gst_plugins_base/gst/volume/gstvolume.c
changeset 0 0e761a78d257
child 7 567bb019e3e3
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gst_plugins_base/gst/volume/gstvolume.c	Thu Dec 17 08:53:32 2009 +0200
@@ -0,0 +1,817 @@
+/* -*- c-basic-offset: 2 -*-
+ * vi:si:et:sw=2:sts=8:ts=8:expandtab
+ *
+ * GStreamer
+ * Copyright (C) 1999-2001 Erik Walthinsen <omega@cse.ogi.edu>
+ * Copyright (C) 2005 Andy Wingo <wingo@pobox.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.
+ */
+
+/**
+ * SECTION:element-volume
+ *
+ * <refsect2>
+ * <para>
+ * The volume element changes the volume of the audio data.
+ * </para>
+ * <title>Example launch line</title>
+ * <para>
+ * <programlisting>
+ * gst-launch -v -m audiotestsrc ! volume volume=0.5 ! level ! fakesink silent=TRUE
+ * </programlisting>
+ * 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.
+ * </para>
+ * </refsect2>
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+#include <gst/gst_global.h>
+#include <string.h>
+#include <gst/gst.h>
+#include <gst/base/gstbasetransform.h>
+#include <gst/audio/audio.h>
+#include <gst/interfaces/mixer.h>
+#include <gst/controller/gstcontroller.h>
+#include <gst/audio/audio.h>
+#include <gst/audio/gstaudiofilter.h>
+
+#include <gst/liboil.h>
+
+#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 <wingo@pobox.com>");
+
+/* 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)
+{
+#ifndef __SYMBIAN32__
+  oil_init ();
+#endif  
+
+  /* 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);
+
+
+#ifdef __SYMBIAN32__
+EXPORT_C 
+#endif
+GstPluginDesc* _GST_PLUGIN_DESC()
+{
+	return &gst_plugin_desc;
+}
+