wrappercamerabinsrc: stop source to do internal reconfiguration safely

In order to be able to change the caps on multiple capsfilters the
source element needs to be stopped, otherwise it will get a few
reconfigure events and might try to renegotiate while the bin
is still transitioning its caps, leading to a not-negotiated failure
and the image capture won't happen because the source will be
unusable.

The solution is to keep the source in paused while the caps are being
changed in the bin, and then bring the element back to playing once
it is done. Unfortunately this increases the image capture latency,
but it should always work.

A possible improvement to reduce the latency is to add another signal
to be called before 'start-capture': 'prepare-capture'. At this step
the camera source should set all caps it needs and get the source
ready for doing the capture as soon as 'start-capture' is called.
This can be done on a future commit

1 files changed, 3 insertions, 0 deletions

diff --git a/gst/camerabin2/gstwrappercamerabinsrc.c b/gst/camerabin2/gstwrappercamerabinsrc.c
index 2e3dda64f..c2111a0b7 100644
--- a/gst/camerabin2/gstwrappercamerabinsrc.c
+++ b/gst/camerabin2/gstwrappercamerabinsrc.c
@@ -828,6 +828,7 @@ start_image_capture (GstWrapperCameraBinSrc * self)
   GstCaps *caps;
 
   GST_DEBUG_OBJECT (self, "Starting image capture");
+  gst_element_set_state (self->src_vid_src, GST_STATE_READY);
 
   if (self->image_renegotiate) {
     /* clean capsfilter caps so they don't interfere here */
@@ -852,6 +853,7 @@ start_image_capture (GstWrapperCameraBinSrc * self)
   }
 
   if (photography) {
+    gst_element_set_state (self->src_vid_src, GST_STATE_PLAYING);
     GST_DEBUG_OBJECT (self, "prepare image capture caps %" GST_PTR_FORMAT,
         self->image_capture_caps);
     ret = gst_photography_prepare_for_capture (photography,
@@ -863,6 +865,7 @@ start_image_capture (GstWrapperCameraBinSrc * self)
         self->image_capture_caps);
     g_mutex_lock (&bcamsrc->capturing_mutex);
     ret = TRUE;
+    gst_element_set_state (self->src_vid_src, GST_STATE_PLAYING);
   }
 
   return ret;