GST Sample Filter

gstmyfilter.cpp

/**
 * SECTION:element-myfilter
 *
 * FIXME:Describe myfilter here.
 *
 * <refsect2>
 * <title>Example launch line</title>
 * |[
 * gst-launch -v -m fakesrc ! myfilter ! fakesink silent=TRUE
 * ]|
 * </refsect2>
 */

#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#include <gst/gst.h>

#include "gstmyfilter.h"

GST_DEBUG_CATEGORY_STATIC (gst_my_filter_debug);
#define GST_CAT_DEFAULT gst_my_filter_debug

/* Filter signals and args */
enum
{
  /* FILL ME */
  LAST_SIGNAL
};

enum
{
  PROP_0,
  PROP_SILENT
};

/* the capabilities of the inputs and outputs.
 *
 * describe the real formats here.
 */
static GstStaticPadTemplate sink_factory = GST_STATIC_PAD_TEMPLATE ("sink",
    GST_PAD_SINK,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS ("ANY")
    );

static GstStaticPadTemplate src_factory = GST_STATIC_PAD_TEMPLATE ("src",
    GST_PAD_SRC,
    GST_PAD_ALWAYS,
    GST_STATIC_CAPS ("ANY")
    );

static GstStaticPadTemplate src2_factory =
GST_STATIC_PAD_TEMPLATE (
  "src2",
  GST_PAD_SRC,
  GST_PAD_REQUEST,
    GST_STATIC_CAPS (
	  "video/x-raw, "
	  "format=(string)RGB, "
	  "width = (int) [1, 2147483647], "
	  "height = (int)[1, 2147483647], "
	  "framerate = (fraction) [0/1, 2147483647/1]"
	  )
);

#define gst_my_filter_parent_class parent_class
G_DEFINE_TYPE (GstMyFilter, gst_my_filter, GST_TYPE_ELEMENT);

static void gst_my_filter_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec);
static void gst_my_filter_get_property (GObject * object, guint prop_id,
    GValue * value, GParamSpec * pspec);

static gboolean gst_my_filter_sink_event (GstPad * pad, GstObject * parent, GstEvent * event);
static GstFlowReturn gst_my_filter_chain (GstPad * pad, GstObject * parent, GstBuffer * buf);

static gboolean gst_my_filter_src_event (GstPad * pad, GstObject * parent, GstEvent * event);
static gboolean gst_my_filter_query (GstPad *pad, GstObject * parent, GstQuery * query);
static GstPad * gst_my_filter_request_new_pad   (GstElement     *element, GstPadTemplate *templ, const gchar    *name, const GstCaps  *caps);
static void gst_my_filter_release_pad (GstElement *element, GstPad *pad);

/* GObject vmethod implementations */

/* initialize the myfilter's class */
static void
gst_my_filter_class_init (GstMyFilterClass * klass)
{
  GObjectClass *gobject_class;
  GstElementClass *gstelement_class;

  gobject_class = (GObjectClass *) klass;
  gstelement_class = (GstElementClass *) klass;

  gobject_class->set_property = gst_my_filter_set_property;
  gobject_class->get_property = gst_my_filter_get_property;

  g_object_class_install_property (gobject_class, PROP_SILENT,
      g_param_spec_boolean ("silent", "Silent", "Produce verbose output ?",
          FALSE, G_PARAM_READWRITE));

  gst_element_class_set_details_simple(gstelement_class,
    "MyFilter",
    "FIXME:Generic",
    "FIXME:Generic Template Element",
    "HarshAggarwal <<user@hostname.org>>");

  gst_element_class_add_pad_template (gstelement_class,
      gst_static_pad_template_get (&src_factory));
  gst_element_class_add_pad_template (gstelement_class,
      gst_static_pad_template_get (&sink_factory));

  gst_element_class_add_pad_template (gstelement_class,
    gst_static_pad_template_get (&src2_factory));

  gstelement_class->request_new_pad = gst_my_filter_request_new_pad;
  gstelement_class->release_pad = gst_my_filter_release_pad;
}

/* initialize the new element
 * instantiate pads and add them to element
 * set pad calback functions
 * initialize instance structure
 */
static void
gst_my_filter_init (GstMyFilter * filter)
{
  filter->sinkpad = gst_pad_new_from_static_template (&sink_factory, "sink");
  gst_pad_set_event_function (filter->sinkpad,
                              GST_DEBUG_FUNCPTR(gst_my_filter_sink_event));
  gst_pad_set_chain_function (filter->sinkpad,
                              GST_DEBUG_FUNCPTR(gst_my_filter_chain));
  GST_PAD_SET_PROXY_CAPS (filter->sinkpad);
  gst_element_add_pad (GST_ELEMENT (filter), filter->sinkpad);

  filter->srcpad = gst_pad_new_from_static_template (&src_factory, "src");
  GST_PAD_SET_PROXY_CAPS (filter->srcpad);
  gst_element_add_pad (GST_ELEMENT (filter), filter->srcpad);

  filter->silent = FALSE;
}

static void
gst_my_filter_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec)
{
  GstMyFilter *filter = GST_MYFILTER (object);

  switch (prop_id) {
    case PROP_SILENT:
      filter->silent = g_value_get_boolean (value);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_my_filter_get_property (GObject * object, guint prop_id,
    GValue * value, GParamSpec * pspec)
{
  GstMyFilter *filter = GST_MYFILTER (object);

  switch (prop_id) {
    case PROP_SILENT:
      g_value_set_boolean (value, filter->silent);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static GstPad *
gst_my_filter_request_new_pad (GstElement     *element,
                   GstPadTemplate *templ,
                   const gchar    *name,
                               const GstCaps  *caps)
{
  GstMyFilter *filter = GST_MYFILTER (element);
  GstMyFilterInputContext *context;

  context = g_new0 (GstMyFilterInputContext, 1);
  context->width = 100;
  context->height = 100;
  context->bpp = 4;

  filter->src2pad = gst_pad_new_from_static_template  (&src2_factory, "src2");

//  GST_PAD_SET_PROXY_CAPS (filter->src2pad);
//  gst_pad_use_fixed_caps(filter->src2pad);//use_fixed_caps

  gst_pad_set_element_private (filter->src2pad, context);

  gst_pad_set_event_function (filter->src2pad,
                              GST_DEBUG_FUNCPTR(gst_my_filter_src_event));
  gst_pad_set_query_function (filter->src2pad, 
		  		GST_DEBUG_FUNCPTR(gst_my_filter_query));
  gst_element_add_pad (element, filter->src2pad);

  return filter->src2pad;
}

static void
gst_my_filter_release_pad (GstElement *element,
                           GstPad *pad)
{
  GstMyFilterInputContext *context;

  g_print("%s:%d --------------- \n", __func__, __LINE__);
  context = gst_pad_get_element_private (pad);
  g_free (context);

  gst_element_remove_pad (element, pad);
}

/* GstElement vmethod implementations */

/* this function handles sink events */
static gboolean
gst_my_filter_sink_event (GstPad * pad, GstObject * parent, GstEvent * event)
{
  GstMyFilter *filter;
  gboolean ret;

  filter = GST_MYFILTER (parent);

  GST_LOG_OBJECT (filter, "Received %s event: %" GST_PTR_FORMAT,
      GST_EVENT_TYPE_NAME (event), event);

  switch (GST_EVENT_TYPE (event)) {
    case GST_EVENT_CAPS:
    {
      GstCaps * caps;

      gst_event_parse_caps (event, &caps);
      /* do something with the caps */

      /* and forward */
      ret = gst_pad_event_default (pad, parent, event);
      break;
    }
    default:
      ret = gst_pad_event_default (pad, parent, event);
      break;
  }
  return ret;
}

/* chain function
 * this function does the actual processing
 */
static GstFlowReturn
gst_my_filter_chain (GstPad * pad, GstObject * parent, GstBuffer * buf)
{
  GstMyFilter *filter;
  GstFlowReturn ret;
  GstBuffer *buffer;
  guint size;

  filter = GST_MYFILTER (parent);

  if (filter->silent == FALSE)
    g_print ("I'm plugged, therefore I'm in.\n");

  ret = gst_pad_push (filter->srcpad, buf);

  if (filter->src2pad) {
#if 1
  GstMyFilterInputContext *context;
	  context = gst_pad_get_element_private (filter->src2pad);
	  GST_DEBUG_OBJECT (filter->src2pad, "push hello");


	  GstCaps *outcaps;
	  outcaps = gst_caps_new_simple ("video/x-raw",
			  "format", G_TYPE_STRING, "RGB",
			  "width", G_TYPE_INT, 300,
			  "height", G_TYPE_INT, 300, 
			  "framerate", GST_TYPE_FRACTION, 24, 1, NULL);
	  ret = gst_pad_set_caps (filter->src2pad, outcaps);




	  ret = gst_pad_push (filter->src2pad, gst_buffer_ref(buf));
          size = context->width * context->height * context->bpp;
	  buffer = gst_buffer_new_and_alloc (size);

	  ret = gst_pad_push (filter->src2pad, buffer);
#else

	  ret = gst_pad_push (filter->src2pad, gst_buffer_ref(buf));
#endif
  }
  /* just push out the incoming buffer without touching it */
  return  ret;
}

/* Functions below print the Capabilities in a human-friendly format */
static gboolean
print_field (GQuark field, const GValue * value, gpointer pfx)
{
  gchar *str = gst_value_serialize (value);

  g_print ("  %15s: %s\n", g_quark_to_string (field), str);
  g_free (str);
  return TRUE;
}

static gboolean
gst_my_filter_setcaps (GstMyFilter *filter,
               GstCaps *caps)
{
  GstStructure *structure;
  int width, height;
  gboolean ret;
  GstCaps *outcaps;

#if 0
  g_print("%s:%d --SET        CAPS------------- \n", __func__, __LINE__);
  structure = gst_caps_get_structure (caps, 0);
  ret = gst_structure_get_int (structure, "width", &width);
  ret = ret && gst_structure_get_int (structure, "height", &height);
  if (!ret) {
	  GST_LOG_OBJECT (filter, "Hello error ----------<<<<< \n");
	  return FALSE;
  }

#endif
  outcaps = gst_caps_new_simple ("video/x-raw",
      "format", G_TYPE_STRING, "RGB",
      "width", G_TYPE_INT, 300,
      "height", G_TYPE_INT, 300, 
      "framerate", GST_TYPE_FRACTION, 24, 1, NULL);
  ret = gst_pad_set_caps (filter->src2pad, outcaps);
  gst_caps_unref (outcaps);

  return ret;
}

static gboolean
gst_my_filter_query (GstPad *pad, GstObject * parent, GstQuery * query)
{
  gboolean ret;
  GstMyFilter *filter = GST_MYFILTER (parent);


  switch (GST_QUERY_TYPE (query)) {
    case GST_QUERY_CAPS:
    {
  g_print("%s:%d --------------- \n", __func__, __LINE__);
#if 0
      GstPad *otherpad;
      GstCaps *temp, *caps, *filt, *tcaps;
      gint i;

      otherpad = (pad == filter->srcpad) ? filter->sinkpad :
                                           filter->srcpad;
      caps = gst_pad_get_allowed_caps (otherpad);

      gst_query_parse_caps (query, &filt);

      /* We support *any* samplerate, indifferent from the samplerate
       * supported by the linked elements on both sides. */
      for (i = 0; i < gst_caps_get_size (caps); i++) {
        GstStructure *structure = gst_caps_get_structure (caps, i);

        gst_structure_remove_field (structure, "rate");
      }

      /* make sure we only return results that intersect our
       * padtemplate */
      tcaps = gst_pad_get_pad_template_caps (pad);
      if (tcaps) {
        temp = gst_caps_intersect (caps, tcaps);
        gst_caps_unref (caps);
        gst_caps_unref (tcaps);
        caps = temp;
      }
      /* filter against the query filter when needed */
      if (filt) {
        temp = gst_caps_intersect (caps, filt);
        gst_caps_unref (caps);
        caps = temp;
      }
      gst_query_set_caps_result (query, caps);
      gst_caps_unref (caps);

#else

  GstCaps *outcaps;
  outcaps = gst_caps_new_simple ("video/x-raw",
		  "width", G_TYPE_INT, 300,
		  "height", G_TYPE_INT, 300,
		  "format", G_TYPE_STRING, "RGB",
		  "framerate", GST_TYPE_FRACTION, 24, 1, NULL);

  if (!gst_pad_set_caps (filter->src2pad, outcaps)) {
	  GST_ELEMENT_ERROR (filter, CORE, NEGOTIATION, (NULL),
			  ("Some debug information here"));
  }

  gst_caps_unref(outcaps);
#endif
      ret = TRUE;
      break;
    }
    default:
      ret = gst_pad_query_default (pad, parent, query);
      break;
  }
  return ret;
}

/* this function handles sink events */
static gboolean
gst_my_filter_src_event (GstPad * pad, GstObject * parent, GstEvent * event)
{
  GstMyFilter *filter;
  gboolean ret;

  filter = GST_MYFILTER (parent);

  g_print("==EVENT===============>>> %s:%d --------------- \n", __func__, __LINE__);
  GST_LOG_OBJECT (filter, "Received %s event: %" GST_PTR_FORMAT,
      GST_EVENT_TYPE_NAME (event), event);

  switch (GST_EVENT_TYPE (event)) {
    case GST_EVENT_CAPS:
    {
      GstCaps * caps;

      gst_event_parse_caps (event, &caps);
      /* do something with the caps */
#if 0
      GstStructure *structure = gst_caps_get_structure(caps, 0);
      g_assert(structure);
      g_print ("%s\n", gst_structure_get_name (structure));
      gst_structure_foreach (structure, print_field, (gpointer) NULL);

 //     const gchar *format = gst_structure_get_string(structure, "format");
//#else

       ret = gst_my_filter_setcaps (filter, caps);
#endif

      /* and forward */
      ret = gst_pad_event_default (pad, parent, event);
      break;
    }
    default:
      ret = gst_pad_event_default (pad, parent, event);
      break;
  }
  return ret;
}

/* entry point to initialize the plug-in
 * initialize the plug-in itself
 * register the element factories and other features
 */
static gboolean
myfilter_init (GstPlugin * myfilter)
{
  /* debug category for fltering log messages
   *
   * exchange the string 'Template myfilter' with your description
   */
  GST_DEBUG_CATEGORY_INIT (gst_my_filter_debug, "myfilter",
      0, "Template myfilter");

  return gst_element_register (myfilter, "myfilter", GST_RANK_NONE,
      GST_TYPE_MYFILTER);
}

/* PACKAGE: this is usually set by autotools depending on some _INIT macro
 * in configure.ac and then written into and defined in config.h, but we can
 * just set it ourselves here in case someone doesn't use autotools to
 * compile this code. GST_PLUGIN_DEFINE needs PACKAGE to be defined.
 */
#ifndef PACKAGE
#define PACKAGE "myfirstmyfilter"
#endif

/* gstreamer looks for this structure to register myfilters
 *
 * exchange the string 'Template myfilter' with your myfilter description
 */
GST_PLUGIN_DEFINE (
    GST_VERSION_MAJOR,
    GST_VERSION_MINOR,
    myfilter,
    "Template myfilter",
    myfilter_init,
    PACKAGE_VERSION,
    GST_LICENSE,
    GST_PACKAGE_NAME,
    GST_PACKAGE_ORIGIN
)