/* -*- c-basic-offset: 2 -*- * vi:si:et:sw=2:sts=8:ts=8:expandtab * * GStreamer * Copyright (C) 1999-2001 Erik Walthinsen * Copyright (C) 2005 Andy Wingo * * 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. */ /** * SECTION:element-volume * * * * The volume element changes the volume of the audio data. * * Example launch line * * * gst-launch -v -m audiotestsrc ! volume volume=0.5 ! level ! fakesink silent=TRUE * * This pipeline shows that the level of audiotestsrc has been halved * (peak values are around -6 dB and RMS around -9 dB) compared to * the same pipeline without the volume element. * * */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include #include #include #include #include #include #include #include #include #include "gstvolume.h" /* some defines for audio processing */ /* the volume factor is a range from 0.0 to (arbitrary) VOLUME_MAX_DOUBLE = 10.0 * we map 1.0 to VOLUME_UNITY_INT* */ #define VOLUME_UNITY_INT8 32 /* internal int for unity 2^(8-3) */ #define VOLUME_UNITY_INT8_BIT_SHIFT 5 /* number of bits to shift for unity */ #define VOLUME_UNITY_INT16 8192 /* internal int for unity 2^(16-3) */ #define VOLUME_UNITY_INT16_BIT_SHIFT 13 /* number of bits to shift for unity */ #define VOLUME_UNITY_INT24 2097152 /* internal int for unity 2^(24-3) */ #define VOLUME_UNITY_INT24_BIT_SHIFT 21 /* number of bits to shift for unity */ #define VOLUME_UNITY_INT32 134217728 /* internal int for unity 2^(32-5) */ #define VOLUME_UNITY_INT32_BIT_SHIFT 27 #define VOLUME_MAX_DOUBLE 10.0 #define VOLUME_MAX_INT8 G_MAXINT8 #define VOLUME_MIN_INT8 G_MININT8 #define VOLUME_MAX_INT16 G_MAXINT16 #define VOLUME_MIN_INT16 G_MININT16 #define VOLUME_MAX_INT24 8388607 #define VOLUME_MIN_INT24 -8388608 #define VOLUME_MAX_INT32 G_MAXINT32 #define VOLUME_MIN_INT32 G_MININT32 /* number of steps we use for the mixer interface to go from 0.0 to 1.0 */ # define VOLUME_STEPS 100 #define GST_CAT_DEFAULT gst_volume_debug GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT); static const GstElementDetails volume_details = GST_ELEMENT_DETAILS ("Volume", "Filter/Effect/Audio", "Set volume on audio/raw streams", "Andy Wingo "); /* Filter signals and args */ enum { /* FILL ME */ LAST_SIGNAL }; enum { PROP_0, PROP_SILENT, PROP_MUTE, PROP_VOLUME }; #define ALLOWED_CAPS \ "audio/x-raw-float, " \ "rate = (int) [ 1, MAX ], " \ "channels = (int) [ 1, MAX ], " \ "endianness = (int) BYTE_ORDER, " \ "width = (int) {32, 64}; " \ "audio/x-raw-int, " \ "channels = (int) [ 1, MAX ], " \ "rate = (int) [ 1, MAX ], " \ "endianness = (int) BYTE_ORDER, " \ "width = (int) 8, " \ "depth = (int) 8, " \ "signed = (bool) TRUE; " \ "audio/x-raw-int, " \ "channels = (int) [ 1, MAX ], " \ "rate = (int) [ 1, MAX ], " \ "endianness = (int) BYTE_ORDER, " \ "width = (int) 16, " \ "depth = (int) 16, " \ "signed = (bool) TRUE; " \ "audio/x-raw-int, " \ "channels = (int) [ 1, MAX ], " \ "rate = (int) [ 1, MAX ], " \ "endianness = (int) BYTE_ORDER, " \ "width = (int) 24, " \ "depth = (int) 24, " \ "signed = (bool) TRUE; " \ "audio/x-raw-int, " \ "channels = (int) [ 1, MAX ], " \ "rate = (int) [ 1, MAX ], " \ "endianness = (int) BYTE_ORDER, " \ "width = (int) 32, " \ "depth = (int) 32, " \ "signed = (bool) TRUE" static void gst_volume_interface_init (GstImplementsInterfaceClass * klass); static void gst_volume_mixer_init (GstMixerClass * iface); #define _init_interfaces(type) \ { \ static const GInterfaceInfo voliface_info = { \ (GInterfaceInitFunc) gst_volume_interface_init, \ NULL, \ NULL \ }; \ static const GInterfaceInfo volmixer_info = { \ (GInterfaceInitFunc) gst_volume_mixer_init, \ NULL, \ NULL \ }; \ \ g_type_add_interface_static (type, GST_TYPE_IMPLEMENTS_INTERFACE, \ &voliface_info); \ g_type_add_interface_static (type, GST_TYPE_MIXER, &volmixer_info); \ } GST_BOILERPLATE_FULL (GstVolume, gst_volume, GstAudioFilter, GST_TYPE_AUDIO_FILTER, _init_interfaces); static void volume_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec); static void volume_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec); static void volume_update_volume (const GValue * value, gpointer data); static void volume_update_mute (const GValue * value, gpointer data); static GstFlowReturn volume_transform_ip (GstBaseTransform * base, GstBuffer * outbuf); static gboolean volume_setup (GstAudioFilter * filter, GstRingBufferSpec * format); static void volume_process_double (GstVolume * this, gpointer bytes, guint n_bytes); static void volume_process_float (GstVolume * this, gpointer bytes, guint n_bytes); static void volume_process_int32 (GstVolume * this, gpointer bytes, guint n_bytes); static void volume_process_int32_clamp (GstVolume * this, gpointer bytes, guint n_bytes); static void volume_process_int24 (GstVolume * this, gpointer bytes, guint n_bytes); static void volume_process_int24_clamp (GstVolume * this, gpointer bytes, guint n_bytes); static void volume_process_int16 (GstVolume * this, gpointer bytes, guint n_bytes); static void volume_process_int16_clamp (GstVolume * this, gpointer bytes, guint n_bytes); static void volume_process_int8 (GstVolume * this, gpointer bytes, guint n_bytes); static void volume_process_int8_clamp (GstVolume * this, gpointer bytes, guint n_bytes); /* helper functions */ static gboolean volume_choose_func (GstVolume * this) { this->process = NULL; if (GST_AUDIO_FILTER (this)->format.caps == NULL) return FALSE; switch (GST_AUDIO_FILTER (this)->format.type) { case GST_BUFTYPE_LINEAR: switch (GST_AUDIO_FILTER (this)->format.width) { case 32: /* only clamp if the gain is greater than 1.0 * FIXME: real_vol_i can change while processing the buffer! */ if (this->real_vol_i32 > VOLUME_UNITY_INT32) this->process = volume_process_int32_clamp; else this->process = volume_process_int32; break; case 24: /* only clamp if the gain is greater than 1.0 * FIXME: real_vol_i can change while processing the buffer! */ if (this->real_vol_i24 > VOLUME_UNITY_INT24) this->process = volume_process_int24_clamp; else this->process = volume_process_int24; break; case 16: /* only clamp if the gain is greater than 1.0 * FIXME: real_vol_i can change while processing the buffer! */ if (this->real_vol_i16 > VOLUME_UNITY_INT16) this->process = volume_process_int16_clamp; else this->process = volume_process_int16; break; case 8: /* only clamp if the gain is greater than 1.0 * FIXME: real_vol_i can change while processing the buffer! */ if (this->real_vol_i16 > VOLUME_UNITY_INT8) this->process = volume_process_int8_clamp; else this->process = volume_process_int8; break; } break; case GST_BUFTYPE_FLOAT: switch (GST_AUDIO_FILTER (this)->format.width) { case 32: this->process = volume_process_float; break; case 64: this->process = volume_process_double; break; } break; default: break; } return (this->process != NULL); } static void volume_update_real_volume (GstVolume * this) { gboolean passthrough = FALSE; if (this->mute) { this->real_vol_f = 0.0; this->real_vol_i8 = this->real_vol_i16 = this->real_vol_i24 = this->real_vol_i32 = 0; } else { this->real_vol_f = this->volume_f; this->real_vol_i8 = this->volume_i8; this->real_vol_i16 = this->volume_i16; this->real_vol_i24 = this->volume_i24; this->real_vol_i32 = this->volume_i32; passthrough = (this->volume_i16 == VOLUME_UNITY_INT16); } if (this->real_vol_f != 0.0) this->silent_buffer = FALSE; volume_choose_func (this); gst_base_transform_set_passthrough (GST_BASE_TRANSFORM (this), passthrough); } /* Mixer interface */ static gboolean gst_volume_interface_supported (GstImplementsInterface * iface, GType type) { g_assert (type == GST_TYPE_MIXER); return TRUE; } static void gst_volume_interface_init (GstImplementsInterfaceClass * klass) { klass->supported = gst_volume_interface_supported; } static const GList * gst_volume_list_tracks (GstMixer * mixer) { GstVolume *this = GST_VOLUME (mixer); g_return_val_if_fail (this != NULL, NULL); g_return_val_if_fail (GST_IS_VOLUME (this), NULL); return this->tracklist; } static void gst_volume_set_volume (GstMixer * mixer, GstMixerTrack * track, gint * volumes) { GstVolume *this = GST_VOLUME (mixer); g_return_if_fail (this != NULL); g_return_if_fail (GST_IS_VOLUME (this)); this->volume_f = (gfloat) volumes[0] / VOLUME_STEPS; this->volume_i32 = this->volume_f * VOLUME_UNITY_INT32; this->volume_i24 = this->volume_f * VOLUME_UNITY_INT24; this->volume_i16 = this->volume_f * VOLUME_UNITY_INT16; this->volume_i8 = this->volume_f * VOLUME_UNITY_INT8; volume_update_real_volume (this); } static void gst_volume_get_volume (GstMixer * mixer, GstMixerTrack * track, gint * volumes) { GstVolume *this = GST_VOLUME (mixer); g_return_if_fail (this != NULL); g_return_if_fail (GST_IS_VOLUME (this)); volumes[0] = (gint) this->volume_f * VOLUME_STEPS; } static void gst_volume_set_mute (GstMixer * mixer, GstMixerTrack * track, gboolean mute) { GstVolume *this = GST_VOLUME (mixer); g_return_if_fail (this != NULL); g_return_if_fail (GST_IS_VOLUME (this)); this->mute = mute; volume_update_real_volume (this); } static void gst_volume_mixer_init (GstMixerClass * klass) { GST_MIXER_TYPE (klass) = GST_MIXER_SOFTWARE; /* default virtual functions */ klass->list_tracks = gst_volume_list_tracks; klass->set_volume = gst_volume_set_volume; klass->get_volume = gst_volume_get_volume; klass->set_mute = gst_volume_set_mute; } /* Element class */ static void gst_volume_dispose (GObject * object) { GstVolume *volume = GST_VOLUME (object); if (volume->tracklist) { if (volume->tracklist->data) g_object_unref (volume->tracklist->data); g_list_free (volume->tracklist); volume->tracklist = NULL; } G_OBJECT_CLASS (parent_class)->dispose (object); } static void gst_volume_base_init (gpointer g_class) { GstElementClass *element_class = GST_ELEMENT_CLASS (g_class); GstAudioFilterClass *filter_class = GST_AUDIO_FILTER_CLASS (g_class); GstCaps *caps; gst_element_class_set_details (element_class, &volume_details); caps = gst_caps_from_string (ALLOWED_CAPS); gst_audio_filter_class_add_pad_templates (filter_class, caps); gst_caps_unref (caps); } static void gst_volume_class_init (GstVolumeClass * klass) { GObjectClass *gobject_class; GstBaseTransformClass *trans_class; GstAudioFilterClass *filter_class; gobject_class = (GObjectClass *) klass; trans_class = (GstBaseTransformClass *) klass; filter_class = (GstAudioFilterClass *) (klass); gobject_class->set_property = volume_set_property; gobject_class->get_property = volume_get_property; gobject_class->dispose = gst_volume_dispose; g_object_class_install_property (gobject_class, PROP_MUTE, g_param_spec_boolean ("mute", "Mute", "mute channel", FALSE, G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE)); g_object_class_install_property (gobject_class, PROP_VOLUME, g_param_spec_double ("volume", "Volume", "volume factor", 0.0, VOLUME_MAX_DOUBLE, 1.0, G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE)); GST_DEBUG_CATEGORY_INIT (GST_CAT_DEFAULT, "volume", 0, "Volume gain"); trans_class->transform_ip = GST_DEBUG_FUNCPTR (volume_transform_ip); filter_class->setup = GST_DEBUG_FUNCPTR (volume_setup); } static void gst_volume_init (GstVolume * this, GstVolumeClass * g_class) { GstMixerTrack *track = NULL; this->mute = FALSE; this->volume_i8 = this->real_vol_i8 = VOLUME_UNITY_INT8; this->volume_i16 = this->real_vol_i16 = VOLUME_UNITY_INT16; this->volume_i24 = this->real_vol_i24 = VOLUME_UNITY_INT24; this->volume_i32 = this->real_vol_i32 = VOLUME_UNITY_INT32; this->volume_f = this->real_vol_f = 1.0; this->tracklist = NULL; track = g_object_new (GST_TYPE_MIXER_TRACK, NULL); if (GST_IS_MIXER_TRACK (track)) { track->label = g_strdup ("volume"); track->num_channels = 1; track->min_volume = 0; track->max_volume = VOLUME_STEPS; track->flags = GST_MIXER_TRACK_SOFTWARE; this->tracklist = g_list_append (this->tracklist, track); } gst_base_transform_set_gap_aware (GST_BASE_TRANSFORM (this), TRUE); } /* NOTE: although it might be tempting to have volume_process_mute() which uses * memset(bytes, 0, nbytes) for the vol=0 case, this has the downside that * unmuting would only take place after processing a buffer. */ static void volume_process_double (GstVolume * this, gpointer bytes, guint n_bytes) { gdouble *data = (gdouble *) bytes; guint i, num_samples = n_bytes / sizeof (gdouble); for (i = 0; i < num_samples; i++) { *data++ *= this->real_vol_f; } } static void volume_process_float (GstVolume * this, gpointer bytes, guint n_bytes) { gfloat *data = (gfloat *) bytes; guint num_samples = n_bytes / sizeof (gfloat); /* guint i; for (i = 0; i < num_samples; i++) { *data++ *= this->real_vol_f; } */ /* time gst-launch 2>/dev/null audiotestsrc wave=7 num-buffers=10000 ! audio/x-raw-float ! volume volume=1.5 ! fakesink * goes from 0m0.850s -> 0m0.717s with liboil */ oil_scalarmultiply_f32_ns (data, data, &this->real_vol_f, num_samples); } static void volume_process_int32 (GstVolume * this, gpointer bytes, guint n_bytes) { gint *data = (gint *) bytes; guint i, num_samples; gint64 val; num_samples = n_bytes / sizeof (gint); for (i = 0; i < num_samples; i++) { /* we use bitshifting instead of dividing by UNITY_INT for speed */ val = (gint64) * data; val = (((gint64) this->real_vol_i32 * val) >> VOLUME_UNITY_INT32_BIT_SHIFT); *data++ = (gint32) val; } } static void volume_process_int32_clamp (GstVolume * this, gpointer bytes, guint n_bytes) { gint *data = (gint *) bytes; guint i, num_samples; gint64 val; num_samples = n_bytes / sizeof (gint); for (i = 0; i < num_samples; i++) { /* we use bitshifting instead of dividing by UNITY_INT for speed */ val = (gint64) * data; val = (((gint64) this->real_vol_i32 * val) >> VOLUME_UNITY_INT32_BIT_SHIFT); *data++ = (gint32) CLAMP (val, VOLUME_MIN_INT32, VOLUME_MAX_INT32); } } #if (G_BYTE_ORDER == G_LITTLE_ENDIAN) #define get_unaligned_i24(_x) ( (((guint8*)_x)[0]) | ((((guint8*)_x)[1]) << 8) | ((((gint8*)_x)[2]) << 16) ) #define write_unaligned_u24(_x,samp) do { *(_x)++ = samp & 0xFF; *(_x)++ = (samp >> 8) & 0xFF; *(_x)++ = (samp >> 16) & 0xFF; } while (0) #else /* BIG ENDIAN */ #define get_unaligned_i24(_x) ( (((guint8*)_x)[2]) | ((((guint8*)_x)[1]) << 8) | ((((gint8*)_x)[0]) << 16) ) #define write_unaligned_u24(_x,samp) do { *(_x)++ = (samp >> 16) & 0xFF; *(_x)++ = (samp >> 8) & 0xFF; *(_x)++ = samp & 0xFF; } while (0) #endif static void volume_process_int24 (GstVolume * this, gpointer bytes, guint n_bytes) { gint8 *data = (gint8 *) bytes; /* treat the data as a byte stream */ guint i, num_samples; guint32 samp; gint64 val; num_samples = n_bytes / (sizeof (gint8) * 3); for (i = 0; i < num_samples; i++) { samp = get_unaligned_i24 (data); val = (gint32) samp; val = (((gint64) this->real_vol_i24 * val) >> VOLUME_UNITY_INT24_BIT_SHIFT); samp = (guint32) val; /* write the value back into the stream */ write_unaligned_u24 (data, samp); } } static void volume_process_int24_clamp (GstVolume * this, gpointer bytes, guint n_bytes) { gint8 *data = (gint8 *) bytes; /* treat the data as a byte stream */ guint i, num_samples; guint32 samp; gint64 val; num_samples = n_bytes / (sizeof (gint8) * 3); for (i = 0; i < num_samples; i++) { samp = get_unaligned_i24 (data); val = (gint32) samp; val = (((gint64) this->real_vol_i24 * val) >> VOLUME_UNITY_INT24_BIT_SHIFT); samp = (guint32) CLAMP (val, VOLUME_MIN_INT24, VOLUME_MAX_INT24); /* write the value back into the stream */ write_unaligned_u24 (data, samp); } } static void volume_process_int16 (GstVolume * this, gpointer bytes, guint n_bytes) { gint16 *data = (gint16 *) bytes; guint num_samples = n_bytes / sizeof (gint16); #if 1 guint i; gint val; for (i = 0; i < num_samples; i++) { /* we use bitshifting instead of dividing by UNITY_INT for speed */ val = (gint) * data; *data++ = (gint16) ((this->real_vol_i16 * val) >> VOLUME_UNITY_INT16_BIT_SHIFT); } #else /* FIXME: need oil_scalarmultiply_s16_ns ? * https://bugs.freedesktop.org/show_bug.cgi?id=7060 * code below * - crashes :/ * - real_vol_i is scaled by VOLUME_UNITY_INT16 and needs the bitshift * time gst-launch 2>/dev/null audiotestsrc wave=7 num-buffers=100 ! volume volume=1.5 ! fakesink */ oil_scalarmult_s16 (data, 0, data, 0, ((gint16 *) (void *) (&this->real_vol_i)), num_samples); #endif } static void volume_process_int16_clamp (GstVolume * this, gpointer bytes, guint n_bytes) { gint16 *data = (gint16 *) bytes; guint i, num_samples; gint val; num_samples = n_bytes / sizeof (gint16); /* FIXME: oil_scalarmultiply_s16_ns ? * https://bugs.freedesktop.org/show_bug.cgi?id=7060 */ for (i = 0; i < num_samples; i++) { /* we use bitshifting instead of dividing by UNITY_INT for speed */ val = (gint) * data; *data++ = (gint16) CLAMP ((this->real_vol_i16 * val) >> VOLUME_UNITY_INT16_BIT_SHIFT, VOLUME_MIN_INT16, VOLUME_MAX_INT16); } } static void volume_process_int8 (GstVolume * this, gpointer bytes, guint n_bytes) { gint8 *data = (gint8 *) bytes; guint num_samples = n_bytes / sizeof (gint8); guint i; gint val; for (i = 0; i < num_samples; i++) { /* we use bitshifting instead of dividing by UNITY_INT for speed */ val = (gint) * data; *data++ = (gint8) ((this->real_vol_i8 * val) >> VOLUME_UNITY_INT8_BIT_SHIFT); } } static void volume_process_int8_clamp (GstVolume * this, gpointer bytes, guint n_bytes) { gint8 *data = (gint8 *) bytes; guint i, num_samples; gint val; num_samples = n_bytes / sizeof (gint8); for (i = 0; i < num_samples; i++) { /* we use bitshifting instead of dividing by UNITY_INT for speed */ val = (gint) * data; *data++ = (gint8) CLAMP ((this->real_vol_i8 * val) >> VOLUME_UNITY_INT8_BIT_SHIFT, VOLUME_MIN_INT8, VOLUME_MAX_INT8); } } /* GstBaseTransform vmethod implementations */ /* get notified of caps and plug in the correct process function */ static gboolean volume_setup (GstAudioFilter * filter, GstRingBufferSpec * format) { GstVolume *this = GST_VOLUME (filter); if (volume_choose_func (this)) { return TRUE; } else { GST_ELEMENT_ERROR (this, CORE, NEGOTIATION, ("Invalid incoming format"), (NULL)); return FALSE; } } /* call the plugged-in process function for this instance * needs to be done with this indirection since volume_transform is * a class-global method */ static GstFlowReturn volume_transform_ip (GstBaseTransform * base, GstBuffer * outbuf) { GstVolume *this = GST_VOLUME (base); GstClockTime timestamp; /* FIXME: if controllers are bound, subdivide GST_BUFFER_SIZE into small * chunks for smooth fades, what is small? 1/10th sec. */ timestamp = GST_BUFFER_TIMESTAMP (outbuf); timestamp = gst_segment_to_stream_time (&base->segment, GST_FORMAT_TIME, timestamp); GST_DEBUG_OBJECT (base, "sync to %" GST_TIME_FORMAT, GST_TIME_ARGS (timestamp)); if (GST_CLOCK_TIME_IS_VALID (timestamp)) gst_object_sync_values (G_OBJECT (this), timestamp); /* don't process data in passthrough-mode */ if (gst_base_transform_is_passthrough (base) || GST_BUFFER_FLAG_IS_SET (outbuf, GST_BUFFER_FLAG_GAP)) return GST_FLOW_OK; if (this->real_vol_f == 0.0) this->silent_buffer = TRUE; this->process (this, GST_BUFFER_DATA (outbuf), GST_BUFFER_SIZE (outbuf)); if (this->silent_buffer) GST_BUFFER_FLAG_SET (outbuf, GST_BUFFER_FLAG_GAP); this->silent_buffer = FALSE; return GST_FLOW_OK; } static void volume_update_mute (const GValue * value, gpointer data) { GstVolume *this = (GstVolume *) data; g_return_if_fail (GST_IS_VOLUME (this)); if (G_VALUE_HOLDS_BOOLEAN (value)) { this->mute = g_value_get_boolean (value); } else if (G_VALUE_HOLDS_INT (value)) { this->mute = (g_value_get_int (value) == 1); } volume_update_real_volume (this); } static void volume_update_volume (const GValue * value, gpointer data) { GstVolume *this = (GstVolume *) data; g_return_if_fail (GST_IS_VOLUME (this)); this->volume_f = g_value_get_double (value); this->volume_i8 = this->volume_f * VOLUME_UNITY_INT8; this->volume_i16 = this->volume_f * VOLUME_UNITY_INT16; this->volume_i24 = this->volume_f * VOLUME_UNITY_INT24; this->volume_i32 = this->volume_f * VOLUME_UNITY_INT32; volume_update_real_volume (this); } static void volume_set_property (GObject * object, guint prop_id, const GValue * value, GParamSpec * pspec) { GstVolume *this = GST_VOLUME (object); switch (prop_id) { case PROP_MUTE: volume_update_mute (value, this); break; case PROP_VOLUME: volume_update_volume (value, this); break; default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); break; } } static void volume_get_property (GObject * object, guint prop_id, GValue * value, GParamSpec * pspec) { GstVolume *this = GST_VOLUME (object); switch (prop_id) { case PROP_MUTE: g_value_set_boolean (value, this->mute); break; case PROP_VOLUME: g_value_set_double (value, this->volume_f); break; default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); break; } } static gboolean plugin_init (GstPlugin * plugin) { oil_init (); /* initialize gst controller library */ gst_controller_init (NULL, NULL); return gst_element_register (plugin, "volume", GST_RANK_NONE, GST_TYPE_VOLUME); } GST_PLUGIN_DEFINE (GST_VERSION_MAJOR, GST_VERSION_MINOR, "volume", "plugin for controlling audio volume", plugin_init, VERSION, GST_LICENSE, GST_PACKAGE_NAME, GST_PACKAGE_ORIGIN);