camerabin: optimize setting new caps for preview image pipeline

Avoid re-creating and linking of preview image pipeline when
setting new preview image caps. Backported from camerabin2.

https://bugzilla.gnome.org/show_bug.cgi?id=639502

gst/camerabin/camerabinpreview.c

@@ -60,124 +60,133 @@ create_element (const gchar * factory_name, const gchar * elem_name,
 
 /**
  * gst_camerabin_preview_create_pipeline:
+ * @element: #GstCameraBin element
  * @caps: pointer to the caps used in pipeline
+ * @src_filter: source filter element
  *
  * Create a preview converter pipeline that outputs the format defined in
  * @caps parameter.
  *
- * Returns: New pipeline, or NULL if error occured.
+ * Returns: New pipeline data structure, or NULL if error occured.
  */
-GstElement *
+GstCameraBinPreviewPipelineData *
-gst_camerabin_preview_create_pipeline (GstCameraBin * camera, GstCaps * caps,
+gst_camerabin_preview_create_pipeline (GstElement * element, GstCaps * caps,
     GstElement * src_filter)
 {
-  GstElement *pipe, *src, *csp, *filter, *vscale, *sink;
+  GstElement *csp, *vscale;
   GError *error = NULL;
+  GstCameraBinPreviewPipelineData *data;
 
-  g_return_val_if_fail (caps != NULL, FALSE);
+  g_return_val_if_fail (caps != NULL, NULL);
 
   GST_DEBUG ("creating elements");
 
-  if (!create_element ("appsrc", "prev_src", &src, &error) ||
+  data = g_new (GstCameraBinPreviewPipelineData, 1);
-      !create_element ("videoscale", NULL, &vscale, &error) ||
-      !create_element ("ffmpegcolorspace", NULL, &csp, &error) ||
-      !create_element ("capsfilter", NULL, &filter, &error) ||
-      !create_element ("fakesink", "prev_sink", &sink, &error))
-    goto no_elements;
 
   /* We have multiple pipelines created by using this function, so we can't
    * give a name to them. Another way would to ensure the uniqueness of the
    * name here*/
-  pipe = gst_pipeline_new (NULL);
+  data->pipeline = gst_pipeline_new (NULL);
-  if (pipe == NULL)
+  if (!data->pipeline)
-    goto no_pipeline;
+    goto create_error;
+
+  if (!create_element ("appsrc", "prev_src", &data->appsrc, &error) ||
+      !create_element ("videoscale", NULL, &vscale, &error) ||
+      !create_element ("ffmpegcolorspace", NULL, &csp, &error) ||
+      !create_element ("capsfilter", NULL, &data->capsfilter, &error) ||
+      !create_element ("fakesink", "prev_sink", &data->appsink, &error))
+    goto create_error;
 
   GST_DEBUG ("adding elements");
-  gst_bin_add_many (GST_BIN (pipe), src, csp, filter, vscale, sink, NULL);
+  gst_bin_add_many (GST_BIN (data->pipeline), data->appsrc, csp,
+      data->capsfilter, vscale, data->appsink, NULL);
   if (src_filter) {
-    gst_bin_add (GST_BIN (pipe), src_filter);
+    gst_bin_add (GST_BIN (data->pipeline), src_filter);
   }
 
+  data->element = element;
+
   GST_DEBUG ("preview format is: %" GST_PTR_FORMAT, caps);
 
-  g_object_set (filter, "caps", caps, NULL);
+  g_object_set (data->capsfilter, "caps", caps, NULL);
-  g_object_set (sink, "preroll-queue-len", 1, "signal-handoffs", TRUE, NULL);
+  g_object_set (data->appsink, "preroll-queue-len", 1, "signal-handoffs", TRUE,
+      NULL);
   g_object_set (vscale, "method", 0, NULL);
 
-  /* FIXME: linking is still way too expensive, profile this properly */
   GST_DEBUG ("linking src->vscale");
-  if (!gst_element_link_pads_full (src, "src", vscale, "sink",
+  if (!gst_element_link_pads (data->appsrc, "src", vscale, "sink"))
-          GST_PAD_LINK_CHECK_CAPS))
+    goto link_error;
-    return FALSE;
 
   if (src_filter) {
-    GST_DEBUG ("linking vscale->filter");
+    GST_DEBUG ("linking vscale->src_filter");
-    if (!gst_element_link_pads_full (vscale, "src", src_filter, "sink",
+    if (!gst_element_link_pads (vscale, "src", src_filter, "sink")) {
-            GST_PAD_LINK_CHECK_CAPS)) {
+      goto link_error;
-      return FALSE;
     }
     GST_DEBUG ("linking filter->csp");
-    if (!gst_element_link_pads_full (src_filter, "src", csp, "sink",
+    if (!gst_element_link_pads (src_filter, "src", csp, "sink")) {
-            GST_PAD_LINK_CHECK_CAPS)) {
+      goto link_error;
-      return FALSE;
     }
   } else {
     GST_DEBUG ("linking vscale->csp");
-    if (!gst_element_link_pads_full (vscale, "src", csp, "sink",
+    if (!gst_element_link_pads (vscale, "src", csp, "sink"))
-            GST_PAD_LINK_CHECK_CAPS))
+      goto link_error;
-      return FALSE;
   }
 
   GST_DEBUG ("linking csp->capsfilter");
-  if (!gst_element_link_pads_full (csp, "src", filter, "sink",
+  if (!gst_element_link_pads (csp, "src", data->capsfilter, "sink"))
-          GST_PAD_LINK_CHECK_CAPS))
+    goto link_error;
-    return FALSE;
 
   GST_DEBUG ("linking capsfilter->sink");
-  if (!gst_element_link_pads_full (filter, "src", sink, "sink",
+  if (!gst_element_link_pads (data->capsfilter, "src", data->appsink, "sink"))
-          GST_PAD_LINK_CHECK_CAPS))
+    goto link_error;
-    return FALSE;
 
-  return pipe;
+  return data;
 
-  /* ERRORS */
+create_error:
-no_elements:
+  if (error) {
-  {
+    GST_WARNING ("Preview pipeline element creation failed: %s",
-    g_warning ("Could not make preview pipeline: %s", error->message);
+        error->message);
     g_error_free (error);
-    return NULL;
-  }
-no_pipeline:
-  {
-    g_warning ("Could not make preview pipeline: %s",
-        "no pipeline (unknown error)");
-    return NULL;
   }
+  if (csp)
+    gst_object_unref (csp);
+  if (vscale)
+    gst_object_unref (vscale);
+  if (data->appsrc)
+    gst_object_unref (data->appsrc);
+  if (data->capsfilter)
+    gst_object_unref (data->capsfilter);
+  if (data->appsink)
+    gst_object_unref (data->appsink);
+
+link_error:
+  GST_WARNING ("Could not create preview pipeline");
+  gst_camerabin_preview_destroy_pipeline (data);
+
+  return NULL;
 }
 
 
 /**
  * gst_camerabin_preview_destroy_pipeline:
- * @camera: camerabin object
+ * @data: the pipeline data to be destroyed
- * @pipeline: the pipeline to be destroyed
  *
  * Destroy preview converter pipeline.
  */
 void
-gst_camerabin_preview_destroy_pipeline (GstCameraBin * camera,
+gst_camerabin_preview_destroy_pipeline (GstCameraBinPreviewPipelineData * data)
-    GstElement * pipeline)
 {
-  g_return_if_fail (pipeline != NULL);
+  if (data->pipeline) {
-
+    gst_element_set_state (data->pipeline, GST_STATE_NULL);
-  gst_element_set_state (pipeline, GST_STATE_NULL);
+    gst_object_unref (data->pipeline);
-  gst_object_unref (pipeline);
+  }
+  g_free (data);
 }
 
 
 /**
  * gst_camerabin_preview_convert:
- * @camera: camerabin object
+ * @data: preview pipeline data to use
- * @pipeline: preview pipeline to use
  * @buf: #GstBuffer that contains the frame to be converted
  *
  * Create a preview image of the given frame.
@@ -185,8 +194,8 @@ gst_camerabin_preview_destroy_pipeline (GstCameraBin * camera,
  * Returns: converted preview image, or NULL if operation failed.
  */
 GstBuffer *
-gst_camerabin_preview_convert (GstCameraBin * camera,
+gst_camerabin_preview_convert (GstCameraBinPreviewPipelineData * data,
-    GstElement * pipeline, GstBuffer * buf)
+    GstBuffer * buf)
 {
   GstMessage *msg;
   GstBuffer *result = NULL;
@@ -198,13 +207,13 @@ gst_camerabin_preview_convert (GstCameraBin * camera,
 
   g_return_val_if_fail (GST_BUFFER_CAPS (buf) != NULL, NULL);
 
-  if (pipeline == NULL) {
+  if (data->pipeline == NULL) {
     GST_WARNING ("pipeline is NULL");
     goto no_pipeline;
   }
 
-  src = gst_bin_get_by_name (GST_BIN (pipeline), "prev_src");
+  src = gst_bin_get_by_name (GST_BIN (data->pipeline), "prev_src");
-  sink = gst_bin_get_by_name (GST_BIN (pipeline), "prev_sink");
+  sink = gst_bin_get_by_name (GST_BIN (data->pipeline), "prev_sink");
 
   if (!src || !sink) {
     GST_WARNING ("pipeline doesn't have src / sink elements");
@@ -222,11 +231,11 @@ gst_camerabin_preview_convert (GstCameraBin * camera,
 
   GST_DEBUG ("running conversion pipeline, source is: %" GST_PTR_FORMAT,
       GST_BUFFER_CAPS (buf));
-  gst_element_set_state (pipeline, GST_STATE_PLAYING);
+  gst_element_set_state (data->pipeline, GST_STATE_PLAYING);
 
   g_signal_emit_by_name (src, "push-buffer", buf, &fret);
 
-  bus = gst_element_get_bus (pipeline);
+  bus = gst_element_get_bus (data->pipeline);
   msg = gst_bus_timed_pop_filtered (bus, (25 * GST_SECOND),
       GST_MESSAGE_ERROR | GST_MESSAGE_EOS);
   gst_object_unref (bus);
@@ -268,7 +277,7 @@ gst_camerabin_preview_convert (GstCameraBin * camera,
 
   g_signal_handlers_disconnect_by_func (sink, G_CALLBACK (save_result),
       &result);
-  gst_element_set_state (pipeline, GST_STATE_READY);
+  gst_element_set_state (data->pipeline, GST_STATE_READY);
 
   GST_BUFFER_FLAGS (buf) = bflags;
 
@@ -297,7 +306,7 @@ no_pipeline:
 
 /**
  * gst_camerabin_preview_send_event:
- * @camera: the #GstCameraBin
+ * @data: preview pipeline data to use
  * @evt: The #GstEvent to be pushed, takes ownership
  *
  * Pushes an event to the preview pipeline.
@@ -305,21 +314,50 @@ no_pipeline:
  * Returns: True if the event was handled
  */
 gboolean
-gst_camerabin_preview_send_event (GstCameraBin * camera, GstElement * pipeline,
+gst_camerabin_preview_send_event (GstCameraBinPreviewPipelineData * data,
     GstEvent * evt)
 {
   GstElement *src;
-  gboolean ret = FALSE;
 
-  src = gst_bin_get_by_name (GST_BIN (pipeline), "prev_src");
+  src = gst_bin_get_by_name (GST_BIN (data->pipeline), "prev_src");
   if (!src) {
     GST_WARNING ("Preview pipeline doesn't have src element, can't push event");
     gst_event_unref (evt);
-  } else {
+    return FALSE;
-    GST_DEBUG_OBJECT (camera, "Pushing event %p to preview pipeline", evt);
-    ret = gst_element_send_event (src, evt);
-    gst_object_unref (src);
   }
 
-  return ret;
+  GST_DEBUG_OBJECT (data->element, "Pushing event %p to preview pipeline", evt);
+
+  return gst_element_send_event (src, evt);
+}
+
+/**
+ * gst_camerabin_preview_set_caps:
+ * @data: preview pipeline data to use
+ * @caps: New #GstCaps to be set for the pipeline
+ *
+ * Sets new caps for the preview pipeline
+ */
+void
+gst_camerabin_preview_set_caps (GstCameraBinPreviewPipelineData * data,
+    GstCaps * caps)
+{
+  GstState state, pending;
+  GstStateChangeReturn ret;
+
+  g_return_if_fail (data->pipeline != NULL);
+  g_return_if_fail (caps != NULL);
+
+  ret = gst_element_get_state (data->pipeline, &state, &pending, 0);
+  if (ret == GST_STATE_CHANGE_FAILURE) {
+    /* make it try again */
+    state = GST_STATE_PLAYING;
+    pending = GST_STATE_VOID_PENDING;
+  }
+
+  gst_element_set_state (data->pipeline, GST_STATE_NULL);
+  g_object_set (data->capsfilter, "caps", caps, NULL);
+  if (pending != GST_STATE_VOID_PENDING)
+    state = pending;
+  gst_element_set_state (data->pipeline, state);
 }

gst/camerabin/camerabinpreview.h

@@ -23,20 +23,35 @@
 
 #include <gst/gst.h>
 
-#include "gstcamerabin.h"
-
 G_BEGIN_DECLS
-    GstElement * gst_camerabin_preview_create_pipeline (GstCameraBin * camera,
-    GstCaps * caps, GstElement * src_filter);
 
-void gst_camerabin_preview_destroy_pipeline (GstCameraBin * camera,
+typedef struct
-    GstElement * pipeline);
+{
+  GstElement *pipeline;
 
-GstBuffer *gst_camerabin_preview_convert (GstCameraBin * camera,
+  GstElement *appsrc;
-    GstElement * pipeline, GstBuffer * buf);
+  GstElement *capsfilter;
+  GstElement *appsink;
 
-gboolean gst_camerabin_preview_send_event (GstCameraBin * camera,
+  GstElement *element;
-    GstElement * pipeline, GstEvent * event);
+} GstCameraBinPreviewPipelineData;
+
+
+GstCameraBinPreviewPipelineData * gst_camerabin_preview_create_pipeline (
+    GstElement *element, GstCaps *caps, GstElement *src_filter);
+
+void gst_camerabin_preview_destroy_pipeline (
+    GstCameraBinPreviewPipelineData *data);
+
+GstBuffer *gst_camerabin_preview_convert (
+    GstCameraBinPreviewPipelineData *data, GstBuffer *buf);
+
+gboolean gst_camerabin_preview_send_event (
+    GstCameraBinPreviewPipelineData *pipeline, GstEvent *event);
+
+void gst_camerabin_preview_set_caps (
+    GstCameraBinPreviewPipelineData *pipeline, GstCaps *caps);
 
 G_END_DECLS
+
 #endif                          /* __CAMERABINPREVIEW_H__ */

gst/camerabin/gstcamerabin.c

@@ -1760,7 +1760,7 @@ camerabin_pad_blocked (GstPad * pad, gboolean blocked, gpointer user_data)
 static gboolean
 gst_camerabin_send_preview (GstCameraBin * camera, GstBuffer * buffer)
 {
-  GstElement *pipeline;
+  GstCameraBinPreviewPipelineData *data;
   GstBuffer *prev = NULL;
   GstStructure *s;
   GstMessage *msg;
@@ -1768,9 +1768,9 @@ gst_camerabin_send_preview (GstCameraBin * camera, GstBuffer * buffer)
 
   GST_DEBUG_OBJECT (camera, "creating preview");
 
-  pipeline = (camera->mode == MODE_IMAGE) ?
+  data = (camera->mode == MODE_IMAGE) ?
       camera->preview_pipeline : camera->video_preview_pipeline;
-  prev = gst_camerabin_preview_convert (camera, pipeline, buffer);
+  prev = gst_camerabin_preview_convert (data, buffer);
 
   GST_DEBUG_OBJECT (camera, "preview created: %p", prev);
 
@@ -1865,12 +1865,11 @@ gst_camerabin_have_img_buffer (GstPad * pad, GstMiniObject * obj,
 
     /* forward tag events to preview pipeline */
     if (camera->preview_caps && GST_EVENT_TYPE (event) == GST_EVENT_TAG) {
-      GstElement *pipeline;
+      GstCameraBinPreviewPipelineData *data;
 
-      pipeline = (camera->mode == MODE_IMAGE) ?
+      data = (camera->mode == MODE_IMAGE) ?
           camera->preview_pipeline : camera->video_preview_pipeline;
-      gst_camerabin_preview_send_event (camera, pipeline,
+      gst_camerabin_preview_send_event (data, gst_event_ref (event));
-          gst_event_ref (event));
     }
   }
 
@@ -3373,12 +3372,11 @@ gst_camerabin_dispose (GObject * object)
   gst_object_unref (camera->vidbin);
 
   if (camera->preview_pipeline) {
-    gst_camerabin_preview_destroy_pipeline (camera, camera->preview_pipeline);
+    gst_camerabin_preview_destroy_pipeline (camera->preview_pipeline);
     camera->preview_pipeline = NULL;
   }
   if (camera->video_preview_pipeline) {
-    gst_camerabin_preview_destroy_pipeline (camera,
+    gst_camerabin_preview_destroy_pipeline (camera->video_preview_pipeline);
-        camera->video_preview_pipeline);
     camera->video_preview_pipeline = NULL;
   }
 
@@ -3525,7 +3523,7 @@ gst_camerabin_set_property (GObject * object, guint prop_id,
       break;
     case ARG_PREVIEW_CAPS:
     {
-      GstElement **prev_pipe = NULL;
+      GstCameraBinPreviewPipelineData **prev_pipe = NULL;
       GstElement **preview_source_filter = NULL;
       GstCaps **prev_caps = NULL;
       GstCaps *new_caps = NULL;
@@ -3545,19 +3543,20 @@ gst_camerabin_set_property (GObject * object, guint prop_id,
       if (prev_caps && !gst_caps_is_equal (*prev_caps, new_caps)) {
         GST_DEBUG_OBJECT (camera,
             "setting preview caps: %" GST_PTR_FORMAT, 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 (new_caps && !gst_caps_is_any (new_caps) &&
             !gst_caps_is_empty (new_caps)) {
-          *prev_pipe =
+          if (!*prev_pipe) {
-              gst_camerabin_preview_create_pipeline (camera, new_caps,
+            *prev_pipe =
-              *preview_source_filter);
+                gst_camerabin_preview_create_pipeline (GST_ELEMENT (camera),
+                new_caps, *preview_source_filter);
+          } else {
+            gst_camerabin_preview_set_caps (*prev_pipe, new_caps);
+          }
         }
       }
       break;
@@ -3568,7 +3567,7 @@ gst_camerabin_set_property (GObject * object, guint prop_id,
             ("camerabin must be in NULL state when setting the preview source filter element"),
             (NULL));
       } else {
-        GstElement **preview_pipe = NULL;
+        GstCameraBinPreviewPipelineData **preview_pipe = NULL;
         GstElement **preview_source_filter = NULL;
         GstCaps *preview_caps = NULL;
 
@@ -3587,10 +3586,10 @@ gst_camerabin_set_property (GObject * object, guint prop_id,
         *preview_source_filter = g_value_dup_object (value);
 
         if (*preview_pipe) {
-          gst_camerabin_preview_destroy_pipeline (camera, *preview_pipe);
+          gst_camerabin_preview_destroy_pipeline (*preview_pipe);
           *preview_pipe =
-              gst_camerabin_preview_create_pipeline (camera, preview_caps,
+              gst_camerabin_preview_create_pipeline (GST_ELEMENT (camera),
-              *preview_source_filter);
+              preview_caps, *preview_source_filter);
         }
       }
       break;

gst/camerabin/gstcamerabin.h

@@ -31,6 +31,7 @@
 #include "gstcamerabin-enum.h"
 #include "camerabinimage.h"
 #include "camerabinvideo.h"
+#include "camerabinpreview.h"
 
 G_BEGIN_DECLS
 /* #defines don't like whitespacey bits */
@@ -147,8 +148,10 @@ struct _GstCameraBin
   GstElement *imgbin;           /* bin that holds image capturing elements */
   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 */
+  /* pipeline for creating preview images */
-  GstElement *video_preview_pipeline;   /* pipeline for creating video preview image */
+  GstCameraBinPreviewPipelineData *preview_pipeline;
+  /* pipeline for creating video preview image */
+  GstCameraBinPreviewPipelineData *video_preview_pipeline;
 
   GstBuffer *video_preview_buffer;      /* buffer for storing video preview */