Mine

 videosrc = gst_element_factory_make("v4lsrc", "v4lsrc"); 
  videosink = gst_element_factory_make("xvimagesink", "xvimagesink");

  g_object_set (G_OBJECT (videosrc), "use-fixed-fps", FALSE, NULL);
  g_object_set (G_OBJECT (videosink), "sync", FALSE, NULL);
  g_object_set (G_OBJECT (videosrc), "is-live", TRUE, NULL);
  /*
     gst_debug_set_threshold_for_name ("audiotestsrc", 5);
     gst_debug_set_threshold_for_name ("rtpdemux", 5);
     gst_debug_set_threshold_for_name ("fakesink", 5);
     gst_debug_set_threshold_for_name ("audiosink", 5);
     gst_debug_set_threshold_for_name ("alsasink", 5);
     */

  src_filter = gst_caps_new_simple ("video/x-raw-yuv", "format", GST_TYPE_FOURCC, GST_MAKE_FOURCC ('I', '4', '2', '0'),"width",
      G_TYPE_INT, 320, "height", G_TYPE_INT, 240,"framerate",GST_TYPE_FRACTION ,15,1, NULL);
  farsight_stream_set_source_filter (video_stream, src_filter);
  gst_caps_unref (src_filter);
sink_filter = gst_caps_new_simple ("video/x-raw-yuv","format", GST_TYPE_FOURCC, GST_MAKE_FOURCC ('I', '4', '2', '0'), "width",
      G_TYPE_INT, 320, "height", G_TYPE_INT, 240,"framerate",GST_TYPE_FRACTION ,15,1, NULL);
  farsight_stream_set_sink_filter (video_stream, sink_filter);
  gst_caps_unref (sink_filter);
  farsight_stream_set_source(video_stream, videosrc);
  farsight_stream_set_sink(video_stream, videosink);