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Modernizing the documentation, making it simpler to read an modify and allowing us to possibly switch to hotdoc in the future.
211 lines
6.5 KiB
C
211 lines
6.5 KiB
C
/* GStreamer Mixer
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* Copyright (C) 2009 Sebastian Dröge <sebastian.droege@collabora.co.uk>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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/**
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* SECTION:gststreamvolume
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* @title: GstStreamVolume
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* @short_description: Interface for elements that provide a stream volume
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*
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* This interface is implemented by elements that provide a stream volume. Examples for
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* such elements are #volume and #playbin.
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*
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* Applications can use this interface to get or set the current stream volume. For this
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* the "volume" #GObject property can be used or the helper functions gst_stream_volume_set_volume()
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* and gst_stream_volume_get_volume(). This volume is always a linear factor, i.e. 0.0 is muted
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* 1.0 is 100%. For showing the volume in a GUI it might make sense to convert it to
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* a different format by using gst_stream_volume_convert_volume(). Volume sliders should usually
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* use a cubic volume.
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*
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* Separate from the volume the stream can also be muted by the "mute" #GObject property or
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* gst_stream_volume_set_mute() and gst_stream_volume_get_mute().
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*
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* Elements that provide some kind of stream volume should implement the "volume" and
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* "mute" #GObject properties and handle setting and getting of them properly.
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* The volume property is defined to be a linear volume factor.
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*
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "streamvolume.h"
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#include <math.h>
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static void
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gst_stream_volume_class_init (GstStreamVolumeInterface * iface)
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{
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g_object_interface_install_property (iface,
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g_param_spec_double ("volume",
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"Volume",
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"Linear volume factor, 1.0=100%",
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0.0, G_MAXDOUBLE, 1.0, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
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g_object_interface_install_property (iface,
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g_param_spec_boolean ("mute",
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"Mute",
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"Mute the audio channel without changing the volume",
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FALSE, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
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}
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GType
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gst_stream_volume_get_type (void)
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{
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static volatile gsize type = 0;
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if (g_once_init_enter (&type)) {
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GType tmp;
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static const GTypeInfo info = {
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sizeof (GstStreamVolumeInterface),
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NULL, /* base_init */
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NULL, /* base_finalize */
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(GClassInitFunc) gst_stream_volume_class_init, /* class_init */
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NULL, /* class_finalize */
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NULL, /* class_data */
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0,
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0, /* n_preallocs */
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NULL /* instance_init */
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};
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tmp = g_type_register_static (G_TYPE_INTERFACE,
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"GstStreamVolume", &info, 0);
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g_type_interface_add_prerequisite (tmp, G_TYPE_OBJECT);
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g_once_init_leave (&type, tmp);
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}
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return type;
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}
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/**
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* gst_stream_volume_get_volume:
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* @volume: #GstStreamVolume that should be used
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* @format: #GstStreamVolumeFormat which should be returned
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*
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* Returns: The current stream volume as linear factor
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*/
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gdouble
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gst_stream_volume_get_volume (GstStreamVolume * volume,
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GstStreamVolumeFormat format)
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{
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gdouble val;
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g_return_val_if_fail (GST_IS_STREAM_VOLUME (volume), 1.0);
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g_object_get (volume, "volume", &val, NULL);
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if (format != GST_STREAM_VOLUME_FORMAT_LINEAR)
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val =
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gst_stream_volume_convert_volume (GST_STREAM_VOLUME_FORMAT_LINEAR,
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format, val);
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return val;
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}
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/**
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* gst_stream_volume_set_volume:
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* @volume: #GstStreamVolume that should be used
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* @format: #GstStreamVolumeFormat of @val
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* @val: Linear volume factor that should be set
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*/
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void
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gst_stream_volume_set_volume (GstStreamVolume * volume,
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GstStreamVolumeFormat format, gdouble val)
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{
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g_return_if_fail (GST_IS_STREAM_VOLUME (volume));
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if (format != GST_STREAM_VOLUME_FORMAT_LINEAR)
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val =
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gst_stream_volume_convert_volume (format,
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GST_STREAM_VOLUME_FORMAT_LINEAR, val);
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g_object_set (volume, "volume", val, NULL);
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}
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/**
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* gst_stream_volume_get_mute:
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* @volume: #GstStreamVolume that should be used
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*
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* Returns: Returns %TRUE if the stream is muted
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*/
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gboolean
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gst_stream_volume_get_mute (GstStreamVolume * volume)
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{
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gboolean val;
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g_return_val_if_fail (GST_IS_STREAM_VOLUME (volume), FALSE);
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g_object_get (volume, "mute", &val, NULL);
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return val;
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}
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/**
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* gst_stream_volume_set_mute:
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* @volume: #GstStreamVolume that should be used
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* @mute: Mute state that should be set
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*/
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void
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gst_stream_volume_set_mute (GstStreamVolume * volume, gboolean mute)
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{
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g_return_if_fail (GST_IS_STREAM_VOLUME (volume));
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g_object_set (volume, "mute", mute, NULL);
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}
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/**
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* gst_stream_volume_convert_volume:
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* @from: #GstStreamVolumeFormat to convert from
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* @to: #GstStreamVolumeFormat to convert to
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* @val: Volume in @from format that should be converted
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*
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* Returns: the converted volume
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*/
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gdouble
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gst_stream_volume_convert_volume (GstStreamVolumeFormat from,
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GstStreamVolumeFormat to, gdouble val)
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{
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switch (from) {
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case GST_STREAM_VOLUME_FORMAT_LINEAR:
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g_return_val_if_fail (val >= 0.0, 0.0);
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switch (to) {
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case GST_STREAM_VOLUME_FORMAT_LINEAR:
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return val;
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case GST_STREAM_VOLUME_FORMAT_CUBIC:
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return pow (val, 1 / 3.0);
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case GST_STREAM_VOLUME_FORMAT_DB:
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return 20.0 * log10 (val);
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}
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break;
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case GST_STREAM_VOLUME_FORMAT_CUBIC:
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g_return_val_if_fail (val >= 0.0, 0.0);
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switch (to) {
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case GST_STREAM_VOLUME_FORMAT_LINEAR:
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return val * val * val;
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case GST_STREAM_VOLUME_FORMAT_CUBIC:
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return val;
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case GST_STREAM_VOLUME_FORMAT_DB:
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return 3.0 * 20.0 * log10 (val);
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}
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break;
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case GST_STREAM_VOLUME_FORMAT_DB:
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switch (to) {
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case GST_STREAM_VOLUME_FORMAT_LINEAR:
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return pow (10.0, val / 20.0);
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case GST_STREAM_VOLUME_FORMAT_CUBIC:
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return pow (10.0, val / (3.0 * 20.0));
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case GST_STREAM_VOLUME_FORMAT_DB:
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return val;
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}
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break;
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}
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g_return_val_if_reached (0.0);
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}
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