format_pref.c

Go to the documentation of this file.

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2010, Digium, Inc.
 *
 * Mark Spencer <markster@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 Format Preference API
 */

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

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 384163 $");

#include "asterisk/_private.h"
#include "asterisk/frame.h"
#include "asterisk/channel.h"
#include "asterisk/utils.h"

void ast_codec_pref_convert(struct ast_codec_pref *pref, char *buf, size_t size, int right)
{
   size_t f_len;
   const struct ast_format_list *f_list = ast_format_list_get(&f_len);
   int x, differential = (int) 'A', mem;
   char *from, *to;

   /* TODO re-evaluate this function.  It is using the order of the formats specified
    * in the global format list in a way that may not be safe. */
   if (right) {
      from = pref->order;
      to = buf;
      mem = size;
   } else {
      to = pref->order;
      from = buf;
      mem = AST_CODEC_PREF_SIZE;
   }

   memset(to, 0, mem);
   for (x = 0; x < AST_CODEC_PREF_SIZE; x++) {
      if (!from[x]) {
         break;
      }
      to[x] = right ? (from[x] + differential) : (from[x] - differential);
      if (!right && to[x] && (to[x] < f_len)) {
         ast_format_copy(&pref->formats[x], &f_list[to[x]-1].format);
      }
   }
   ast_format_list_destroy(f_list);
}

int ast_codec_pref_string(struct ast_codec_pref *pref, char *buf, size_t size)
{
   int x;
   struct ast_format format;
   size_t total_len, slen;
   const char *formatname;

   memset(buf, 0, size);
   total_len = size;
   buf[0] = '(';
   total_len--;
   for (x = 0; x < AST_CODEC_PREF_SIZE; x++) {
      if (total_len <= 0)
         break;
      if (!(ast_codec_pref_index(pref, x, &format)))
         break;
      if ((formatname = ast_getformatname(&format))) {
         slen = strlen(formatname);
         if (slen > total_len)
            break;
         strncat(buf, formatname, total_len - 1); /* safe */
         total_len -= slen;
      }
      if (total_len && x < AST_CODEC_PREF_SIZE - 1 && ast_codec_pref_index(pref, x + 1, &format)) {
         strncat(buf, "|", total_len - 1); /* safe */
         total_len--;
      }
   }
   if (total_len) {
      strncat(buf, ")", total_len - 1); /* safe */
      total_len--;
   }

   return size - total_len;
}

struct ast_format *ast_codec_pref_index(struct ast_codec_pref *pref, int idx, struct ast_format *result)
{
   if ((idx >= 0) && (idx < sizeof(pref->order)) && pref->formats[idx].id) {
      ast_format_copy(result, &pref->formats[idx]);
   } else {
      ast_format_clear(result);
      return NULL;
   }

   return result;
}

/*! \brief Remove codec from pref list */
void ast_codec_pref_remove(struct ast_codec_pref *pref, struct ast_format *format)
{
   struct ast_codec_pref oldorder;
   int x, y = 0;
   size_t f_len = 0;
   const struct ast_format_list *f_list;

   if (!pref->order[0]) {
      return;
   }

   f_list = ast_format_list_get(&f_len);
   memcpy(&oldorder, pref, sizeof(oldorder));
   memset(pref, 0, sizeof(*pref));

   for (x = 0; x < f_len; x++) {
      if (!oldorder.order[x]) {
         break;
      }
      if (ast_format_cmp(&f_list[oldorder.order[x]-1].format, format) == AST_FORMAT_CMP_NOT_EQUAL) {
         pref->order[y] = oldorder.order[x];
         ast_format_copy(&pref->formats[y], &oldorder.formats[x]);
         pref->framing[y++] = oldorder.framing[x];
      }
   }
   ast_format_list_destroy(f_list);
}

/*! \brief Append codec to list */
int ast_codec_pref_append(struct ast_codec_pref *pref, struct ast_format *format)
{
   int x, newindex = 0;
   size_t f_len = 0;
   const struct ast_format_list *f_list = ast_format_list_get(&f_len);

   ast_codec_pref_remove(pref, format);

   for (x = 0; x < f_len; x++) {
      if (ast_format_cmp(&f_list[x].format, format) == AST_FORMAT_CMP_EQUAL) {
         newindex = x + 1;
         break;
      }
   }

   if (newindex) {
      for (x = 0; x < f_len; x++) {
         if (!pref->order[x]) {
            pref->order[x] = newindex;
            ast_format_copy(&pref->formats[x], format);
            break;
         }
      }
   }

   ast_format_list_destroy(f_list);
   return x;
}

/*! \brief Prepend codec to list */
void ast_codec_pref_prepend(struct ast_codec_pref *pref, struct ast_format *format, int only_if_existing)
{
   int x, newindex = 0;
   size_t f_len = 0;
   const struct ast_format_list *f_list = ast_format_list_get(&f_len);

   /* First step is to get the codecs "index number" */
   for (x = 0; x < f_len; x++) {
      if (ast_format_cmp(&f_list[x].format, format) == AST_FORMAT_CMP_EQUAL) {
         newindex = x + 1;
         break;
      }
   }
   /* Done if its unknown */
   if (!newindex) {
      ast_format_list_destroy(f_list);
      return;
   }

   /* Now find any existing occurrence, or the end */
   for (x = 0; x < AST_CODEC_PREF_SIZE; x++) {
      if (!pref->order[x] || pref->order[x] == newindex)
         break;
   }

   /* If we failed to find any occurrence, set to the end */
   if (x == AST_CODEC_PREF_SIZE) {
      --x;
   }

   if (only_if_existing && !pref->order[x]) {
      ast_format_list_destroy(f_list);
      return;
   }

   /* Move down to make space to insert - either all the way to the end,
      or as far as the existing location (which will be overwritten) */
   for (; x > 0; x--) {
      pref->order[x] = pref->order[x - 1];
      pref->framing[x] = pref->framing[x - 1];
      ast_format_copy(&pref->formats[x], &pref->formats[x - 1]);
   }

   /* And insert the new entry */
   pref->order[0] = newindex;
   pref->framing[0] = 0; /* ? */
   ast_format_copy(&pref->formats[0], format);
   ast_format_list_destroy(f_list);
}

/*! \brief Set packet size for codec */
int ast_codec_pref_setsize(struct ast_codec_pref *pref, struct ast_format *format, int framems)
{
   int x, idx = -1;
   size_t f_len = 0;
   const struct ast_format_list *f_list = ast_format_list_get(&f_len);

   for (x = 0; x < f_len; x++) {
      if (ast_format_cmp(&f_list[x].format, format) == AST_FORMAT_CMP_EQUAL) {
         idx = x;
         break;
      }
   }

   if (idx < 0) {
      ast_format_list_destroy(f_list);
      return -1;
   }

   /* size validation */
   if (!framems)
      framems = f_list[idx].def_ms;

   if (f_list[idx].inc_ms && framems % f_list[idx].inc_ms) /* avoid division by zero */
      framems -= framems % f_list[idx].inc_ms;

   if (framems < f_list[idx].min_ms)
      framems = f_list[idx].min_ms;

   if (framems > f_list[idx].max_ms)
      framems = f_list[idx].max_ms;

   for (x = 0; x < f_len; x++) {
      if (pref->order[x] == (idx + 1)) {
         pref->framing[x] = framems;
         break;
      }
   }

   ast_format_list_destroy(f_list);
   return x;
}

/*! \brief Get packet size for codec */
struct ast_format_list ast_codec_pref_getsize(struct ast_codec_pref *pref, struct ast_format *format)
{
   int x, idx = -1, framems = 0;
   struct ast_format_list fmt = { { 0, }, };
   size_t f_len = 0;
   const struct ast_format_list *f_list = ast_format_list_get(&f_len);

   for (x = 0; x < f_len; x++) {
      if (ast_format_cmp(&f_list[x].format, format) == AST_FORMAT_CMP_EQUAL) {
         fmt = f_list[x];
         idx = x;
         break;
      }
   }

   if (idx < 0) {
      ast_log(AST_LOG_WARNING, "Format %s unknown; unable to get preferred codec packet size\n", ast_getformatname(format));
      ast_format_list_destroy(f_list);
      return fmt;
   }

   for (x = 0; x < f_len; x++) {
      if (pref->order[x] == (idx + 1)) {
         framems = pref->framing[x];
         break;
      }
   }

   /* size validation */
   if (!framems)
      framems = f_list[idx].def_ms;

   if (f_list[idx].inc_ms && framems % f_list[idx].inc_ms) /* avoid division by zero */
      framems -= framems % f_list[idx].inc_ms;

   if (framems < f_list[idx].min_ms)
      framems = f_list[idx].min_ms;

   if (framems > f_list[idx].max_ms)
      framems = f_list[idx].max_ms;

   fmt.cur_ms = framems;
   ast_format_list_destroy(f_list);
   return fmt;
}

/*! \brief Pick a codec */
struct ast_format *ast_codec_choose(struct ast_codec_pref *pref, struct ast_format_cap *cap, int find_best, struct ast_format *result)
{
   int x, slot, found = 0;
   size_t f_len = 0;
   const struct ast_format_list *f_list = ast_format_list_get(&f_len);

   for (x = 0; x < f_len; x++) {
      slot = pref->order[x];

      if (!slot)
         break;
      if (ast_format_cap_get_compatible_format(cap, &f_list[slot-1].format, result)) {
         found = 1; /*format is found and stored in result */
         break;
      }
   }
   ast_format_list_destroy(f_list);
   if (found && (AST_FORMAT_GET_TYPE(result->id) == AST_FORMAT_TYPE_AUDIO)) {
      return result;
   }
   ast_format_clear(result);
   ast_debug(4, "Could not find preferred codec - %s\n", find_best ? "Going for the best codec" : "Returning zero codec");

   return find_best ? ast_best_codec(cap, result) : NULL;
}