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GStreamer Good Plugins 0.10 Plugins Reference Manual | ![]() |
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GObject +----GstObject +----GstElement +----GstBaseTransform +----GstAudioFilter +----GstSpectrum
"bands" guint : Read / Write "interval" guint64 : Read / Write "message" gboolean : Read / Write "threshold" gint : Read / Write "message-magnitude" gboolean : Read / Write "message-phase" gboolean : Read / Write
The Spectrum element analyzes the frequency spectrum of an audio signal.
If the GstSpectrum:message property is TRUE, it sends analysis results as
application messages named
"spectrum"
after each interval of time given
by the GstSpectrum:interval property.
The message's structure contains some combination of these fields:
GstClockTime
"endtime"
:
the end time of the buffer that triggered the message. Always present.
GstValueList of gfloat
"magnitude"
:
the level for each frequency band in dB. All values below the value of the
GstSpectrum:threshold property will be set to the threshold. Only present
if the message-magnitude property is true.
GstValueList of gfloat
"phase"
:
The phase for each frequency band. The value is between -pi and pi. Only
present if the message-phase property is true.
This element cannot be used with the gst-launch command in a sensible way. This sample code demonstrates how to use it in an application.
/* GStreamer * Copyright (C) 2006 Stefan Kost <ensonic@users.sf.net> * Copyright (C) 2008 Jan Schmidt <jan.schmidt@sun.com> * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Library General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Library General Public License for more details. * * You should have received a copy of the GNU Library General Public * License along with this library; if not, write to the * Free Software Foundation, Inc., 59 Temple Place - Suite 330, * Boston, MA 02111-1307, USA. */ #include <string.h> #include <stdlib.h> #include <gst/gst.h> static guint spect_bands = 20; #define AUDIOFREQ 32000 /* receive spectral data from element message */ gboolean message_handler (GstBus * bus, GstMessage * message, gpointer data) { if (message->type == GST_MESSAGE_ELEMENT) { const GstStructure *s = gst_message_get_structure (message); const gchar *name = gst_structure_get_name (s); GstClockTime endtime; if (strcmp (name, "spectrum") == 0) { const GValue *magnitudes; const GValue *phases; const GValue *mag, *phase; gdouble freq; guint i; if (!gst_structure_get_clock_time (s, "endtime", &endtime)) endtime = GST_CLOCK_TIME_NONE; g_print ("New spectrum message, endtime %" GST_TIME_FORMAT "\n", GST_TIME_ARGS (endtime)); magnitudes = gst_structure_get_value (s, "magnitude"); phases = gst_structure_get_value (s, "phase"); for (i = 0; i < spect_bands; ++i) { freq = (gdouble) ((AUDIOFREQ / 2) * i + AUDIOFREQ / 4) / spect_bands; mag = gst_value_list_get_value (magnitudes, i); phase = gst_value_list_get_value (phases, i); if (mag != NULL && phase != NULL) { g_print ("band %d (freq %g): magnitude %f dB phase %f\n", i, freq, g_value_get_float (mag), g_value_get_float (phase)); } } g_print ("\n"); } } return TRUE; } int main (int argc, char *argv[]) { GstElement *bin; GstElement *src, *audioconvert, *spectrum, *sink; GstBus *bus; GstCaps *caps; GMainLoop *loop; gst_init (&argc, &argv); bin = gst_pipeline_new ("bin"); src = gst_element_factory_make ("audiotestsrc", "src"); g_object_set (G_OBJECT (src), "wave", 0, "freq", 6000.0, NULL); audioconvert = gst_element_factory_make ("audioconvert", NULL); g_assert (audioconvert); spectrum = gst_element_factory_make ("spectrum", "spectrum"); g_object_set (G_OBJECT (spectrum), "bands", spect_bands, "threshold", -80, "message", TRUE, "message-phase", TRUE, NULL); sink = gst_element_factory_make ("fakesink", "sink"); g_object_set (G_OBJECT (sink), "sync", TRUE, NULL); gst_bin_add_many (GST_BIN (bin), src, audioconvert, spectrum, sink, NULL); caps = gst_caps_new_simple ("audio/x-raw-int", "rate", G_TYPE_INT, AUDIOFREQ, NULL); if (!gst_element_link (src, audioconvert) || !gst_element_link_filtered (audioconvert, spectrum, caps) || !gst_element_link (spectrum, sink)) { fprintf (stderr, "can't link elements\n"); exit (1); } gst_caps_unref (caps); bus = gst_element_get_bus (bin); gst_bus_add_watch (bus, message_handler, NULL); gst_object_unref (bus); gst_element_set_state (bin, GST_STATE_PLAYING); /* we need to run a GLib main loop to get the messages */ loop = g_main_loop_new (NULL, FALSE); g_main_loop_run (loop); gst_element_set_state (bin, GST_STATE_NULL); gst_object_unref (bin); return 0; }
Last reviewed on 2008-02-09 (0.10.6)
plugin | spectrum |
author | Erik Walthinsen <omega@cse.ogi.edu>, Stefan Kost <ensonic@users.sf.net>, Sebastian Dröge <slomo@circular-chaos.org> |
class | Filter/Analyzer/Audio |
name | src |
direction | source |
presence | always |
details | audio/x-raw-int, width=(int)16, depth=(int)16, signed=(boolean)true, endianness=(int)1234, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ]; audio/x-raw-int, width=(int)32, depth=(int)32, signed=(boolean)true, endianness=(int)1234, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ]; audio/x-raw-float, width=(int){ 32, 64 }, endianness=(int)1234, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ] |
name | sink |
direction | sink |
presence | always |
details | audio/x-raw-int, width=(int)16, depth=(int)16, signed=(boolean)true, endianness=(int)1234, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ]; audio/x-raw-int, width=(int)32, depth=(int)32, signed=(boolean)true, endianness=(int)1234, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ]; audio/x-raw-float, width=(int){ 32, 64 }, endianness=(int)1234, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ] |
interval
" property"interval" guint64 : Read / Write
Interval of time between message posts (in nanoseconds).
Allowed values: >= 1
Default value: 100000000
message
" property"message" gboolean : Read / Write
Post a level message for each passed interval.
Default value: TRUE
threshold
" property"threshold" gint : Read / Write
dB threshold for result. All lower values will be set to this.
Allowed values: <= 0
Default value: -60
message-magnitude
" property"message-magnitude" gboolean : Read / Write
Post the magnitude of the spectrum.
Default value: TRUE