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 ("ANY")
);

#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 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);
  filter->src2pad = gst_pad_new_from_template (templ, name);

  gst_pad_set_element_private (filter->src2pad, context);

  g_print("%s:%d --------------- \n", __func__, __LINE__);
  gst_pad_set_event_function (filter->src2pad,
                              GST_DEBUG_FUNCPTR(gst_my_filter_src_event));
  GST_PAD_SET_PROXY_CAPS (filter->src2pad);
  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;

  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) {
	  GST_DEBUG_OBJECT (filter->src2pad, "push hello");
	  ret = gst_pad_push (filter->src2pad, gst_buffer_ref(buf));
  }
  /* just push out the incoming buffer without touching it */
  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);

  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;
}

/* 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
)