func_volume.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2007, Digium, Inc.
 *
 * Joshua Colp <jcolp@digium.com> 
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Technology independent volume control
 *
 * \author Joshua Colp <jcolp@digium.com> 
 *
 * \ingroup functions
 *
 */

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 135680 $")

#include "asterisk/module.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/utils.h"
#include "asterisk/audiohook.h"

struct volume_information {
   struct ast_audiohook audiohook;
   int tx_gain;
   int rx_gain;
};

static void destroy_callback(void *data)
{
   struct volume_information *vi = data;

   /* Destroy the audiohook, and destroy ourselves */
   ast_audiohook_destroy(&vi->audiohook);
   free(vi);

   return;
}

/*! \brief Static structure for datastore information */
static const struct ast_datastore_info volume_datastore = {
   .type = "volume",
   .destroy = destroy_callback
};

static int volume_callback(struct ast_audiohook *audiohook, struct ast_channel *chan, struct ast_frame *frame, enum ast_audiohook_direction direction)
{
   struct ast_datastore *datastore = NULL;
   struct volume_information *vi = NULL;
   int *gain = NULL;

   /* If the audiohook is stopping it means the channel is shutting down.... but we let the datastore destroy take care of it */
   if (audiohook->status == AST_AUDIOHOOK_STATUS_DONE)
      return 0;

   /* Grab datastore which contains our gain information */
   if (!(datastore = ast_channel_datastore_find(chan, &volume_datastore, NULL)))
      return 0;

   vi = datastore->data;

   /* If this is DTMF then allow them to increase/decrease the gains */
   if (frame->frametype == AST_FRAME_DTMF) {
      /* Only use DTMF coming from the source... not going to it */
      if (direction != AST_AUDIOHOOK_DIRECTION_READ)
         return 0;
      if (frame->subclass == '*') {
         vi->tx_gain += 1;
         vi->rx_gain += 1;
      } else if (frame->subclass == '#') {
         vi->tx_gain -= 1;
         vi->rx_gain -= 1;
      }
   } else if (frame->frametype == AST_FRAME_VOICE) {
      /* Based on direction of frame grab the gain, and confirm it is applicable */
      if (!(gain = (direction == AST_AUDIOHOOK_DIRECTION_READ) ? &vi->rx_gain : &vi->tx_gain) || !*gain)
         return 0;
      /* Apply gain to frame... easy as pi */
      ast_frame_adjust_volume(frame, *gain);
   }

   return 0;
}

static int volume_write(struct ast_channel *chan, const char *cmd, char *data, const char *value)
{
   struct ast_datastore *datastore = NULL;
   struct volume_information *vi = NULL;
   int is_new = 0;

   if (!(datastore = ast_channel_datastore_find(chan, &volume_datastore, NULL))) {
      /* Allocate a new datastore to hold the reference to this volume and audiohook information */
      if (!(datastore = ast_datastore_alloc(&volume_datastore, NULL)))
         return 0;
      if (!(vi = ast_calloc(1, sizeof(*vi)))) {
         ast_datastore_free(datastore);
         return 0;
      }
      ast_audiohook_init(&vi->audiohook, AST_AUDIOHOOK_TYPE_MANIPULATE, "Volume");
      vi->audiohook.manipulate_callback = volume_callback;
      ast_set_flag(&vi->audiohook, AST_AUDIOHOOK_WANTS_DTMF);
      is_new = 1;
   } else {
      vi = datastore->data;
   }

   /* Adjust gain on volume information structure */
   if (!strcasecmp(data, "tx"))
      vi->tx_gain = atoi(value);
   else if (!strcasecmp(data, "rx"))
      vi->rx_gain = atoi(value);

   if (is_new) {
      datastore->data = vi;
      ast_channel_datastore_add(chan, datastore);
      ast_audiohook_attach(chan, &vi->audiohook);
   }

   return 0;
}

static struct ast_custom_function volume_function = {
   .name = "VOLUME",
   .synopsis = "Set the TX or RX volume of a channel",
   .syntax = "VOLUME(TX|RX)",
   .desc =
   "  The VOLUME function can be used to increase or decrease the tx or\n"
   "rx gain of any channel.  For example:\n"
   "  Set(VOLUME(TX)=3)\n"
   "  Set(VOLUME(RX)=2)\n",
   .write = volume_write,
};

static int unload_module(void)
{
   return ast_custom_function_unregister(&volume_function);
}

static int load_module(void)
{
   return ast_custom_function_register(&volume_function);
}

AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Technology independent volume control");