audiohook.c

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 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 Audiohooks Architecture
 *
 * \author Joshua Colp <jcolp@digium.com>
 */

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

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision$")

#include <signal.h>

#include "asterisk/channel.h"
#include "asterisk/utils.h"
#include "asterisk/lock.h"
#include "asterisk/linkedlists.h"
#include "asterisk/audiohook.h"
#include "asterisk/slinfactory.h"
#include "asterisk/frame.h"
#include "asterisk/translate.h"
#include "asterisk/format_cache.h"

#define AST_AUDIOHOOK_SYNC_TOLERANCE 100 /*!< Tolerance in milliseconds for audiohooks synchronization */
#define AST_AUDIOHOOK_SMALL_QUEUE_TOLERANCE 100 /*!< When small queue is enabled, this is the maximum amount of audio that can remain queued at a time. */

#define DEFAULT_INTERNAL_SAMPLE_RATE 8000

struct ast_audiohook_translate {
	struct ast_trans_pvt *trans_pvt;
	struct ast_format *format;
};

struct ast_audiohook_list {
	/* If all the audiohooks in this list are capable
	 * of processing slinear at any sample rate, this
	 * variable will be set and the sample rate will
	 * be preserved during ast_audiohook_write_list()*/
	int native_slin_compatible;
	int list_internal_samp_rate;/*!< Internal sample rate used when writing to the audiohook list */

	struct ast_audiohook_translate in_translate[2];
	struct ast_audiohook_translate out_translate[2];
	AST_LIST_HEAD_NOLOCK(, ast_audiohook) spy_list;
	AST_LIST_HEAD_NOLOCK(, ast_audiohook) whisper_list;
	AST_LIST_HEAD_NOLOCK(, ast_audiohook) manipulate_list;
};

static int audiohook_set_internal_rate(struct ast_audiohook *audiohook, int rate, int reset)
{
	struct ast_format *slin;

	if (audiohook->hook_internal_samp_rate == rate) {
		return 0;
	}

	audiohook->hook_internal_samp_rate = rate;

	slin = ast_format_cache_get_slin_by_rate(rate);

	/* Setup the factories that are needed for this audiohook type */
	switch (audiohook->type) {
	case AST_AUDIOHOOK_TYPE_SPY:
	case AST_AUDIOHOOK_TYPE_WHISPER:
		if (reset) {
			ast_slinfactory_destroy(&audiohook->read_factory);
			ast_slinfactory_destroy(&audiohook->write_factory);
		}
		ast_slinfactory_init_with_format(&audiohook->read_factory, slin);
		ast_slinfactory_init_with_format(&audiohook->write_factory, slin);
		break;
	default:
		break;
	}

	return 0;
}

/*! \brief Initialize an audiohook structure
 *
 * \param audiohook Audiohook structure
 * \param type
 * \param source, init_flags
 *
 * \return Returns 0 on success, -1 on failure
 */
int ast_audiohook_init(struct ast_audiohook *audiohook, enum ast_audiohook_type type, const char *source, enum ast_audiohook_init_flags init_flags)
{
	/* Need to keep the type and source */
	audiohook->type = type;
	audiohook->source = source;

	/* Initialize lock that protects our audiohook */
	ast_mutex_init(&audiohook->lock);
	ast_cond_init(&audiohook->trigger, NULL);

	audiohook->init_flags = init_flags;

	/* initialize internal rate at 8khz, this will adjust if necessary */
	audiohook_set_internal_rate(audiohook, DEFAULT_INTERNAL_SAMPLE_RATE, 0);

	/* Since we are just starting out... this audiohook is new */
	ast_audiohook_update_status(audiohook, AST_AUDIOHOOK_STATUS_NEW);

	return 0;
}

/*! \brief Destroys an audiohook structure
 * \param audiohook Audiohook structure
 * \return Returns 0 on success, -1 on failure
 */
int ast_audiohook_destroy(struct ast_audiohook *audiohook)
{
	/* Drop the factories used by this audiohook type */
	switch (audiohook->type) {
	case AST_AUDIOHOOK_TYPE_SPY:
	case AST_AUDIOHOOK_TYPE_WHISPER:
		ast_slinfactory_destroy(&audiohook->read_factory);
		ast_slinfactory_destroy(&audiohook->write_factory);
		break;
	default:
		break;
	}

	/* Destroy translation path if present */
	if (audiohook->trans_pvt)
		ast_translator_free_path(audiohook->trans_pvt);

	ao2_cleanup(audiohook->format);

	/* Lock and trigger be gone! */
	ast_cond_destroy(&audiohook->trigger);
	ast_mutex_destroy(&audiohook->lock);

	return 0;
}

#define SHOULD_MUTE(hook, dir) \
	((ast_test_flag(hook, AST_AUDIOHOOK_MUTE_READ) && (dir == AST_AUDIOHOOK_DIRECTION_READ)) || \
	(ast_test_flag(hook, AST_AUDIOHOOK_MUTE_WRITE) && (dir == AST_AUDIOHOOK_DIRECTION_WRITE)) || \
	(ast_test_flag(hook, AST_AUDIOHOOK_MUTE_READ | AST_AUDIOHOOK_MUTE_WRITE) == (AST_AUDIOHOOK_MUTE_READ | AST_AUDIOHOOK_MUTE_WRITE)))

/*! \brief Writes a frame into the audiohook structure
 * \param audiohook Audiohook structure
 * \param direction Direction the audio frame came from
 * \param frame Frame to write in
 * \return Returns 0 on success, -1 on failure
 */
int ast_audiohook_write_frame(struct ast_audiohook *audiohook, enum ast_audiohook_direction direction, struct ast_frame *frame)
{
	struct ast_slinfactory *factory = (direction == AST_AUDIOHOOK_DIRECTION_READ ? &audiohook->read_factory : &audiohook->write_factory);
	struct ast_slinfactory *other_factory = (direction == AST_AUDIOHOOK_DIRECTION_READ ? &audiohook->write_factory : &audiohook->read_factory);
	struct timeval *rwtime = (direction == AST_AUDIOHOOK_DIRECTION_READ ? &audiohook->read_time : &audiohook->write_time), previous_time = *rwtime;
	int our_factory_samples;
	int our_factory_ms;
	int other_factory_samples;
	int other_factory_ms;

	/* Update last feeding time to be current */
	*rwtime = ast_tvnow();

	our_factory_samples = ast_slinfactory_available(factory);
	our_factory_ms = ast_tvdiff_ms(*rwtime, previous_time) + (our_factory_samples / (audiohook->hook_internal_samp_rate / 1000));
	other_factory_samples = ast_slinfactory_available(other_factory);
	other_factory_ms = other_factory_samples / (audiohook->hook_internal_samp_rate / 1000);

	if (ast_test_flag(audiohook, AST_AUDIOHOOK_TRIGGER_SYNC) && (our_factory_ms - other_factory_ms > AST_AUDIOHOOK_SYNC_TOLERANCE)) {
		ast_debug(1, "Flushing audiohook %p so it remains in sync\n", audiohook);
		ast_slinfactory_flush(factory);
		ast_slinfactory_flush(other_factory);
	}

	if (ast_test_flag(audiohook, AST_AUDIOHOOK_SMALL_QUEUE) && ((our_factory_ms > AST_AUDIOHOOK_SMALL_QUEUE_TOLERANCE) || (other_factory_ms > AST_AUDIOHOOK_SMALL_QUEUE_TOLERANCE))) {
		ast_debug(1, "Audiohook %p has stale audio in its factories. Flushing them both\n", audiohook);
		ast_slinfactory_flush(factory);
		ast_slinfactory_flush(other_factory);
	}

	/* Write frame out to respective factory */
	ast_slinfactory_feed(factory, frame);

	/* If we need to notify the respective handler of this audiohook, do so */
	if ((ast_test_flag(audiohook, AST_AUDIOHOOK_TRIGGER_MODE) == AST_AUDIOHOOK_TRIGGER_READ) && (direction == AST_AUDIOHOOK_DIRECTION_READ)) {
		ast_cond_signal(&audiohook->trigger);
	} else if ((ast_test_flag(audiohook, AST_AUDIOHOOK_TRIGGER_MODE) == AST_AUDIOHOOK_TRIGGER_WRITE) && (direction == AST_AUDIOHOOK_DIRECTION_WRITE)) {
		ast_cond_signal(&audiohook->trigger);
	} else if (ast_test_flag(audiohook, AST_AUDIOHOOK_TRIGGER_SYNC)) {
		ast_cond_signal(&audiohook->trigger);
	}

	return 0;
}

static struct ast_frame *audiohook_read_frame_single(struct ast_audiohook *audiohook, size_t samples, enum ast_audiohook_direction direction)
{
	struct ast_slinfactory *factory = (direction == AST_AUDIOHOOK_DIRECTION_READ ? &audiohook->read_factory : &audiohook->write_factory);
	int vol = (direction == AST_AUDIOHOOK_DIRECTION_READ ? audiohook->options.read_volume : audiohook->options.write_volume);
	short buf[samples];
	struct ast_frame frame = {
		.frametype = AST_FRAME_VOICE,
		.subclass.format = ast_format_cache_get_slin_by_rate(audiohook->hook_internal_samp_rate),
		.data.ptr = buf,
		.datalen = sizeof(buf),
		.samples = samples,
	};

	/* Ensure the factory is able to give us the samples we want */
	if (samples > ast_slinfactory_available(factory)) {
		return NULL;
	}

	/* Read data in from factory */
	if (!ast_slinfactory_read(factory, buf, samples)) {
		return NULL;
	}

	if (SHOULD_MUTE(audiohook, direction)) {
		/* Swap frame data for zeros if mute is required */
		ast_frame_clear(&frame);
	} else if (vol) {
		/* If a volume adjustment needs to be applied apply it */
		ast_frame_adjust_volume(&frame, vol);
	}

	return ast_frdup(&frame);
}

static struct ast_frame *audiohook_read_frame_both(struct ast_audiohook *audiohook, size_t samples, struct ast_frame **read_reference, struct ast_frame **write_reference)
{
	int count;
	int usable_read;
	int usable_write;
	short adjust_value;
	short buf1[samples];
	short buf2[samples];
	short *read_buf = NULL;
	short *write_buf = NULL;
	struct ast_frame frame = {
		.frametype = AST_FRAME_VOICE,
		.datalen = sizeof(buf1),
		.samples = samples,
	};

	/* Make sure both factories have the required samples */
	usable_read = (ast_slinfactory_available(&audiohook->read_factory) >= samples ? 1 : 0);
	usable_write = (ast_slinfactory_available(&audiohook->write_factory) >= samples ? 1 : 0);

	if (!usable_read && !usable_write) {
		/* If both factories are unusable bail out */
		ast_debug(1, "Read factory %p and write factory %p both fail to provide %zu samples\n", &audiohook->read_factory, &audiohook->write_factory, samples);
		return NULL;
	}

	/* If we want to provide only a read factory make sure we aren't waiting for other audio */
	if (usable_read && !usable_write && (ast_tvdiff_ms(ast_tvnow(), audiohook->write_time) < (samples/8)*2)) {
		ast_debug(3, "Write factory %p was pretty quick last time, waiting for them.\n", &audiohook->write_factory);
		return NULL;
	}

	/* If we want to provide only a write factory make sure we aren't waiting for other audio */
	if (usable_write && !usable_read && (ast_tvdiff_ms(ast_tvnow(), audiohook->read_time) < (samples/8)*2)) {
		ast_debug(3, "Read factory %p was pretty quick last time, waiting for them.\n", &audiohook->read_factory);
		return NULL;
	}

	/* Start with the read factory... if there are enough samples, read them in */
	if (usable_read) {
		if (ast_slinfactory_read(&audiohook->read_factory, buf1, samples)) {
			read_buf = buf1;

			if ((ast_test_flag(audiohook, AST_AUDIOHOOK_MUTE_READ))) {
				/* Clear the frame data if we are muting */
				memset(buf1, 0, sizeof(buf1));
			} else if (audiohook->options.read_volume) {
				/* Adjust read volume if need be */
				adjust_value = abs(audiohook->options.read_volume);
				for (count = 0; count < samples; count++) {
					if (audiohook->options.read_volume > 0) {
						ast_slinear_saturated_multiply(&buf1[count], &adjust_value);
					} else if (audiohook->options.read_volume < 0) {
						ast_slinear_saturated_divide(&buf1[count], &adjust_value);
					}
				}
			}
		}
	} else {
		ast_debug(1, "Failed to get %d samples from read factory %p\n", (int)samples, &audiohook->read_factory);
	}

	/* Move on to the write factory... if there are enough samples, read them in */
	if (usable_write) {
		if (ast_slinfactory_read(&audiohook->write_factory, buf2, samples)) {
			write_buf = buf2;

			if ((ast_test_flag(audiohook, AST_AUDIOHOOK_MUTE_WRITE))) {
				/* Clear the frame data if we are muting */
				memset(buf2, 0, sizeof(buf2));
			} else if (audiohook->options.write_volume) {
				/* Adjust write volume if need be */
				adjust_value = abs(audiohook->options.write_volume);
				for (count = 0; count < samples; count++) {
					if (audiohook->options.write_volume > 0) {
						ast_slinear_saturated_multiply(&buf2[count], &adjust_value);
					} else if (audiohook->options.write_volume < 0) {
						ast_slinear_saturated_divide(&buf2[count], &adjust_value);
					}
				}
			}
		}
	} else {
		ast_debug(1, "Failed to get %d samples from write factory %p\n", (int)samples, &audiohook->write_factory);
	}

	frame.subclass.format = ast_format_cache_get_slin_by_rate(audiohook->hook_internal_samp_rate);

	/* Basically we figure out which buffer to use... and if mixing can be done here */
	if (read_buf && read_reference) {
		frame.data.ptr = read_buf;
		*read_reference = ast_frdup(&frame);
	}
	if (write_buf && write_reference) {
		frame.data.ptr = write_buf;
		*write_reference = ast_frdup(&frame);
	}

	/* Make the correct buffer part of the built frame, so it gets duplicated. */
	if (read_buf) {
		frame.data.ptr = read_buf;
		if (write_buf) {
			for (count = 0; count < samples; count++) {
				ast_slinear_saturated_add(read_buf++, write_buf++);
			}
		}
	} else if (write_buf) {
		frame.data.ptr = write_buf;
	} else {
		return NULL;
	}

	/* Yahoo, a combined copy of the audio! */
	return ast_frdup(&frame);
}

static struct ast_frame *audiohook_read_frame_helper(struct ast_audiohook *audiohook, size_t samples, enum ast_audiohook_direction direction, struct ast_format *format, struct ast_frame **read_reference, struct ast_frame **write_reference)
{
	struct ast_frame *read_frame = NULL, *final_frame = NULL;
	struct ast_format *slin;

	/*
	 * Update the rate if compatibility mode is turned off or if it is
	 * turned on and the format rate is higher than the current rate.
	 *
	 * This makes it so any unnecessary rate switching/resetting does
	 * not take place and also any associated audiohook_list's internal
	 * sample rate maintains the highest sample rate between hooks.
	 */
	if (!ast_test_flag(audiohook, AST_AUDIOHOOK_COMPATIBLE) ||
	    (ast_test_flag(audiohook, AST_AUDIOHOOK_COMPATIBLE) &&
	      ast_format_get_sample_rate(format) > audiohook->hook_internal_samp_rate)) {
		audiohook_set_internal_rate(audiohook, ast_format_get_sample_rate(format), 1);
	}

	/* If the sample rate of the requested format differs from that of the underlying audiohook
	 * sample rate determine how many samples we actually need to get from the audiohook. This
	 * needs to occur as the signed linear factory stores them at the rate of the audiohook.
	 * We do this by determining the duration of audio they've requested and then determining
	 * how many samples that would be in the audiohook format.
	 */
	if (ast_format_get_sample_rate(format) != audiohook->hook_internal_samp_rate) {
		samples = (audiohook->hook_internal_samp_rate / 1000) * (samples / (ast_format_get_sample_rate(format) / 1000));
	}

	if (!(read_frame = (direction == AST_AUDIOHOOK_DIRECTION_BOTH ?
		audiohook_read_frame_both(audiohook, samples, read_reference, write_reference) :
		audiohook_read_frame_single(audiohook, samples, direction)))) {
		return NULL;
	}

	slin = ast_format_cache_get_slin_by_rate(audiohook->hook_internal_samp_rate);

	/* If they don't want signed linear back out, we'll have to send it through the translation path */
	if (ast_format_cmp(format, slin) != AST_FORMAT_CMP_EQUAL) {
		/* Rebuild translation path if different format then previously */
		if (ast_format_cmp(format, audiohook->format) == AST_FORMAT_CMP_NOT_EQUAL) {
			if (audiohook->trans_pvt) {
				ast_translator_free_path(audiohook->trans_pvt);
				audiohook->trans_pvt = NULL;
			}

			/* Setup new translation path for this format... if we fail we can't very well return signed linear so free the frame and return nothing */
			if (!(audiohook->trans_pvt = ast_translator_build_path(format, slin))) {
				ast_frfree(read_frame);
				return NULL;
			}
			ao2_replace(audiohook->format, format);
		}
		/* Convert to requested format, and allow the read in frame to be freed */
		final_frame = ast_translate(audiohook->trans_pvt, read_frame, 1);
	} else {
		final_frame = read_frame;
	}

	return final_frame;
}

/*! \brief Reads a frame in from the audiohook structure
 * \param audiohook Audiohook structure
 * \param samples Number of samples wanted in requested output format
 * \param direction Direction the audio frame came from
 * \param format Format of frame remote side wants back
 * \return Returns frame on success, NULL on failure
 */
struct ast_frame *ast_audiohook_read_frame(struct ast_audiohook *audiohook, size_t samples, enum ast_audiohook_direction direction, struct ast_format *format)
{
	return audiohook_read_frame_helper(audiohook, samples, direction, format, NULL, NULL);
}

/*! \brief Reads a frame in from the audiohook structure
 * \param audiohook Audiohook structure
 * \param samples Number of samples wanted
 * \param direction Direction the audio frame came from
 * \param format Format of frame remote side wants back
 * \param read_frame frame pointer for copying read frame data
 * \param write_frame frame pointer for copying write frame data
 * \return Returns frame on success, NULL on failure
 */
struct ast_frame *ast_audiohook_read_frame_all(struct ast_audiohook *audiohook, size_t samples, struct ast_format *format, struct ast_frame **read_frame, struct ast_frame **write_frame)
{
	return audiohook_read_frame_helper(audiohook, samples, AST_AUDIOHOOK_DIRECTION_BOTH, format, read_frame, write_frame);
}

static void audiohook_list_set_samplerate_compatibility(struct ast_audiohook_list *audiohook_list)
{
	struct ast_audiohook *ah = NULL;

	/*
	 * Anytime the samplerate compatibility is set (attach/remove an audiohook) the
	 * list's internal sample rate needs to be reset so that the next time processing
	 * through write_list, if needed, it will get updated to the correct rate.
	 *
	 * A list's internal rate always chooses the higher between its own rate and a
	 * given rate. If the current rate is being driven by an audiohook that wanted a
	 * higher rate then when this audiohook is removed the list's rate would remain
	 * at that level when it should be lower, and with no way to lower it since any
	 * rate compared against it would be lower.
	 *
	 * By setting it back to the lowest rate it can recalulate the new highest rate.
	 */
	audiohook_list->list_internal_samp_rate = DEFAULT_INTERNAL_SAMPLE_RATE;

	audiohook_list->native_slin_compatible = 1;
	AST_LIST_TRAVERSE(&audiohook_list->manipulate_list, ah, list) {
		if (!(ah->init_flags & AST_AUDIOHOOK_MANIPULATE_ALL_RATES)) {
			audiohook_list->native_slin_compatible = 0;
			return;
		}
	}
}

/*! \brief Attach audiohook to channel
 * \param chan Channel
 * \param audiohook Audiohook structure
 * \return Returns 0 on success, -1 on failure
 */
int ast_audiohook_attach(struct ast_channel *chan, struct ast_audiohook *audiohook)
{
	ast_channel_lock(chan);

	if (!ast_channel_audiohooks(chan)) {
		struct ast_audiohook_list *ahlist;
		/* Whoops... allocate a new structure */
		if (!(ahlist = ast_calloc(1, sizeof(*ahlist)))) {
			ast_channel_unlock(chan);
			return -1;
		}
		ast_channel_audiohooks_set(chan, ahlist);
		AST_LIST_HEAD_INIT_NOLOCK(&ast_channel_audiohooks(chan)->spy_list);
		AST_LIST_HEAD_INIT_NOLOCK(&ast_channel_audiohooks(chan)->whisper_list);
		AST_LIST_HEAD_INIT_NOLOCK(&ast_channel_audiohooks(chan)->manipulate_list);
		/* This sample rate will adjust as necessary when writing to the list. */
		ast_channel_audiohooks(chan)->list_internal_samp_rate = DEFAULT_INTERNAL_SAMPLE_RATE;
	}

	/* Drop into respective list */
	if (audiohook->type == AST_AUDIOHOOK_TYPE_SPY) {
		AST_LIST_INSERT_TAIL(&ast_channel_audiohooks(chan)->spy_list, audiohook, list);
	} else if (audiohook->type == AST_AUDIOHOOK_TYPE_WHISPER) {
		AST_LIST_INSERT_TAIL(&ast_channel_audiohooks(chan)->whisper_list, audiohook, list);
	} else if (audiohook->type == AST_AUDIOHOOK_TYPE_MANIPULATE) {
		AST_LIST_INSERT_TAIL(&ast_channel_audiohooks(chan)->manipulate_list, audiohook, list);
	}

	/*
	 * Initialize the audiohook's rate to the default. If it needs to be,
	 * it will get updated later.
	 */
	audiohook_set_internal_rate(audiohook, DEFAULT_INTERNAL_SAMPLE_RATE, 1);
	audiohook_list_set_samplerate_compatibility(ast_channel_audiohooks(chan));

	/* Change status over to running since it is now attached */
	ast_audiohook_update_status(audiohook, AST_AUDIOHOOK_STATUS_RUNNING);

	if (ast_channel_is_bridged(chan)) {
		ast_channel_set_unbridged_nolock(chan, 1);
	}

	ast_channel_unlock(chan);

	return 0;
}

/*! \brief Update audiohook's status
 * \param audiohook Audiohook structure
 * \param status Audiohook status enum
 *
 * \note once status is updated to DONE, this function can not be used to set the
 * status back to any other setting.  Setting DONE effectively locks the status as such.
 */

void ast_audiohook_update_status(struct ast_audiohook *audiohook, enum ast_audiohook_status status)
{
	ast_audiohook_lock(audiohook);
	if (audiohook->status != AST_AUDIOHOOK_STATUS_DONE) {
		audiohook->status = status;
		ast_cond_signal(&audiohook->trigger);
	}
	ast_audiohook_unlock(audiohook);
}

/*! \brief Detach audiohook from channel
 * \param audiohook Audiohook structure
 * \return Returns 0 on success, -1 on failure
 */
int ast_audiohook_detach(struct ast_audiohook *audiohook)
{
	if (audiohook->status == AST_AUDIOHOOK_STATUS_NEW || audiohook->status == AST_AUDIOHOOK_STATUS_DONE) {
		return 0;
	}

	ast_audiohook_update_status(audiohook, AST_AUDIOHOOK_STATUS_SHUTDOWN);

	while (audiohook->status != AST_AUDIOHOOK_STATUS_DONE) {
		ast_audiohook_trigger_wait(audiohook);
	}

	return 0;
}

void ast_audiohook_detach_list(struct ast_audiohook_list *audiohook_list)
{
	int i;
	struct ast_audiohook *audiohook;

	if (!audiohook_list) {
		return;
	}

	/* Drop any spies */
	while ((audiohook = AST_LIST_REMOVE_HEAD(&audiohook_list->spy_list, list))) {
		ast_audiohook_update_status(audiohook, AST_AUDIOHOOK_STATUS_DONE);
	}

	/* Drop any whispering sources */
	while ((audiohook = AST_LIST_REMOVE_HEAD(&audiohook_list->whisper_list, list))) {
		ast_audiohook_update_status(audiohook, AST_AUDIOHOOK_STATUS_DONE);
	}

	/* Drop any manipulaters */
	while ((audiohook = AST_LIST_REMOVE_HEAD(&audiohook_list->manipulate_list, list))) {
		ast_audiohook_update_status(audiohook, AST_AUDIOHOOK_STATUS_DONE);
		audiohook->manipulate_callback(audiohook, NULL, NULL, 0);
	}

	/* Drop translation paths if present */
	for (i = 0; i < 2; i++) {
		if (audiohook_list->in_translate[i].trans_pvt) {
			ast_translator_free_path(audiohook_list->in_translate[i].trans_pvt);
			ao2_cleanup(audiohook_list->in_translate[i].format);
		}
		if (audiohook_list->out_translate[i].trans_pvt) {
			ast_translator_free_path(audiohook_list->out_translate[i].trans_pvt);
			ao2_cleanup(audiohook_list->in_translate[i].format);
		}
	}

	/* Free ourselves */
	ast_free(audiohook_list);
}

/*! \brief find an audiohook based on its source
 * \param audiohook_list The list of audiohooks to search in
 * \param source The source of the audiohook we wish to find
 * \return Return the corresponding audiohook or NULL if it cannot be found.
 */
static struct ast_audiohook *find_audiohook_by_source(struct ast_audiohook_list *audiohook_list, const char *source)
{
	struct ast_audiohook *audiohook = NULL;

	AST_LIST_TRAVERSE(&audiohook_list->spy_list, audiohook, list) {
		if (!strcasecmp(audiohook->source, source)) {
			return audiohook;
		}
	}

	AST_LIST_TRAVERSE(&audiohook_list->whisper_list, audiohook, list) {
		if (!strcasecmp(audiohook->source, source)) {
			return audiohook;
		}
	}

	AST_LIST_TRAVERSE(&audiohook_list->manipulate_list, audiohook, list) {
		if (!strcasecmp(audiohook->source, source)) {
			return audiohook;
		}
	}

	return NULL;
}

static void audiohook_move(struct ast_channel *old_chan, struct ast_channel *new_chan, struct ast_audiohook *audiohook)
{
	enum ast_audiohook_status oldstatus;

	/* By locking both channels and the audiohook, we can assure that
	 * another thread will not have a chance to read the audiohook's status
	 * as done, even though ast_audiohook_remove signals the trigger
	 * condition.
	 */
	ast_audiohook_lock(audiohook);
	oldstatus = audiohook->status;

	ast_audiohook_remove(old_chan, audiohook);
	ast_audiohook_attach(new_chan, audiohook);

	audiohook->status = oldstatus;
	ast_audiohook_unlock(audiohook);
}

void ast_audiohook_move_by_source(struct ast_channel *old_chan, struct ast_channel *new_chan, const char *source)
{
	struct ast_audiohook *audiohook;

	if (!ast_channel_audiohooks(old_chan)) {
		return;
	}

	audiohook = find_audiohook_by_source(ast_channel_audiohooks(old_chan), source);
	if (!audiohook) {
		return;
	}

	audiohook_move(old_chan, new_chan, audiohook);
}

void ast_audiohook_move_all(struct ast_channel *old_chan, struct ast_channel *new_chan)
{
	struct ast_audiohook *audiohook;
	struct ast_audiohook_list *audiohook_list;

	audiohook_list = ast_channel_audiohooks(old_chan);
	if (!audiohook_list) {
		return;
	}

	AST_LIST_TRAVERSE_SAFE_BEGIN(&audiohook_list->spy_list, audiohook, list) {
		audiohook_move(old_chan, new_chan, audiohook);
	}
	AST_LIST_TRAVERSE_SAFE_END;

	AST_LIST_TRAVERSE_SAFE_BEGIN(&audiohook_list->whisper_list, audiohook, list) {
		audiohook_move(old_chan, new_chan, audiohook);
	}
	AST_LIST_TRAVERSE_SAFE_END;

	AST_LIST_TRAVERSE_SAFE_BEGIN(&audiohook_list->manipulate_list, audiohook, list) {
		audiohook_move(old_chan, new_chan, audiohook);
	}
	AST_LIST_TRAVERSE_SAFE_END;
}

/*! \brief Detach specified source audiohook from channel
 * \param chan Channel to detach from
 * \param source Name of source to detach
 * \return Returns 0 on success, -1 on failure
 */
int ast_audiohook_detach_source(struct ast_channel *chan, const char *source)
{
	struct ast_audiohook *audiohook = NULL;

	ast_channel_lock(chan);

	/* Ensure the channel has audiohooks on it */
	if (!ast_channel_audiohooks(chan)) {
		ast_channel_unlock(chan);
		return -1;
	}

	audiohook = find_audiohook_by_source(ast_channel_audiohooks(chan), source);

	ast_channel_unlock(chan);

	if (audiohook && audiohook->status != AST_AUDIOHOOK_STATUS_DONE) {
		ast_audiohook_update_status(audiohook, AST_AUDIOHOOK_STATUS_SHUTDOWN);
	}

	return (audiohook ? 0 : -1);
}

/*!
 * \brief Remove an audiohook from a specified channel
 *
 * \param chan Channel to remove from
 * \param audiohook Audiohook to remove
 *
 * \return Returns 0 on success, -1 on failure
 *
 * \note The channel does not need to be locked before calling this function
 */
int ast_audiohook_remove(struct ast_channel *chan, struct ast_audiohook *audiohook)
{
	ast_channel_lock(chan);

	if (!ast_channel_audiohooks(chan)) {
		ast_channel_unlock(chan);
		return -1;
	}

	if (audiohook->type == AST_AUDIOHOOK_TYPE_SPY) {
		AST_LIST_REMOVE(&ast_channel_audiohooks(chan)->spy_list, audiohook, list);
	} else if (audiohook->type == AST_AUDIOHOOK_TYPE_WHISPER) {
		AST_LIST_REMOVE(&ast_channel_audiohooks(chan)->whisper_list, audiohook, list);
	} else if (audiohook->type == AST_AUDIOHOOK_TYPE_MANIPULATE) {
		AST_LIST_REMOVE(&ast_channel_audiohooks(chan)->manipulate_list, audiohook, list);
	}

	audiohook_list_set_samplerate_compatibility(ast_channel_audiohooks(chan));
	ast_audiohook_update_status(audiohook, AST_AUDIOHOOK_STATUS_DONE);

	if (ast_channel_is_bridged(chan)) {
		ast_channel_set_unbridged_nolock(chan, 1);
	}

	ast_channel_unlock(chan);

	return 0;
}

/*! \brief Pass a DTMF frame off to be handled by the audiohook core
 * \param chan Channel that the list is coming off of
 * \param audiohook_list List of audiohooks
 * \param direction Direction frame is coming in from
 * \param frame The frame itself
 * \return Return frame on success, NULL on failure
 */
static struct ast_frame *dtmf_audiohook_write_list(struct ast_channel *chan, struct ast_audiohook_list *audiohook_list, enum ast_audiohook_direction direction, struct ast_frame *frame)
{
	struct ast_audiohook *audiohook = NULL;
	int removed = 0;

	AST_LIST_TRAVERSE_SAFE_BEGIN(&audiohook_list->manipulate_list, audiohook, list) {
		ast_audiohook_lock(audiohook);
		if (audiohook->status != AST_AUDIOHOOK_STATUS_RUNNING) {
			AST_LIST_REMOVE_CURRENT(list);
			removed = 1;
			ast_audiohook_update_status(audiohook, AST_AUDIOHOOK_STATUS_DONE);
			ast_audiohook_unlock(audiohook);
			audiohook->manipulate_callback(audiohook, NULL, NULL, 0);
			if (ast_channel_is_bridged(chan)) {
				ast_channel_set_unbridged_nolock(chan, 1);
			}
			continue;
		}
		if (ast_test_flag(audiohook, AST_AUDIOHOOK_WANTS_DTMF)) {
			audiohook->manipulate_callback(audiohook, chan, frame, direction);
		}
		ast_audiohook_unlock(audiohook);
	}
	AST_LIST_TRAVERSE_SAFE_END;

	/* if an audiohook got removed, reset samplerate compatibility */
	if (removed) {
		audiohook_list_set_samplerate_compatibility(audiohook_list);
	}
	return frame;
}

static struct ast_frame *audiohook_list_translate_to_slin(struct ast_audiohook_list *audiohook_list,
	enum ast_audiohook_direction direction, struct ast_frame *frame)
{
	struct ast_audiohook_translate *in_translate = (direction == AST_AUDIOHOOK_DIRECTION_READ ?
		&audiohook_list->in_translate[0] : &audiohook_list->in_translate[1]);
	struct ast_frame *new_frame = frame;
	struct ast_format *slin;

	/*
	 * If we are capable of sample rates other that 8khz, update the internal
	 * audiohook_list's rate and higher sample rate audio arrives. If native
	 * slin compatibility is turned on all audiohooks in the list will be
	 * updated as well during read/write processing.
	 */
	audiohook_list->list_internal_samp_rate =
		MAX(ast_format_get_sample_rate(frame->subclass.format), audiohook_list->list_internal_samp_rate);

	slin = ast_format_cache_get_slin_by_rate(audiohook_list->list_internal_samp_rate);
	if (ast_format_cmp(frame->subclass.format, slin) == AST_FORMAT_CMP_EQUAL) {
		return new_frame;
	}

	if (!in_translate->format ||
		ast_format_cmp(frame->subclass.format, in_translate->format) != AST_FORMAT_CMP_EQUAL) {
		struct ast_trans_pvt *new_trans;

		new_trans = ast_translator_build_path(slin, frame->subclass.format);
		if (!new_trans) {
			return NULL;
		}

		if (in_translate->trans_pvt) {
			ast_translator_free_path(in_translate->trans_pvt);
		}
		in_translate->trans_pvt = new_trans;

		ao2_replace(in_translate->format, frame->subclass.format);
	}

	if (!(new_frame = ast_translate(in_translate->trans_pvt, frame, 0))) {
		return NULL;
	}

	return new_frame;
}

static struct ast_frame *audiohook_list_translate_to_native(struct ast_audiohook_list *audiohook_list,
	enum ast_audiohook_direction direction, struct ast_frame *slin_frame, struct ast_format *outformat)
{
	struct ast_audiohook_translate *out_translate = (direction == AST_AUDIOHOOK_DIRECTION_READ ? &audiohook_list->out_translate[0] : &audiohook_list->out_translate[1]);
	struct ast_frame *outframe = NULL;
	if (ast_format_cmp(slin_frame->subclass.format, outformat) == AST_FORMAT_CMP_NOT_EQUAL) {
		/* rebuild translators if necessary */
		if (ast_format_cmp(out_translate->format, outformat) == AST_FORMAT_CMP_NOT_EQUAL) {
			if (out_translate->trans_pvt) {
				ast_translator_free_path(out_translate->trans_pvt);
			}
			if (!(out_translate->trans_pvt = ast_translator_build_path(outformat, slin_frame->subclass.format))) {
				return NULL;
			}
			ao2_replace(out_translate->format, outformat);
		}
		/* translate back to the format the frame came in as. */
		if (!(outframe = ast_translate(out_translate->trans_pvt, slin_frame, 0))) {
			return NULL;
		}
	}
	return outframe;
}

/*!
 *\brief Set the audiohook's internal sample rate to the audiohook_list's rate,
 *       but only when native slin compatibility is turned on.
 *
 * \param audiohook_list audiohook_list data object
 * \param audiohook the audiohook to update
 * \param rate the current max internal sample rate
 */
static void audiohook_list_set_hook_rate(struct ast_audiohook_list *audiohook_list,
					 struct ast_audiohook *audiohook, int *rate)
{
	/* The rate should always be the max between itself and the hook */
	if (audiohook->hook_internal_samp_rate > *rate) {
		*rate = audiohook->hook_internal_samp_rate;
	}

	/*
	 * If native slin compatibility is turned on then update the audiohook
	 * with the audiohook_list's current rate. Note, the audiohook's rate is
	 * set to the audiohook_list's rate and not the given rate. If there is
	 * a change in rate the hook's rate is changed on its next check.
	 */
	if (audiohook_list->native_slin_compatible) {
		ast_set_flag(audiohook, AST_AUDIOHOOK_COMPATIBLE);
		audiohook_set_internal_rate(audiohook, audiohook_list->list_internal_samp_rate, 1);
	} else {
		ast_clear_flag(audiohook, AST_AUDIOHOOK_COMPATIBLE);
	}
}

/*!
 * \brief Pass an AUDIO frame off to be handled by the audiohook core
 *
 * \details
 * This function has 3 ast_frames and 3 parts to handle each.  At the beginning of this
 * function all 3 frames, start_frame, middle_frame, and end_frame point to the initial
 * input frame.
 *
 * Part_1: Translate the start_frame into SLINEAR audio if it is not already in that
 *         format.  The result of this part is middle_frame is guaranteed to be in
 *         SLINEAR format for Part_2.
 * Part_2: Send middle_frame off to spies and manipulators.  At this point middle_frame is
 *         either a new frame as result of the translation, or points directly to the start_frame
 *         because no translation to SLINEAR audio was required.
 * Part_3: Translate end_frame's audio back into the format of start frame if necessary.  This
 *         is only necessary if manipulation of middle_frame occurred.
 *
 * \param chan Channel that the list is coming off of
 * \param audiohook_list List of audiohooks
 * \param direction Direction frame is coming in from
 * \param frame The frame itself
 * \return Return frame on success, NULL on failure
 */
static struct ast_frame *audio_audiohook_write_list(struct ast_channel *chan, struct ast_audiohook_list *audiohook_list, enum ast_audiohook_direction direction, struct ast_frame *frame)
{
	struct ast_frame *start_frame = frame, *middle_frame = frame, *end_frame = frame;
	struct ast_audiohook *audiohook = NULL;
	int samples;
	int middle_frame_manipulated = 0;
	int removed = 0;
	int internal_sample_rate;

	/* ---Part_1. translate start_frame to SLINEAR if necessary. */
	if (!(middle_frame = audiohook_list_translate_to_slin(audiohook_list, direction, start_frame))) {
		return frame;
	}

	/* If the translation resulted in an interpolated frame then immediately return as audiohooks
	 * rely on actual media being present to do things.
	 */
	if (!middle_frame->data.ptr) {
		if (middle_frame != start_frame) {
			ast_frfree(middle_frame);
		}
		return start_frame;
	}

	samples = middle_frame->samples;

	/*
	 * While processing each audiohook check to see if the internal sample rate needs
	 * to be adjusted (it should be the highest rate specified between formats and
	 * hooks). The given audiohook_list's internal sample rate is then set to the
	 * updated value before returning.
	 *
	 * If slin compatibility mode is turned on then an audiohook's internal sample
	 * rate is set to its audiohook_list's rate. If an audiohook_list's rate is
	 * adjusted during this pass then the change is picked up by the audiohooks
	 * on the next pass.
	 */
	internal_sample_rate = audiohook_list->list_internal_samp_rate;

	/* ---Part_2: Send middle_frame to spy and manipulator lists.  middle_frame is guaranteed to be SLINEAR here.*/
	/* Queue up signed linear frame to each spy */
	AST_LIST_TRAVERSE_SAFE_BEGIN(&audiohook_list->spy_list, audiohook, list) {
		ast_audiohook_lock(audiohook);
		if (audiohook->status != AST_AUDIOHOOK_STATUS_RUNNING) {
			AST_LIST_REMOVE_CURRENT(list);
			removed = 1;
			ast_audiohook_update_status(audiohook, AST_AUDIOHOOK_STATUS_DONE);
			ast_audiohook_unlock(audiohook);
			if (ast_channel_is_bridged(chan)) {
				ast_channel_set_unbridged_nolock(chan, 1);
			}
			continue;
		}
		audiohook_list_set_hook_rate(audiohook_list, audiohook, &internal_sample_rate);
		ast_audiohook_write_frame(audiohook, direction, middle_frame);
		ast_audiohook_unlock(audiohook);
	}
	AST_LIST_TRAVERSE_SAFE_END;

	/* If this frame is being written out to the channel then we need to use whisper sources */
	if (!AST_LIST_EMPTY(&audiohook_list->whisper_list)) {
		int i = 0;
		short read_buf[samples], combine_buf[samples], *data1 = NULL, *data2 = NULL;
		memset(&combine_buf, 0, sizeof(combine_buf));
		AST_LIST_TRAVERSE_SAFE_BEGIN(&audiohook_list->whisper_list, audiohook, list) {
			struct ast_slinfactory *factory = (direction == AST_AUDIOHOOK_DIRECTION_READ ? &audiohook->read_factory : &audiohook->write_factory);
			ast_audiohook_lock(audiohook);
			if (audiohook->status != AST_AUDIOHOOK_STATUS_RUNNING) {
				AST_LIST_REMOVE_CURRENT(list);