gstreamer/tests/examples/controller/audio-example.c

/*
 * audio-example.c
 *
 * Builds a pipeline with audiotestsource->alsasink and sweeps frequency and
 * volume.
 *
 * Needs gst-plugin-base installed.
 */

#include <gst/gst.h>
#include <gst/controller/gstinterpolationcontrolsource.h>

gint
main (gint argc, gchar ** argv)
{
  gint res = 1;
  GstElement *src, *sink;
  GstElement *bin;
  GstInterpolationControlSource *csource1, *csource2;
  GstTimedValueControlSource *cs;
  GstClock *clock;
  GstClockID clock_id;
  GstClockReturn wait_ret;

  gst_init (&argc, &argv);

  /* build pipeline */
  bin = gst_pipeline_new ("pipeline");
  clock = gst_pipeline_get_clock (GST_PIPELINE (bin));
  src = gst_element_factory_make ("audiotestsrc", "gen_audio");
  if (!src) {
    GST_WARNING ("need audiotestsrc from gst-plugins-base");
    goto Error;
  }
  sink = gst_element_factory_make ("autoaudiosink", "play_audio");
  if (!sink) {
    GST_WARNING ("need autoaudiosink from gst-plugins-base");
    goto Error;
  }

  gst_bin_add_many (GST_BIN (bin), src, sink, NULL);
  if (!gst_element_link (src, sink)) {
    GST_WARNING ("can't link elements");
    goto Error;
  }

  /* square wave
     g_object_set (G_OBJECT(src), "wave", 1, NULL);
   */

  csource1 = gst_interpolation_control_source_new ();
  csource2 = gst_interpolation_control_source_new ();

  gst_object_set_control_source (GST_OBJECT (src), "volume",
      GST_CONTROL_SOURCE (csource1));
  gst_object_set_control_source (GST_OBJECT (src), "freq",
      GST_CONTROL_SOURCE (csource2));

  /* Set interpolation mode */

  g_object_set (csource1, "mode", GST_INTERPOLATION_MODE_LINEAR, NULL);
  g_object_set (csource2, "mode", GST_INTERPOLATION_MODE_LINEAR, NULL);

  /* set control values */
  cs = (GstTimedValueControlSource *) csource1;
  gst_timed_value_control_source_set (cs, 0 * GST_SECOND, 0.0);
  gst_timed_value_control_source_set (cs, 5 * GST_SECOND, 1.0);

  g_object_unref (csource1);

  cs = (GstTimedValueControlSource *) csource2;
  gst_timed_value_control_source_set (cs, 0 * GST_SECOND, 220.0);
  gst_timed_value_control_source_set (cs, 3 * GST_SECOND, 3520.0);
  gst_timed_value_control_source_set (cs, 6 * GST_SECOND, 440.0);

  g_object_unref (csource2);

  clock_id =
      gst_clock_new_single_shot_id (clock,
      gst_clock_get_time (clock) + (7 * GST_SECOND));

  /* run for 7 seconds */
  if (gst_element_set_state (bin, GST_STATE_PLAYING)) {
    if ((wait_ret = gst_clock_id_wait (clock_id, NULL)) != GST_CLOCK_OK) {
      GST_WARNING ("clock_id_wait returned: %d", wait_ret);
    }
    gst_element_set_state (bin, GST_STATE_NULL);
  }

  /* cleanup */
  gst_clock_id_unref (clock_id);
  gst_object_unref (G_OBJECT (clock));
  gst_object_unref (G_OBJECT (bin));
  res = 0;
Error:
  return (res);
}