func_volume.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2011, Digium, Inc.
 *
 * Joshua Colp <[email protected]>
 *
 * 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 <[email protected]>
 *
 * \ingroup functions
 *
 */

/*** MODULEINFO
 <support_level>core</support_level>
 ***/

#include "asterisk.h"

#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 or get 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;
 float tx_gain;
 float 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_lock(&vi->audiohook);
 ast_audiohook_detach(&vi->audiohook);
 ast_audiohook_unlock(&vi->audiohook);
 ast_audiohook_destroy(&vi->audiohook);
 ast_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;
 float *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.integer == '*') {
 vi->tx_gain += 1;
 vi->rx_gain += 1;
 } else if (frame->subclass.integer == '#') {
 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_float(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);
 );

 if (!chan) {
 ast_log(LOG_WARNING, "No channel was provided to %s function.\n", cmd);
 return -1;
 }

 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", AST_AUDIOHOOK_MANIPULATE_ALL_RATES);
 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 = atof(value);
 } else if (!strcasecmp(args.direction, "rx")) {
 vi->rx_gain = atof(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, NULL, args.options);
 vi->flags = flags.flags;
 } else {
 vi->flags = 0;
 }

 return 0;
}

static int volume_read(struct ast_channel *chan, const char *cmd, char *data, char *buffer, size_t buflen)
{
 struct ast_datastore *datastore = NULL;
 struct volume_information *vi = NULL;

 /* Separate options from argument */

 AST_DECLARE_APP_ARGS(args,
 AST_APP_ARG(direction);
 AST_APP_ARG(options);
 );

 if (!chan) {
 ast_log(LOG_WARNING, "No channel was provided to %s function.\n", cmd);
 return -1;
 }

 AST_STANDARD_APP_ARGS(args, data);

 ast_channel_lock(chan);
 if (!(datastore = ast_channel_datastore_find(chan, &volume_datastore, NULL))) {
 ast_channel_unlock(chan);
 return -1; /* no active audiohook, nothing to read */
 } else {
 ast_channel_unlock(chan);
 vi = datastore->data;
 }

 /* Obtain current gain using 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")) {
 snprintf(buffer, buflen, "%f", vi->tx_gain);
 } else if (!strcasecmp(args.direction, "rx")) {
 snprintf(buffer, buflen, "%f", vi->rx_gain);
 } else {
 ast_log(LOG_ERROR, "Direction must be either RX or TX\n");
 }

 return 0;
}

static struct ast_custom_function volume_function = {
 .name = "VOLUME",
 .write = volume_write,
 .read = volume_read,
};

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");