select: new filter to drop frames based on offset and skip

Motivation was to select only odd or even frames.

gst/CMakeLists.txt

@@ -4,4 +4,5 @@ endif (OPENCV_FOUND)
 
 add_subdirectory (extractcolor)
 add_subdirectory (misb)
+add_subdirectory (select)
 add_subdirectory (videoadjust)

gst/select/CMakeLists.txt

@@ -0,0 +1,28 @@
+set (SOURCES
+  gstselect.c
+  )
+
+set (HEADERS
+  gstselect.h)
+
+include_directories (AFTER
+  ${ORC_INCLUDE_DIR})
+
+set (libname libgstselect)
+
+add_library (${libname} MODULE
+  ${SOURCES}
+  ${HEADERS})
+
+target_link_libraries (${libname}
+  ${ORC_LIBRARIES}
+  ${GLIB2_LIBRARIES}
+  ${GOBJECT_LIBRARIES}
+  ${GSTREAMER_LIBRARY}
+  ${GSTREAMER_BASE_LIBRARY}
+  ${GSTREAMER_VIDEO_LIBRARY})
+
+set (pdbfile "${CMAKE_CURRENT_BINARY_DIR}/\${CMAKE_INSTALL_CONFIG_NAME}/${libname}.pdb")
+install (FILES ${pdbfile} DESTINATION lib/gstreamer-1.0 COMPONENT pdb)
+install(TARGETS ${libname}
+  LIBRARY DESTINATION lib/gstreamer-1.0)

gst/select/gstselect.c

@@ -0,0 +1,265 @@
+/* GStreamer
+ * Copyright (C) <1999> Erik Walthinsen <[email protected]>
+ * Copyright (C) <2003> David Schleef <[email protected]>
+ * Copyright (C) 2003 Arwed v. Merkatz <[email protected]>
+ * Copyright (C) 2006 Mark Nauwelaerts <[email protected]>
+ * Copyright (C) 2015 United States Government, Joshua M. Doe <[email protected]>
+ *
+ * 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.
+ */
+
+/**
+* SECTION:element-select
+*
+* Selects buffers from offset and skip.
+*
+* <refsect2>
+* <title>Example launch line</title>
+* |[
+* gst-launch videotestsrc ! select ! autovideosink
+* ]|
+* </refsect2>
+*/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "gstselect.h"
+
+enum
+{
+  PROP_0,
+  PROP_OFFSET,
+  PROP_SKIP,
+  PROP_LAST
+};
+
+#define DEFAULT_PROP_OFFSET 0
+#define DEFAULT_PROP_SKIP 0
+
+/* the capabilities of the inputs and outputs */
+static GstStaticPadTemplate gst_select_sink_template =
+GST_STATIC_PAD_TEMPLATE ("sink",
+    GST_PAD_SINK,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS ("ANY")
+    );
+
+static GstStaticPadTemplate gst_select_src_template =
+GST_STATIC_PAD_TEMPLATE ("src",
+    GST_PAD_SRC,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS ("ANY")
+    );
+
+
+/* GObject vmethod declarations */
+static void gst_select_set_property (GObject * object, guint prop_id,
+    const GValue * value, GParamSpec * pspec);
+static void gst_select_get_property (GObject * object, guint prop_id,
+    GValue * value, GParamSpec * pspec);
+static void gst_select_dispose (GObject * object);
+
+/* GstBaseTransform vmethod declarations */
+static GstFlowReturn gst_select_transform_ip (GstBaseTransform * trans,
+    GstBuffer * buf);
+
+/* GstSelect method declarations */
+static void gst_select_reset (GstSelect * filter);
+
+/* setup debug */
+GST_DEBUG_CATEGORY_STATIC (select_debug);
+#define GST_CAT_DEFAULT select_debug
+
+G_DEFINE_TYPE (GstSelect, gst_select, GST_TYPE_BASE_TRANSFORM);
+
+/************************************************************************/
+/* GObject vmethod implementations                                      */
+/************************************************************************/
+
+/**
+ * gst_select_dispose:
+ * @object: #GObject.
+ *
+ */
+static void
+gst_select_dispose (GObject * object)
+{
+  GstSelect *select = GST_SELECT (object);
+
+  GST_DEBUG ("dispose");
+
+  gst_select_reset (select);
+
+  /* chain up to the parent class */
+  G_OBJECT_CLASS (gst_select_parent_class)->dispose (object);
+}
+
+/**
+ * gst_select_class_init:
+ * @object: #GstSelectClass.
+ *
+ */
+static void
+gst_select_class_init (GstSelectClass * klass)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+  GstElementClass *gstelement_class = GST_ELEMENT_CLASS (klass);
+  GstBaseTransformClass *gstbasetransform_class =
+      GST_BASE_TRANSFORM_CLASS (klass);
+
+  GST_DEBUG_CATEGORY_INIT (select_debug, "select", 0, "Video Levels Filter");
+
+  GST_DEBUG ("class init");
+
+  /* Register GObject vmethods */
+  gobject_class->dispose = GST_DEBUG_FUNCPTR (gst_select_dispose);
+  gobject_class->set_property = GST_DEBUG_FUNCPTR (gst_select_set_property);
+  gobject_class->get_property = GST_DEBUG_FUNCPTR (gst_select_get_property);
+
+  /* Install GObject properties */
+  g_object_class_install_property (gobject_class, PROP_OFFSET,
+      g_param_spec_int ("offset", "Buffer offset",
+          "First buffer offset to pass", 0, G_MAXINT, DEFAULT_PROP_OFFSET,
+          G_PARAM_STATIC_STRINGS | G_PARAM_READWRITE |
+          GST_PARAM_MUTABLE_PLAYING));
+  g_object_class_install_property (gobject_class, PROP_SKIP,
+      g_param_spec_int ("skip", "Buffers to skip", "Number of buffers to skip",
+          0, G_MAXINT, DEFAULT_PROP_OFFSET,
+          G_PARAM_STATIC_STRINGS | G_PARAM_READWRITE |
+          GST_PARAM_MUTABLE_PLAYING));
+
+  gst_element_class_add_pad_template (gstelement_class,
+      gst_static_pad_template_get (&gst_select_sink_template));
+  gst_element_class_add_pad_template (gstelement_class,
+      gst_static_pad_template_get (&gst_select_src_template));
+
+  gst_element_class_set_static_metadata (gstelement_class,
+      "Select buffer filter", "Filter/Effect",
+      "Selects buffers based on buffer offset",
+      "Joshua M. Doe <[email protected]>");
+
+  /* Register GstBaseTransform vmethods */
+  gstbasetransform_class->transform_ip =
+      GST_DEBUG_FUNCPTR (gst_select_transform_ip);
+}
+
+static void
+gst_select_init (GstSelect * trans)
+{
+  GST_DEBUG_OBJECT (trans, "init class instance");
+
+  trans->offset = DEFAULT_PROP_OFFSET;
+  trans->skip = DEFAULT_PROP_SKIP;
+
+  gst_base_transform_set_in_place (GST_BASE_TRANSFORM (trans), TRUE);
+
+  gst_select_reset (trans);
+}
+
+static void
+gst_select_set_property (GObject * object, guint prop_id,
+    const GValue * value, GParamSpec * pspec)
+{
+  GstSelect *filt = GST_SELECT (object);
+
+  GST_DEBUG_OBJECT (filt, "setting property %s", pspec->name);
+
+  switch (prop_id) {
+    case PROP_OFFSET:
+      filt->offset = g_value_get_int (value);
+      break;
+    case PROP_SKIP:
+      filt->skip = g_value_get_int (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static void
+gst_select_get_property (GObject * object, guint prop_id, GValue * value,
+    GParamSpec * pspec)
+{
+  GstSelect *filt = GST_SELECT (object);
+
+  GST_DEBUG_OBJECT (filt, "getting property %s", pspec->name);
+
+  switch (prop_id) {
+    case PROP_OFFSET:
+      g_value_set_int (value, filt->offset);
+      break;
+    case PROP_SKIP:
+      g_value_set_int (value, filt->skip);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static GstFlowReturn
+gst_select_transform_ip (GstBaseTransform * trans, GstBuffer * buf)
+{
+  GstSelect *filt = GST_SELECT (trans);
+  guint64 buf_offset = GST_BUFFER_OFFSET (buf);
+
+  if (buf_offset < filt->offset) {
+    GST_LOG_OBJECT (filt,
+        "Dropping buffer %d since it's before the chosen offset %d",
+        buf_offset, filt->offset);
+    return GST_BASE_TRANSFORM_FLOW_DROPPED;
+  }
+
+  if ((filt->offset - buf_offset) % (filt->skip + 1)) {
+    GST_LOG_OBJECT (filt,
+        "Dropping buffer %d since it's been chosen to be skipped", buf_offset);
+    return GST_BASE_TRANSFORM_FLOW_DROPPED;
+  }
+
+  return GST_FLOW_OK;
+}
+
+
+static void
+gst_select_reset (GstSelect * filt)
+{
+}
+
+static gboolean
+plugin_init (GstPlugin * plugin)
+{
+  GST_DEBUG_CATEGORY_INIT (GST_CAT_DEFAULT, "select", 0, "select");
+
+  GST_DEBUG ("plugin_init");
+
+  GST_CAT_INFO (GST_CAT_DEFAULT, "registering select element");
+
+  if (!gst_element_register (plugin, "select", GST_RANK_NONE, GST_TYPE_SELECT)) {
+    return FALSE;
+  }
+
+  return TRUE;
+}
+
+GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
+    GST_VERSION_MINOR,
+    select,
+    "Filter that selects which buffers to pass",
+    plugin_init, GST_PACKAGE_VERSION, GST_PACKAGE_LICENSE, GST_PACKAGE_NAME,
+    GST_PACKAGE_ORIGIN);

gst/select/gstselect.h

@@ -0,0 +1,71 @@
+/* GStreamer
+ * Copyright (C) <1999> Erik Walthinsen <[email protected]>
+ * Copyright (C) <2003> David Schleef <[email protected]>
+ * Copyright (C) 2003 Arwed v. Merkatz <[email protected]>
+ * Copyright (C) 2006 Mark Nauwelaerts <[email protected]>
+ * Copyright (C) 2015 United States Government, Joshua M. Doe <[email protected]>
+ *
+ * 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.
+ */
+
+
+#ifndef __GST_SELECT_H__
+#define __GST_SELECT_H__
+
+#include <gst/base/gstbasetransform.h>
+
+G_BEGIN_DECLS
+
+#define GST_TYPE_SELECT \
+  (gst_select_get_type())
+#define GST_SELECT(obj) \
+  (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_SELECT,GstSelect))
+#define GST_SELECT_CLASS(klass) \
+  (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_SELECT,GstSelectClass))
+#define GST_IS_SELECT(obj) \
+  (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_SELECT))
+#define GST_IS_SELECT_CLASS(klass) \
+  (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_SELECT))
+
+typedef struct _GstSelect GstSelect;
+typedef struct _GstSelectClass GstSelectClass;
+
+/**
+* GstSelect:
+* @element: the parent element.
+*
+*
+* The opaque GstSelect data structure.
+*/
+struct _GstSelect
+{
+  GstBaseTransform element;
+
+  /* properties */
+  gint offset;
+  gint skip;
+};
+
+struct _GstSelectClass
+{
+  GstBaseTransformClass parent_class;
+};
+
+GType gst_select_get_type(void);
+
+G_END_DECLS
+
+#endif /* __GST_SELECT_H__ */