func_volume.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2011, 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: 310585 $")

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

/*** DOCUMENTATION
   <function name="VOLUME" language="en_US">
      <synopsis>
         Set the TX or RX volume of a channel.
      </synopsis>
      <syntax>
         <parameter name="direction" required="true">
            <para>Must be <literal>TX</literal> or <literal>RX</literal>.</para>
         </parameter>
         <parameter name="options">
            <optionlist>
               <option name="p">
                  <para>Enable DTMF volume control</para>
               </option>
            </optionlist>
         </parameter>
      </syntax>
      <description>
         <para>The VOLUME function can be used to increase or decrease the <literal>tx</literal> or
         <literal>rx</literal> gain of any channel.</para>
         <para>For example:</para>
         <para>Set(VOLUME(TX)=3)</para>
         <para>Set(VOLUME(RX)=2)</para>
         <para>Set(VOLUME(TX,p)=3)</para>
         <para>Set(VOLUME(RX,p)=3></para>
      </description>
   </function>
 ***/

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

enum volume_flags {
   VOLUMEFLAG_CHANGE = (1 << 1),
};

AST_APP_OPTIONS(volume_opts, {
   AST_APP_OPTION('p', VOLUMEFLAG_CHANGE),
});

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 (ast_test_flag(vi, VOLUMEFLAG_CHANGE)) {
      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;
         }
      }
   }

   
   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;

   /* Separate options from argument */
   
   AST_DECLARE_APP_ARGS(args,
      AST_APP_ARG(direction);
      AST_APP_ARG(options);
   );
   
   AST_STANDARD_APP_ARGS(args, data);

   ast_channel_lock(chan);
   if (!(datastore = ast_channel_datastore_find(chan, &volume_datastore, NULL))) {
      ast_channel_unlock(chan);
      /* 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 {
      ast_channel_unlock(chan);
      vi = datastore->data;
   }

   /* Adjust gain on volume information structure */
   if (ast_strlen_zero(args.direction)) {
      ast_log(LOG_ERROR, "Direction must be specified for VOLUME function\n");
      return -1;
   }

   if (!strcasecmp(args.direction, "tx")) { 
      vi->tx_gain = atoi(value); 
   } else if (!strcasecmp(args.direction, "rx")) {
      vi->rx_gain = atoi(value);
   } else {
      ast_log(LOG_ERROR, "Direction must be either RX or TX\n");
   }

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

   /* Add Option data to struct */
   
   if (!ast_strlen_zero(args.options)) {
      struct ast_flags flags = { 0 };
      ast_app_parse_options(volume_opts, &flags, &data, args.options);
      vi->flags = flags.flags;
   } else { 
      vi->flags = 0; 
   }

   return 0;
}

static struct ast_custom_function volume_function = {
   .name = "VOLUME",
   .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");