translate.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2006, Digium, Inc.
 *
 * Mark Spencer <[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 Translate via the use of pseudo channels
 *
 * \author Mark Spencer <[email protected]>
 */

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

#include "asterisk.h"

#include <sys/time.h>
#include <sys/resource.h>
#include <math.h>

#include "asterisk/lock.h"
#include "asterisk/channel.h"
#include "asterisk/translate.h"
#include "asterisk/module.h"
#include "asterisk/frame.h"
#include "asterisk/sched.h"
#include "asterisk/cli.h"
#include "asterisk/term.h"
#include "asterisk/format.h"
#include "asterisk/linkedlists.h"

/*! \todo
 * TODO: sample frames for each supported input format.
 * We build this on the fly, by taking an SLIN frame and using
 * the existing converter to play with it.
 */

/*! max sample recalc */
#define MAX_RECALC 1000

/*! \brief the list of translators */
static AST_RWLIST_HEAD_STATIC(translators, ast_translator);

struct translator_path {
 struct ast_translator *step; /*!< Next step translator */
 uint32_t table_cost; /*!< Complete table cost to destination */
 uint8_t multistep; /*!< Multiple conversions required for this translation */
};

/*!
 * \brief a matrix that, for any pair of supported formats,
 * indicates the total cost of translation and the first step.
 * The full path can be reconstricted iterating on the matrix
 * until step->dstfmt == desired_format.
 *
 * Array indexes are 'src' and 'dest', in that order.
 *
 * Note: the lock in the 'translators' list is also used to protect
 * this structure.
 */
static struct translator_path **__matrix;

/*!
 * \brief table for converting index to format values.
 *
 * \note this table is protected by the table_lock.
 */
static unsigned int *__indextable;

/*! protects the __indextable for resizing */
static ast_rwlock_t tablelock;

/* index size starts at this*/
#define INIT_INDEX 32
/* index size grows by this as necessary */
#define GROW_INDEX 16

/*! the current largest index used by the __matrix and __indextable arrays*/
static int cur_max_index;
/*! the largest index that can be used in either the __indextable or __matrix before resize must occur */
static int index_size;

static void matrix_rebuild(int samples);

/*!
 * \internal
 * \brief converts codec id to index value.
 */
static int codec_to_index(unsigned int id)
{
 int x;

 ast_rwlock_rdlock(&tablelock);
 for (x = 0; x < cur_max_index; x++) {
 if (__indextable[x] == id) {
 /* format already exists in index2format table */
 ast_rwlock_unlock(&tablelock);
 return x;
 }
 }
 ast_rwlock_unlock(&tablelock);
 return -1; /* not found */
}

/*!
 * \internal
 * \brief converts codec to index value.
 */
static int codec2index(struct ast_codec *codec)
{
 return codec_to_index(codec->id);
}

/*!
 * \internal
 * \brief converts format to codec index value.
 */
static int format2index(struct ast_format *format)
{
 return codec_to_index(ast_format_get_codec_id(format));
}

/*!
 * \internal
 * \brief add a new codec to the matrix and index table structures.
 *
 * \note it is perfectly safe to call this on codecs already indexed.
 *
 * \retval 0, success
 * \retval -1, matrix and index table need to be resized
 */
static int add_codec2index(struct ast_codec *codec)
{
 if (codec2index(codec) != -1) {
 /* format is already already indexed */
 return 0;
 }

 ast_rwlock_wrlock(&tablelock);
 if (cur_max_index == (index_size)) {
 ast_rwlock_unlock(&tablelock);
 return -1; /* hit max length */
 }
 __indextable[cur_max_index] = codec->id;
 cur_max_index++;
 ast_rwlock_unlock(&tablelock);

 return 0;
}

/*!
 * \internal
 * \brief converts index value back to codec
 */
static struct ast_codec *index2codec(int index)
{
 struct ast_codec *codec;

 if (index >= cur_max_index) {
 return 0;
 }
 ast_rwlock_rdlock(&tablelock);
 codec = ast_codec_get_by_id(__indextable[index]);
 ast_rwlock_unlock(&tablelock);

 return codec;
}

/*!
 * \internal
 * \brief resize both the matrix and index table so they can represent
 * more translators
 *
 * \note _NO_ locks can be held prior to calling this function
 *
 * \retval 0, success
 * \retval -1, failure. Old matrix and index table can still be used though
 */
static int matrix_resize(int init)
{
 struct translator_path **tmp_matrix = NULL;
 unsigned int *tmp_table = NULL;
 int old_index;
 int x;

 AST_RWLIST_WRLOCK(&translators);
 ast_rwlock_wrlock(&tablelock);

 old_index = index_size;
 if (init) {
 index_size += INIT_INDEX;
 } else {
 index_size += GROW_INDEX;
 }

 /* make new 2d array of translator_path structures */
 if (!(tmp_matrix = ast_calloc(1, sizeof(struct translator_path *) * (index_size)))) {
 goto resize_cleanup;
 }

 for (x = 0; x < index_size; x++) {
 if (!(tmp_matrix[x] = ast_calloc(1, sizeof(struct translator_path) * (index_size)))) {
 goto resize_cleanup;
 }
 }

 /* make new index table */
 if (!(tmp_table = ast_calloc(1, sizeof(unsigned int) * index_size))) {
 goto resize_cleanup;
 }

 /* if everything went well this far, free the old and use the new */
 if (!init) {
 for (x = 0; x < old_index; x++) {
 ast_free(__matrix[x]);
 }
 ast_free(__matrix);

 memcpy(tmp_table, __indextable, sizeof(unsigned int) * old_index);
 ast_free(__indextable);
 }

 /* now copy them over */
 __matrix = tmp_matrix;
 __indextable = tmp_table;

 matrix_rebuild(0);
 ast_rwlock_unlock(&tablelock);
 AST_RWLIST_UNLOCK(&translators);

 return 0;

resize_cleanup:
 ast_rwlock_unlock(&tablelock);
 AST_RWLIST_UNLOCK(&translators);
 if (tmp_matrix) {
 for (x = 0; x < index_size; x++) {
 ast_free(tmp_matrix[x]);
 }
 ast_free(tmp_matrix);
 }
 ast_free(tmp_table);

 return -1;
}

/*!
 * \internal
 * \brief reinitialize the __matrix during matrix rebuild
 *
 * \note must be protected by the translators list lock
 */
static void matrix_clear(void)
{
 int x;
 for (x = 0; x < index_size; x++) {
 memset(__matrix[x], '\0', sizeof(struct translator_path) * (index_size));
 }
}

/*!
 * \internal
 * \brief get a matrix entry
 *
 * \note This function must be protected by the translators list lock
 */
static struct translator_path *matrix_get(unsigned int x, unsigned int y)
{
 return __matrix[x] + y;
}

/*
 * wrappers around the translator routines.
 */

static void destroy(struct ast_trans_pvt *pvt)
{
 struct ast_translator *t = pvt->t;

 if (t->destroy) {
 t->destroy(pvt);
 }
 ao2_cleanup(pvt->f.subclass.format);
 if (pvt->explicit_dst) {
 ao2_ref(pvt->explicit_dst, -1);
 pvt->explicit_dst = NULL;
 }
 ast_free(pvt);
 ast_module_unref(t->module);
}

/*!
 * \brief Allocate the descriptor, required outbuf space,
 * and possibly desc.
 */
static struct ast_trans_pvt *newpvt(struct ast_translator *t, struct ast_format *explicit_dst)
{
 struct ast_trans_pvt *pvt;
 int len;
 char *ofs;

 /*
 * compute the required size adding private descriptor,
 * buffer, AST_FRIENDLY_OFFSET.
 */
 len = sizeof(*pvt) + t->desc_size;
 if (t->buf_size)
 len += AST_FRIENDLY_OFFSET + t->buf_size;
 pvt = ast_calloc(1, len);
 if (!pvt) {
 return NULL;
 }
 pvt->t = t;
 ofs = (char *)(pvt + 1); /* pointer to data space */
 if (t->desc_size) { /* first comes the descriptor */
 pvt->pvt = ofs;
 ofs += t->desc_size;
 }
 if (t->buf_size) {/* finally buffer and header */
 pvt->outbuf.c = ofs + AST_FRIENDLY_OFFSET;
 }
 /*
 * If the format has an attribute module, explicit_dst includes the (joined)
 * result of the SDP negotiation. For example with the Opus Codec, the format
 * knows whether both parties want to do forward-error correction (FEC).
 */
 pvt->explicit_dst = ao2_bump(explicit_dst);

 ast_module_ref(t->module);

 /* call local init routine, if present */
 if (t->newpvt && t->newpvt(pvt)) {
 ast_free(pvt);
 ast_module_unref(t->module);
 return NULL;
 }

 /* Setup normal static translation frame. */
 pvt->f.frametype = AST_FRAME_VOICE;
 pvt->f.mallocd = 0;
 pvt->f.offset = AST_FRIENDLY_OFFSET;
 pvt->f.src = pvt->t->name;
 pvt->f.data.ptr = pvt->outbuf.c;

 /*
 * If the translator has not provided a format
 * A) use the joined one,
 * B) use the cached one, or
 * C) create one.
 */
 if (!pvt->f.subclass.format) {
 pvt->f.subclass.format = ao2_bump(pvt->explicit_dst);

 if (!pvt->f.subclass.format && !ast_strlen_zero(pvt->t->format)) {
 pvt->f.subclass.format = ast_format_cache_get(pvt->t->format);
 }

 if (!pvt->f.subclass.format) {
 struct ast_codec *codec = ast_codec_get(t->dst_codec.name,
 t->dst_codec.type, t->dst_codec.sample_rate);
 if (!codec) {
 ast_log(LOG_ERROR, "Unable to get destination codec\n");
 destroy(pvt);
 return NULL;
 }
 pvt->f.subclass.format = ast_format_create(codec);
 ao2_ref(codec, -1);
 }

 if (!pvt->f.subclass.format) {
 ast_log(LOG_ERROR, "Unable to create format\n");
 destroy(pvt);
 return NULL;
 }
 }

 return pvt;
}

/*! \brief framein wrapper, deals with bound checks. */
static int framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
{
 /* Copy the last in jb timing info to the pvt */
 ast_copy_flags(&pvt->f, f, AST_FRFLAG_HAS_TIMING_INFO);
 pvt->f.ts = f->ts;
 pvt->f.len = f->len;
 pvt->f.seqno = f->seqno;

 if (f->samples == 0) {
 /* Do not log empty audio frame */
 if (!f->src || strcasecmp(f->src, "ast_prod")) {
 ast_log(LOG_WARNING, "no samples for %s\n", pvt->t->name);
 }
 }
 if (pvt->t->buffer_samples) { /* do not pass empty frames to callback */
 int src_srate = pvt->t->src_codec.sample_rate;
 int dst_srate = pvt->t->dst_codec.sample_rate;

 ast_assert(src_srate > 0);

 if (f->datalen == 0) { /* perform native PLC if available */
 /* If the codec has native PLC, then do that */
 if (!pvt->t->native_plc)
 return 0;
 }

 if (pvt->samples + (f->samples * dst_srate / src_srate) > pvt->t->buffer_samples) {
 ast_log(LOG_WARNING, "Out of buffer space\n");
 return -1;
 }
 }
 /* we require a framein routine, wouldn't know how to do
 * it otherwise.
 */
 return pvt->t->framein(pvt, f);
}

/*! \brief generic frameout routine.
 * If samples and datalen are 0, take whatever is in pvt
 * and reset them, otherwise take the values in the caller and
 * leave alone the pvt values.
 */
struct ast_frame *ast_trans_frameout(struct ast_trans_pvt *pvt,
 int datalen, int samples)
{
 struct ast_frame *f = &pvt->f;

 if (samples) {
 f->samples = samples;
 } else {
 if (pvt->samples == 0) {
 return NULL;
 }
 f->samples = pvt->samples;
 pvt->samples = 0;
 }
 if (datalen) {
 f->datalen = datalen;
 f->data.ptr = pvt->outbuf.c;
 } else {
 f->datalen = pvt->datalen;
 if (!f->datalen) {
 f->data.ptr = NULL;
 } else {
 f->data.ptr = pvt->outbuf.c;
 }
 pvt->datalen = 0;
 }

 return ast_frisolate(f);
}

static struct ast_frame *default_frameout(struct ast_trans_pvt *pvt)
{
 return ast_trans_frameout(pvt, 0, 0);
}

/* end of callback wrappers and helpers */

void ast_translator_free_path(struct ast_trans_pvt *p)
{
 struct ast_trans_pvt *pn = p;
 while ( (p = pn) ) {
 pn = p->next;
 destroy(p);
 }
}

/*! \brief Build a chain of translators based upon the given source and dest formats */
struct ast_trans_pvt *ast_translator_build_path(struct ast_format *dst, struct ast_format *src)
{
 struct ast_trans_pvt *head = NULL, *tail = NULL;
 int src_index, dst_index;

 src_index = format2index(src);
 dst_index = format2index(dst);

 if (src_index < 0 || dst_index < 0) {
 ast_log(LOG_WARNING, "No translator path: (%s codec is not valid)\n", src_index < 0 ? "starting" : "ending");
 return NULL;
 }

 AST_RWLIST_RDLOCK(&translators);

 while (src_index != dst_index) {
 struct ast_trans_pvt *cur;
 struct ast_format *explicit_dst = NULL;
 struct ast_translator *t = matrix_get(src_index, dst_index)->step;
 if (!t) {
 ast_log(LOG_WARNING, "No translator path from %s to %s\n",
 ast_format_get_name(src), ast_format_get_name(dst));
 AST_RWLIST_UNLOCK(&translators);
 ast_translator_free_path(head);
 return NULL;
 }
 if ((t->dst_codec.sample_rate == ast_format_get_sample_rate(dst)) && (t->dst_codec.type == ast_format_get_type(dst))) {
 explicit_dst = dst;
 }
 if (!(cur = newpvt(t, explicit_dst))) {
 ast_log(LOG_WARNING, "Failed to build translator step from %s to %s\n",
 ast_format_get_name(src), ast_format_get_name(dst));
 ast_translator_free_path(head);
 AST_RWLIST_UNLOCK(&translators);
 return NULL;
 }
 if (!head) {
 head = cur;
 } else {
 tail->next = cur;
 }
 tail = cur;
 cur->nextin = cur->nextout = ast_tv(0, 0);
 /* Keep going if this isn't the final destination */
 src_index = cur->t->dst_fmt_index;
 }

 AST_RWLIST_UNLOCK(&translators);
 return head;
}

static struct ast_frame *generate_interpolated_slin(struct ast_trans_pvt *p, struct ast_frame *f)
{
 struct ast_frame res = { AST_FRAME_VOICE };

 /*
 * If we've gotten here then we should have an interpolated frame that was not handled
 * by the translation codec. So create an interpolated frame in the appropriate format
 * that was going to be written. This frame might be handled later by other resources.
 * For instance, generic plc.
 *
 * Note, generic plc is currently only available for the format type 'slin' (8KHz only -
 * The generic plc code appears to have been based around that). Generic plc is filled
 * in later on frame write.
 */
 if (!ast_opt_generic_plc || f->datalen != 0 ||
 ast_format_cmp(p->explicit_dst, ast_format_slin) == AST_FORMAT_CMP_NOT_EQUAL) {
 return NULL;
 }

 res.subclass.format = ast_format_cache_get_slin_by_rate(8000); /* ref bumped on dup */
 res.samples = f->samples;
 res.datalen = 0;
 res.data.ptr = NULL;
 res.offset = AST_FRIENDLY_OFFSET;

 return ast_frdup(&res);
}

/*! \brief do the actual translation */
struct ast_frame *ast_translate(struct ast_trans_pvt *path, struct ast_frame *f, int consume)
{
 struct ast_trans_pvt *p = path;
 struct ast_frame *out;
 struct timeval delivery;
 int has_timing_info;
 long ts;
 long len;
 int seqno;

 if (f->frametype == AST_FRAME_RTCP) {
 /* Just pass the feedback to the right callback, if it exists.
 * This "translation" does nothing so return a null frame. */
 struct ast_trans_pvt *tp;
 for (tp = p; tp; tp = tp->next) {
 if (tp->t->feedback)
 tp->t->feedback(tp, f);
 }
 return &ast_null_frame;
 }

 has_timing_info = ast_test_flag(f, AST_FRFLAG_HAS_TIMING_INFO);
 ts = f->ts;
 len = f->len;
 seqno = f->seqno;

 if (!ast_tvzero(f->delivery)) {
 if (!ast_tvzero(path->nextin)) {
 /* Make sure this is in line with what we were expecting */
 if (!ast_tveq(path->nextin, f->delivery)) {
 /* The time has changed between what we expected and this
 most recent time on the new packet. If we have a
 valid prediction adjust our output time appropriately */
 if (!ast_tvzero(path->nextout)) {
 path->nextout = ast_tvadd(path->nextout,
 ast_tvsub(f->delivery, path->nextin));
 }
 path->nextin = f->delivery;
 }
 } else {
 /* This is our first pass. Make sure the timing looks good */
 path->nextin = f->delivery;
 path->nextout = f->delivery;
 }
 /* Predict next incoming sample */
 path->nextin = ast_tvadd(path->nextin, ast_samp2tv(
 f->samples, ast_format_get_sample_rate(f->subclass.format)));
 }
 delivery = f->delivery;
 for (out = f; out && p ; p = p->next) {
 struct ast_frame *current = out;

 do {
 framein(p, current);
 current = AST_LIST_NEXT(current, frame_list);
 } while (current);
 if (out != f) {
 ast_frfree(out);
 }
 out = p->t->frameout(p);
 }

 if (!out) {
 out = generate_interpolated_slin(path, f);
 }

 if (out) {
 /* we have a frame, play with times */
 if (!ast_tvzero(delivery)) {
 struct ast_frame *current = out;

 do {
 /* Regenerate prediction after a discontinuity */
 if (ast_tvzero(path->nextout)) {
 path->nextout = ast_tvnow();
 }

 /* Use next predicted outgoing timestamp */
 current->delivery = path->nextout;

 /* Invalidate prediction if we're entering a silence period */
 if (current->frametype == AST_FRAME_CNG) {
 path->nextout = ast_tv(0, 0);
 /* Predict next outgoing timestamp from samples in this
 frame. */
 } else {
 path->nextout = ast_tvadd(path->nextout, ast_samp2tv(
 current->samples, ast_format_get_sample_rate(current->subclass.format)));
 }

 if (f->samples != current->samples && ast_test_flag(current, AST_FRFLAG_HAS_TIMING_INFO)) {
 ast_debug(4, "Sample size different %d vs %d\n", f->samples, current->samples);
 ast_clear_flag(current, AST_FRFLAG_HAS_TIMING_INFO);
 }
 current = AST_LIST_NEXT(current, frame_list);
 } while (current);
 } else {
 out->delivery = ast_tv(0, 0);
 ast_set2_flag(out, has_timing_info, AST_FRFLAG_HAS_TIMING_INFO);
 if (has_timing_info) {
 out->ts = ts;
 out->len = len;
 out->seqno = seqno;
 }
 /* Invalidate prediction if we're entering a silence period */
 if (out->frametype == AST_FRAME_CNG) {
 path->nextout = ast_tv(0, 0);
 }
 }
 }
 if (consume) {
 ast_frfree(f);
 }
 return out;
}

/*!
 * \internal
 * \brief Compute the computational cost of a single translation step.
 *
 * \note This function is only used to decide which translation path to
 * use between two translators with identical src and dst formats. Computational
 * cost acts only as a tie breaker. This is done so hardware translators
 * can naturally have precedence over software translators.
 */
static void generate_computational_cost(struct ast_translator *t, int seconds)
{
 int num_samples = 0;
 struct ast_trans_pvt *pvt;
 struct rusage start;
 struct rusage end;
 int cost;
 int out_rate = t->dst_codec.sample_rate;

 if (!seconds) {
 seconds = 1;
 }

 /* If they don't make samples, give them a terrible score */
 if (!t->sample) {
 ast_debug(3, "Translator '%s' does not produce sample frames.\n", t->name);
 t->comp_cost = 999999;
 return;
 }

 pvt = newpvt(t, NULL);
 if (!pvt) {
 ast_log(LOG_WARNING, "Translator '%s' appears to be broken and will probably fail.\n", t->name);
 t->comp_cost = 999999;
 return;
 }

 getrusage(RUSAGE_SELF, &start);

 /* Call the encoder until we've processed the required number of samples */
 while (num_samples < seconds * out_rate) {
 struct ast_frame *f = t->sample();
 if (!f) {
 ast_log(LOG_WARNING, "Translator '%s' failed to produce a sample frame.\n", t->name);
 destroy(pvt);
 t->comp_cost = 999999;
 return;
 }
 framein(pvt, f);
 ast_frfree(f);
 while ((f = t->frameout(pvt))) {
 num_samples += f->samples;
 ast_frfree(f);
 }
 }

 getrusage(RUSAGE_SELF, &end);

 cost = ((end.ru_utime.tv_sec - start.ru_utime.tv_sec) * 1000000) + end.ru_utime.tv_usec - start.ru_utime.tv_usec;
 cost += ((end.ru_stime.tv_sec - start.ru_stime.tv_sec) * 1000000) + end.ru_stime.tv_usec - start.ru_stime.tv_usec;

 destroy(pvt);

 t->comp_cost = cost / seconds;

 if (!t->comp_cost) {
 t->comp_cost = 1;
 }
}

/*!
 * \internal
 *
 * \brief If no table cost value was pre set by the translator. An attempt is made to
 * automatically generate that cost value from the cost table based on our src and
 * dst formats.
 *
 * \note This function allows older translators built before the translation cost
 * changed away from using onely computational time to continue to be registered
 * correctly. It is expected that translators built after the introduction of this
 * function will manually assign their own table cost value.
 *
 * \note This function is safe to use on any audio formats that used to be defined in the
 * first 64 bits of the old bit field codec representation.
 *
 * \retval Table Cost value greater than 0.
 * \retval 0 on error.
 */
static int generate_table_cost(struct ast_codec *src, struct ast_codec *dst)
{
 int src_rate = src->sample_rate;
 int src_ll = 0;
 int dst_rate = dst->sample_rate;
 int dst_ll = 0;

 if ((src->type != AST_MEDIA_TYPE_AUDIO) ||
 (dst->type != AST_MEDIA_TYPE_AUDIO)) {
 /* This method of generating table cost is limited to audio.
 * Translators for media other than audio must manually set their
 * table cost. */
 return 0;
 }

 src_ll = !strcmp(src->name, "slin");
 dst_ll = !strcmp(dst->name, "slin");
 if (src_ll) {
 if (dst_ll && (src_rate == dst_rate)) {
 return AST_TRANS_COST_LL_LL_ORIGSAMP;
 } else if (!dst_ll && (src_rate == dst_rate)) {
 return AST_TRANS_COST_LL_LY_ORIGSAMP;
 } else if (dst_ll && (src_rate < dst_rate)) {
 return AST_TRANS_COST_LL_LL_UPSAMP;
 } else if (!dst_ll && (src_rate < dst_rate)) {
 return AST_TRANS_COST_LL_LY_UPSAMP;
 } else if (dst_ll && (src_rate > dst_rate)) {
 return AST_TRANS_COST_LL_LL_DOWNSAMP;
 } else if (!dst_ll && (src_rate > dst_rate)) {
 return AST_TRANS_COST_LL_LY_DOWNSAMP;
 } else {
 return AST_TRANS_COST_LL_UNKNOWN;
 }
 } else {
 if (dst_ll && (src_rate == dst_rate)) {
 return AST_TRANS_COST_LY_LL_ORIGSAMP;
 } else if (!dst_ll && (src_rate == dst_rate)) {
 return AST_TRANS_COST_LY_LY_ORIGSAMP;
 } else if (dst_ll && (src_rate < dst_rate)) {
 return AST_TRANS_COST_LY_LL_UPSAMP;
 } else if (!dst_ll && (src_rate < dst_rate)) {
 return AST_TRANS_COST_LY_LY_UPSAMP;
 } else if (dst_ll && (src_rate > dst_rate)) {
 return AST_TRANS_COST_LY_LL_DOWNSAMP;
 } else if (!dst_ll && (src_rate > dst_rate)) {
 return AST_TRANS_COST_LY_LY_DOWNSAMP;
 } else {
 return AST_TRANS_COST_LY_UNKNOWN;
 }
 }
}

/*!
 * \brief rebuild a translation matrix.
 * \note This function expects the list of translators to be locked
*/
static void matrix_rebuild(int samples)
{
 struct ast_translator *t;
 int newtablecost;
 int x; /* source format index */
 int y; /* intermediate format index */
 int z; /* destination format index */

 ast_debug(1, "Resetting translation matrix\n");

 matrix_clear();

 /* first, compute all direct costs */
 AST_RWLIST_TRAVERSE(&translators, t, list) {
 if (!t->active) {
 continue;
 }

 x = t->src_fmt_index;
 z = t->dst_fmt_index;

 if (samples) {
 generate_computational_cost(t, samples);
 }

 /* This new translator is the best choice if any of the below are true.
 * 1. no translation path is set between x and z yet.
 * 2. the new table cost is less.
 * 3. the new computational cost is less. Computational cost is only used
 * to break a tie between two identical translation paths.
 */
 if (!matrix_get(x, z)->step ||
 (t->table_cost < matrix_get(x, z)->step->table_cost) ||
 (t->comp_cost < matrix_get(x, z)->step->comp_cost)) {

 matrix_get(x, z)->step = t;
 matrix_get(x, z)->table_cost = t->table_cost;
 }
 }

 /*
 * For each triple x, y, z of distinct formats, check if there is
 * a path from x to z through y which is cheaper than what is
 * currently known, and in case, update the matrix.
 * Repeat until the matrix is stable.
 */
 for (;;) {
 int changed = 0;
 for (x = 0; x < cur_max_index; x++) { /* source format */
 for (y = 0; y < cur_max_index; y++) { /* intermediate format */
 if (x == y) { /* skip ourselves */
 continue;
 }
 for (z = 0; z < cur_max_index; z++) { /* dst format */
 if ((z == x || z == y) || /* skip null conversions */
 !matrix_get(x, y)->step || /* no path from x to y */
 !matrix_get(y, z)->step) { /* no path from y to z */
 continue;
 }

 /* calculate table cost from x->y->z */
 newtablecost = matrix_get(x, y)->table_cost + matrix_get(y, z)->table_cost;

 /* if no step already exists between x and z OR the new cost of using the intermediate
 * step is cheaper, use this step. */
 if (!matrix_get(x, z)->step || (newtablecost < matrix_get(x, z)->table_cost)) {
 matrix_get(x, z)->step = matrix_get(x, y)->step;
 matrix_get(x, z)->table_cost = newtablecost;
 matrix_get(x, z)->multistep = 1;
 changed++;

 if (DEBUG_ATLEAST(10)) {
 struct ast_codec *x_codec = index2codec(x);
 struct ast_codec *y_codec = index2codec(y);
 struct ast_codec *z_codec = index2codec(z);

 ast_log(LOG_DEBUG,
 "Discovered %u cost path from %s to %s, via %s\n",
 matrix_get(x, z)->table_cost, x_codec->name,
 y_codec->name, z_codec->name);

 ao2_ref(x_codec, -1);
 ao2_ref(y_codec, -1);
 ao2_ref(z_codec, -1);
 }
 }
 }
 }
 }
 if (!changed) {
 break;
 }
 }
}

static void codec_append_name(const struct ast_codec *codec, struct ast_str **buf)
{
 if (codec) {
 ast_str_append(buf, 0, "(%s@%u)", codec->name, codec->sample_rate);
 } else {
 ast_str_append(buf, 0, "(nothing)");
 }
}

const char *ast_translate_path_to_str(struct ast_trans_pvt *p, struct ast_str **str)
{
 if (!p || !p->t) {
 return "";
 }

 ast_str_reset(*str);
 codec_append_name(&p->t->src_codec, str);
 while (p) {
 ast_str_append(str, 0, "->");
 codec_append_name(&p->t->dst_codec, str);
 p = p->next;
 }

 return ast_str_buffer(*str);
}

static char *complete_trans_path_choice(const char *word)
{
 int i = 1;
 int wordlen = strlen(word);
 struct ast_codec *codec;

 while ((codec = ast_codec_get_by_id(i))) {
 ++i;
 if (codec->type != AST_MEDIA_TYPE_AUDIO) {
 ao2_ref(codec, -1);
 continue;
 }
 if (!strncasecmp(word, codec->name, wordlen)) {
 if (ast_cli_completion_add(ast_strdup(codec->name))) {
 ao2_ref(codec, -1);
 break;
 }
 }
 ao2_ref(codec, -1);
 }

 return NULL;
}

static void handle_cli_recalc(struct ast_cli_args *a)
{
 int time = a->argv[4] ? atoi(a->argv[4]) : 1;

 if (time <= 0) {
 ast_cli(a->fd, " Recalc must be greater than 0. Defaulting to 1.\n");
 time = 1;
 }

 if (time > MAX_RECALC) {
 ast_cli(a->fd, " Maximum limit of recalc exceeded by %d, truncating value to %d\n", time - MAX_RECALC, MAX_RECALC);
 time = MAX_RECALC;
 }
 ast_cli(a->fd, " Recalculating Codec Translation (number of sample seconds: %d)\n\n", time);
 AST_RWLIST_WRLOCK(&translators);
 matrix_rebuild(time);
 AST_RWLIST_UNLOCK(&translators);
}

static char *handle_show_translation_table(struct ast_cli_args *a)
{
 int x, y, i, k;
 int longest = 7; /* slin192 */
 int max_codec_index = 0, curlen = 0;
 struct ast_str *out = ast_str_create(1024);
 struct ast_codec *codec;

 /* Get the length of the longest (usable?) codec name,
 so we know how wide the left side should be */
 for (i = 1; (codec = ast_codec_get_by_id(i)); ao2_ref(codec, -1), ++i) {
 ++max_codec_index;
 if (codec->type != AST_MEDIA_TYPE_AUDIO) {
 continue;
 }
 curlen = strlen(codec->name);
 if (curlen > longest) {
 longest = curlen;
 }
 }

 AST_RWLIST_RDLOCK(&translators);
 ast_cli(a->fd, " Translation times between formats (in microseconds) for one second of data\n");
 ast_cli(a->fd, " Source Format (Rows) Destination Format (Columns)\n\n");

 for (i = 0; i <= max_codec_index; i++) {
 struct ast_codec *row = i ? ast_codec_get_by_id(i) : NULL;

 x = -1;
 if ((i > 0) && (row->type != AST_MEDIA_TYPE_AUDIO)) {
 ao2_ref(row, -1);
 continue;
 }

 if ((i > 0) && (x = codec2index(row)) == -1) {
 ao2_ref(row, -1);
 continue;
 }

 ast_str_set(&out, 0, " ");
 for (k = 0; k <= max_codec_index; k++) {
 int adjust = 0;
 struct ast_codec *col = k ? ast_codec_get_by_id(k) : NULL;

 y = -1;
 if ((k > 0) && (col->type != AST_MEDIA_TYPE_AUDIO)) {
 ao2_ref(col, -1);
 continue;
 }

 if ((k > 0) && (y = codec2index(col)) == -1) {
 ao2_ref(col, -1);
 continue;
 }

 if (k > 0) {
 curlen = strlen(col->name);
 if (!strcmp(col->name, "slin") ||
 !strcmp(col->name, "speex") ||
 !strcmp(col->name, "silk")) {
 adjust = log10(col->sample_rate / 1000) + 1;
 curlen = curlen + adjust;
 }
 }

 if (curlen < 5) {
 curlen = 5;
 }

 if (x >= 0 && y >= 0 && matrix_get(x, y)->step) {
 /* Actual codec output */
 ast_str_append(&out, 0, "%*u", curlen + 1, (matrix_get(x, y)->table_cost/100));
 } else if (i == 0 && k > 0) {
 /* Top row - use a dynamic size */
 if (!strcmp(col->name, "slin") ||
 !strcmp(col->name, "speex") ||
 !strcmp(col->name, "silk")) {
 ast_str_append(&out, 0, "%*s%u", curlen - adjust + 1,
 col->name, col->sample_rate / 1000);
 } else {
 ast_str_append(&out, 0, "%*s", curlen + 1, col->name);
 }
 } else if (k == 0 && i > 0) {
 /* Left column - use a static size. */
 if (!strcmp(row->name, "slin") ||
 !strcmp(row->name, "speex") ||
 !strcmp(row->name, "silk")) {
 int adjust_row = log10(row->sample_rate / 1000) + 1;
 ast_str_append(&out, 0, "%*s%u", longest - adjust_row,
 row->name, row->sample_rate / 1000);
 } else {
 ast_str_append(&out, 0, "%*s", longest, row->name);
 }
 } else if (x >= 0 && y >= 0) {
 /* Codec not supported */
 ast_str_append(&out, 0, "%*s", curlen + 1, "-");
 } else {
 /* Upper left hand corner */
 ast_str_append(&out, 0, "%*s", longest, "");
 }
 ao2_cleanup(col);
 }
 ast_str_append(&out, 0, "\n");
 ast_cli(a->fd, "%s", ast_str_buffer(out));
 ao2_cleanup(row);
 }
 ast_free(out);
 AST_RWLIST_UNLOCK(&translators);
 return CLI_SUCCESS;
}

static char *handle_show_translation_path(struct ast_cli_args *a, const char *codec_name, unsigned int sample_rate)
{
 int i = 1;
 struct ast_str *str = ast_str_alloca(1024);
 struct ast_translator *step;
 struct ast_codec *dst_codec;
 struct ast_codec *src_codec = ast_codec_get(codec_name, AST_MEDIA_TYPE_AUDIO, sample_rate);

 if (!src_codec) {
 ast_cli(a->fd, "Source codec \"%s\" is not found.\n", codec_name);
 return CLI_FAILURE;
 }

 AST_RWLIST_RDLOCK(&translators);
 ast_cli(a->fd, "--- Translation paths SRC Codec \"%s\" sample rate %u ---\n",
 codec_name, src_codec->sample_rate);

 while ((dst_codec = ast_codec_get_by_id(i))) {
 int src, dst;
 char src_buffer[64];
 char dst_buffer[64];

 ++i;
 if (src_codec == dst_codec ||
 dst_codec->type != AST_MEDIA_TYPE_AUDIO) {
 ao2_ref(dst_codec, -1);
 continue;
 }

 dst = codec2index(dst_codec);
 src = codec2index(src_codec);

 if (src < 0 || dst < 0) {
 ast_str_set(&str, 0, "No Translation Path");
 } else {
 step = matrix_get(src, dst)->step;

 if (step) {
 codec_append_name(&step->src_codec, &str);
 while (src != dst) {
 src = step->dst_fmt_index;
 step = matrix_get(src, dst)->step;
 if (!step) {
 ast_str_append(&str, 0, "->");
 codec_append_name(dst_codec, &str);
 break;
 }
 ast_str_append(&str, 0, "->");
 codec_append_name(&step->src_codec, &str);
 }
 }
 }

 snprintf(src_buffer, sizeof(src_buffer), "%s:%u", src_codec->name, src_codec->sample_rate);
 snprintf(dst_buffer, sizeof(dst_buffer), "%s:%u", dst_codec->name, dst_codec->sample_rate);
 ast_cli(a->fd, "\t%-16.16s To %-16.16s: %-60.60s\n",
 src_buffer, dst_buffer, ast_str_buffer(str));
 ast_str_reset(str);
 ao2_ref(dst_codec, -1);
 }
 AST_RWLIST_UNLOCK(&translators);
 ao2_ref(src_codec, -1);
 return CLI_SUCCESS;
}

static char *handle_cli_core_show_translation(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
 static const char * const option[] = { "recalc", "paths", NULL };

 switch (cmd) {
 case CLI_INIT:
 e->command = "core show translation";
 e->usage =
 "Usage: 'core show translation' can be used in two ways.\n"
 " 1. 'core show translation [recalc [<recalc seconds>]]\n"
 " Displays known codec translators and the cost associated\n"
 " with each conversion. If the argument 'recalc' is supplied along\n"
 " with optional number of seconds to test a new test will be performed\n"
 " as the chart is being displayed.\n"
 " 2. 'core show translation paths [codec [sample_rate]]'\n"
 " This will display all the translation paths associated with a codec.\n"
 " If a codec has multiple sample rates, the sample rate must be\n"
 " provided as well.\n";
 return NULL;
 case CLI_GENERATE:
 if (a->pos == 3) {
 return ast_cli_complete(a->word, option, -1);
 }
 if (a->pos == 4 && !strcasecmp(a->argv[3], option[1])) {
 return complete_trans_path_choice(a->word);
 }
 /* BUGBUG - add tab completion for sample rates */
 return NULL;
 }

 if (a->argc > 6)
 return CLI_SHOWUSAGE;

 if (a->argv[3] && !strcasecmp(a->argv[3], option[1]) && a->argc == 5) { /* show paths */
 return handle_show_translation_path(a, a->argv[4], 0);
 } else if (a->argv[3] && !strcasecmp(a->argv[3], option[1]) && a->argc == 6) {
 unsigned int sample_rate;
 if (sscanf(a->argv[5], "%30u", &sample_rate) != 1) {
 ast_cli(a->fd, "Invalid sample rate: %s.\n", a->argv[5]);
 return CLI_FAILURE;
 }
 return handle_show_translation_path(a, a->argv[4], sample_rate);
 } else if (a->argv[3] && !strcasecmp(a->argv[3], option[0])) { /* recalc and then fall through to show table */
 handle_cli_recalc(a);
 } else if (a->argc > 3) { /* wrong input */
 return CLI_SHOWUSAGE;
 }

 return handle_show_translation_table(a);
}

static struct ast_cli_entry cli_translate[] = {
 AST_CLI_DEFINE(handle_cli_core_show_translation, "Display translation matrix")
};

/*! \brief register codec translator */
int __ast_register_translator(struct ast_translator *t, struct ast_module *mod)
{
 struct ast_translator *u;
 char tmp[80];
 RAII_VAR(struct ast_codec *, src_codec, NULL, ao2_cleanup);
 RAII_VAR(struct ast_codec *, dst_codec, NULL, ao2_cleanup);

 src_codec = ast_codec_get(t->src_codec.name, t->src_codec.type, t->src_codec.sample_rate);
 if (!src_codec) {
 ast_assert(0);
 ast_log(LOG_WARNING, "Failed to register translator: unknown source codec %s\n", t->src_codec.name);
 return -1;
 }

 dst_codec = ast_codec_get(t->dst_codec.name, t->dst_codec.type, t->dst_codec.sample_rate);
 if (!dst_codec) {
 ast_log(LOG_WARNING, "Failed to register translator: unknown destination codec %s\n", t->dst_codec.name);
 return -1;
 }

 if (add_codec2index(src_codec) || add_codec2index(dst_codec)) {
 if (matrix_resize(0)) {
 ast_log(LOG_WARNING, "Translator matrix can not represent any more translators. Out of resources.\n");
 return -1;
 }
 add_codec2index(src_codec);
 add_codec2index(dst_codec);
 }

 if (!mod) {
 ast_log(LOG_WARNING, "Missing module pointer, you need to supply one\n");
 return -1;
 }

 if (!t->buf_size) {
 ast_log(LOG_WARNING, "empty buf size, you need to supply one\n");
 return -1;
 }
 if (!t->table_cost && !(t->table_cost = generate_table_cost(src_codec, dst_codec))) {
 ast_log(LOG_WARNING, "Table cost could not be generated for %s, "
 "Please set table_cost variable on translator.\n", t->name);
 return -1;
 }

 t->module = mod;
 t->src_fmt_index = codec2index(src_codec);
 t->dst_fmt_index = codec2index(dst_codec);
 t->active = 1;

 if (t->src_fmt_index < 0 || t->dst_fmt_index < 0) {
 ast_log(LOG_WARNING, "Invalid translator path: (%s codec is not valid)\n", t->src_fmt_index < 0 ? "starting" : "ending");
 return -1;
 }
 if (t->src_fmt_index >= cur_max_index) {
 ast_log(LOG_WARNING, "Source codec %s is larger than cur_max_index\n", t->src_codec.name);
 return -1;
 }

 if (t->dst_fmt_index >= cur_max_index) {
 ast_log(LOG_WARNING, "Destination codec %s is larger than cur_max_index\n", t->dst_codec.name);
 return -1;
 }

 if (t->buf_size) {
 /*
 * Align buf_size properly, rounding up to the machine-specific
 * alignment for pointers.
 */
 struct _test_align { void *a, *b; } p;
 int align = (char *)&p.b - (char *)&p.a;

 t->buf_size = ((t->buf_size + align - 1) / align) * align;
 }

 if (t->frameout == NULL) {
 t->frameout = default_frameout;
 }

 generate_computational_cost(t, 1);

 ast_verb(2, "Registered translator '%s' from codec %s to %s, table cost, %d, computational cost %d\n",
 term_color(tmp, t->name, COLOR_MAGENTA, COLOR_BLACK, sizeof(tmp)),
 t->src_codec.name, t->dst_codec.name, t->table_cost, t->comp_cost);

 AST_RWLIST_WRLOCK(&translators);

 /* find any existing translators that provide this same srcfmt/dstfmt,
 and put this one in order based on computational cost */
 AST_RWLIST_TRAVERSE_SAFE_BEGIN(&translators, u, list) {
 if ((u->src_fmt_index == t->src_fmt_index) &&
 (u->dst_fmt_index == t->dst_fmt_index) &&
 (u->comp_cost > t->comp_cost)) {
 AST_RWLIST_INSERT_BEFORE_CURRENT(t, list);
 t = NULL;
 break;
 }
 }
 AST_RWLIST_TRAVERSE_SAFE_END;

 /* if no existing translator was found for this codec combination,
 add it to the beginning of the list */
 if (t) {
 AST_RWLIST_INSERT_HEAD(&translators, t, list);
 }

 matrix_rebuild(0);

 AST_RWLIST_UNLOCK(&translators);

 return 0;
}

/*! \brief unregister codec translator */
int ast_unregister_translator(struct ast_translator *t)
{
 char tmp[80];
 struct ast_translator *u;
 int found = 0;

 AST_RWLIST_WRLOCK(&translators);
 AST_RWLIST_TRAVERSE_SAFE_BEGIN(&translators, u, list) {
 if (u == t) {
 AST_RWLIST_REMOVE_CURRENT(list);
 ast_verb(2, "Unregistered translator '%s' from codec %s to %s\n",
 term_color(tmp, t->name, COLOR_MAGENTA, COLOR_BLACK, sizeof(tmp)),
 t->src_codec.name, t->dst_codec.name);
 found = 1;
 break;
 }
 }
 AST_RWLIST_TRAVERSE_SAFE_END;

 if (found && !ast_shutting_down()) {
 matrix_rebuild(0);
 }

 AST_RWLIST_UNLOCK(&translators);

 return (u ? 0 : -1);
}

void ast_translator_activate(struct ast_translator *t)
{
 AST_RWLIST_WRLOCK(&translators);
 t->active = 1;
 matrix_rebuild(0);
 AST_RWLIST_UNLOCK(&translators);
}

void ast_translator_deactivate(struct ast_translator *t)
{
 AST_RWLIST_WRLOCK(&translators);
 t->active = 0;
 matrix_rebuild(0);
 AST_RWLIST_UNLOCK(&translators);
}

/*! Calculate the absolute difference between sample rate of two formats. */
#define format_sample_rate_absdiff(fmt1, fmt2) ({ \
 unsigned int rate1 = ast_format_get_sample_rate(fmt1); \
 unsigned int rate2 = ast_format_get_sample_rate(fmt2); \
 (rate1 > rate2 ? rate1 - rate2 : rate2 - rate1); \
})

/*! \brief Calculate our best translator source format, given costs, and a desired destination */
int ast_translator_best_choice(struct ast_format_cap *dst_cap,
 struct ast_format_cap *src_cap,
 struct ast_format **dst_fmt_out,
 struct ast_format **src_fmt_out)
{
 unsigned int besttablecost = INT_MAX;
 unsigned int beststeps = INT_MAX;
 struct ast_format *fmt;
 struct ast_format *dst;
 struct ast_format *src;
 RAII_VAR(struct ast_format *, best, NULL, ao2_cleanup);
 RAII_VAR(struct ast_format *, bestdst, NULL, ao2_cleanup);
 struct ast_format_cap *joint_cap;
 int i;
 int j;

 if (ast_format_cap_empty(dst_cap) || ast_format_cap_empty(src_cap)) {
 ast_log(LOG_ERROR, "Cannot determine best translation path since one capability supports no formats\n");
 return -1;
 }

 joint_cap = ast_format_cap_alloc(AST_FORMAT_CAP_FLAG_DEFAULT);
 if (!joint_cap) {
 return -1;
 }
 ast_format_cap_get_compatible(dst_cap, src_cap, joint_cap);

 for (i = 0; i < ast_format_cap_count(joint_cap); ++i, ao2_cleanup(fmt)) {
 fmt = ast_format_cap_get_format(joint_cap, i);
 if (!fmt
 || ast_format_get_type(fmt) != AST_MEDIA_TYPE_AUDIO) {
 continue;
 }

 if (!best
 || ast_format_get_sample_rate(best) < ast_format_get_sample_rate(fmt)) {
 ao2_replace(best, fmt);
 }
 }
 ao2_ref(joint_cap, -1);

 if (best) {
 ao2_replace(*dst_fmt_out, best);
 ao2_replace(*src_fmt_out, best);
 return 0;
 }

 /* need to translate */
 AST_RWLIST_RDLOCK(&translators);
 for (i = 0; i < ast_format_cap_count(dst_cap); ++i, ao2_cleanup(dst)) {
 dst = ast_format_cap_get_format(dst_cap, i);
 if (!dst
 || ast_format_get_type(dst) != AST_MEDIA_TYPE_AUDIO) {
 continue;
 }

 for (j = 0; j < ast_format_cap_count(src_cap); ++j, ao2_cleanup(src)) {
 int x;
 int y;

 src = ast_format_cap_get_format(src_cap, j);
 if (!src
 || ast_format_get_type(src) != AST_MEDIA_TYPE_AUDIO) {
 continue;
 }

 x = format2index(src);
 y = format2index(dst);
 if (x < 0 || y < 0) {
 continue;
 }
 if (!matrix_get(x, y) || !(matrix_get(x, y)->step)) {
 continue;
 }
 if (matrix_get(x, y)->table_cost < besttablecost
 || matrix_get(x, y)->multistep < beststeps) {
 /* better than what we have so far */
 ao2_replace(best, src);
 ao2_replace(bestdst, dst);
 besttablecost = matrix_get(x, y)->table_cost;
 beststeps = matrix_get(x, y)->multistep;
 } else if (matrix_get(x, y)->table_cost == besttablecost
 && matrix_get(x, y)->multistep == beststeps) {
 unsigned int gap_selected = format_sample_rate_absdiff(best, bestdst);
 unsigned int gap_current = format_sample_rate_absdiff(src, dst);

 if (gap_current < gap_selected) {
 /* better than what we have so far */
 ao2_replace(best, src);
 ao2_replace(bestdst, dst);
 besttablecost = matrix_get(x, y)->table_cost;
 beststeps = matrix_get(x, y)->multistep;
 }
 }
 }
 }
 AST_RWLIST_UNLOCK(&translators);

 if (!best) {
 return -1;
 }
 ao2_replace(*dst_fmt_out, bestdst);
 ao2_replace(*src_fmt_out, best);
 return 0;
}

unsigned int ast_translate_path_steps(struct ast_format *dst_format, struct ast_format *src_format)
{
 unsigned int res = -1;
 /* convert bitwise format numbers into array indices */
 int src = format2index(src_format);
 int dest = format2index(dst_format);

 if (src < 0 || dest < 0) {
 ast_log(LOG_WARNING, "No translator path: (%s codec is not valid)\n", src < 0 ? "starting" : "ending");
 return -1;
 }
 AST_RWLIST_RDLOCK(&translators);

 if (matrix_get(src, dest)->step) {
 res = matrix_get(src, dest)->multistep + 1;
 }

 AST_RWLIST_UNLOCK(&translators);

 return res;
}

static void check_translation_path(
 struct ast_format_cap *dest, struct ast_format_cap *src,
 struct ast_format_cap *result, struct ast_format *src_fmt,
 enum ast_media_type type)
{
 int i;

 if (ast_format_get_type(src_fmt) != type) {
 return;
 }

 /* For a given source format, traverse the list of
 known formats to determine whether there exists
 a translation path from the source format to the
 destination format. */
 for (i = ast_format_cap_count(result) - 1; 0 <= i; i--) {
 int index, src_index;
 RAII_VAR(struct ast_format *, fmt, ast_format_cap_get_format(result, i), ao2_cleanup);

 if (ast_format_get_type(fmt) != type) {
 continue;
 }

 /* if this is not a desired format, nothing to do */
 if (ast_format_cap_iscompatible_format(dest, fmt) == AST_FORMAT_CMP_NOT_EQUAL) {
 continue;
 }

 /* if the source is supplying this format, then
 we can leave it in the result */
 if (ast_format_cap_iscompatible_format(src, fmt) == AST_FORMAT_CMP_EQUAL) {
 continue;
 }

 /* if this is a pass-through format, not in the source,
 we cannot transcode. Therefore, remove it from the result */
 src_index = format2index(src_fmt);
 index = format2index(fmt);
 if (src_index < 0 || index < 0) {
 ast_format_cap_remove(result, fmt);
 continue;
 }

 /* if we don't have a translation path from the src
 to this format, remove it from the result */
 if (!matrix_get(src_index, index)->step) {
 ast_format_cap_remove(result, fmt);
 continue;
 }

 /* now check the opposite direction */
 if (!matrix_get(index, src_index)->step) {
 ast_format_cap_remove(result, fmt);
 }
 }

}

void ast_translate_available_formats(struct ast_format_cap *dest, struct ast_format_cap *src, struct ast_format_cap *result)
{
 struct ast_format *cur_dest, *cur_src;
 int index;

 for (index = 0; index < ast_format_cap_count(dest); ++index) {
 if (!(cur_dest = ast_format_cap_get_format(dest, index))) {
 continue;
 }

 /* We give preference to a joint format structure if possible */
 if ((cur_src = ast_format_cap_get_compatible_format(src, cur_dest))) {
 ast_format_cap_append(result, cur_src, 0);
 ao2_ref(cur_src, -1);
 } else {
 /* Otherwise we just use the destination format */
 ast_format_cap_append(result, cur_dest, 0);
 }
 ao2_ref(cur_dest, -1);
 }

 /* if we don't have a source format, we just have to try all
 possible destination formats */
 if (!src) {
 return;
 }

 for (index = 0; index < ast_format_cap_count(src); ++index) {
 if (!(cur_src = ast_format_cap_get_format(src, index))) {
 continue;
 }

 AST_RWLIST_RDLOCK(&translators);
 check_translation_path(dest, src, result,
 cur_src, AST_MEDIA_TYPE_AUDIO);
 check_translation_path(dest, src, result,
 cur_src, AST_MEDIA_TYPE_VIDEO);
 AST_RWLIST_UNLOCK(&translators);
 ao2_ref(cur_src, -1);
 }
}

static void translate_shutdown(void)
{
 int x;
 ast_cli_unregister_multiple(cli_translate, ARRAY_LEN(cli_translate));

 ast_rwlock_wrlock(&tablelock);
 for (x = 0; x < index_size; x++) {
 ast_free(__matrix[x]);
 }
 ast_free(__matrix);
 __matrix = NULL;
 ast_free(__indextable);
 __indextable = NULL;
 ast_rwlock_unlock(&tablelock);
 ast_rwlock_destroy(&tablelock);
}

int ast_translate_init(void)
{
 int res = 0;
 ast_rwlock_init(&tablelock);
 res = matrix_resize(1);
 res |= ast_cli_register_multiple(cli_translate, ARRAY_LEN(cli_translate));
 ast_register_cleanup(translate_shutdown);
 return res;
}