From: Filippo Argiolas <filippo.argiolas@gmail.com>
Date: Mon, 11 Aug 2008 07:52:16 +0000 (+0200)
Subject: [143/906] Add init and reset callbacks in GstGLFilter to run arbitrary gl code at... 
X-Git-Tag: 1.19.3~507^2~12389
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=b0f30ff1251b1896fbd65804c7e608da9bae63c5;p=platform%2Fupstream%2Fgstreamer.git

[143/906] Add init and reset callbacks in GstGLFilter to run arbitrary gl code at start and stop. Useful to init and cleanup custom gl resources.
---

diff --git a/gst-libs/gst/gl/gstgldisplay.c b/gst-libs/gst/gl/gstgldisplay.c
index c3d433c..6cf6323 100644
--- a/gst-libs/gst/gl/gstgldisplay.c
+++ b/gst-libs/gst/gl/gstgldisplay.c
@@ -1,6 +1,7 @@
 /*
  * GStreamer
  * Copyright (C) 2008 Julien Isorce <julien.isorce@gmail.com>
+ * Copyright (C) 2008 Filippo Argiolas <filippo.argiolas@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
diff --git a/gst-libs/gst/gl/gstgldisplay.h b/gst-libs/gst/gl/gstgldisplay.h
index 1ff3dbb..d4aa82d 100644
--- a/gst-libs/gst/gl/gstgldisplay.h
+++ b/gst-libs/gst/gl/gstgldisplay.h
@@ -1,6 +1,7 @@
 /* 
  * GStreamer
  * Copyright (C) 2008 Julien Isorce <julien.isorce@gmail.com>
+ * Copyright (C) 2008 Filippo Argiolas <filippo.argiolas@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
diff --git a/gst-libs/gst/gl/gstglfilter.c b/gst-libs/gst/gl/gstglfilter.c
index 1d753af..fa61126 100644
--- a/gst-libs/gst/gl/gstglfilter.c
+++ b/gst-libs/gst/gl/gstglfilter.c
@@ -1,6 +1,7 @@
 /* 
  * GStreamer
  * Copyright (C) 2008 Julien Isorce <julien.isorce@gmail.com>
+ * Copyright (C) 2008 Filippo Argiolas <filippo.argiolas@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ -29,45 +30,48 @@ GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);
 
 
 static GstStaticPadTemplate gst_gl_filter_src_pad_template =
-GST_STATIC_PAD_TEMPLATE ("src",
-    GST_PAD_SRC,
-    GST_PAD_ALWAYS,
-    GST_STATIC_CAPS (GST_GL_VIDEO_CAPS)
+  GST_STATIC_PAD_TEMPLATE ("src",
+			   GST_PAD_SRC,
+			   GST_PAD_ALWAYS,
+			   GST_STATIC_CAPS (GST_GL_VIDEO_CAPS)
     );
 
 static GstStaticPadTemplate gst_gl_filter_sink_pad_template =
-GST_STATIC_PAD_TEMPLATE ("sink",
-    GST_PAD_SINK,
-    GST_PAD_ALWAYS,
-    GST_STATIC_CAPS (GST_GL_VIDEO_CAPS)
+  GST_STATIC_PAD_TEMPLATE ("sink",
+			   GST_PAD_SINK,
+			   GST_PAD_ALWAYS,
+			   GST_STATIC_CAPS (GST_GL_VIDEO_CAPS)
     );
 
-#define DEBUG_INIT(bla) \
+#define DEBUG_INIT(bla)							\
   GST_DEBUG_CATEGORY_INIT (gst_gl_filter_debug, "glfilter", 0, "glfilter element");
 
 GST_BOILERPLATE_FULL (GstGLFilter, gst_gl_filter, GstBaseTransform,
-    GST_TYPE_BASE_TRANSFORM, DEBUG_INIT);
+		      GST_TYPE_BASE_TRANSFORM, DEBUG_INIT);
 
 static void gst_gl_filter_set_property (GObject * object, guint prop_id,
-    const GValue * value, GParamSpec * pspec);
+					const GValue * value, GParamSpec * pspec);
 static void gst_gl_filter_get_property (GObject * object, guint prop_id,
-    GValue * value, GParamSpec * pspec);
+					GValue * value, GParamSpec * pspec);
 
 static GstCaps* gst_gl_filter_transform_caps (GstBaseTransform* bt,
-    GstPadDirection direction, GstCaps* caps);
+					      GstPadDirection direction, GstCaps* caps);
 static void gst_gl_filter_reset (GstGLFilter * filter);
 static gboolean gst_gl_filter_start (GstBaseTransform * bt);
 static gboolean gst_gl_filter_stop (GstBaseTransform * bt);
 static gboolean gst_gl_filter_get_unit_size (GstBaseTransform * trans,
-    GstCaps * caps, guint * size);
+					     GstCaps * caps, guint * size);
 static GstFlowReturn gst_gl_filter_transform (GstBaseTransform * bt,
-    GstBuffer * inbuf, GstBuffer * outbuf);
+					      GstBuffer * inbuf, GstBuffer * outbuf);
 static GstFlowReturn gst_gl_filter_prepare_output_buffer (GstBaseTransform *
-    trans, GstBuffer * input, gint size, GstCaps * caps, GstBuffer ** buf);
+							  trans, GstBuffer * input, gint size, GstCaps * caps, GstBuffer ** buf);
 static gboolean gst_gl_filter_set_caps (GstBaseTransform * bt, GstCaps * incaps,
-    GstCaps * outcaps);
+					GstCaps * outcaps);
 static gboolean gst_gl_filter_do_transform (GstGLFilter * filter,
-    GstGLBuffer * inbuf, GstGLBuffer * outbuf);
+					    GstGLBuffer * inbuf, GstGLBuffer * outbuf);
+/* GstGLDisplayThreadFunc */
+static void gst_gl_filter_start_gl (GstGLDisplay *display, gpointer data);
+static void gst_gl_filter_stop_gl (GstGLDisplay *display, gpointer data);
 
 
 static void
@@ -76,244 +80,271 @@ gst_gl_filter_base_init (gpointer klass)
   GstElementClass *element_class = GST_ELEMENT_CLASS (klass);
 
   gst_element_class_add_pad_template (element_class,
-      gst_static_pad_template_get (&gst_gl_filter_src_pad_template));
+				      gst_static_pad_template_get (&gst_gl_filter_src_pad_template));
   gst_element_class_add_pad_template (element_class,
-      gst_static_pad_template_get (&gst_gl_filter_sink_pad_template));
+				      gst_static_pad_template_get (&gst_gl_filter_sink_pad_template));
 }
 
 static void
 gst_gl_filter_class_init (GstGLFilterClass * klass)
 {
-    GObjectClass *gobject_class;
-
-    gobject_class = (GObjectClass *) klass;
-    gobject_class->set_property = gst_gl_filter_set_property;
-    gobject_class->get_property = gst_gl_filter_get_property;
-
-    GST_BASE_TRANSFORM_CLASS (klass)->transform_caps =
-        gst_gl_filter_transform_caps;
-    GST_BASE_TRANSFORM_CLASS (klass)->transform = gst_gl_filter_transform;
-    GST_BASE_TRANSFORM_CLASS (klass)->start = gst_gl_filter_start;
-    GST_BASE_TRANSFORM_CLASS (klass)->stop = gst_gl_filter_stop;
-    GST_BASE_TRANSFORM_CLASS (klass)->set_caps = gst_gl_filter_set_caps;
-    GST_BASE_TRANSFORM_CLASS (klass)->get_unit_size = gst_gl_filter_get_unit_size;
-    GST_BASE_TRANSFORM_CLASS (klass)->prepare_output_buffer =
-      gst_gl_filter_prepare_output_buffer;
-
-    klass->set_caps = NULL;
-    klass->filter = NULL;
-    klass->onInitFBO = NULL;
-    klass->onReset = NULL;
+  GObjectClass *gobject_class;
+
+  gobject_class = (GObjectClass *) klass;
+  gobject_class->set_property = gst_gl_filter_set_property;
+  gobject_class->get_property = gst_gl_filter_get_property;
+
+  GST_BASE_TRANSFORM_CLASS (klass)->transform_caps =
+    gst_gl_filter_transform_caps;
+  GST_BASE_TRANSFORM_CLASS (klass)->transform = gst_gl_filter_transform;
+  GST_BASE_TRANSFORM_CLASS (klass)->start = gst_gl_filter_start;
+  GST_BASE_TRANSFORM_CLASS (klass)->stop = gst_gl_filter_stop;
+  GST_BASE_TRANSFORM_CLASS (klass)->set_caps = gst_gl_filter_set_caps;
+  GST_BASE_TRANSFORM_CLASS (klass)->get_unit_size = gst_gl_filter_get_unit_size;
+  GST_BASE_TRANSFORM_CLASS (klass)->prepare_output_buffer =
+    gst_gl_filter_prepare_output_buffer;
+
+  klass->set_caps = NULL;
+  klass->filter = NULL;
+  klass->display_init_cb = NULL;
+  klass->display_reset_cb = NULL;
+  klass->onInitFBO = NULL;
+  klass->onReset = NULL;
 }
 
 static void
 gst_gl_filter_init (GstGLFilter * filter, GstGLFilterClass * klass)
 {
-    //gst_element_create_all_pads (GST_ELEMENT (filter));
+  //gst_element_create_all_pads (GST_ELEMENT (filter));
 
-    filter->sinkpad = gst_element_get_static_pad (GST_ELEMENT (filter), "sink");
-    filter->srcpad = gst_element_get_static_pad (GST_ELEMENT (filter), "src");
+  filter->sinkpad = gst_element_get_static_pad (GST_ELEMENT (filter), "sink");
+  filter->srcpad = gst_element_get_static_pad (GST_ELEMENT (filter), "src");
 
-    gst_gl_filter_reset (filter);
+  gst_gl_filter_reset (filter);
 }
 
 static void
 gst_gl_filter_set_property (GObject * object, guint prop_id,
-    const GValue * value, GParamSpec * pspec)
+			    const GValue * value, GParamSpec * pspec)
 {
-    //GstGLFilter *filter = GST_GL_FILTER (object);
-
-    switch (prop_id) 
-    {
-        default:
-            G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
-            break;
-    }
+  //GstGLFilter *filter = GST_GL_FILTER (object);
+
+  switch (prop_id) 
+  {
+  default:
+    G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    break;
+  }
 }
 
 static void
 gst_gl_filter_get_property (GObject * object, guint prop_id,
-    GValue * value, GParamSpec * pspec)
+			    GValue * value, GParamSpec * pspec)
 {
-    //GstGLFilter *filter = GST_GL_FILTER (object);
-
-    switch (prop_id) 
-    {
-        default:
-            G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
-            break;
-    }
+  //GstGLFilter *filter = GST_GL_FILTER (object);
+
+  switch (prop_id) 
+  {
+  default:
+    G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    break;
+  }
 }
 
 static void
 gst_gl_filter_reset (GstGLFilter* filter)
 {
-    GstGLFilterClass* filter_class = GST_GL_FILTER_GET_CLASS (filter);
+  GstGLFilterClass* filter_class = GST_GL_FILTER_GET_CLASS (filter);
     
-    if (filter_class->onReset)
-        filter_class->onReset (filter);
+  if (filter_class->onReset)
+    filter_class->onReset (filter);
     
-    if (filter->display) 
-    {
-        //blocking call, delete the FBO
-        gst_gl_display_del_fbo (filter->display, filter->fbo, 
-            filter->depthbuffer);
-        g_object_unref (filter->display);
-        filter->display = NULL;
+  if (filter->display) 
+  {
+    if (filter_class->display_reset_cb != NULL) {
+      gst_gl_display_thread_add (filter->display, gst_gl_filter_stop_gl, filter);
     }
-    filter->width = 0;
-    filter->height = 0;
-    filter->fbo = 0;
-    filter->depthbuffer = 0;
+    //blocking call, delete the FBO
+    gst_gl_display_del_fbo (filter->display, filter->fbo, 
+			    filter->depthbuffer);
+    g_object_unref (filter->display);
+    filter->display = NULL;
+  }
+  filter->width = 0;
+  filter->height = 0;
+  filter->fbo = 0;
+  filter->depthbuffer = 0;
 }
 
 static gboolean
 gst_gl_filter_start (GstBaseTransform* bt)
 {
-    return TRUE;
+  return TRUE;
 }
 
 static gboolean
 gst_gl_filter_stop (GstBaseTransform* bt)
 {
-    GstGLFilter *filter = GST_GL_FILTER (bt);
+  GstGLFilter *filter = GST_GL_FILTER (bt);
+
+  gst_gl_filter_reset (filter);
 
-    gst_gl_filter_reset (filter);
+  return TRUE;
+}
+
+static void
+gst_gl_filter_start_gl (GstGLDisplay *display, gpointer data)
+{
+  GstGLFilter *filter = GST_GL_FILTER (data);
+  GstGLFilterClass *filter_class = GST_GL_FILTER_GET_CLASS (filter);
+  
+  filter_class->display_init_cb (filter);
+}
 
-    return TRUE;
+static void
+gst_gl_filter_stop_gl (GstGLDisplay *display, gpointer data)
+{
+  GstGLFilter *filter = GST_GL_FILTER (data);
+  GstGLFilterClass *filter_class = GST_GL_FILTER_GET_CLASS (filter);
+  
+  filter_class->display_reset_cb (filter);
 }
 
 static GstCaps*
 gst_gl_filter_transform_caps (GstBaseTransform* bt,
-    GstPadDirection direction, GstCaps* caps)
+			      GstPadDirection direction, GstCaps* caps)
 {
-    //GstGLFilter* filter = GST_GL_FILTER (bt);
-    GstStructure* structure = gst_caps_get_structure (caps, 0);
-    GstCaps* ret = gst_caps_copy (caps);
-    const GValue* par = NULL;
+  //GstGLFilter* filter = GST_GL_FILTER (bt);
+  GstStructure* structure = gst_caps_get_structure (caps, 0);
+  GstCaps* ret = gst_caps_copy (caps);
+  const GValue* par = NULL;
 
-    structure = gst_structure_copy (gst_caps_get_structure (ret, 0));
+  structure = gst_structure_copy (gst_caps_get_structure (ret, 0));
 
-    gst_structure_set (structure,
-        "width", GST_TYPE_INT_RANGE, 1, G_MAXINT,
-        "height", GST_TYPE_INT_RANGE, 1, G_MAXINT, NULL);
+  gst_structure_set (structure,
+		     "width", GST_TYPE_INT_RANGE, 1, G_MAXINT,
+		     "height", GST_TYPE_INT_RANGE, 1, G_MAXINT, NULL);
 
-    gst_caps_merge_structure (ret, gst_structure_copy (structure));
+  gst_caps_merge_structure (ret, gst_structure_copy (structure));
 
-    if ((par = gst_structure_get_value (structure, "pixel-aspect-ratio"))) 
-    {
-        gst_structure_set (structure,
-            "pixel-aspect-ratio", GST_TYPE_FRACTION_RANGE, 0, 1, G_MAXINT, 1, NULL);
-        gst_caps_merge_structure (ret, structure);
-    } 
-    else
-        gst_structure_free (structure);
+  if ((par = gst_structure_get_value (structure, "pixel-aspect-ratio"))) 
+  {
+    gst_structure_set (structure,
+		       "pixel-aspect-ratio", GST_TYPE_FRACTION_RANGE, 0, 1, G_MAXINT, 1, NULL);
+    gst_caps_merge_structure (ret, structure);
+  } 
+  else
+    gst_structure_free (structure);
 
-    GST_DEBUG_OBJECT (bt, "returning caps: %" GST_PTR_FORMAT, ret);
+  GST_DEBUG_OBJECT (bt, "returning caps: %" GST_PTR_FORMAT, ret);
 
-    return ret;
+  return ret;
 }
 
 
 static gboolean
 gst_gl_filter_get_unit_size (GstBaseTransform* trans, GstCaps* caps,
-    guint* size)
+			     guint* size)
 {
-    gboolean ret = FALSE;
-    gint width = 0;
-    gint height = 0;
+  gboolean ret = FALSE;
+  gint width = 0;
+  gint height = 0;
 
-    ret = gst_gl_buffer_parse_caps (caps, &width, &height);
-    if (ret) 
-        *size = gst_gl_buffer_get_size (width, height);
+  ret = gst_gl_buffer_parse_caps (caps, &width, &height);
+  if (ret) 
+    *size = gst_gl_buffer_get_size (width, height);
 
-    return TRUE;
+  return TRUE;
 }
 
 static GstFlowReturn
 gst_gl_filter_prepare_output_buffer (GstBaseTransform* trans,
-    GstBuffer* inbuf, gint size, GstCaps* caps, GstBuffer** buf)
+				     GstBuffer* inbuf, gint size, GstCaps* caps, GstBuffer** buf)
 {
-    GstGLFilter* filter = NULL;
-    GstGLBuffer* gl_inbuf = GST_GL_BUFFER (inbuf);
-    GstGLBuffer* gl_outbuf = NULL;
+  GstGLFilter* filter = NULL;
+  GstGLBuffer* gl_inbuf = GST_GL_BUFFER (inbuf);
+  GstGLBuffer* gl_outbuf = NULL;
 
-    filter = GST_GL_FILTER (trans);
+  filter = GST_GL_FILTER (trans);
 
-    if (filter->display == NULL)
-    {
-        GstGLFilterClass* filter_class = GST_GL_FILTER_GET_CLASS (filter);
+  if (filter->display == NULL)
+  {
+    GstGLFilterClass* filter_class = GST_GL_FILTER_GET_CLASS (filter);
         
-        filter->display = g_object_ref (gl_inbuf->display);
+    filter->display = g_object_ref (gl_inbuf->display);
 
-        //blocking call, generate a FBO
-        gst_gl_display_gen_fbo (filter->display, filter->width, filter->height,
-            &filter->fbo, &filter->depthbuffer);
+    //blocking call, generate a FBO
+    gst_gl_display_gen_fbo (filter->display, filter->width, filter->height,
+			    &filter->fbo, &filter->depthbuffer);
 
-        if (filter_class->onInitFBO)
-            filter_class->onInitFBO (filter);
+    if (filter_class->display_init_cb != NULL) {
+      gst_gl_display_thread_add (filter->display, gst_gl_filter_start_gl, filter);
     }
 
-    gl_outbuf = gst_gl_buffer_new (filter->display,
-            filter->width, filter->height);
+    if (filter_class->onInitFBO)
+      filter_class->onInitFBO (filter);
+  }
+
+  gl_outbuf = gst_gl_buffer_new (filter->display,
+				 filter->width, filter->height);
 
-    *buf = GST_BUFFER (gl_outbuf);
-    gst_buffer_set_caps (*buf, caps);
+  *buf = GST_BUFFER (gl_outbuf);
+  gst_buffer_set_caps (*buf, caps);
 
-    if (gl_outbuf->texture)
-        return GST_FLOW_OK;
-    else
-        return GST_FLOW_UNEXPECTED;
+  if (gl_outbuf->texture)
+    return GST_FLOW_OK;
+  else
+    return GST_FLOW_UNEXPECTED;
 }
 
 static gboolean
 gst_gl_filter_set_caps (GstBaseTransform* bt, GstCaps* incaps,
-    GstCaps* outcaps)
+			GstCaps* outcaps)
 {
-    GstGLFilter* filter = GST_GL_FILTER (bt);
-    gboolean ret = FALSE;
-    GstGLFilterClass* filter_class = GST_GL_FILTER_GET_CLASS (filter);
+  GstGLFilter* filter = GST_GL_FILTER (bt);
+  gboolean ret = FALSE;
+  GstGLFilterClass* filter_class = GST_GL_FILTER_GET_CLASS (filter);
 
-    ret = gst_gl_buffer_parse_caps (outcaps, &filter->width, &filter->height);
+  ret = gst_gl_buffer_parse_caps (outcaps, &filter->width, &filter->height);
 
-    if (filter_class->set_caps)
-        filter_class->set_caps (filter, incaps, outcaps);
+  if (filter_class->set_caps)
+    filter_class->set_caps (filter, incaps, outcaps);
 
-    if (!ret) 
-    {
-        GST_DEBUG ("bad caps");
-        return FALSE;
-    }
+  if (!ret) 
+  {
+    GST_DEBUG ("bad caps");
+    return FALSE;
+  }
 
-    GST_ERROR ("set_caps %d %d", filter->width, filter->height);
+  GST_ERROR ("set_caps %d %d", filter->width, filter->height);
 
-    return ret;
+  return ret;
 }
 
 static GstFlowReturn
 gst_gl_filter_transform (GstBaseTransform* bt, GstBuffer* inbuf,
-    GstBuffer* outbuf)
+			 GstBuffer* outbuf)
 {
-    GstGLFilter* filter;
-    GstGLBuffer* gl_inbuf = GST_GL_BUFFER (inbuf);
-    GstGLBuffer* gl_outbuf = GST_GL_BUFFER (outbuf);
+  GstGLFilter* filter;
+  GstGLBuffer* gl_inbuf = GST_GL_BUFFER (inbuf);
+  GstGLBuffer* gl_outbuf = GST_GL_BUFFER (outbuf);
 
-    filter = GST_GL_FILTER (bt);
+  filter = GST_GL_FILTER (bt);
 
-    gst_gl_filter_do_transform (filter, gl_inbuf, gl_outbuf);
+  gst_gl_filter_do_transform (filter, gl_inbuf, gl_outbuf);
 
-    return GST_FLOW_OK;
+  return GST_FLOW_OK;
 }
 
 static gboolean
 gst_gl_filter_do_transform (GstGLFilter* filter,
-    GstGLBuffer* inbuf, GstGLBuffer* outbuf)
+			    GstGLBuffer* inbuf, GstGLBuffer* outbuf)
 {
-    GstGLFilterClass* filter_class = GST_GL_FILTER_GET_CLASS (filter);
+  GstGLFilterClass* filter_class = GST_GL_FILTER_GET_CLASS (filter);
 
-    filter_class->filter (filter, inbuf, outbuf);
+  filter_class->filter (filter, inbuf, outbuf);
 
-    return TRUE;
+  return TRUE;
 }
 
 /* convenience functions to simplify filter development */
@@ -323,11 +354,11 @@ gst_gl_filter_render_to_target (GstGLFilter *filter,
 				GLuint input, GLuint target,
 				GLCB func, gpointer data)
 {
-     gst_gl_display_use_fbo (filter->display, filter->width, filter->height, 
-			     filter->fbo, filter->depthbuffer, target, 
-			     func, 
-			     filter->width, filter->height, input,
-			     0, filter->width, 0, filter->height,
-			     GST_GL_DISPLAY_PROJECTION_ORTHO2D,
-			     data);
+  gst_gl_display_use_fbo (filter->display, filter->width, filter->height, 
+			  filter->fbo, filter->depthbuffer, target, 
+			  func, 
+			  filter->width, filter->height, input,
+			  0, filter->width, 0, filter->height,
+			  GST_GL_DISPLAY_PROJECTION_ORTHO2D,
+			  data);
 }
diff --git a/gst-libs/gst/gl/gstglfilter.h b/gst-libs/gst/gl/gstglfilter.h
index 1c0286e..f4b85b0 100644
--- a/gst-libs/gst/gl/gstglfilter.h
+++ b/gst-libs/gst/gl/gstglfilter.h
@@ -1,6 +1,7 @@
 /* 
  * GStreamer
  * Copyright (C) 2008 Julien Isorce <julien.isorce@gmail.com>
+ * Copyright (C) 2008 Filippo Argiolas <filippo.argiolas@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ -40,34 +41,42 @@ typedef struct _GstGLFilterClass GstGLFilterClass;
 
 
 typedef gboolean (*GstGLFilterSetCaps) (GstGLFilter* filter, 
-    GstCaps* incaps, GstCaps* outcaps);
+					GstCaps* incaps, GstCaps* outcaps);
 typedef gboolean (*GstGLFilterProcessFunc) (GstGLFilter *filter,
-    GstGLBuffer *inbuf, GstGLBuffer *outbuf);
+					    GstGLBuffer *inbuf, GstGLBuffer *outbuf);
 typedef void (*GstGLFilterOnInitFBO) (GstGLFilter *filter);
 typedef void (*GstGLFilterOnReset) (GstGLFilter *filter);
 
+typedef void (*GstGLFilterGLStartFunc) (GstGLFilter *filter);
+typedef void (*GstGLFilterGLStopFunc) (GstGLFilter *filter);
+
 struct _GstGLFilter
 {
-    GstBaseTransform base_transform;
+  GstBaseTransform base_transform;
 
-    GstPad *srcpad;
-    GstPad *sinkpad;
+  GstPad *srcpad;
+  GstPad *sinkpad;
 
-    GstGLDisplay *display;
+  GstGLDisplay *display;
 
-    gint width;
-    gint height;
-    GLuint fbo;
-    GLuint depthbuffer;
+  gint width;
+  gint height;
+  GLuint fbo;
+  GLuint depthbuffer;
 };
 
 struct _GstGLFilterClass
 {
-    GstBaseTransformClass base_transform_class;
-    GstGLFilterSetCaps set_caps;
-    GstGLFilterProcessFunc filter;
-    GstGLFilterOnInitFBO onInitFBO;
-    GstGLFilterOnReset onReset;
+  GstBaseTransformClass base_transform_class;
+  GstGLFilterSetCaps set_caps;
+  GstGLFilterProcessFunc filter;
+  GstGLFilterOnInitFBO onInitFBO;
+  
+  GstGLFilterOnReset onReset;
+
+  /* useful to init and cleanup custom gl resources */
+  GstGLFilterGLStartFunc display_init_cb; /* run arbitrary gl code at start */
+  GstGLFilterGLStopFunc display_reset_cb; /* run arbitrary gl code at stop */
 };
 
 GType gst_gl_filter_get_type(void);
diff --git a/gst/gl/gstglfilterblur.c b/gst/gl/gstglfilterblur.c
index 8731737..2feb08e 100644
--- a/gst/gl/gstglfilterblur.c
+++ b/gst/gl/gstglfilterblur.c
@@ -94,6 +94,25 @@ static gboolean gst_gl_filterblur_filter (GstGLFilter * filter,
 static void gst_gl_filterblur_hcallback (gint width, gint height, guint texture, gpointer stuff);
 static void gst_gl_filterblur_vcallback (gint width, gint height, guint texture, gpointer stuff);
 
+
+static void 
+gst_gl_filterblur_init_resources (GstGLFilter *filter)
+{
+//  GstGLFilterBlur *filterblur = GST_GL_FILTERBLUR (filter);
+  
+  /* dummy gl call to test if we really are in a  gl context */
+  g_print ("\nStart!!!: %s\n\n", glGetString (GL_VERSION));
+}
+
+static void 
+gst_gl_filterblur_reset_resources (GstGLFilter *filter)
+{
+//  GstGLFilterBlur *filterblur = GST_GL_FILTERBLUR (filter);
+
+  /* dummy gl call to test if we really are in a  gl context */
+  g_print ("\nStop!!!: %s\n\n", glGetString (GL_VENDOR)); 
+}
+
 static void
 gst_gl_filterblur_base_init (gpointer klass)
 {
@@ -112,6 +131,8 @@ gst_gl_filterblur_class_init (GstGLFilterBlurClass * klass)
   gobject_class->get_property = gst_gl_filterblur_get_property;
 
   GST_GL_FILTER_CLASS (klass)->filter = gst_gl_filterblur_filter;
+  GST_GL_FILTER_CLASS (klass)->display_init_cb = gst_gl_filterblur_init_resources;
+  GST_GL_FILTER_CLASS (klass)->display_reset_cb = gst_gl_filterblur_reset_resources;
   GST_GL_FILTER_CLASS (klass)->onInitFBO = gst_gl_filterblur_init_shader;
   GST_GL_FILTER_CLASS (klass)->onReset = gst_gl_filter_filterblur_reset;
 }