Example of dynamic pipeline in Gstreamer (recording + display). Stop recording at will by hitting ctrl+c.

gstreamer-recording-dynamic.c

#include <string.h>
#include <gst/gst.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

// v4l2src ! tee name=t t. ! x264enc ! mp4mux ! filesink location=/home/rish/Desktop/okay.264 t. ! videoconvert ! autovideosink

static GMainLoop *loop;
static GstElement *pipeline, *src, *tee, *encoder, *muxer, *filesink, *videoconvert, *videosink, *queue_record, *queue_display;
static GstBus *bus;
static GstPad *teepad;
static gboolean recording = FALSE;
static gint counter = 0;

static void finalize();

static gboolean
message_cb (GstBus * bus, GstMessage * message, gpointer user_data)
{
  switch (GST_MESSAGE_TYPE (message)) {
    case GST_MESSAGE_ERROR:{
      GError *err = NULL;
      gchar *name, *debug = NULL;

      name = gst_object_get_path_string (message->src);
      gst_message_parse_error (message, &err, &debug);

      g_printerr ("ERROR: from element %s: %s\n", name, err->message);
      if (debug != NULL)
        g_printerr ("Additional debug info:\n%s\n", debug);

      g_error_free (err);
      g_free (debug);
      g_free (name);

      g_main_loop_quit (loop);
      break;
    }
    case GST_MESSAGE_WARNING:{
		GError *err = NULL;
		gchar *name, *debug = NULL;

		name = gst_object_get_path_string (message->src);
		gst_message_parse_warning (message, &err, &debug);

		g_printerr ("ERROR: from element %s: %s\n", name, err->message);
		if (debug != NULL)
		g_printerr ("Additional debug info:\n%s\n", debug);

		g_error_free (err);
		g_free (debug);
		g_free (name);
		break;
    }
    case GST_MESSAGE_EOS: {
		g_print ("Got EOS\n");
		// g_main_loop_quit (loop);
		// gst_element_set_state (pipeline, GST_STATE_NULL);
		// g_main_loop_unref (loop);
		// gst_object_unref (pipeline);
		// exit(0);
		break;
	}
	case GST_MESSAGE_ELEMENT: {
    	const GstStructure *s = gst_message_get_structure (message);

    	if (gst_structure_has_name (s, "GstBinForwarded")) {
	        GstMessage *forward_msg = NULL;

	        gst_structure_get (s, "message", GST_TYPE_MESSAGE, &forward_msg, NULL);
	        if (GST_MESSAGE_TYPE (forward_msg) == GST_MESSAGE_EOS) {
	            g_print ("EOS from element %s\n", GST_OBJECT_NAME (GST_MESSAGE_SRC (forward_msg)));	
	            finalize();
	        }
	        gst_message_unref (forward_msg);
    	}
    	break;
	}
    default:
		break;
  }

  return TRUE;
}

static void finalize() {
	gst_bin_remove(GST_BIN (pipeline), queue_record);
	gst_bin_remove(GST_BIN (pipeline), encoder);
	gst_bin_remove(GST_BIN (pipeline), muxer);
	gst_bin_remove(GST_BIN (pipeline), filesink);

	gst_element_set_state(queue_record, GST_STATE_NULL);
	gst_element_set_state(encoder, GST_STATE_NULL);
	gst_element_set_state(muxer, GST_STATE_NULL);
	gst_element_set_state(filesink, GST_STATE_NULL);

	gst_object_unref(queue_record);
	gst_object_unref(encoder);
	gst_object_unref(muxer);
	gst_object_unref(filesink);

	gst_element_release_request_pad (tee, teepad);
	gst_object_unref (teepad);

	recording = FALSE;
	g_print("Unlinked\n");
}

static GstPadProbeReturn unlink_cb(GstPad *pad, GstPadProbeInfo *info, gpointer user_data) {
	g_print("Unlinking...");
	GstPad *sinkpad;
	sinkpad = gst_element_get_static_pad (queue_record, "sink");
	gst_pad_unlink (teepad, sinkpad);
	gst_object_unref (sinkpad);

	gst_element_send_event(encoder, gst_event_new_eos()); 

	return GST_PAD_PROBE_REMOVE;
}

void stopRecording() {
	g_print("stopRecording\n");
	gst_pad_add_probe(teepad, GST_PAD_PROBE_TYPE_IDLE, unlink_cb, NULL, (GDestroyNotify) g_free);
}

void startRecording() {
	g_print("startRecording\n");
	GstPad *sinkpad;
    GstPadTemplate *templ;

	templ = gst_element_class_get_pad_template(GST_ELEMENT_GET_CLASS(tee), "src_%u");
    teepad = gst_element_request_pad(tee, templ, NULL, NULL);
	queue_record = gst_element_factory_make("queue", "queue_record");
	encoder = gst_element_factory_make("x264enc", NULL);
	muxer = gst_element_factory_make("mp4mux", NULL);
	filesink = gst_element_factory_make("filesink", NULL);
	char *file_name = (char*) malloc(100 * sizeof(char));
	sprintf(file_name, "/home/rish/Desktop/rec%d.mp4", counter++);
	g_print("file created %s\n",file_name);
	g_object_set(filesink, "location", file_name, NULL);
	g_object_set(encoder, "tune", 4, NULL);
	free(file_name);

	gst_bin_add_many(GST_BIN(pipeline), gst_object_ref(queue_record), gst_object_ref(encoder), gst_object_ref(muxer), gst_object_ref(filesink), NULL);
	gst_element_link_many(queue_record, encoder, muxer, filesink, NULL);

	gst_element_sync_state_with_parent(queue_record);
	gst_element_sync_state_with_parent(encoder);
	gst_element_sync_state_with_parent(muxer);
	gst_element_sync_state_with_parent(filesink);

	sinkpad = gst_element_get_static_pad(queue_record, "sink");
	gst_pad_link(teepad, sinkpad);
	gst_object_unref(sinkpad);

	recording = TRUE;
}

int sigintHandler(int unused) {
	g_print("You ctrl-c!\n");
	if (recording)
		stopRecording();
	else
		startRecording();
	return 0;
}

int main(int argc, char *argv[])
{
	signal(SIGINT, sigintHandler);
	gst_init (&argc, &argv);

	pipeline = gst_pipeline_new(NULL);
	src = gst_element_factory_make("v4l2src", NULL);
	tee = gst_element_factory_make("tee", "tee");
	queue_display = gst_element_factory_make("queue", "queue_display");
	videoconvert = gst_element_factory_make("videoconvert", NULL);
	videosink = gst_element_factory_make("autovideosink", NULL);

	if (!pipeline || !src || !tee || !videoconvert || !videosink || !queue_display) {
		g_error("Failed to create elements");
		return -1;
	}

	gst_bin_add_many(GST_BIN(pipeline), src, tee, queue_display, videoconvert, videosink, NULL);
	if (!gst_element_link_many(src, tee, NULL) 
		|| !gst_element_link_many(tee, queue_display, videoconvert, videosink, NULL)) {
		g_error("Failed to link elements");
		return -2;
	}

	g_object_set(GST_BIN(pipeline), "message-forward", TRUE, NULL);

	startRecording();
	loop = g_main_loop_new(NULL, FALSE);

	bus = gst_pipeline_get_bus(GST_PIPELINE (pipeline));
	gst_bus_add_signal_watch(bus);
	g_signal_connect(G_OBJECT(bus), "message", G_CALLBACK(message_cb), NULL);
	gst_object_unref(GST_OBJECT(bus));

	gst_element_set_state(pipeline, GST_STATE_PLAYING);

	g_print("Starting loop\n");
	g_main_loop_run(loop);

	return 0;
}

Is it available in python gst also ?