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https://gitlab.freedesktop.org/gstreamer/gstreamer.git
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90 lines
2.7 KiB
C
90 lines
2.7 KiB
C
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#include <string.h>
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#include <math.h>
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#include <gst/gst.h>
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gboolean
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message_handler (GstBus * bus, GstMessage * message, gpointer data)
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{
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if (message->type == GST_MESSAGE_APPLICATION) {
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const GstStructure *s = gst_message_get_structure (message);
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const gchar *name = gst_structure_get_name (s);
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if (strcmp (name, "level") == 0) {
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gint channels;
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gdouble endtime, rms_dB, peak_dB, decay_dB;
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gdouble rms;
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const GValue *list;
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const GValue *value;
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if (!gst_structure_get_double (s, "endtime", &endtime))
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g_warning ("Could not parse endtime");
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list = gst_structure_get_value (s, "rms");
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/* we can get the number of channels as the length of any of the value
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* lists */
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channels = gst_value_list_get_size (list);
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/* we will only get values for the first channel, since we know sinesrc
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* is mono */
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value = gst_value_list_get_value (list, 0);
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rms_dB = g_value_get_double (value);
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list = gst_structure_get_value (s, "peak");
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value = gst_value_list_get_value (list, 0);
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peak_dB = g_value_get_double (value);
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list = gst_structure_get_value (s, "decay");
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value = gst_value_list_get_value (list, 0);
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decay_dB = g_value_get_double (value);
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g_print ("endtime: %f, channels: %d\n", endtime, channels);
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g_print ("RMS: %f dB, peak: %f dB, decay: %f dB\n",
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rms_dB, peak_dB, decay_dB);
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/* converting from dB to normal gives us a value between 0.0 and 1.0 */
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rms = pow (10, rms_dB / 20);
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g_print ("normalized rms value: %f\n", rms);
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}
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}
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/* we handled the message we want, and ignored the ones we didn't want.
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* so the core can unref the message for us */
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return TRUE;
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}
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int
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main (int argc, char *argv[])
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{
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GstElement *sinesrc, *level, *fakesink;
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GstElement *pipeline;
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GstBus *bus;
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gint watch_id;
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GMainLoop *loop;
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gst_init (&argc, &argv);
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pipeline = gst_pipeline_new (NULL);
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g_assert (pipeline);
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sinesrc = gst_element_factory_make ("sinesrc", NULL);
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g_assert (sinesrc);
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level = gst_element_factory_make ("level", NULL);
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g_assert (level);
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fakesink = gst_element_factory_make ("fakesink", NULL);
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g_assert (fakesink);
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gst_bin_add_many (GST_BIN (pipeline), sinesrc, level, fakesink, NULL);
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gst_element_link (sinesrc, level);
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gst_element_link (level, fakesink);
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/* make sure we'll get messages */
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g_object_set (G_OBJECT (level), "message", TRUE, NULL);
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bus = gst_element_get_bus (pipeline);
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watch_id = gst_bus_add_watch (bus, message_handler, NULL);
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gst_element_set_state (pipeline, GST_STATE_PLAYING);
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/* we need to run a GLib main loop to get the messages */
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loop = g_main_loop_new (NULL, FALSE);
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g_main_loop_run (loop);
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return 0;
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}
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