gstreamer/gst-libs/gst/interfaces/mixer.c
Wim Taymans 7fb914d5b6 interfaces: clean up
Remove deprecated bits
Fix FIXMES
Indent
Add padding
2011-11-11 18:49:09 +01:00

821 lines
24 KiB
C

/* GStreamer Mixer
* Copyright (C) 2003 Ronald Bultje <rbultje@ronald.bitfreak.net>
*
* mixer.c: mixer design virtual class function wrappers
*
* 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.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "mixer.h"
#include "interfaces-marshal.h"
#define GST_MIXER_MESSAGE_NAME "gst-mixer-message"
/**
* SECTION:gstmixer
* @short_description: Interface for elements that provide mixer operations
* @see_also: alsamixer, oss4mixer, sunaudiomixer
*
* Basic interface for hardware mixer controls.
*
* Applications rarely need to use this interface, it is provided mainly
* for system-level mixer applets and the like. Volume control in playback
* applications should be done using a <classname>volume</classname>
* element or, if available, using the <quote>volume</quote> property of
* the audio sink element used (as provided by <classname>pulsesink</classname>
* for example), or even better: just use the <classname>playbin2</classname>
* element's <quote>volume</quote> property.
*
* Usage: In order to use the <classname>GstMixer</classname> interface, the
* element needs to be at least in READY state (so that the element has opened
* the mixer device). Once the element has been set to READY state or higher,
* it can be cast to a <classname>GstMixer</classname> using the GST_MIXER
* macro (in C) and the mixer API can be used.
*/
/* FIXME 0.11: check if we need to add API for sometimes-supportedness
* (aka making up for GstImplementsInterface removal) */
static void gst_mixer_class_init (GstMixerInterface * iface);
GType
gst_mixer_get_type (void)
{
static GType gst_mixer_type = 0;
if (!gst_mixer_type) {
static const GTypeInfo gst_mixer_info = {
sizeof (GstMixerInterface),
(GBaseInitFunc) gst_mixer_class_init,
NULL,
NULL,
NULL,
NULL,
0,
0,
NULL,
};
gst_mixer_type = g_type_register_static (G_TYPE_INTERFACE,
"GstMixer", &gst_mixer_info, 0);
}
return gst_mixer_type;
}
static void
gst_mixer_class_init (GstMixerInterface * iface)
{
iface->mixer_type = GST_MIXER_SOFTWARE;
/* default virtual functions */
iface->list_tracks = NULL;
iface->set_volume = NULL;
iface->get_volume = NULL;
iface->set_mute = NULL;
iface->set_record = NULL;
iface->set_option = NULL;
iface->get_option = NULL;
}
/**
* gst_mixer_list_tracks:
* @mixer: the #GstMixer (a #GstElement) to get the tracks from.
*
* Returns a list of available tracks for this mixer/element. Note
* that it is allowed for sink (output) elements to only provide
* the output tracks in this list. Likewise, for sources (inputs),
* it is allowed to only provide input elements in this list.
*
* Returns: A #GList consisting of zero or more #GstMixerTracks.
* The list is owned by the #GstMixer instance and must not be freed
* or modified.
*/
const GList *
gst_mixer_list_tracks (GstMixer * mixer)
{
GstMixerInterface *iface;
g_return_val_if_fail (mixer != NULL, NULL);
iface = GST_MIXER_GET_INTERFACE (mixer);
if (iface->list_tracks) {
return iface->list_tracks (mixer);
}
return NULL;
}
/**
* gst_mixer_set_volume:
* @mixer: The #GstMixer (a #GstElement) that owns the track.
* @track: The #GstMixerTrack to set the volume on.
* @volumes: an array of integers (of size track->num_channels)
* that gives the wanted volume for each channel in
* this track.
*
* Sets the volume on each channel in a track. Short note about
* naming: a track is defined as one separate stream owned by
* the mixer/element, such as 'Line-in' or 'Microphone'. A
* channel is said to be a mono-stream inside this track. A
* stereo track thus contains two channels.
*/
void
gst_mixer_set_volume (GstMixer * mixer, GstMixerTrack * track, gint * volumes)
{
GstMixerInterface *iface;
g_return_if_fail (mixer != NULL);
g_return_if_fail (track != NULL);
g_return_if_fail (volumes != NULL);
iface = GST_MIXER_GET_INTERFACE (mixer);
if (iface->set_volume) {
iface->set_volume (mixer, track, volumes);
}
}
/**
* gst_mixer_get_volume:
* @mixer: the #GstMixer (a #GstElement) that owns the track
* @track: the GstMixerTrack to get the volume from.
* @volumes: a pre-allocated array of integers (of size
* track->num_channels) to store the current volume
* of each channel in the given track in.
*
* Get the current volume(s) on the given track.
*/
void
gst_mixer_get_volume (GstMixer * mixer, GstMixerTrack * track, gint * volumes)
{
GstMixerInterface *iface;
g_return_if_fail (mixer != NULL);
g_return_if_fail (track != NULL);
g_return_if_fail (volumes != NULL);
iface = GST_MIXER_GET_INTERFACE (mixer);
if (iface->get_volume) {
iface->get_volume (mixer, track, volumes);
} else {
gint i;
for (i = 0; i < track->num_channels; i++) {
volumes[i] = 0;
}
}
}
/**
* gst_mixer_set_mute:
* @mixer: the #GstMixer (a #GstElement) that owns the track.
* @track: the #GstMixerTrack to operate on.
* @mute: a boolean value indicating whether to turn on or off
* muting.
*
* Mutes or unmutes the given channel. To find out whether a
* track is currently muted, use GST_MIXER_TRACK_HAS_FLAG ().
*/
void
gst_mixer_set_mute (GstMixer * mixer, GstMixerTrack * track, gboolean mute)
{
GstMixerInterface *iface;
g_return_if_fail (mixer != NULL);
g_return_if_fail (track != NULL);
iface = GST_MIXER_GET_INTERFACE (mixer);
if (iface->set_mute) {
iface->set_mute (mixer, track, mute);
}
}
/**
* gst_mixer_set_record:
* @mixer: The #GstMixer (a #GstElement) that owns the track.
* @track: the #GstMixerTrack to operate on.
* @record: a boolean value that indicates whether to turn on
* or off recording.
*
* Enables or disables recording on the given track. Note that
* this is only possible on input tracks, not on output tracks
* (see GST_MIXER_TRACK_HAS_FLAG () and the GST_MIXER_TRACK_INPUT
* flag).
*/
void
gst_mixer_set_record (GstMixer * mixer, GstMixerTrack * track, gboolean record)
{
GstMixerInterface *iface = GST_MIXER_GET_INTERFACE (mixer);
if (iface->set_record) {
iface->set_record (mixer, track, record);
}
}
/**
* gst_mixer_set_option:
* @mixer: The #GstMixer (a #GstElement) that owns the optionlist.
* @opts: The #GstMixerOptions that we operate on.
* @value: The requested new option value.
*
* Sets a name/value option in the mixer to the requested value.
*/
void
gst_mixer_set_option (GstMixer * mixer, GstMixerOptions * opts, gchar * value)
{
GstMixerInterface *iface;
g_return_if_fail (mixer != NULL);
g_return_if_fail (opts != NULL);
iface = GST_MIXER_GET_INTERFACE (mixer);
if (iface->set_option) {
iface->set_option (mixer, opts, value);
}
}
/**
* gst_mixer_get_option:
* @mixer: The #GstMixer (a #GstElement) that owns the optionlist.
* @opts: The #GstMixerOptions that we operate on.
*
* Get the current value of a name/value option in the mixer.
*
* Returns: current value of the name/value option.
*/
const gchar *
gst_mixer_get_option (GstMixer * mixer, GstMixerOptions * opts)
{
GstMixerInterface *iface;
g_return_val_if_fail (mixer != NULL, NULL);
g_return_val_if_fail (opts != NULL, NULL);
iface = GST_MIXER_GET_INTERFACE (mixer);
if (iface->get_option) {
return iface->get_option (mixer, opts);
}
return NULL;
}
/**
* gst_mixer_get_mixer_type:
* @mixer: The #GstMixer implementation
*
* Get the #GstMixerType of this mixer implementation.
*
* Returns: A the #GstMixerType.
*
* Since: 0.10.24
*/
GstMixerType
gst_mixer_get_mixer_type (GstMixer * mixer)
{
GstMixerInterface *iface = GST_MIXER_GET_INTERFACE (mixer);
return iface->mixer_type;
}
/**
* gst_mixer_get_mixer_flags:
* @mixer: The #GstMixer implementation
*
* Get the set of supported flags for this mixer implementation.
*
* Returns: A set of or-ed GstMixerFlags for supported features.
*/
GstMixerFlags
gst_mixer_get_mixer_flags (GstMixer * mixer)
{
GstMixerInterface *iface;
g_return_val_if_fail (mixer != NULL, FALSE);
iface = GST_MIXER_GET_INTERFACE (mixer);
if (iface->get_mixer_flags) {
return iface->get_mixer_flags (mixer);
}
return GST_MIXER_FLAG_NONE;
}
/**
* gst_mixer_mute_toggled:
* @mixer: the #GstMixer (a #GstElement) that owns the track
* @track: the GstMixerTrack that has change mute state.
* @mute: the new state of the mute flag on the track
*
* This function is called by the mixer implementation to produce
* a notification message on the bus indicating that the given track
* has changed mute state.
*
* This function only works for GstElements that are implementing the
* GstMixer interface, and the element needs to have been provided a bus.
*/
void
gst_mixer_mute_toggled (GstMixer * mixer, GstMixerTrack * track, gboolean mute)
{
GstStructure *s;
GstMessage *m;
g_return_if_fail (mixer != NULL);
g_return_if_fail (GST_IS_ELEMENT (mixer));
g_return_if_fail (track != NULL);
s = gst_structure_new (GST_MIXER_MESSAGE_NAME,
"type", G_TYPE_STRING, "mute-toggled",
"track", GST_TYPE_MIXER_TRACK, track, "mute", G_TYPE_BOOLEAN, mute, NULL);
m = gst_message_new_element (GST_OBJECT (mixer), s);
if (gst_element_post_message (GST_ELEMENT (mixer), m) == FALSE) {
GST_WARNING ("This element has no bus, therefore no message sent!");
}
}
/**
* gst_mixer_record_toggled:
* @mixer: the #GstMixer (a #GstElement) that owns the track
* @track: the GstMixerTrack that has changed recording state.
* @record: the new state of the record flag on the track
*
* This function is called by the mixer implementation to produce
* a notification message on the bus indicating that the given track
* has changed recording state.
*
* This function only works for GstElements that are implementing the
* GstMixer interface, and the element needs to have been provided a bus.
*/
void
gst_mixer_record_toggled (GstMixer * mixer,
GstMixerTrack * track, gboolean record)
{
GstStructure *s;
GstMessage *m;
g_return_if_fail (mixer != NULL);
g_return_if_fail (GST_IS_ELEMENT (mixer));
g_return_if_fail (track != NULL);
s = gst_structure_new (GST_MIXER_MESSAGE_NAME,
"type", G_TYPE_STRING, "record-toggled",
"track", GST_TYPE_MIXER_TRACK, track,
"record", G_TYPE_BOOLEAN, record, NULL);
m = gst_message_new_element (GST_OBJECT (mixer), s);
if (gst_element_post_message (GST_ELEMENT (mixer), m) == FALSE) {
GST_WARNING ("This element has no bus, therefore no message sent!");
}
}
/**
* gst_mixer_volume_changed:
* @mixer: the #GstMixer (a #GstElement) that owns the track
* @track: the GstMixerTrack that has changed.
* @volumes: Array of volume values, one per channel on the mixer track.
*
* This function is called by the mixer implementation to produce
* a notification message on the bus indicating that the volume(s) for the
* given track have changed.
*
* This function only works for GstElements that are implementing the
* GstMixer interface, and the element needs to have been provided a bus.
*/
void
gst_mixer_volume_changed (GstMixer * mixer,
GstMixerTrack * track, gint * volumes)
{
GstStructure *s;
GstMessage *m;
GValue l = { 0, };
GValue v = { 0, };
gint i;
g_return_if_fail (mixer != NULL);
g_return_if_fail (GST_IS_ELEMENT (mixer));
g_return_if_fail (track != NULL);
s = gst_structure_new (GST_MIXER_MESSAGE_NAME,
"type", G_TYPE_STRING, "volume-changed",
"track", GST_TYPE_MIXER_TRACK, track, NULL);
g_value_init (&l, GST_TYPE_ARRAY);
g_value_init (&v, G_TYPE_INT);
/* FIXME 0.11: pass track->num_channels to the function */
for (i = 0; i < track->num_channels; ++i) {
g_value_set_int (&v, volumes[i]);
gst_value_array_append_value (&l, &v);
}
g_value_unset (&v);
gst_structure_set_value (s, "volumes", &l);
g_value_unset (&l);
m = gst_message_new_element (GST_OBJECT (mixer), s);
if (gst_element_post_message (GST_ELEMENT (mixer), m) == FALSE) {
GST_WARNING ("This element has no bus, therefore no message sent!");
}
}
/**
* gst_mixer_option_changed:
* @mixer: the #GstMixer (a #GstElement) that owns the options
* @opts: the GstMixerOptions that has changed value.
* @value: the new value of the GstMixerOptions.
*
* This function is called by the mixer implementation to produce
* a notification message on the bus indicating that the given options
* object has changed state.
*
* This function only works for GstElements that are implementing the
* GstMixer interface, and the element needs to have been provided a bus.
*/
void
gst_mixer_option_changed (GstMixer * mixer,
GstMixerOptions * opts, const gchar * value)
{
GstStructure *s;
GstMessage *m;
g_return_if_fail (mixer != NULL);
g_return_if_fail (GST_IS_ELEMENT (mixer));
g_return_if_fail (opts != NULL);
s = gst_structure_new (GST_MIXER_MESSAGE_NAME,
"type", G_TYPE_STRING, "option-changed",
"options", GST_TYPE_MIXER_OPTIONS, opts,
"value", G_TYPE_STRING, value, NULL);
m = gst_message_new_element (GST_OBJECT (mixer), s);
if (gst_element_post_message (GST_ELEMENT (mixer), m) == FALSE) {
GST_WARNING ("This element has no bus, therefore no message sent!");
}
}
/**
* gst_mixer_options_list_changed:
* @mixer: the #GstMixer (a #GstElement) that owns the options
* @opts: the GstMixerOptions whose list of values has changed
*
* This function is called by the mixer implementation to produce
* a notification message on the bus indicating that the list of possible
* options of a given options object has changed.
*
* The new options are not contained in the message on purpose. Applications
* should call gst_mixer_options_get_values() on @opts to make @opts update
* its internal state and obtain the new list of values.
*
* This function only works for GstElements that are implementing the
* GstMixer interface, and the element needs to have been provided a bus
* for this to work.
*
* Since: 0.10.18
*/
void
gst_mixer_options_list_changed (GstMixer * mixer, GstMixerOptions * opts)
{
GstStructure *s;
GstMessage *m;
g_return_if_fail (mixer != NULL);
g_return_if_fail (GST_IS_ELEMENT (mixer));
g_return_if_fail (opts != NULL);
g_return_if_fail (GST_IS_MIXER_OPTIONS (opts));
/* we do not include the new list here on purpose, so that the application
* has to use gst_mixer_options_get_values() to get the new list, which then
* allows the mixer options object to update the internal GList in a somewhat
* thread-safe way at least */
s = gst_structure_new (GST_MIXER_MESSAGE_NAME,
"type", G_TYPE_STRING, "options-list-changed",
"options", GST_TYPE_MIXER_OPTIONS, opts, NULL);
m = gst_message_new_element (GST_OBJECT (mixer), s);
if (gst_element_post_message (GST_ELEMENT (mixer), m) == FALSE) {
GST_WARNING ("This element has no bus, therefore no message sent!");
}
}
/**
* gst_mixer_mixer_changed:
* @mixer: the #GstMixer (a #GstElement) which has changed
*
* This function is called by the mixer implementation to produce
* a notification message on the bus indicating that the list of available
* mixer tracks for a given mixer object has changed. Applications should
* rebuild their interface when they receive this message.
*
* This function only works for GstElements that are implementing the
* GstMixer interface, and the element needs to have been provided a bus.
*
* Since: 0.10.18
*/
void
gst_mixer_mixer_changed (GstMixer * mixer)
{
GstStructure *s;
GstMessage *m;
g_return_if_fail (mixer != NULL);
g_return_if_fail (GST_IS_ELEMENT (mixer));
s = gst_structure_new (GST_MIXER_MESSAGE_NAME,
"type", G_TYPE_STRING, "mixer-changed", NULL);
m = gst_message_new_element (GST_OBJECT (mixer), s);
if (gst_element_post_message (GST_ELEMENT (mixer), m) == FALSE) {
GST_WARNING ("This element has no bus, therefore no message sent!");
}
}
static gboolean
gst_mixer_message_is_mixer_message (GstMessage * message)
{
const GstStructure *s;
if (message == NULL)
return FALSE;
if (GST_MESSAGE_TYPE (message) != GST_MESSAGE_ELEMENT)
return FALSE;
s = gst_message_get_structure (message);
return gst_structure_has_name (s, GST_MIXER_MESSAGE_NAME);
}
/**
* gst_mixer_message_get_type:
* @message: A GstMessage to inspect.
*
* Check a bus message to see if it is a GstMixer notification
* message and return the GstMixerMessageType identifying which
* type of notification it is.
*
* Returns: The type of the GstMixerMessage, or GST_MIXER_MESSAGE_INVALID
* if the message is not a GstMixer notification.
*
* Since: 0.10.14
*/
GstMixerMessageType
gst_mixer_message_get_type (GstMessage * message)
{
const GstStructure *s;
const gchar *m_type;
if (!gst_mixer_message_is_mixer_message (message))
return GST_MIXER_MESSAGE_INVALID;
s = gst_message_get_structure (message);
m_type = gst_structure_get_string (s, "type");
g_return_val_if_fail (m_type != NULL, GST_MIXER_MESSAGE_INVALID);
if (g_str_equal (m_type, "mute-toggled"))
return GST_MIXER_MESSAGE_MUTE_TOGGLED;
else if (g_str_equal (m_type, "record-toggled"))
return GST_MIXER_MESSAGE_RECORD_TOGGLED;
else if (g_str_equal (m_type, "volume-changed"))
return GST_MIXER_MESSAGE_VOLUME_CHANGED;
else if (g_str_equal (m_type, "option-changed"))
return GST_MIXER_MESSAGE_OPTION_CHANGED;
else if (g_str_equal (m_type, "options-list-changed"))
return GST_MIXER_MESSAGE_OPTIONS_LIST_CHANGED;
else if (g_str_equal (m_type, "mixer-changed"))
return GST_MIXER_MESSAGE_MIXER_CHANGED;
return GST_MIXER_MESSAGE_INVALID;
}
#define GST_MIXER_MESSAGE_HAS_TYPE(msg,msg_type) \
(gst_mixer_message_get_type (msg) == GST_MIXER_MESSAGE_ ## msg_type)
/**
* gst_mixer_message_parse_mute_toggled:
* @message: A mute-toggled change notification message.
* @track: Pointer to hold a GstMixerTrack object, or NULL.
* @mute: A pointer to a gboolean variable, or NULL.
*
* Extracts the contents of a mute-toggled bus message. Reads
* the GstMixerTrack that has changed, and the new value of the mute
* flag.
*
* The GstMixerTrack remains valid until the message is freed.
*
* Since: 0.10.14
*/
void
gst_mixer_message_parse_mute_toggled (GstMessage * message,
GstMixerTrack ** track, gboolean * mute)
{
const GstStructure *s;
g_return_if_fail (gst_mixer_message_is_mixer_message (message));
g_return_if_fail (GST_MIXER_MESSAGE_HAS_TYPE (message, MUTE_TOGGLED));
s = gst_message_get_structure (message);
if (track) {
const GValue *v = gst_structure_get_value (s, "track");
g_return_if_fail (v != NULL);
*track = (GstMixerTrack *) g_value_get_object (v);
g_return_if_fail (GST_IS_MIXER_TRACK (*track));
}
if (mute)
g_return_if_fail (gst_structure_get_boolean (s, "mute", mute));
}
/**
* gst_mixer_message_parse_record_toggled:
* @message: A record-toggled change notification message.
* @track: Pointer to hold a GstMixerTrack object, or NULL.
* @record: A pointer to a gboolean variable, or NULL.
*
* Extracts the contents of a record-toggled bus message. Reads
* the GstMixerTrack that has changed, and the new value of the
* recording flag.
*
* The GstMixerTrack remains valid until the message is freed.
*
* Since: 0.10.14
*/
void
gst_mixer_message_parse_record_toggled (GstMessage * message,
GstMixerTrack ** track, gboolean * record)
{
const GstStructure *s;
g_return_if_fail (gst_mixer_message_is_mixer_message (message));
g_return_if_fail (GST_MIXER_MESSAGE_HAS_TYPE (message, RECORD_TOGGLED));
s = gst_message_get_structure (message);
if (track) {
const GValue *v = gst_structure_get_value (s, "track");
g_return_if_fail (v != NULL);
*track = (GstMixerTrack *) g_value_get_object (v);
g_return_if_fail (GST_IS_MIXER_TRACK (*track));
}
if (record)
g_return_if_fail (gst_structure_get_boolean (s, "record", record));
}
/**
* gst_mixer_message_parse_volume_changed:
* @message: A volume-changed change notification message.
* @track: Pointer to hold a GstMixerTrack object, or NULL.
* @volumes: A pointer to receive an array of gint values, or NULL.
* @num_channels: Result location to receive the number of channels, or NULL.
*
* Parses a volume-changed notification message and extracts the track object
* it refers to, as well as an array of volumes and the size of the volumes array.
*
* The track object remains valid until the message is freed.
*
* The caller must free the array returned in the volumes parameter using g_free
* when they are done with it.
*
* Since: 0.10.14
*/
void
gst_mixer_message_parse_volume_changed (GstMessage * message,
GstMixerTrack ** track, gint ** volumes, gint * num_channels)
{
const GstStructure *s;
g_return_if_fail (gst_mixer_message_is_mixer_message (message));
g_return_if_fail (GST_MIXER_MESSAGE_HAS_TYPE (message, VOLUME_CHANGED));
s = gst_message_get_structure (message);
if (track) {
const GValue *v = gst_structure_get_value (s, "track");
g_return_if_fail (v != NULL);
*track = (GstMixerTrack *) g_value_get_object (v);
g_return_if_fail (GST_IS_MIXER_TRACK (*track));
}
if (volumes || num_channels) {
gint n_chans, i;
const GValue *v = gst_structure_get_value (s, "volumes");
g_return_if_fail (v != NULL);
g_return_if_fail (GST_VALUE_HOLDS_ARRAY (v));
n_chans = gst_value_array_get_size (v);
if (num_channels)
*num_channels = n_chans;
if (volumes) {
*volumes = g_new (gint, n_chans);
for (i = 0; i < n_chans; i++) {
const GValue *e = gst_value_array_get_value (v, i);
g_return_if_fail (e != NULL && G_VALUE_HOLDS_INT (e));
(*volumes)[i] = g_value_get_int (e);
}
}
}
}
/**
* gst_mixer_message_parse_option_changed:
* @message: A volume-changed change notification message.
* @options: Pointer to hold a GstMixerOptions object, or NULL.
* @value: Result location to receive the new options value, or NULL.
*
* Extracts the GstMixerOptions and new value from a option-changed bus notification
* message.
*
* The options and value returned remain valid until the message is freed.
*
* Since: 0.10.14
*/
void
gst_mixer_message_parse_option_changed (GstMessage * message,
GstMixerOptions ** options, const gchar ** value)
{
const GstStructure *s;
g_return_if_fail (gst_mixer_message_is_mixer_message (message));
g_return_if_fail (GST_MIXER_MESSAGE_HAS_TYPE (message, OPTION_CHANGED));
s = gst_message_get_structure (message);
if (options) {
const GValue *v = gst_structure_get_value (s, "options");
g_return_if_fail (v != NULL);
*options = (GstMixerOptions *) g_value_get_object (v);
g_return_if_fail (GST_IS_MIXER_OPTIONS (*options));
}
if (value)
*value = gst_structure_get_string (s, "value");
}
/**
* gst_mixer_message_parse_options_list_changed:
* @message: A volume-changed change notification message.
* @options: Pointer to hold a GstMixerOptions object, or NULL.
*
* Extracts the GstMixerOptions whose value list has changed from an
* options-list-changed bus notification message.
*
* The options object returned remains valid until the message is freed. You
* do not need to unref it.
*
* Since: 0.10.18
*/
void
gst_mixer_message_parse_options_list_changed (GstMessage * message,
GstMixerOptions ** options)
{
const GstStructure *s;
g_return_if_fail (gst_mixer_message_is_mixer_message (message));
g_return_if_fail (GST_MIXER_MESSAGE_HAS_TYPE (message, OPTIONS_LIST_CHANGED));
s = gst_message_get_structure (message);
if (options) {
const GValue *v = gst_structure_get_value (s, "options");
g_return_if_fail (v != NULL);
*options = (GstMixerOptions *) g_value_get_object (v);
g_return_if_fail (GST_IS_MIXER_OPTIONS (*options));
}
}