GstCaps *gst_dshow_new_video_caps (GstVideoFormat video_format,
     const gchar * name, GstCapturePinMediaType * pin_mediatype);

sys/dshowsrcwrapper/gstdshowaudiosrc.cpp

@@ -452,6 +452,13 @@ gst_dshowaudiosrc_prepare (GstAudioSrc * asrc, GstAudioRingBufferSpec * spec)
   HRESULT hres;
   IPin *input_pin = NULL;
   GstDshowAudioSrc *src = GST_DSHOWAUDIOSRC (asrc);
+  GstCaps *current_caps = gst_pad_get_current_caps (GST_BASE_SRC_PAD (asrc));
+
+  if (gst_caps_is_equal (spec->caps, current_caps)) {
+    gst_caps_unref (current_caps);
+    return TRUE;
+  }
+  gst_caps_unref (current_caps);
 
   /* In 1.0, prepare() seems to be called in the PLAYING state. Most
      of the time you can't do much on a running graph. */
@@ -511,6 +518,18 @@ gst_dshowaudiosrc_prepare (GstAudioSrc * asrc, GstAudioRingBufferSpec * spec)
           spec->segtotal = 2;
         };
         GST_INFO ("Configuring with segsize:%d segtotal:%d", spec->segsize, spec->segtotal);
+
+        if (gst_dshow_is_pin_connected (pin_mediatype->capture_pin)) {
+          GST_DEBUG_OBJECT (src,
+              "capture_pin already connected, disconnecting");
+          src->filter_graph->Disconnect (pin_mediatype->capture_pin);
+        }
+
+        if (gst_dshow_is_pin_connected (input_pin)) {
+          GST_DEBUG_OBJECT (src, "input_pin already connected, disconnecting");
+          src->filter_graph->Disconnect (input_pin);
+        }
+
         hres = src->filter_graph->ConnectDirect (pin_mediatype->capture_pin,
             input_pin, NULL);
         input_pin->Release ();

sys/dshowsrcwrapper/gstdshowvideosrc.cpp

@@ -576,6 +576,13 @@ gst_dshowvideosrc_set_caps (GstBaseSrc * bsrc, GstCaps * caps)
   IPin *input_pin = NULL;
   GstDshowVideoSrc *src = GST_DSHOWVIDEOSRC (bsrc);
   GstStructure *s = gst_caps_get_structure (caps, 0);
+  GstCaps *current_caps = gst_pad_get_current_caps (GST_BASE_SRC_PAD (bsrc));
+
+  if (gst_caps_is_equal (caps, current_caps)) {
+    gst_caps_unref (current_caps);
+    return TRUE;
+  }
+  gst_caps_unref (current_caps);
 
   /* Same remark as in gstdshowaudiosrc. */
   gboolean was_running = src->is_running;
@@ -654,6 +661,16 @@ gst_dshowvideosrc_set_caps (GstBaseSrc * bsrc, GstCaps * caps)
           goto error;
         }
 
+        if (gst_dshow_is_pin_connected (pin_mediatype->capture_pin)) {
+          GST_DEBUG_OBJECT (src,
+              "capture_pin already connected, disconnecting");
+          src->filter_graph->Disconnect (pin_mediatype->capture_pin);
+        }
+
+        if (gst_dshow_is_pin_connected (input_pin)) {
+          GST_DEBUG_OBJECT (src, "input_pin already connected, disconnecting");
+          src->filter_graph->Disconnect (input_pin);
+        }
 
         hres = src->filter_graph->ConnectDirect (pin_mediatype->capture_pin,
             input_pin, pin_mediatype->mediatype);