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
 *
 */
 
/*** 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>
            <example title="Increase volume">
            same => n,Set(VOLUME(TX)=3)
            </example>
            <example title="Increase volume">
            same => n,Set(VOLUME(RX)=2)
            </example>
            <example title="Increase volume with DTMF control">
            same => n,Set(VOLUME(TX,p)=3)
            </example>
            <example title="Increase RX volume with DTMF control">
            same => n,Set(VOLUME(RX,p)=3)
            </example>
            <example title="Decrease RX volume">
            same => n,Set(VOLUME(RX)=-4)
            </example>
            <example title="Reset to normal">
            same => n,Set(VOLUME(RX)=0)
            </example>
        </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");