camerabin: preview image sending optimization

 * decouple image capturing from image post-processing and encoding
 * post image-captured message after image is captured
 * post preview-image message with snapshot of captured image

1 files changed, 257 insertions, 0 deletions

diff --git a/gst/camerabin/camerabinpreview.c b/gst/camerabin/camerabinpreview.c
new file mode 100644
index 00000000..b64b2143
--- /dev/null
+++ b/gst/camerabin/camerabinpreview.c
@@ -0,0 +1,257 @@
+/*
+* GStreamer
+* Copyright (C) 2009 Nokia Corporation <multimedia@maemo.org>
+*
+* This library is free software; you can redistribute it and/or
+* modify it under the terms of the GNU Library General Public
+* License as published by the Free Software Foundation; either
+* version 2 of the License, or (at your option) any later version.
+*
+* This library is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+* Library General Public License for more details.
+*
+* You should have received a copy of the GNU Library General Public
+* License along with this library; if not, write to the
+* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+* Boston, MA 02111-1307, USA.
+*/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <gst/gst.h>
+#include <string.h>
+
+#include "camerabingeneral.h"
+#include "camerabinpreview.h"
+
+static void
+save_result (GstElement * sink, GstBuffer * buf, GstPad * pad, gpointer data)
+{
+  GstBuffer **p_buf = (GstBuffer **) data;
+
+  *p_buf = gst_buffer_ref (buf);
+
+  GST_DEBUG ("received converted buffer %p with caps %" GST_PTR_FORMAT,
+      *p_buf, GST_BUFFER_CAPS (*p_buf));
+}
+
+static gboolean
+create_element (const gchar * factory_name, const gchar * elem_name,
+    GstElement ** element, GError ** err)
+{
+  *element = gst_element_factory_make (factory_name, elem_name);
+  if (*element)
+    return TRUE;
+
+  if (err && *err == NULL) {
+    *err = g_error_new (GST_CORE_ERROR, GST_CORE_ERROR_MISSING_PLUGIN,
+        "cannot create element '%s' - please check your GStreamer installation",
+        factory_name);
+  }
+
+  return FALSE;
+}
+
+
+/**
+ * gst_camerabin_preview_create_pipeline:
+ * @camera: camerabin object
+ *
+ * Create a preview converter pipeline.
+ *
+ * Returns: TRUE if pipeline was constructed, otherwise FALSE.
+ */
+gboolean
+gst_camerabin_preview_create_pipeline (GstCameraBin * camera)
+{
+  GstElement *src, *csp, *filter, *vscale, *sink;
+  GError *error = NULL;
+
+  if (!camera->preview_caps) {
+    return FALSE;
+  }
+
+  /* Destroy old pipeline, if any */
+  gst_camerabin_preview_destroy_pipeline (camera);
+
+  GST_DEBUG ("creating elements");
+
+  if (!create_element ("appsrc", "prev_src", &src, &error) ||
+      !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;
+
+  camera->preview_pipeline = gst_pipeline_new ("preview-pipeline");
+  if (camera->preview_pipeline == NULL)
+    goto no_pipeline;
+
+  GST_DEBUG ("adding elements");
+  gst_bin_add_many (GST_BIN (camera->preview_pipeline),
+      src, csp, filter, vscale, sink, NULL);
+
+  g_object_set (filter, "caps", camera->preview_caps, NULL);
+  g_object_set (sink, "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 (src, "src", vscale, "sink"))
+    return FALSE;
+
+  GST_DEBUG ("linking vscale->csp");
+  if (!gst_element_link_pads (vscale, "src", csp, "sink"))
+    return FALSE;
+
+  GST_DEBUG ("linking csp->capsfilter");
+  if (!gst_element_link_pads (csp, "src", filter, "sink"))
+    return FALSE;
+
+  GST_DEBUG ("linking capsfilter->sink");
+  if (!gst_element_link_pads (filter, "src", sink, "sink"))
+    return FALSE;
+
+  return TRUE;
+
+  /* ERRORS */
+no_elements:
+  {
+    g_warning ("Could not make preview pipeline: %s", error->message);
+    g_error_free (error);
+    return FALSE;
+  }
+no_pipeline:
+  {
+    g_warning ("Could not make preview pipeline: %s",
+        "no pipeline (unknown error)");
+    return FALSE;
+  }
+}
+
+
+/**
+ * gst_camerabin_preview_destroy_pipeline:
+ * @camera: camerabin object
+ *
+ * Destroy preview converter pipeline.
+ */
+void
+gst_camerabin_preview_destroy_pipeline (GstCameraBin * camera)
+{
+  if (camera->preview_pipeline) {
+    gst_element_set_state (camera->preview_pipeline, GST_STATE_NULL);
+    gst_object_unref (camera->preview_pipeline);
+    camera->preview_pipeline = NULL;
+  }
+}
+
+
+/**
+ * gst_camerabin_preview_convert:
+ * @camera: camerabin object
+ * @buf: #GstBuffer that contains the frame to be converted
+ *
+ * Create a preview image of the given frame.
+ *
+ * Returns: converted preview image, or NULL if operation failed.
+ */
+GstBuffer *
+gst_camerabin_preview_convert (GstCameraBin * camera, GstBuffer * buf)
+{
+  GstMessage *msg;
+  GstBuffer *result = NULL;
+  GError *error = NULL;
+  GstBus *bus;
+  GstElement *src, *sink;
+  GstBufferFlag bflags;
+  GstFlowReturn fret;
+
+  g_return_val_if_fail (GST_BUFFER_CAPS (buf) != NULL, NULL);
+
+  if (camera->preview_pipeline == NULL) {
+    GST_WARNING ("pipeline is NULL");
+    goto no_pipeline;
+  }
+
+  src = gst_bin_get_by_name (GST_BIN (camera->preview_pipeline), "prev_src");
+  sink = gst_bin_get_by_name (GST_BIN (camera->preview_pipeline), "prev_sink");
+
+  if (!src || !sink) {
+    GST_WARNING ("pipeline doesn't have src / sink elements");
+    goto no_pipeline;
+  }
+
+  g_object_set (src, "size", (gint64) GST_BUFFER_SIZE (buf),
+      "blocksize", (guint32) GST_BUFFER_SIZE (buf),
+      "caps", GST_BUFFER_CAPS (buf), "num-buffers", 1, NULL);
+
+  g_signal_connect (sink, "handoff", G_CALLBACK (save_result), &result);
+
+  bflags = GST_BUFFER_FLAGS (buf);
+  GST_BUFFER_FLAG_SET (buf, GST_BUFFER_FLAG_READONLY);
+
+  GST_DEBUG ("running conversion pipeline");
+  gst_element_set_state (camera->preview_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);
+  msg =
+      gst_bus_poll (bus, GST_MESSAGE_ERROR | GST_MESSAGE_EOS, 25 * GST_SECOND);
+
+  if (msg) {
+    switch (GST_MESSAGE_TYPE (msg)) {
+      case GST_MESSAGE_EOS:{
+        if (result) {
+          GST_DEBUG ("preview image successful: result = %p", result);
+        } else {
+          GST_WARNING ("EOS but no result frame?!");
+        }
+        break;
+      }
+      case GST_MESSAGE_ERROR:{
+        gchar *dbg = NULL;
+
+        gst_message_parse_error (msg, &error, &dbg);
+        if (error) {
+          g_warning ("Could not make preview image: %s", error->message);
+          GST_DEBUG ("%s [debug: %s]", error->message, GST_STR_NULL (dbg));
+          g_error_free (error);
+        } else {
+          g_warning ("Could not make preview image (and NULL error!)");
+        }
+        g_free (dbg);
+        result = NULL;
+        break;
+      }
+      default:{
+        g_return_val_if_reached (NULL);
+      }
+    }
+  } else {
+    g_warning ("Could not make preview image: %s", "timeout during conversion");
+    result = NULL;
+  }
+
+  g_signal_handlers_disconnect_by_func (sink, G_CALLBACK (save_result),
+      &result);
+  gst_element_set_state (camera->preview_pipeline, GST_STATE_READY);
+
+  GST_BUFFER_FLAGS (buf) = bflags;
+
+  return result;
+
+  /* ERRORS */
+no_pipeline:
+  {
+    g_warning ("Could not make preview image: %s",
+        "no pipeline (unknown error)");
+    return NULL;
+  }
+}