gstreamer/ext/lv2/gstlv2.c

/* GStreamer
 * Copyright (C) 1999 Erik Walthinsen <omega@cse.ogi.edu>
 *               2001 Steve Baker <stevebaker_org@yahoo.co.uk>
 *               2003 Andy Wingo <wingo at 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-lv2
 * @short_description: bridge for LV2.
 *
 * LV2 is a standard for plugins and matching host applications,
 * mainly targeted at audio processing and generation.  It is intended as
 * a successor to LADSPA (Linux Audio Developer's Simple Plugin API).
 *
 * The LV2 element is a bridge for plugins using the
 * <ulink url="http://www.lv2plug.in/">LV2</ulink> API.  It scans all
 * installed LV2 plugins and registers them as gstreamer elements.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <string.h>
#include <math.h>
#include <glib.h>
#include <gst/audio/audio.h>
#include <gst/controller/gstcontroller.h>
#include <gst/audio/multichannel.h>

#include "gstlv2.h"
#include <slv2/slv2.h>

#define GST_SLV2_PLUGIN_QDATA g_quark_from_static_string("slv2-plugin")

static void gst_lv2_set_property (GObject * object,
    guint prop_id, const GValue * value, GParamSpec * pspec);

static void gst_lv2_get_property (GObject * object,
    guint prop_id, GValue * value, GParamSpec * pspec);

static gboolean gst_lv2_setup (GstSignalProcessor * sigproc, guint sample_rate);
static gboolean gst_lv2_start (GstSignalProcessor * sigproc);
static void gst_lv2_stop (GstSignalProcessor * sigproc);
static void gst_lv2_cleanup (GstSignalProcessor * sigproc);
static void gst_lv2_process (GstSignalProcessor * sigproc, guint nframes);

static SLV2World world;
static SLV2Value audio_class;
static SLV2Value control_class;
static SLV2Value input_class;
static SLV2Value output_class;
static SLV2Value integer_prop;
static SLV2Value toggled_prop;
static SLV2Value in_place_broken_pred;
static SLV2Value in_group_pred;
static SLV2Value has_role_pred;
static SLV2Value lv2_symbol_pred;

static SLV2Value center_role;
static SLV2Value left_role;
static SLV2Value right_role;
static SLV2Value rear_center_role;
static SLV2Value rear_left_role;
static SLV2Value rear_right_role;
static SLV2Value lfe_role;
static SLV2Value center_left_role;
static SLV2Value center_right_role;
static SLV2Value side_left_role;
static SLV2Value side_right_role;

static GstSignalProcessorClass *parent_class;

static GstPlugin *gst_lv2_plugin;

GST_DEBUG_CATEGORY_STATIC (lv2_debug);
#define GST_CAT_DEFAULT lv2_debug

/** Convert an LV2 port role to a Gst channel positon
 * WARNING: If the group has only a single port,
 * GST_AUDIO_CHANNEL_POSITION_FRONT_CENTER will be returned for pg:centerRole
 * (which is used by LV2 for mono groups), but this is not correct.  In this
 * case the value must be changed to GST_AUDIO_CHANNEL_POSITION_FRONT_MONO
 * (this can't be done by this function because this information isn't known
 * at the time it is used).
 */
static GstAudioChannelPosition
gst_lv2_role_to_position (SLV2Value role)
{
  /* Front.  Mono and left/right are mututally exclusive */
  if (slv2_value_equals (role, center_role)) {

    return GST_AUDIO_CHANNEL_POSITION_FRONT_CENTER;
  } else if (slv2_value_equals (role, left_role)) {
    return GST_AUDIO_CHANNEL_POSITION_FRONT_LEFT;
  } else if (slv2_value_equals (role, right_role)) {
    return GST_AUDIO_CHANNEL_POSITION_FRONT_RIGHT;

    /* Rear. Left/right and center are mututally exclusive */
  } else if (slv2_value_equals (role, rear_center_role)) {
    return GST_AUDIO_CHANNEL_POSITION_REAR_CENTER;
  } else if (slv2_value_equals (role, rear_left_role)) {
    return GST_AUDIO_CHANNEL_POSITION_REAR_LEFT;
  } else if (slv2_value_equals (role, rear_right_role)) {
    return GST_AUDIO_CHANNEL_POSITION_REAR_RIGHT;

    /* Subwoofer/low-frequency-effects */
  } else if (slv2_value_equals (role, lfe_role)) {
    return GST_AUDIO_CHANNEL_POSITION_LFE;

    /* Center front speakers. Center and left/right_of_center
     * are mutually exclusive */
  } else if (slv2_value_equals (role, center_left_role)) {
    return GST_AUDIO_CHANNEL_POSITION_FRONT_LEFT_OF_CENTER;
  } else if (slv2_value_equals (role, center_right_role)) {
    return GST_AUDIO_CHANNEL_POSITION_FRONT_RIGHT_OF_CENTER;

    /* sides */
  } else if (slv2_value_equals (role, side_left_role)) {
    return GST_AUDIO_CHANNEL_POSITION_SIDE_LEFT;
  } else if (slv2_value_equals (role, side_right_role)) {
    return GST_AUDIO_CHANNEL_POSITION_SIDE_RIGHT;
  }

  return GST_AUDIO_CHANNEL_POSITION_INVALID;
}

/** Find and return the group @a uri in @a groups, or NULL if not found */
static GstLV2Group *
gst_lv2_class_find_group (GArray * groups, SLV2Value uri)
{
  int i = 0;
  for (; i < groups->len; ++i)
    if (slv2_value_equals (g_array_index (groups, GstLV2Group, i).uri, uri))
      return &g_array_index (groups, GstLV2Group, i);
  return NULL;
}

static GstAudioChannelPosition *
gst_lv2_build_positions (GstLV2Group * group)
{
  int i;
  GstAudioChannelPosition *positions = NULL;
  if (group->has_roles) {
    positions = malloc (group->ports->len * sizeof (GstAudioChannelPosition));
    for (i = 0; i < group->ports->len; ++i)
      positions[i] = g_array_index (group->ports, GstLV2Port, i).position;

    // Fix up mono groups (see WARNING above)
    if (group->ports->len == 1)
      positions[0] = GST_AUDIO_CHANNEL_POSITION_FRONT_MONO;
  }
  return positions;
}

static gint
gst_lv2_compare_symbol (gconstpointer a, gconstpointer b, gpointer data)
{
  return strcmp (slv2_value_as_string ((SLV2Value) a),
      slv2_value_as_string ((SLV2Value) b));
}

static void
gst_lv2_base_init (gpointer g_class)
{
  GstLV2Class *klass = (GstLV2Class *) g_class;
  GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
  GstSignalProcessorClass *gsp_class = GST_SIGNAL_PROCESSOR_CLASS (g_class);
  GstElementDetails *details;
  SLV2Plugin lv2plugin;
  SLV2Value val;
  SLV2Values values = NULL, sub_values = NULL;
  SLV2Value prev = NULL;
  GstLV2Group *group = NULL;
  GstAudioChannelPosition position = GST_AUDIO_CHANNEL_POSITION_INVALID;
  GstAudioChannelPosition mono_position = GST_AUDIO_CHANNEL_POSITION_FRONT_MONO;
  GstAudioChannelPosition *positions = NULL;
  guint j, in_pad_index = 0, out_pad_index = 0, in_prop_index = 0;
  gchar *klass_tags;
  GTree *control_port_indices = g_tree_new_full (gst_lv2_compare_symbol,
      NULL, NULL, free);

  GST_DEBUG ("base_init %p", g_class);

  lv2plugin = (SLV2Plugin) g_type_get_qdata (G_OBJECT_CLASS_TYPE (klass),
      GST_SLV2_PLUGIN_QDATA);

  g_assert (lv2plugin);

  gsp_class->num_group_in = 0;
  gsp_class->num_group_out = 0;
  gsp_class->num_audio_in = 0;
  gsp_class->num_audio_out = 0;
  gsp_class->num_control_in = 0;
  gsp_class->num_control_out = 0;

  klass->in_groups = g_array_new (FALSE, TRUE, sizeof (GstLV2Group));
  klass->out_groups = g_array_new (FALSE, TRUE, sizeof (GstLV2Group));
  klass->audio_in_ports = g_array_new (FALSE, TRUE, sizeof (GstLV2Port));
  klass->audio_out_ports = g_array_new (FALSE, TRUE, sizeof (GstLV2Port));
  klass->control_in_ports = g_array_new (FALSE, TRUE, sizeof (GstLV2Port));
  klass->control_out_ports = g_array_new (FALSE, TRUE, sizeof (GstLV2Port));

  /* find ports and groups */
  for (j = 0; j < slv2_plugin_get_num_ports (lv2plugin); j++) {
    const SLV2Port port = slv2_plugin_get_port_by_index (lv2plugin, j);
    const gboolean is_input = slv2_port_is_a (lv2plugin, port, input_class);
    gboolean in_group = FALSE;
    struct _GstLV2Port desc;
    desc.index = j;
    desc.pad = 0;
    desc.role = NULL;
    desc.position = GST_AUDIO_CHANNEL_POSITION_INVALID;

    /* we only care about audio port groups (for multi-channel) */
    if (slv2_port_is_a (lv2plugin, port, audio_class))
      values = slv2_port_get_value (lv2plugin, port, in_group_pred);
    else
      values = NULL;

    if (slv2_values_size (values) > 0) {
      /* port is part of a group */
      SLV2Value group_uri = slv2_values_get_at (values, 0);
      GArray *groups = is_input ? klass->in_groups : klass->out_groups;
      GstLV2Group *group = gst_lv2_class_find_group (groups, group_uri);
      in_group = TRUE;
      if (group == NULL) {
        GstLV2Group g;
        g.uri = slv2_value_duplicate (group_uri);
        g.pad = is_input ? in_pad_index++ : out_pad_index++;
        g.ports = g_array_new (FALSE, TRUE, sizeof (GstLV2Port));
        g.has_roles = TRUE;
        g.symbol = NULL;
        sub_values = slv2_plugin_get_value_for_subject (lv2plugin, group_uri,
            lv2_symbol_pred);
        /* symbol is mandatory */
        if (slv2_values_size (sub_values) > 0) {
          g.symbol = slv2_value_duplicate (slv2_values_get_at (sub_values, 0));
          if (!gst_element_class_get_pad_template (element_class,
                  slv2_value_as_string (g.symbol))) {
            g_array_append_val (groups, g);
            group = &g_array_index (groups, GstLV2Group, groups->len - 1);
            assert (group);
            assert (slv2_value_equals (group->uri, group_uri));
          } else {
            GST_WARNING ("plugin %s has duplicate group symbol '%s'\n",
                slv2_value_as_string (slv2_plugin_get_uri (lv2plugin)),
                slv2_value_as_string (g.symbol));
            in_group = FALSE;
          }
        } else {
          GST_WARNING ("plugin %s has illegal group with no symbol\n",
              slv2_value_as_string (slv2_plugin_get_uri (lv2plugin)));
          in_group = FALSE;
        }
      }

      if (in_group) {
        position = GST_AUDIO_CHANNEL_POSITION_INVALID;
        sub_values = slv2_port_get_value (lv2plugin, port, has_role_pred);
        if (slv2_values_size (sub_values) > 0) {
          SLV2Value role = slv2_values_get_at (sub_values, 0);
          position = gst_lv2_role_to_position (role);
        }
        slv2_values_free (sub_values);
        if (position != GST_AUDIO_CHANNEL_POSITION_INVALID) {
          desc.position = position;
          g_array_append_val (group->ports, desc);
        } else {
          in_group = FALSE;
        }
      }
    }

    if (!in_group) {
      /* port is not part of a group, or it is part of a group but that group
       * is illegal so we just ignore it */
      if (slv2_port_is_a (lv2plugin, port, audio_class)) {
        desc.pad = is_input ? in_pad_index++ : out_pad_index++;
        if (is_input) {
          g_array_append_val (klass->audio_in_ports, desc);
        } else {
          g_array_append_val (klass->audio_out_ports, desc);
        }
      } else if (slv2_port_is_a (lv2plugin, port, control_class)) {
        if (is_input) {
          gint *prop_num = malloc (sizeof (gint));
          desc.pad = in_prop_index++;
          *prop_num = desc.pad;
          g_tree_insert (control_port_indices, slv2_port_get_symbol (lv2plugin,
                  port), prop_num);
          g_array_append_val (klass->control_in_ports, desc);
        } else {
          g_array_append_val (klass->control_out_ports, desc);
        }
      } else {
        /* unknown port type */
        continue;
      }
    }
    slv2_values_free (values);
  }

  gsp_class->num_group_in = klass->in_groups->len;
  gsp_class->num_group_out = klass->out_groups->len;
  gsp_class->num_audio_in = klass->audio_in_ports->len;
  gsp_class->num_audio_out = klass->audio_out_ports->len;
  gsp_class->num_control_in = klass->control_in_ports->len;
  gsp_class->num_control_out = klass->control_out_ports->len;

  /* add input group pad templates */
  for (j = 0; j < gsp_class->num_group_in; ++j) {
    group = &g_array_index (klass->in_groups, GstLV2Group, j);
    if (group->has_roles) {
      positions = gst_lv2_build_positions (group);
    }

    gst_signal_processor_class_add_pad_template (gsp_class,
        slv2_value_as_string (group->symbol),
        GST_PAD_SINK, j, group->ports->len, positions);

    if (group->has_roles) {
      free (positions);
      positions = NULL;
    }
  }

  /* add output group pad templates */
  for (j = 0; j < gsp_class->num_group_out; ++j) {
    group = &g_array_index (klass->out_groups, GstLV2Group, j);
    if (group->has_roles) {
      positions = gst_lv2_build_positions (group);
    }

    gst_signal_processor_class_add_pad_template (gsp_class,
        slv2_value_as_string (group->symbol),
        GST_PAD_SRC, j, group->ports->len, positions);

    if (group->has_roles) {
      free (positions);
      positions = NULL;
    }
  }

  /* add non-grouped input port pad templates */
  for (j = 0; j < gsp_class->num_audio_in; ++j) {
    struct _GstLV2Port *desc =
        &g_array_index (klass->audio_in_ports, GstLV2Port, j);
    SLV2Port port = slv2_plugin_get_port_by_index (lv2plugin, desc->index);
    const gchar *name =
        slv2_value_as_string (slv2_port_get_symbol (lv2plugin, port));
    gst_signal_processor_class_add_pad_template (gsp_class, name, GST_PAD_SINK,
        j, 1, &mono_position);
  }

  /* add non-grouped output port pad templates */
  for (j = 0; j < gsp_class->num_audio_out; ++j) {
    struct _GstLV2Port *desc =
        &g_array_index (klass->audio_out_ports, GstLV2Port, j);
    SLV2Port port = slv2_plugin_get_port_by_index (lv2plugin, desc->index);
    const gchar *name =
        slv2_value_as_string (slv2_port_get_symbol (lv2plugin, port));
    gst_signal_processor_class_add_pad_template (gsp_class, name, GST_PAD_SINK,
        j, 1, &mono_position);
  }

  /* find presets */
  values = slv2_plugin_query_sparql (lv2plugin,
      "PREFIX pset: <http://lv2plug.in/ns/dev/presets#>\n"
      "PREFIX dc:   <http://dublincore.org/documents/dcmi-namespace/>\n"
      "SELECT ?preset ?name ?sym ?val WHERE {\n"
      "  <>      pset:hasPreset ?preset .\n"
      "  ?preset dc:title       ?name ;\n"
      "          lv2:port       ?port .\n"
      "  ?port   lv2:symbol     ?sym ;\n"
      "          pset:value     ?val .\n" "}\n");
  for (; !slv2_results_finished (values); slv2_results_next (values)) {
    SLV2Value preset = slv2_results_get_binding_value (values, 0);
    SLV2Value name = slv2_results_get_binding_value (values, 1);
    SLV2Value sym = slv2_results_get_binding_value (values, 2);
    SLV2Value val = slv2_results_get_binding_value (values, 3);
    GstLV2Preset *p = NULL;
    const gint *index = NULL;
    GstLV2PresetValue preset_val;

    if (!klass->presets)
      klass->presets = g_array_new (FALSE, TRUE, sizeof (GstLV2Preset));

    if (!slv2_value_equals (prev, preset)) {
      struct _GstLV2Preset new_preset;
      new_preset.uri = preset;
      new_preset.name = name;
      new_preset.values = NULL;
      g_array_append_val (klass->presets, new_preset);
    }
    p = &g_array_index (klass->presets, GstLV2Preset, klass->presets->len - 1);
    prev = p->uri;

    /* we don't understand non-float port values */
    if (!slv2_value_is_float (val)) {
      continue;
    }

    /* look up port by symbol (we need the index) */
    index = (gint *) g_tree_lookup (control_port_indices, sym);
    if (!index) {
      /* we don't know about this port, just ignore it */
      continue;
    }

    preset_val.index = *index;
    preset_val.value = slv2_value_as_float (val);
    if (!p->values)
      p->values = g_array_new (FALSE, TRUE, sizeof (GstLV2PresetValue));
    g_array_append_val (p->values, preset_val);
  }

  g_tree_destroy (control_port_indices);

  /* construct the element details struct */
  details = g_new0 (GstElementDetails, 1);
  val = slv2_plugin_get_name (lv2plugin);
  if (val) {
    details->longname = g_strdup (slv2_value_as_string (val));
    slv2_value_free (val);
  } else {
    details->longname = g_strdup ("no description available");
  }
  details->description = details->longname;
  val = slv2_plugin_get_author_name (lv2plugin);
  if (val) {
    details->author = g_strdup (slv2_value_as_string (val));
    slv2_value_free (val);
  } else {
    details->author = g_strdup ("no author available");
  }

  if (gsp_class->num_audio_in == 0)
    klass_tags = "Source/Audio/LV2";
  else if (gsp_class->num_audio_out == 0) {
    if (gsp_class->num_control_out == 0)
      klass_tags = "Sink/Audio/LV2";
    else
      klass_tags = "Sink/Analyzer/Audio/LV2";
  } else
    klass_tags = "Filter/Effect/Audio/LV2";

  details->klass = klass_tags;
  GST_INFO ("tags : %s", details->klass);
  gst_element_class_set_details (element_class, details);
  g_free (details->longname);
  g_free (details->author);
  g_free (details);

  if (!slv2_plugin_has_feature (lv2plugin, in_place_broken_pred))
    GST_SIGNAL_PROCESSOR_CLASS_SET_CAN_PROCESS_IN_PLACE (klass);

  klass->plugin = lv2plugin;
}

static gchar *
gst_lv2_class_get_param_name (GstLV2Class * klass, gint portnum)
{
  SLV2Plugin lv2plugin = klass->plugin;
  SLV2Port port = slv2_plugin_get_port_by_index (lv2plugin, portnum);
  return g_strdup (slv2_value_as_string (slv2_port_get_symbol (lv2plugin,
              port)));
}

static GParamSpec *
gst_lv2_class_get_param_spec (GstLV2Class * klass, gint portnum)
{
  SLV2Plugin lv2plugin = klass->plugin;
  SLV2Port port = slv2_plugin_get_port_by_index (lv2plugin, portnum);
  SLV2Value lv2def, lv2min, lv2max;
  GParamSpec *ret;
  gchar *name;
  gint perms;
  gfloat lower = 0.0f, upper = 1.0f, def = 0.0f;

  name = gst_lv2_class_get_param_name (klass, portnum);
  perms = G_PARAM_READABLE;
  if (slv2_port_is_a (lv2plugin, port, input_class))
    perms |= G_PARAM_WRITABLE | G_PARAM_CONSTRUCT;
  if (slv2_port_is_a (lv2plugin, port, control_class))
    perms |= GST_PARAM_CONTROLLABLE;

  if (slv2_port_has_property (lv2plugin, port, toggled_prop)) {
    ret = g_param_spec_boolean (name, name, name, FALSE, perms);
    g_free (name);
    return ret;
  }

  slv2_port_get_range (lv2plugin, port, &lv2def, &lv2min, &lv2max);

  if (lv2def)
    def = slv2_value_as_float (lv2def);
  if (lv2min)
    lower = slv2_value_as_float (lv2min);
  if (lv2max)
    upper = slv2_value_as_float (lv2max);

  slv2_value_free (lv2def);
  slv2_value_free (lv2min);
  slv2_value_free (lv2max);

  if (def < lower) {
    GST_WARNING ("%s has lower bound %f > default %f\n",
        slv2_value_as_string (slv2_plugin_get_uri (lv2plugin)), lower, def);
    lower = def;
  }

  if (def > upper) {
    GST_WARNING ("%s has upper bound %f < default %f\n",
        slv2_value_as_string (slv2_plugin_get_uri (lv2plugin)), upper, def);
    upper = def;
  }

  if (slv2_port_has_property (lv2plugin, port, integer_prop))
    ret = g_param_spec_int (name, name, name, lower, upper, def, perms);
  else
    ret = g_param_spec_float (name, name, name, lower, upper, def, perms);

  g_free (name);

  return ret;
}

static void
gst_lv2_class_init (GstLV2Class * klass, SLV2Plugin lv2plugin)
{
  GObjectClass *gobject_class;
  GstSignalProcessorClass *gsp_class;
  GParamSpec *preset_spec;
  gint i, offset = 1;

  GST_DEBUG ("class_init %p", klass);

  gobject_class = (GObjectClass *) klass;
  gobject_class->set_property = gst_lv2_set_property;
  gobject_class->get_property = gst_lv2_get_property;

  gsp_class = GST_SIGNAL_PROCESSOR_CLASS (klass);
  gsp_class->setup = gst_lv2_setup;
  gsp_class->start = gst_lv2_start;
  gsp_class->stop = gst_lv2_stop;
  gsp_class->cleanup = gst_lv2_cleanup;
  gsp_class->process = gst_lv2_process;

  klass->plugin = lv2plugin;

  /* register preset property */
  if (klass->presets) {
    gint perms =
        G_PARAM_READABLE | G_PARAM_WRITABLE | G_PARAM_CONSTRUCT |
        GST_PARAM_CONTROLLABLE;
    preset_spec =
        g_param_spec_int ("preset", "preset", "preset", 0,
        klass->presets->len - 1, 0, perms);
    g_object_class_install_property (G_OBJECT_CLASS (klass), 1, preset_spec);

    /* if there is a preset property, then port properties are offset by 2
     * relative to lv2 port index (rather than 1) */
    offset = 2;
  }

  /* register control port properties */

  for (i = 0; i < gsp_class->num_control_in; i++) {
    GParamSpec *p;

    p = gst_lv2_class_get_param_spec (klass,
        g_array_index (klass->control_in_ports, GstLV2Port, i).index);

    /* control properties have an offset of (offset) */
    g_object_class_install_property (G_OBJECT_CLASS (klass), i + offset, p);
  }

  for (i = 0; i < gsp_class->num_control_out; i++) {
    GParamSpec *p;

    p = gst_lv2_class_get_param_spec (klass,
        g_array_index (klass->control_out_ports, GstLV2Port, i).index);

    /* control properties have an offset of (offset), and we already added num_control_in */
    g_object_class_install_property (G_OBJECT_CLASS (klass),
        gsp_class->num_control_in + i + offset, p);
  }
}

static void
gst_lv2_init (GstLV2 * lv2, GstLV2Class * klass)
{
  lv2->plugin = klass->plugin;
  lv2->instance = NULL;
  lv2->activated = FALSE;
  lv2->current_preset = 0;
}

static void
gst_lv2_set_property (GObject * object, guint prop_id, const GValue * value,
    GParamSpec * pspec)
{
  GstSignalProcessor *gsp;
  GstSignalProcessorClass *gsp_class;
  GstLV2 *lv2;
  GstLV2Class *lv2_class;
  gint i;

  gsp = GST_SIGNAL_PROCESSOR (object);
  gsp_class = GST_SIGNAL_PROCESSOR_GET_CLASS (object);
  lv2 = (GstLV2 *) gsp;
  lv2_class = (GstLV2Class *) gsp_class;

  /* remember, properties have an offset of 1, or 2 if there are presets */
  prop_id--;

  if (lv2_class->presets) {
    if (prop_id == 0) {
      GstLV2Preset *preset;
      gint num = g_value_get_int (value);
      if (num > lv2_class->presets->len) {
        GST_WARNING ("Preset number out of range\n");
        return;
      }
      preset = &g_array_index (lv2_class->presets, GstLV2Preset, num);

      /* apply preset controls */
      for (i = 0; i < preset->values->len; ++i) {
        GstLV2PresetValue *preset_value =
            &g_array_index (preset->values, GstLV2PresetValue, i);
        GstLV2Port *desc =
            &g_array_index (lv2_class->control_in_ports, GstLV2Port,
            preset_value->index);
        gsp->control_in[prop_id] = preset_value->value;
      }
      lv2->current_preset = num;
      return;
    } else {
      prop_id--;
    }
  }

  /* only input ports */
  g_return_if_fail (prop_id < gsp_class->num_control_in);

  /* now see what type it is */
  switch (pspec->value_type) {
    case G_TYPE_BOOLEAN:
      gsp->control_in[prop_id] = g_value_get_boolean (value) ? 0.0f : 1.0f;
      break;
    case G_TYPE_INT:
      gsp->control_in[prop_id] = g_value_get_int (value);
      break;
    case G_TYPE_FLOAT:
      gsp->control_in[prop_id] = g_value_get_float (value);
      break;
    default:
      g_assert_not_reached ();
  }
}

static void
gst_lv2_get_property (GObject * object, guint prop_id, GValue * value,
    GParamSpec * pspec)
{
  GstSignalProcessor *gsp;
  GstSignalProcessorClass *gsp_class;
  GstLV2 *lv2;
  GstLV2Class *lv2_class;
  gfloat *controls;

  gsp = GST_SIGNAL_PROCESSOR (object);
  gsp_class = GST_SIGNAL_PROCESSOR_GET_CLASS (object);
  lv2 = (GstLV2 *) gsp;
  lv2_class = (GstLV2Class *) gsp_class;

  /* remember, properties have an offset of 1 */
  prop_id--;
  if (lv2_class->presets != NULL) {
    if (prop_id == 0) {
      g_value_set_int (value, lv2->current_preset);
      return;
    } else {
      prop_id--;
    }
  }

  if (prop_id < gsp_class->num_control_in) {
    controls = gsp->control_in;
  } else if (prop_id < gsp_class->num_control_in + gsp_class->num_control_out) {
    controls = gsp->control_out;
    prop_id -= gsp_class->num_control_in;
  } else {
    g_return_if_reached ();
  }

  /* now see what type it is */
  switch (pspec->value_type) {
    case G_TYPE_BOOLEAN:
      g_value_set_boolean (value, controls[prop_id] > 0.0f);
      break;
    case G_TYPE_INT:
      g_value_set_int (value, CLAMP (controls[prop_id], G_MININT, G_MAXINT));
      break;
    case G_TYPE_FLOAT:
      g_value_set_float (value, controls[prop_id]);
      break;
    default:
      g_return_if_reached ();
  }
}

static gboolean
gst_lv2_setup (GstSignalProcessor * gsp, guint sample_rate)
{
  GstLV2 *lv2;
  GstLV2Class *oclass;
  GstSignalProcessorClass *gsp_class;
  gint i;

  gsp_class = GST_SIGNAL_PROCESSOR_GET_CLASS (gsp);
  lv2 = (GstLV2 *) gsp;
  oclass = (GstLV2Class *) gsp_class;

  g_return_val_if_fail (lv2->activated == FALSE, FALSE);

  GST_DEBUG_OBJECT (lv2, "instantiating the plugin at %d Hz", sample_rate);

  lv2->instance = slv2_plugin_instantiate (oclass->plugin, sample_rate, NULL);

  g_return_val_if_fail (lv2->instance != NULL, FALSE);

  /* connect the control ports */
  for (i = 0; i < gsp_class->num_control_in; i++)
    slv2_instance_connect_port (lv2->instance,
        g_array_index (oclass->control_in_ports, GstLV2Port, i).index,
        &(gsp->control_in[i]));
  for (i = 0; i < gsp_class->num_control_out; i++)
    slv2_instance_connect_port (lv2->instance,
        g_array_index (oclass->control_out_ports, GstLV2Port, i).index,
        &(gsp->control_out[i]));

  return TRUE;
}

static gboolean
gst_lv2_start (GstSignalProcessor * gsp)
{
  GstLV2 *lv2 = (GstLV2 *) gsp;

  g_return_val_if_fail (lv2->activated == FALSE, FALSE);
  g_return_val_if_fail (lv2->instance != NULL, FALSE);

  GST_DEBUG_OBJECT (lv2, "activating");

  slv2_instance_activate (lv2->instance);

  lv2->activated = TRUE;

  return TRUE;
}

static void
gst_lv2_stop (GstSignalProcessor * gsp)
{
  GstLV2 *lv2 = (GstLV2 *) gsp;

  g_return_if_fail (lv2->activated == TRUE);
  g_return_if_fail (lv2->instance != NULL);

  GST_DEBUG_OBJECT (lv2, "deactivating");

  slv2_instance_deactivate (lv2->instance);

  lv2->activated = FALSE;
}

static void
gst_lv2_cleanup (GstSignalProcessor * gsp)
{
  GstLV2 *lv2 = (GstLV2 *) gsp;

  g_return_if_fail (lv2->activated == FALSE);
  g_return_if_fail (lv2->instance != NULL);

  GST_DEBUG_OBJECT (lv2, "cleaning up");

  slv2_instance_free (lv2->instance);

  lv2->instance = NULL;
}

static void
gst_lv2_process (GstSignalProcessor * gsp, guint nframes)
{
  GstSignalProcessorClass *gsp_class;
  GstLV2 *lv2;
  GstLV2Class *oclass;
  GstLV2Group *lv2_group;
  GstLV2Port *lv2_port;
  GstSignalProcessorGroup *gst_group;
  guint i, j;

  gsp_class = GST_SIGNAL_PROCESSOR_GET_CLASS (gsp);
  lv2 = (GstLV2 *) gsp;
  oclass = (GstLV2Class *) gsp_class;

  for (i = 0; i < gsp_class->num_group_in; i++) {
    lv2_group = &g_array_index (oclass->in_groups, GstLV2Group, i);
    gst_group = &gsp->group_in[i];
    for (j = 0; j < lv2_group->ports->len; ++j) {
      lv2_port = &g_array_index (lv2_group->ports, GstLV2Port, j);
      slv2_instance_connect_port (lv2->instance, lv2_port->index,
          gst_group->buffer + (j * nframes));
    }
  }
  for (i = 0; i < gsp_class->num_audio_in; i++) {
    lv2_port = &g_array_index (oclass->audio_in_ports, GstLV2Port, i);
    slv2_instance_connect_port (lv2->instance, lv2_port->index,
        gsp->audio_in[i]);
  }
  for (i = 0; i < gsp_class->num_group_out; i++) {
    lv2_group = &g_array_index (oclass->out_groups, GstLV2Group, i);
    gst_group = &gsp->group_out[i];
    for (j = 0; j < lv2_group->ports->len; ++j) {
      lv2_port = &g_array_index (lv2_group->ports, GstLV2Port, j);
      slv2_instance_connect_port (lv2->instance, lv2_port->index,
          gst_group->buffer + (j * nframes));
    }
  }
  for (i = 0; i < gsp_class->num_audio_out; i++) {
    lv2_port = &g_array_index (oclass->audio_out_ports, GstLV2Port, i);
    slv2_instance_connect_port (lv2->instance, lv2_port->index,
        gsp->audio_out[i]);
  }

  slv2_instance_run (lv2->instance, nframes);
}

/* search the plugin path
 */
static gboolean
lv2_plugin_discover (void)
{
  guint i;
  SLV2Plugins plugins = slv2_world_get_all_plugins (world);
  for (i = 0; i < slv2_plugins_size (plugins); ++i) {
    SLV2Plugin lv2plugin = slv2_plugins_get_at (plugins, i);
    GTypeInfo typeinfo = {
      sizeof (GstLV2Class),
      (GBaseInitFunc) gst_lv2_base_init,
      NULL,
      (GClassInitFunc) gst_lv2_class_init,
      NULL,
      lv2plugin,
      sizeof (GstLV2),
      0,
      (GInstanceInitFunc) gst_lv2_init,
    };

    GType type;

    /* construct the type name from plugin URI */
    gchar *type_name = g_strdup_printf ("%s",
        slv2_value_as_uri (slv2_plugin_get_uri (lv2plugin)));
    g_strcanon (type_name, G_CSET_A_2_Z G_CSET_a_2_z G_CSET_DIGITS "-+", '-');

    /* if it's already registered, drop it */
    if (g_type_from_name (type_name))
      goto next;

    /* create the type */
    type =
        g_type_register_static (GST_TYPE_SIGNAL_PROCESSOR, type_name, &typeinfo,
        0);

    /* FIXME: not needed anymore when we can add pad templates, etc in class_init
     * as class_data contains the LADSPA_Descriptor too */
    g_type_set_qdata (type, GST_SLV2_PLUGIN_QDATA, (gpointer) lv2plugin);

    if (!gst_element_register (gst_lv2_plugin, type_name, GST_RANK_NONE, type))
      goto next;

  next:
    g_free (type_name);
  }
  return TRUE;
}

static gboolean
plugin_init (GstPlugin * plugin)
{
  GST_DEBUG_CATEGORY_INIT (lv2_debug, "lv2",
      GST_DEBUG_FG_GREEN | GST_DEBUG_BG_BLACK | GST_DEBUG_BOLD, "LV2");

  world = slv2_world_new ();
  slv2_world_load_all (world);

  audio_class = slv2_value_new_uri (world, SLV2_PORT_CLASS_AUDIO);
  control_class = slv2_value_new_uri (world, SLV2_PORT_CLASS_CONTROL);
  input_class = slv2_value_new_uri (world, SLV2_PORT_CLASS_INPUT);
  output_class = slv2_value_new_uri (world, SLV2_PORT_CLASS_OUTPUT);

#define NS_LV2 "http://lv2plug.in/ns/lv2core#"
#define NS_PG  "http://lv2plug.in/ns/dev/port-groups#"

  integer_prop = slv2_value_new_uri (world, NS_LV2 "integer");
  toggled_prop = slv2_value_new_uri (world, NS_LV2 "toggled");
  in_place_broken_pred = slv2_value_new_uri (world, NS_LV2 "inPlaceBroken");
  in_group_pred = slv2_value_new_uri (world, NS_PG "inGroup");
  has_role_pred = slv2_value_new_uri (world, NS_PG "role");
  lv2_symbol_pred = slv2_value_new_string (world, NS_LV2 "symbol");

  center_role = slv2_value_new_uri (world, NS_PG "centerChannel");
  left_role = slv2_value_new_uri (world, NS_PG "leftChannel");
  right_role = slv2_value_new_uri (world, NS_PG "rightChannel");
  rear_center_role = slv2_value_new_uri (world, NS_PG "rearCenterChannel");
  rear_left_role = slv2_value_new_uri (world, NS_PG "rearLeftChannel");
  rear_right_role = slv2_value_new_uri (world, NS_PG "rearRightChannel");
  lfe_role = slv2_value_new_uri (world, NS_PG "lfeChannel");
  center_left_role = slv2_value_new_uri (world, NS_PG "centerLeftChannel");
  center_right_role = slv2_value_new_uri (world, NS_PG "centerRightChannel");
  side_left_role = slv2_value_new_uri (world, NS_PG "sideLeftChannel");
  side_right_role = slv2_value_new_uri (world, NS_PG "sideRightChannel");

  parent_class = g_type_class_ref (GST_TYPE_SIGNAL_PROCESSOR);

  gst_lv2_plugin = plugin;

  return lv2_plugin_discover ();
}

#ifdef __GNUC__
__attribute__ ((destructor))
#endif
     static void plugin_cleanup (GstPlugin * plugin)
{
  slv2_value_free (audio_class);
  slv2_value_free (control_class);
  slv2_value_free (input_class);
  slv2_value_free (output_class);

  slv2_value_free (integer_prop);
  slv2_value_free (toggled_prop);
  slv2_value_free (in_place_broken_pred);
  slv2_value_free (in_group_pred);
  slv2_value_free (has_role_pred);
  slv2_value_free (lv2_symbol_pred);

  slv2_value_free (center_role);
  slv2_value_free (left_role);
  slv2_value_free (right_role);
  slv2_value_free (rear_center_role);
  slv2_value_free (rear_left_role);
  slv2_value_free (rear_right_role);
  slv2_value_free (lfe_role);
  slv2_value_free (center_left_role);
  slv2_value_free (center_right_role);
  slv2_value_free (side_left_role);
  slv2_value_free (side_right_role);

  slv2_world_free (world);
}

GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
    GST_VERSION_MINOR,
    "lv2",
    "All LV2 plugins",
    plugin_init, VERSION, GST_LICENSE, GST_PACKAGE_NAME, GST_PACKAGE_ORIGIN)