camerabin: implement video preview creation

Completes preview creation mechanism to be able to provide a preview
image for video clips too.

gst/camerabin/camerabinpreview.c

@@ -59,24 +59,20 @@ create_element (const gchar * factory_name, const gchar * elem_name,
 
 /**
  * gst_camerabin_preview_create_pipeline:
- * @camera: camerabin object
+ * @caps: pointer to the caps used in pipeline
  *
- * Create a preview converter pipeline.
+ * Create a preview converter pipeline that outputs the format defined in
+ * @caps parameter.
  *
- * Returns: TRUE if pipeline was constructed, otherwise FALSE.
+ * Returns: New pipeline, or NULL if error occured.
  */
-gboolean
+GstElement *
-gst_camerabin_preview_create_pipeline (GstCameraBin * camera)
+gst_camerabin_preview_create_pipeline (GstCameraBin * camera, GstCaps * caps)
 {
-  GstElement *src, *csp, *filter, *vscale, *sink;
+  GstElement *pipe, *src, *csp, *filter, *vscale, *sink;
   GError *error = NULL;
 
-  if (!camera->preview_caps) {
+  g_return_val_if_fail (caps != NULL, FALSE);
-    return FALSE;
-  }
-
-  /* Destroy old pipeline, if any */
-  gst_camerabin_preview_destroy_pipeline (camera);
 
   GST_DEBUG ("creating elements");
 
@@ -87,17 +83,19 @@ gst_camerabin_preview_create_pipeline (GstCameraBin * camera)
       !create_element ("fakesink", "prev_sink", &sink, &error))
     goto no_elements;
 
-  camera->preview_pipeline = gst_pipeline_new ("preview-pipeline");
+  /* We have multiple pipelines created by using this function, so we can't
-  if (camera->preview_pipeline == NULL)
+   * give a name to them. Another way would to ensure the uniqueness of the
+   * name here*/
+  pipe = gst_pipeline_new (NULL);
+  if (pipe == NULL)
     goto no_pipeline;
 
   GST_DEBUG ("adding elements");
-  gst_bin_add_many (GST_BIN (camera->preview_pipeline),
+  gst_bin_add_many (GST_BIN (pipe), src, csp, filter, vscale, sink, NULL);
-      src, csp, filter, vscale, sink, NULL);
 
-  GST_DEBUG ("preview format is: %" GST_PTR_FORMAT, camera->preview_caps);
+  GST_DEBUG ("preview format is: %" GST_PTR_FORMAT, caps);
 
-  g_object_set (filter, "caps", camera->preview_caps, NULL);
+  g_object_set (filter, "caps", caps, NULL);
   g_object_set (sink, "preroll-queue-len", 1, "signal-handoffs", TRUE, NULL);
   g_object_set (vscale, "method", 0, NULL);
 
@@ -118,20 +116,20 @@ gst_camerabin_preview_create_pipeline (GstCameraBin * camera)
   if (!gst_element_link_pads (filter, "src", sink, "sink"))
     return FALSE;
 
-  return TRUE;
+  return pipe;
 
   /* ERRORS */
 no_elements:
   {
     g_warning ("Could not make preview pipeline: %s", error->message);
     g_error_free (error);
-    return FALSE;
+    return NULL;
   }
 no_pipeline:
   {
     g_warning ("Could not make preview pipeline: %s",
         "no pipeline (unknown error)");
-    return FALSE;
+    return NULL;
   }
 }
 
@@ -139,23 +137,25 @@ no_pipeline:
 /**
  * gst_camerabin_preview_destroy_pipeline:
  * @camera: camerabin object
+ * @pipeline: the pipeline to be destroyed
  *
  * Destroy preview converter pipeline.
  */
 void
-gst_camerabin_preview_destroy_pipeline (GstCameraBin * camera)
+gst_camerabin_preview_destroy_pipeline (GstCameraBin * camera,
+    GstElement * pipeline)
 {
-  if (camera->preview_pipeline) {
+  g_return_if_fail (pipeline != NULL);
-    gst_element_set_state (camera->preview_pipeline, GST_STATE_NULL);
+
-    gst_object_unref (camera->preview_pipeline);
+  gst_element_set_state (pipeline, GST_STATE_NULL);
-    camera->preview_pipeline = NULL;
+  gst_object_unref (pipeline);
-  }
 }
 
 
 /**
  * gst_camerabin_preview_convert:
  * @camera: camerabin object
+ * @pipeline: preview pipeline to use
  * @buf: #GstBuffer that contains the frame to be converted
  *
  * Create a preview image of the given frame.
@@ -163,7 +163,8 @@ gst_camerabin_preview_destroy_pipeline (GstCameraBin * camera)
  * Returns: converted preview image, or NULL if operation failed.
  */
 GstBuffer *
-gst_camerabin_preview_convert (GstCameraBin * camera, GstBuffer * buf)
+gst_camerabin_preview_convert (GstCameraBin * camera,
+    GstElement * pipeline, GstBuffer * buf)
 {
   GstMessage *msg;
   GstBuffer *result = NULL;
@@ -175,13 +176,13 @@ gst_camerabin_preview_convert (GstCameraBin * camera, GstBuffer * buf)
 
   g_return_val_if_fail (GST_BUFFER_CAPS (buf) != NULL, NULL);
 
-  if (camera->preview_pipeline == NULL) {
+  if (pipeline == NULL) {
     GST_WARNING ("pipeline is NULL");
     goto no_pipeline;
   }
 
-  src = gst_bin_get_by_name (GST_BIN (camera->preview_pipeline), "prev_src");
+  src = gst_bin_get_by_name (GST_BIN (pipeline), "prev_src");
-  sink = gst_bin_get_by_name (GST_BIN (camera->preview_pipeline), "prev_sink");
+  sink = gst_bin_get_by_name (GST_BIN (pipeline), "prev_sink");
 
   if (!src || !sink) {
     GST_WARNING ("pipeline doesn't have src / sink elements");
@@ -199,12 +200,12 @@ gst_camerabin_preview_convert (GstCameraBin * camera, GstBuffer * buf)
 
   GST_DEBUG ("running conversion pipeline, source is: %" GST_PTR_FORMAT,
       GST_BUFFER_CAPS (buf));
-  gst_element_set_state (camera->preview_pipeline, GST_STATE_PLAYING);
+  gst_element_set_state (pipeline, GST_STATE_PLAYING);
 
   g_signal_emit_by_name (src, "push-buffer", buf, &fret);
 
   /* TODO: do we need to use a bus poll, can we just register a callback to the bus? */
-  bus = gst_element_get_bus (camera->preview_pipeline);
+  bus = gst_element_get_bus (pipeline);
   msg =
       gst_bus_poll (bus, GST_MESSAGE_ERROR | GST_MESSAGE_EOS, 25 * GST_SECOND);
 
@@ -245,7 +246,7 @@ gst_camerabin_preview_convert (GstCameraBin * camera, GstBuffer * buf)
 
   g_signal_handlers_disconnect_by_func (sink, G_CALLBACK (save_result),
       &result);
-  gst_element_set_state (camera->preview_pipeline, GST_STATE_READY);
+  gst_element_set_state (pipeline, GST_STATE_READY);
 
   GST_BUFFER_FLAGS (buf) = bflags;
 

gst/camerabin/camerabinpreview.h

@@ -26,12 +26,14 @@
 #include "gstcamerabin.h"
 
 G_BEGIN_DECLS
-    gboolean gst_camerabin_preview_create_pipeline (GstCameraBin * camera);
+    GstElement * gst_camerabin_preview_create_pipeline (GstCameraBin * camera,
+    GstCaps * caps);
 
-void gst_camerabin_preview_destroy_pipeline (GstCameraBin * camera);
+void gst_camerabin_preview_destroy_pipeline (GstCameraBin * camera,
+    GstElement * pipeline);
 
 GstBuffer *gst_camerabin_preview_convert (GstCameraBin * camera,
-    GstBuffer * buf);
+    GstElement * pipeline, GstBuffer * buf);
 
 G_END_DECLS
 #endif                          /* __CAMERABINPREVIEW_H__ */

gst/camerabin/gstcamerabin.c

@@ -91,6 +91,22 @@
  * </para>
  * </refsect2>
  * <refsect2>
+ * <title>Video and image previews</title>
+ * <para>
+ * GstCameraBin contains "preview-caps" property, which is used to determine
+ * whether the application wants a preview image of the captured picture or
+ * video. When set, a GstMessage named "preview-image" will be sent. This
+ * message will contain a GstBuffer holding the preview image, converted
+ * to a format defined by those preview caps. The ownership of the preview
+ * image is kept in GstCameraBin, so application should ref the preview buffer
+ * object if it needs to use it elsewhere than in message handler.
+ * 
+ * Defining preview caps is done by selecting the capturing mode first and
+ * then setting the property. Camerabin remembers caps separately for both
+ * modes, so it is not necessary to set the caps again after changing the mode.
+ * </para>
+ * </refsect2>
+ * <refsect2>
  * <note>
  * <para>
  * Since the muxers tested so far have problems with discontinous buffers, QoS
@@ -876,18 +892,12 @@ camerabin_dispose_elements (GstCameraBin * camera)
   }
 
   /* Free caps */
-  if (camera->image_capture_caps) {
+  gst_caps_replace (&camera->image_capture_caps, NULL);
-    gst_caps_replace (&camera->image_capture_caps, NULL);
+  gst_caps_replace (&camera->view_finder_caps, NULL);
-  }
+  gst_caps_replace (&camera->allowed_caps, NULL);
-  if (camera->view_finder_caps) {
+  gst_caps_replace (&camera->preview_caps, NULL);
-    gst_caps_replace (&camera->view_finder_caps, NULL);
+  gst_caps_replace (&camera->video_preview_caps, NULL);
-  }
+  gst_buffer_replace (&camera->video_preview_buffer, NULL);
-  if (camera->allowed_caps) {
-    gst_caps_replace (&camera->allowed_caps, NULL);
-  }
-  if (camera->preview_caps) {
-    gst_caps_replace (&camera->preview_caps, NULL);
-  }
 
   if (camera->event_tags) {
     gst_tag_list_free (camera->event_tags);
@@ -1678,6 +1688,7 @@ image_pad_blocked (GstPad * pad, gboolean blocked, gpointer user_data)
 static gboolean
 gst_camerabin_send_preview (GstCameraBin * camera, GstBuffer * buffer)
 {
+  GstElement *pipeline;
   GstBuffer *prev = NULL;
   GstStructure *s;
   GstMessage *msg;
@@ -1685,7 +1696,9 @@ gst_camerabin_send_preview (GstCameraBin * camera, GstBuffer * buffer)
 
   GST_DEBUG_OBJECT (camera, "creating preview");
 
-  prev = gst_camerabin_preview_convert (camera, buffer);
+  pipeline = (camera->mode == MODE_IMAGE) ?
+      camera->preview_pipeline : camera->video_preview_pipeline;
+  prev = gst_camerabin_preview_convert (camera, pipeline, buffer);
 
   GST_DEBUG_OBJECT (camera, "preview created: %p", prev);
 
@@ -1789,6 +1802,13 @@ gst_camerabin_have_vid_buffer (GstPad * pad, GstBuffer * buffer,
   gboolean ret = TRUE;
   GST_LOG ("got video buffer %p with size %d",
       buffer, GST_BUFFER_SIZE (buffer));
+
+  if (camera->video_preview_caps &&
+      !camera->video_preview_buffer && !camera->stop_requested) {
+    GST_DEBUG ("storing video preview %p", buffer);
+    camera->video_preview_buffer = gst_buffer_copy (buffer);
+  }
+
   if (G_UNLIKELY (camera->stop_requested)) {
     gst_camerabin_send_video_eos (camera);
     ret = FALSE;                /* Drop buffer */
@@ -1972,6 +1992,12 @@ gst_camerabin_do_stop (GstCameraBin * camera)
     GST_DEBUG_OBJECT (camera, "mark stop");
     camera->stop_requested = TRUE;
 
+    if (camera->video_preview_caps && camera->video_preview_buffer) {
+      gst_camerabin_send_preview (camera, camera->video_preview_buffer);
+      gst_buffer_unref (camera->video_preview_buffer);
+      camera->video_preview_buffer = NULL;
+    }
+
     /* Take special care when stopping paused video capture */
     if ((camera->active_bin == camera->vidbin) && camera->paused) {
       /* Send eos event to video bin before setting it to playing */
@@ -2709,6 +2735,8 @@ gst_camerabin_init (GstCameraBin * camera, GstCameraBinClass * gclass)
   camera->pad_src_vid = NULL;
   camera->pad_view_vid = NULL;
 
+  camera->video_preview_buffer = NULL;
+
   /* source elements */
   camera->src_vid_src = NULL;
   camera->src_filter = NULL;
@@ -2753,7 +2781,15 @@ gst_camerabin_dispose (GObject * object)
   gst_element_set_state (camera->vidbin, GST_STATE_NULL);
   gst_object_unref (camera->vidbin);
 
-  gst_camerabin_preview_destroy_pipeline (camera);
+  if (camera->preview_pipeline) {
+    gst_camerabin_preview_destroy_pipeline (camera, camera->preview_pipeline);
+    camera->preview_pipeline = NULL;
+  }
+  if (camera->video_preview_pipeline) {
+    gst_camerabin_preview_destroy_pipeline (camera,
+        camera->video_preview_pipeline);
+    camera->video_preview_pipeline = NULL;
+  }
 
   camerabin_destroy_elements (camera);
   camerabin_dispose_elements (camera);
@@ -2878,24 +2914,39 @@ gst_camerabin_set_property (GObject * object, guint prop_id,
       }
       break;
     case ARG_PREVIEW_CAPS:
-      /* Currently camerabin only provides preview for images, so we don't
+    {
-       * even handle video mode */
+      GstElement **prev_pipe = NULL;
+      GstCaps **prev_caps = NULL;
+      GstCaps *new_caps = NULL;
+
       if (camera->mode == MODE_IMAGE) {
-        GstCaps *new_caps = NULL;
+        prev_pipe = &camera->preview_pipeline;
+        prev_caps = &camera->preview_caps;
+      } else if (camera->mode == MODE_VIDEO) {
+        prev_pipe = &camera->video_preview_pipeline;
+        prev_caps = &camera->video_preview_caps;
+      }
 
-        new_caps = (GstCaps *) gst_value_get_caps (value);
+      new_caps = (GstCaps *) gst_value_get_caps (value);
+
+      if (prev_caps && !gst_caps_is_equal (*prev_caps, new_caps)) {
         GST_DEBUG_OBJECT (camera,
-            "setting preview caps: %" GST_PTR_FORMAT " -> %" GST_PTR_FORMAT,
+            "setting preview caps: %" GST_PTR_FORMAT, new_caps);
-            camera->preview_caps, new_caps);
+        if (*prev_pipe) {
+          gst_camerabin_preview_destroy_pipeline (camera, *prev_pipe);
+          *prev_pipe = NULL;
+        }
+        GST_OBJECT_LOCK (camera);
+        gst_caps_replace (prev_caps, new_caps);
+        GST_OBJECT_UNLOCK (camera);
 
-        if (!gst_caps_is_equal (camera->preview_caps, new_caps)) {
+        if (new_caps && !gst_caps_is_any (new_caps) &&
-          GST_OBJECT_LOCK (camera);
+            !gst_caps_is_empty (new_caps)) {
-          gst_caps_replace (&camera->preview_caps, new_caps);
+          *prev_pipe = gst_camerabin_preview_create_pipeline (camera, new_caps);
-          GST_OBJECT_UNLOCK (camera);
-          gst_camerabin_preview_create_pipeline (camera);
         }
       }
       break;
+    }
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -2968,7 +3019,10 @@ gst_camerabin_get_property (GObject * object, guint prop_id,
       gst_value_set_caps (value, camera->view_finder_caps);
       break;
     case ARG_PREVIEW_CAPS:
-      gst_value_set_caps (value, camera->preview_caps);
+      if (camera->mode == MODE_IMAGE)
+        gst_value_set_caps (value, camera->preview_caps);
+      else if (camera->mode == MODE_VIDEO)
+        gst_value_set_caps (value, camera->video_preview_caps);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);

gst/camerabin/gstcamerabin.h

@@ -87,6 +87,9 @@ struct _GstCameraBin
   /* Caps used to create preview image */
   GstCaps *preview_caps;
 
+  /* Caps used to create video preview image */
+  GstCaps *video_preview_caps;
+
   /* The digital zoom (from 100% to 1000%) */
   gint zoom;
 
@@ -110,6 +113,9 @@ struct _GstCameraBin
   GstElement *vidbin;           /*  bin that holds video capturing elements */
   GstElement *active_bin;       /* image or video bin that is currently in use */
   GstElement *preview_pipeline; /* pipeline for creating preview images */
+  GstElement *video_preview_pipeline;   /* pipeline for creating video preview image */
+
+  GstBuffer *video_preview_buffer;      /* buffer for storing video preview */
 
   /* source elements */
   GstElement *src_vid_src;